CN119815803A

CN119815803A - Inverter and speed regulation method of cooling fan thereof, and photovoltaic system

Info

Publication number: CN119815803A
Application number: CN202510081323.6A
Authority: CN
Inventors: 李俊杰; 辛凯; 于心宇
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2025-04-11
Also published as: CN115119474A; CN115119474B

Abstract

The present application provides an inverter and a speed regulation method for its cooling fan, as well as a photovoltaic system, wherein the inverter includes a controller, a power module, an input port and an output port, a temperature detection device, and at least one cooling fan. The temperature detection device is used to detect a first temperature when the power module outputs a first signal and a second temperature when the power module outputs a second signal, and the detection time of the first temperature is before the detection time of the second temperature. Furthermore, the controller is used to: adjust the target fan duty cycle according to the second signal, the change between the first signal and the second signal, the second temperature, and the change between the first temperature and the second temperature, so as to quickly control the speed of each cooling fan in at least one cooling fan, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module, effectively suppressing the temperature cycle of the power module, improving the safety and reliability of the power module, and having strong applicability.

Description

Inverter, speed regulating method of cooling fan of inverter and photovoltaic system

The present application is a divisional application, the application number of which is 202210645675.6, the application date of which is 2022, month 06 and 09, and the entire contents of which are incorporated herein by reference.

Technical Field

The application relates to the technical field of electronic power, in particular to an inverter, a speed regulating method of a cooling fan of the inverter and a photovoltaic system.

Background

In order to ensure that the inverter runs safely and reliably, a fan in the inverter can cool and dissipate heat generated by the power module so that the temperature of the power module is smaller than the safe allowable junction temperature, and therefore the normal operation of the power module is ensured. In the process of cooling and radiating the heat generated by the power module, the temperature circulation of the power module can be restrained by adjusting the rotating speed of the fan, so that the safety and the reliability of the power module are improved.

In the prior art, the start-stop temperature point of the fan is adjusted according to the running state of the inverter to dynamically fit the rotating speed curve of the fan, and the rotating speed of the fan is adjusted according to the rotating speed curve to quickly cool the power module, so that the safe running of the power module is ensured. However, under the condition that the power of the inverter suddenly changes (or the power frequently changes), the fan is frequently started and stopped to increase the temperature cycle times and the temperature cycle amplitude of the power module, so that the temperature cycle of the power module cannot be effectively restrained, the safety of the power module is poor, and the applicability is poor.

Disclosure of Invention

The application provides an inverter, a speed regulating method of a cooling fan of the inverter and a photovoltaic system, which can reduce the temperature cycle times and the temperature cycle amplitude of a power module, and effectively inhibit the temperature cycle of the power module, thereby improving the safety and the reliability of the power module and having strong applicability.

In a first aspect, the present application provides an inverter, where the inverter includes a controller, a power module, an input port, an output port, a temperature detecting device, and at least one cooling fan, where the power module and the at least one cooling fan may form a cooling system in the inverter, and the at least one cooling fan refers to one or more cooling fans. The input port is used for receiving a direct current input signal, and the output port is used for outputting a first signal and a second signal. The power module is configured to perform ac-dc conversion on a dc input signal to output a first signal or a second signal, where each of the first signal and the second signal may include, but is not limited to, an output power or an output current. At this time, the temperature detection device is used for detecting a first temperature when the power module outputs a first signal and a second temperature when the power module outputs a second signal, so that the instantaneity and the accuracy of temperature sampling are guaranteed. Wherein the detection time of the first temperature is before the detection time of the second temperature. Further, the controller is used for adjusting the duty ratio of the target fan according to the second signal, the variation between the first signal and the second signal, the second temperature and the variation between the first temperature and the second temperature so as to control the rotating speed of each cooling fan in at least one cooling fan. At this time, the cooling fans are operated at the rotation speeds of the cooling fans to cool the power module.

In the application, the first signal, the second signal, the first temperature and the second temperature are all real-time detection data, namely, the variation between the first signal and the second signal and the variation between the first temperature and the second temperature are real-time variation, so that the controller can dynamically adjust the duty ratio of the target fan according to the real-time detection data and the real-time variation to rapidly control the rotating speed of each cooling fan, the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, the temperature cycle of the power module is effectively restrained, and the safety of the power module is improved.

With reference to the first aspect, in a first possible implementation manner, the inverter further includes a power board and a radiator, where the power board is used to carry the power module, and the radiator is used to radiate heat from the power module. The first temperature or the second temperature includes a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

With reference to the first aspect or the first possible implementation manner of the first aspect, in a second possible implementation manner, the variation between the first signal and the second signal includes at least one of a difference value, a variation rate, a variation direction, and a time difference value between the first signal and the second signal. The amount of change between the first temperature and the second temperature includes at least one of a difference between the first temperature and the second temperature, a rate of change, a direction of change, and a detection time difference.

With reference to any one of the first aspect to the second possible implementation manner of the first aspect, in a third possible implementation manner, in adjusting the target fan duty cycle, the controller is configured to obtain a first duty cycle parameter based on the second temperature and the second signal, where the first duty cycle parameter is a steady state adjustment amount reflecting the rotational speed of the fan. The controller may further obtain a second duty cycle parameter based on an amount of change between the first signal and the second signal, and obtain a third duty cycle parameter based on an amount of change between the first temperature and the second temperature. The second duty ratio parameter is a dynamic adjustment quantity reflecting the rotating speed of the fan, so that the influence of illumination and load mutation on the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, and the temperature cycle times and the temperature cycle amplitude of the power module can be reduced. The third duty ratio parameter is a dynamic adjustment quantity reflecting the rotation speed of the fan, and can reduce the influence of the start and stop of the cooling fan and the ambient temperature on the temperature cycle times and the temperature cycle amplitude of the power module, thereby reducing the temperature cycle amplitude of the power module in a power fluctuation scene, i.e. avoiding the temperature cycle amplitude of the power module in the power fluctuation scene from greatly fluctuating.

Further, the controller may further adjust the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter. Because the first duty ratio parameter is a steady-state adjustment quantity reflecting the fan rotating speed, and the second duty ratio parameter and the third duty ratio parameter are dynamic adjustment quantities reflecting the fan rotating speed, the target fan duty ratio can reflect the steady-state adjustment quantity and the dynamic adjustment quantity of the fan rotating speed at the same time, the accuracy of the target fan duty ratio is improved, the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, and therefore the temperature cycle of the power module is effectively restrained, and the safety of the power module is improved.

With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner, the controller is configured to obtain a weighting coefficient of each of the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter, and adjust the target fan duty cycle based on each of the duty cycle parameters and the weighting coefficient thereof. The weighting coefficient is greater than or equal to 0 and less than or equal to 1, and the weighting coefficient can be preset parameters set by an inverter in a factory, parameters set by a user or parameters dynamically adjusted according to specific working conditions of the inverter. It can be understood that the controller realizes flexible control of the parameter proportion of each duty ratio through the weighting coefficient, thereby reducing the temperature cycle times and the temperature cycle amplitude of the power module and improving the safety of the power module.

With reference to any one of the first aspect to the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner, after adjusting the target fan duty cycle, the controller is configured to control a rotation speed of a part of the at least one cooling fan to be 0 and a rotation speed of another part of the at least one cooling fan to be the first rotation speed if the target fan duty cycle is less than a preset duty cycle threshold. The number of the other part of the cooling fans and the first rotating speed are determined by the second temperature and the second signal, the first rotating speed is smaller than a preset rotating speed threshold value, the number of the other part of the cooling fans can be understood as the running number of the cooling fans, and the first rotating speed can be understood as the running rotating speed of the cooling fans. The preset rotation speed threshold here refers to a maximum rotation speed value of the cooling fan in a low speed section. When the rotation speed of one part of the cooling fans is 0, one part of the cooling fans can be obtained to not run, and when the rotation speed of the other part of the cooling fans is the first rotation speed, the other part of the cooling fans can be obtained to run in a low-speed section. It can be understood that, under the condition that the duty ratio of the target fan is smaller than the preset duty ratio threshold, the controller can flexibly control the running number and the running rotating speed of the cooling fans in the low-speed section, so that the cooling efficiency range of the cooling system in the inverter can be expanded, the temperature cycle times of the power module are effectively restrained, the loss of the inverter is greatly reduced, and the applicability is stronger.

The controller is further configured to control a rotational speed of at least one cooling fan to be a second rotational speed based on the target fan duty ratio when the target fan duty ratio is greater than or equal to a preset duty ratio threshold. The second rotating speed is greater than the first rotating speed, and the second rotating speed refers to any rotating speed value of the cooling fan running in the high-speed section. It can be understood that, when the duty ratio of the target fan is greater than or equal to the preset duty ratio threshold, the controller can control all the cooling fans to run simultaneously so as to quickly cool the power module, thereby improving the cooling efficiency of the inverter and having strong applicability. In summary, the controller may compare the duty ratio of the target fan with the preset duty ratio threshold, and flexibly control at least one cooling fan to operate in the low-speed section or the high-speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency, and having stronger applicability.

In a second aspect, the present application provides a method for adjusting a speed of a radiator fan of an inverter, the method being applicable to a controller in the inverter, the inverter further comprising a power module and at least one radiator fan. In the method, the controller can detect the first temperature when the power module outputs the first signal and the second temperature when the power module outputs the second signal, so that the instantaneity and the accuracy of temperature sampling are ensured. Wherein each of the first signal and the second signal may include, but is not limited to, an output power or an output current, the detection time of the first temperature being before the detection time of the second temperature. Further, the controller may adjust the target fan duty ratio according to the second signal, the amount of change between the first signal and the second signal, the second temperature, and the amount of change between the first temperature and the second temperature to control the rotational speed of each of the at least one cooling fan.

With reference to the second aspect, in a first possible implementation manner, the inverter further includes a power board and a heat radiator, where the power board is used to carry the power module, and the heat radiator is used to dissipate heat from the power module. The first temperature or the second temperature includes a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

With reference to the second aspect or the first possible implementation manner of the second aspect, in a second possible implementation manner, the variation between the first signal and the second signal includes at least one of a difference value, a variation rate, a variation direction, and a time difference value between the first signal and the second signal. The amount of change between the first temperature and the second temperature includes at least one of a difference between the first temperature and the second temperature, a rate of change, a direction of change, and a detection time difference.

With reference to any one of the second aspect to the second possible implementation manner of the second aspect, in a third possible implementation manner, in adjusting the target fan duty cycle, the controller is configured to obtain a first duty cycle parameter based on the second temperature and the second signal, where the first duty cycle parameter is a steady state adjustment amount reflecting the rotational speed of the fan. The controller may further obtain a second duty cycle parameter based on an amount of change between the first signal and the second signal, and obtain a third duty cycle parameter based on an amount of change between the first temperature and the second temperature. The second duty ratio parameter is a dynamic adjustment quantity reflecting the rotating speed of the fan, so that the influence of illumination and load mutation on the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, the third duty ratio parameter is a dynamic adjustment quantity reflecting the rotating speed of the fan, the influence of the start and stop of the cooling fan and the environmental temperature on the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, and the temperature cycle amplitude of the power module in a power fluctuation scene can be reduced, namely, the temperature cycle amplitude of the power module in the power fluctuation scene is prevented from greatly fluctuating.

With reference to the third possible implementation manner of the second aspect, in a fourth possible implementation manner, the controller may obtain a weighting coefficient of each of the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter, and adjust the target fan duty cycle based on each of the duty cycle parameters and the weighting coefficient thereof. The weighting coefficient of any one duty ratio parameter is greater than or equal to 0 and less than or equal to 1, and the weighting coefficient can be preset parameters set by an inverter in a factory, parameters set by a user or parameters dynamically adjusted according to specific working conditions of the inverter. It can be understood that the controller realizes flexible control of the parameter proportion of each duty ratio through the weighting coefficient, thereby reducing the temperature cycle times and the temperature cycle amplitude of the power module and improving the safety of the power module.

With reference to any one of the second aspect to the fourth possible implementation manner of the second aspect, in a fifth possible implementation manner, after adjusting the target fan duty cycle, the controller controls the rotation speed of a part of the at least one cooling fan to be 0 and the rotation speed of another part of the at least one cooling fan to be the first rotation speed if the target fan duty cycle is smaller than a preset duty cycle threshold. The number of the other part of the cooling fans and the first rotating speed are determined by the second temperature and the second signal, the first rotating speed is smaller than a preset rotating speed threshold value, the number of the other part of the cooling fans can be understood as the running number of the cooling fans, and the first rotating speed can be understood as the running rotating speed of the cooling fans. The preset rotation speed threshold here refers to a maximum rotation speed value of the cooling fan in a low speed section. When the rotation speed of one part of the cooling fans is 0, one part of the cooling fans can be obtained to not run, and when the rotation speed of the other part of the cooling fans is the first rotation speed, the other part of the cooling fans can be obtained to run in a low-speed section. It can be understood that, when the duty ratio of the target fan is smaller than the preset duty ratio threshold, the controller can flexibly control the operation number and the operation rotation speed of the cooling fan in the low-speed section, for example, flexibly control different operation number combinations and different operation rotation speed combinations, so that the cooling efficiency range of the cooling system in the inverter can be expanded, that is, the equivalent efficiency adjusting range of the cooling system is improved, thereby effectively inhibiting the temperature cycle times of the power module, greatly reducing the loss of the inverter, and having stronger applicability.

The controller may further control the rotational speed of the at least one cooling fan to be the second rotational speed based on the target fan duty ratio when the target fan duty ratio is greater than or equal to a preset duty ratio threshold. The second rotating speed is greater than the first rotating speed, and the second rotating speed refers to any rotating speed value of the cooling fan running in the high-speed section. It can be understood that, when the duty ratio of the target fan is greater than or equal to the preset duty ratio threshold, the controller can control all the cooling fans to run simultaneously so as to quickly cool the power module, thereby improving the cooling efficiency of the inverter and having strong applicability. In summary, the controller may compare the duty ratio of the target fan with the preset duty ratio threshold, and flexibly control at least one cooling fan to operate in the low-speed section or the high-speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency, and having stronger applicability.

In a third aspect, the present application provides a photovoltaic system comprising a photovoltaic array and an inverter as provided in any one of the above first to fifth possible embodiments of the first aspect connected to the photovoltaic array, and wherein an output of the inverter may be connected to an ac power grid, wherein the connection comprises a direct connection or an indirect connection. In the process of supplying power to the ac power grid, the inverter may convert the dc voltage provided by the photovoltaic array into an ac voltage and supply power to the ac power grid based on the ac voltage. Under the condition that the inverter comprises the heat radiation system and the controller, the controller can detect the health state of the heat radiation system in real time to ensure the reliable operation of the inverter, so that the power supply reliability and the power supply safety of the inverter are higher, the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is strong.

With reference to the third aspect, in a first possible implementation manner, the above photovoltaic system further includes a dc combiner box, and the photovoltaic array may be connected to an input end of the inverter through the dc combiner box, and an output end of the inverter may be connected (e.g., directly connected or indirectly connected) to an ac power grid. In the process of supplying power to the alternating current power grid, the direct current combiner box can combine direct current voltages provided by each photovoltaic group string in the photovoltaic array and output the direct current voltages to the inverter, and at the moment, the inverter (such as a centralized photovoltaic inverter) can supply power to the alternating current power grid based on the combined direct current voltages. In the power supply process, the power supply reliability and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner, the photovoltaic system further includes a box-type transformer, and an output end of the inverter may be connected to an ac power grid through the box-type transformer. In the process of supplying power to the alternating current power grid, the direct current combiner box can combine direct current voltages provided by each photovoltaic group string in the photovoltaic array and output the direct current voltages to the inverter, and at the moment, the inverter (such as a centralized photovoltaic inverter) can supply power to the alternating current power grid based on the combined direct current voltages. In the power supply process, the power supply reliability and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

With reference to the third aspect, in a third possible implementation manner, the photovoltaic system further includes an ac combiner box, where the photovoltaic array may be connected to an input end of the ac combiner box through an inverter, and an output end of the ac combiner box may be connected (e.g., directly connected or indirectly connected) to an ac power grid. In the process of supplying power to the alternating current power grid, the inverter can provide alternating current voltage to the alternating current junction box based on direct current provided by the photovoltaic array, and the alternating current junction box can supply power to the alternating current power grid by the alternating current voltage input by the inverter (such as a string type photovoltaic inverter). In the power supply process, the power supply reliability and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

With reference to the third possible implementation manner of the third aspect, in a fourth possible implementation manner, the photovoltaic system further includes a box-type transformer, and an output end of the ac combiner box may be connected to an ac power grid through the box-type transformer. In the process of supplying power to an alternating current power grid, an alternating current combiner box can combine alternating current voltages input by an inverter (such as a string type photovoltaic inverter) and output the combined alternating current voltages to a box-type transformer, and at the moment, the box-type transformer can supply power to the alternating current power grid based on the combined alternating current voltages. In the power supply process, the power supply reliability and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

With reference to the third aspect, in a fifth possible implementation manner, the photovoltaic system further includes a Direct Current (DC)/DC converter and a direct current bus, where the photovoltaic array may be connected to an input end of the inverter through the DC/DC converter and the direct current bus, and an output end of the inverter may be connected to an ac power grid. In the process of supplying power to the alternating current power grid, the DC/DC converter can convert the direct current voltage provided by the photovoltaic array into a target direct current voltage, and output the target direct current voltage to the inverter through the direct current bus. At this time, the inverter may convert the target direct-current voltage into an alternating-current voltage and supply the alternating-current grid with power based on the alternating-current voltage. In the power supply process, the power supply reliability and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

In the application, the controller can dynamically adjust the duty ratio of the target fan according to the second signal, the variation between the first signal and the second signal, the second temperature and the variation between the first temperature and the second temperature so as to rapidly control the rotating speed of each cooling fan, and the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, thereby improving the safety of the power module, in addition, the service life damage of the power module is reduced, and the reliability of the power module is improved. Further, the controller can compare the duty ratio of the target fan with a preset duty ratio threshold value, and flexibly control at least one cooling fan to run in a low-speed section or a high-speed section according to a comparison result, so that the working range of the cooling system can be widened to improve the cooling efficiency, and the applicability is stronger.

Drawings

Fig. 1 is a schematic diagram of an application scenario of an inverter provided by the present application;

Fig. 2 is a schematic structural diagram of an inverter according to the present application;

FIG. 3A is a schematic diagram showing an effect of suppressing temperature cycling of a power module according to the present application;

FIG. 3B is a schematic diagram showing another effect of suppressing temperature cycling of the power module according to the present application;

fig. 4 is another schematic structural diagram of an inverter provided by the present application;

FIG. 5 is a schematic view of a photovoltaic system according to the present application;

FIG. 6 is another schematic structural view of the photovoltaic system provided by the present application;

FIG. 7 is another schematic view of the photovoltaic system provided by the present application;

FIG. 8 is another schematic structural view of the photovoltaic system provided by the present application;

Fig. 9 is a schematic flow chart of a speed regulation method of an inverter radiator fan according to the present application;

Fig. 10 is another flow chart of the speed regulating method of the inverter cooling fan provided by the application.

Detailed Description

The inverter (an alternating current-direct current converter) provided by the application is suitable for various application fields such as a new energy intelligent micro-grid field, a power transmission-distribution field or a new energy field (such as a photovoltaic grid-connected field or a wind power grid-connected field), a photovoltaic power generation field (such as a photovoltaic inverter), a wind power generation field, a high-power converter field (such as converting direct current voltage into high-power high-voltage alternating current), or an electric equipment field (such as various electric equipment) and the like, and can be specifically determined according to practical application scenes, and the inverter is not limited herein.

The inverter provided by the application can be suitable for high-power inverter application scenes and medium-low-power inverter application scenes, such as a photovoltaic power supply application scene, a wind power grid-connected power supply scene, an electric automobile charging scene or other application scenes, and the photovoltaic power supply application scene is taken as an example for illustration and is not repeated. Referring to fig. 1, fig. 1 is a schematic diagram of an application scenario of an inverter provided by the present application. As shown in fig. 1, the photovoltaic system includes a photovoltaic array, a DC/DC converter, a positive DC bus, a negative DC bus, and an inverter, where the photovoltaic array may be connected to an input end of the DC/DC converter, an output end of the DC/DC converter may be connected to an input end of the inverter through the positive DC bus and the negative DC bus, and an output end of the inverter may be used to connect to a power grid. The photovoltaic array may be formed by connecting a plurality of photovoltaic strings in series and parallel, wherein one photovoltaic string may include a plurality of photovoltaic modules (may also be called solar panels or photovoltaic panels), and the inverter includes a power module and n heat dissipation fans. In the process of supplying power to the alternating current power grid by the photovoltaic system, the DC/DC converter can output target direct current voltage to the inverter based on direct current provided by the photovoltaic array, and at the moment, the power module in the inverter can perform alternating current-direct current conversion on the target direct current voltage, so that the output alternating current voltage supplies power to the alternating current power grid.

In this power supply process, since the n heat dissipation fans cool and dissipate heat generated by the power module, accurate control of the rotational speeds of the n heat dissipation fans is particularly important. In controlling the rotational speeds of the n cooling fans, a controller (not shown) in the inverter may detect a first temperature when the power module outputs a first signal and a second temperature when the power module outputs a second signal, wherein each of the first signal and the second signal includes an output power or an output current, and a detection time of the first temperature is before a detection time of the second temperature. Further, the controller can adjust the duty ratio of the target fan according to the second signal, the variation between the first signal and the second signal and the variation between the first temperature and the second temperature so as to rapidly control the rotating speed of each cooling fan in the n cooling fans, and can reduce the temperature cycle times (which can be simply called as the temperature cycle times) and the temperature cycle amplitude (which can also be called as the temperature fluctuation amplitude) of the power module, thereby effectively inhibiting the temperature cycle of the power module so as to improve the safety and the reliability of the power module, further improving the power supply reliability and the power supply safety of the inverter, and having strong applicability.

The inverter, the photovoltaic system and the working principle thereof provided by the application are exemplified below with reference to fig. 2 to 8.

Referring to fig. 2, fig. 2 is a schematic structural diagram of an inverter provided by the present application. As shown in fig. 2, the inverter 1 includes a controller 10, a power module 11, input and output ports 12 and 13, a temperature detecting device 14, and at least one heat dissipating fan (i.e., one or more heat dissipating fans such as heat dissipating fans 15a to 15 n), and the power module 11 and the heat dissipating fans 15a to 15n may constitute a heat dissipating system in the inverter 1. The input port 12 is used to receive a dc input signal, which may be provided by the photovoltaic array of fig. 1, for example. The output port is for outputting a first signal and a second signal, wherein the first signal and the second signal may be provided by the power module 11.

In some possible embodiments, the power module 11 refers to a functional module integrated with core power electronic switching devices (such as semiconductor switching devices) inside the inverter 1. Among them, the above semiconductor switching devices include, but are not limited to, insulated gate bipolar transistors (i nsu L ATED GATE b i po L AR TRANS I stor, which may be abbreviated as IGBTs), metal oxide semiconductor field effect transistors (meta-oxide-semiconductor f ie l d-EFFECT TRANS I stor, which may be abbreviated as MOSFETs), and other types of switching devices. And, the above-mentioned semiconductor switching device may be made of silicon semiconductor material S i, or silicon carbide S iC of third generation wide bandgap semiconductor material, or gallium nitride GaN, or diamond, or zinc oxide ZnO, or other materials, and the specific type of the switching device may be determined by the actual circuit topology and the actual operation requirement of the inverter 1, which is not limited herein. The power module 11 may perform ac-dc conversion on the dc input signal to output the first signal or the second signal. Wherein each of the first and second signals includes, but is not limited to, an output power or an output current, which may be understood as an output signal of the power module 11.

In some possible embodiments, the temperature detection device 14 may be disposed outside the controller 10, alternatively, the temperature detection device 14 may be disposed within the controller 10. The temperature detecting device 14 includes, but is not limited to, at least one of a thermocouple, a positive temperature coefficient (pos it ive temperature coeff ic ient, PTC) thermistor, a negative temperature coefficient (negat ive temperature coeff ic ient, NTC) thermistor, a silicon resistance temperature sensor, and a I C temperature sensor, wherein the positive temperature coefficient thermistor may be simply referred to as a PTC thermistor, and the negative temperature coefficient thermistor may be simply referred to as an NTC thermistor.

In some possible embodiments, the temperature detecting device 14 may detect a first temperature when the power module 11 outputs the first signal and a second temperature when the power module 11 outputs the second signal, so as to ensure real-time performance and accuracy of temperature detection. Wherein the detection time of the first temperature is before the detection time of the second temperature. In an embodiment, the inverter 1 further comprises a power board for carrying the power module 11 and a heat sink for dissipating heat from the power module 11, which are not shown in fig. 2. The above-described first temperature or second temperature may be understood as a temperature of the power module 11, and the first temperature or second temperature includes, but is not limited to, a temperature of the power module 11, an internal air temperature of the inverter 1, a temperature of the power board, or a temperature of the heat sink. The temperature detection device 14 may establish wired or wireless communication with the controller 10 to transmit temperature data, including, for example, a first temperature and a second temperature. For convenience of description, the first temperature or the second temperature including the temperature of the power module 11 will be described as an example, and will not be described in detail. At this time, the second signal is the current output signal of the power module 11, and the second temperature is the current temperature of the power module 11.

In some possible embodiments, the controller 10 adjusts the target fan duty ratio according to the second signal, the amount of change between the first signal and the second signal, and the amount of change between the first temperature and the second temperature to control the rotation speed of each of the heat dissipating fans 15a to 15 n. At this time, each heat radiation fan is operated at the rotation speed of each heat radiation fan to radiate heat from the power module 11. Because the first signal, the second signal, the first temperature and the second temperature are all real-time detection data, namely the variation between the first signal and the second signal and the variation between the first temperature and the second temperature are real-time variation, the controller 10 can dynamically adjust the duty ratio of the target fan according to the real-time detection data and the real-time variation so as to quickly control the rotating speed of each cooling fan, the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, the temperature cycle of the power module is effectively restrained, and the safety of the power module is improved. The temperature cycle here can be understood as an environmental temperature cycle of the inverter 1 at different time scales where different natural environments exist.

In some possible embodiments, the amount of change between the first temperature and the second temperature includes at least one of a difference between the first temperature and the second temperature, a rate of change, a direction of change, and a time difference. Wherein the rate of change is the ratio between the difference between the first temperature and the second temperature and the difference in detection time. The direction of change is a temperature change trend of the power module 11, and the direction of change includes a positive increase or a negative decrease. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and the detection time difference is larger than 0. In the case where the first temperature is greater than the second temperature, the difference and the change rate between the first temperature and the second temperature are less than 0, and the change direction between the first temperature and the second temperature is decreased in the negative direction, that is, the temperature change trend of the power module 11 is decreased in the negative direction. In the case where the first temperature is smaller than the second temperature, it is possible to obtain a difference and a change rate between the first temperature and the second temperature greater than 0, the change direction between the first temperature and the second temperature being a positive increase, i.e., the temperature change trend of the power module 11 being a positive increase.

In some possible embodiments, the amount of change between the first signal and the second signal includes, but is not limited to, at least one of a difference between the first signal and the second signal, a rate of change, a direction of change, a time difference. Wherein the rate of change is the ratio between the difference between the first signal and the second signal and the time difference. The change direction is an output change trend of the power module 11, the change direction includes positive increase or negative decrease, the output change trend of the power module 11 is a power change trend in the case that each of the first signal and the second signal is output power, and the output change trend of the power module 11 is a current change trend in the case that each of the first signal and the second signal is output current. The time difference is the difference between the detection time of the first signal and the detection time of the second signal, and the time difference is greater than 0. In the case where the first signal is larger than the second signal, the difference and the change rate between the first signal and the second signal are smaller than 0, and the change direction between the first signal and the second signal is decreased in the negative direction, that is, the output change trend of the power module 11 is decreased in the negative direction. In the case where the first signal is smaller than the second signal, the difference and the change rate between the first signal and the second signal are greater than 0, and the change direction between the first signal and the second signal is a positive increase, that is, the output change trend of the power module 11 is a positive increase.

In some possible embodiments, the controller 10 may detect the operation state of the inverter 1 in real time, where detecting the operation state of the inverter 1 in real time includes detecting a first signal and a second signal output by the power module 11 through the output port 13, and detecting a first temperature when the first signal is output by the power module 11 and a second temperature when the second signal is output by the power module 11 from the temperature detection device 14, so that accuracy and instantaneity of temperature detection and output signal detection may be ensured, and applicability is strong.

In some possible embodiments, after detecting the operation state of the inverter 1, the controller 10 may obtain the first duty cycle parameter d ₁ based on the second signal and the second temperature. The first duty ratio parameter d ₁ may be understood as a fan speed control amount, and the first duty ratio parameter d ₁ is a steady-state adjustment amount reflecting the fan speed. Specifically, the controller 10 outputs the first duty ratio parameter d ₁ based on the second temperature and the monotonic mapping relationship between the second signal and the fan rotation speed, that is, the input parameter of the monotonic mapping relationship is the second temperature and the second signal, and the output parameter of the monotonic mapping relationship is the first duty ratio parameter d ₁. The implementation of the monotonic mapping relationship includes, but is not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be represented by an increase in the first duty cycle parameter d ₁ in the case of an increase in the temperature of the power module 11 or an increase in the output signal of the power module 11, and a decrease in the first duty cycle parameter d ₁ in the case of a decrease in the temperature of the power module 11 or a decrease in the output signal of the power module 11.

Optionally, the controller 10 may further obtain a first duty cycle parameter d ₁₁ based on the second signal and another first duty cycle parameter d ₁₂ based on the second temperature, where the first duty cycle parameter d ₁₁ and the first duty cycle parameter d ₁₂ may be understood as fan speed control amounts, and the first duty cycle parameter d ₁₁ is a steady state adjustment amount reflecting the fan speed associated with the second signal, and the first duty cycle parameter d ₁₂ is a steady state adjustment amount reflecting the fan speed associated with the second temperature. For convenience of description, the first duty cycle parameter d ₁ will be described as an example, and will not be described in detail.

In some possible embodiments, the controller 10 obtains the second duty cycle parameter d ₂ based on the amount of change between the first signal and the second signal, and obtains the third duty cycle parameter d ₃ based on the amount of change between the first temperature and the second temperature. The second duty ratio parameter d ₂ may be understood as a fan rotation speed control amount, and the second duty ratio parameter d ₂ is a dynamic adjustment amount reflecting the fan rotation speed, which can reduce the influence of light irradiation and load mutation on the temperature cycle times and the temperature cycle amplitude of the power module 11, thereby reducing the temperature cycle times and the temperature cycle amplitude of the power module 11 and effectively inhibiting the temperature cycle of the power module 11. The third duty ratio parameter d ₃ may be understood as a fan rotation speed control amount, and the third duty ratio parameter d ₃ is a dynamic adjustment amount reflecting the fan rotation speed, so that the influence of the start and stop of the cooling fan and the ambient temperature on the temperature cycle times and the temperature cycle amplitude of the power module 11 can be reduced, and the temperature cycle amplitude of the power module 11 in the power fluctuation scene can be reduced, i.e. the temperature cycle amplitude of the power module 11 in the power fluctuation scene is prevented from greatly fluctuating.

Specifically, the controller 10 may further output the second duty ratio parameter d ₂ based on a monotonic mapping relationship between the variation between the first signal and the second signal and the fan rotation speed, that is, the input parameter of the monotonic mapping relationship is the variation between the first signal and the second signal, and the output parameter of the monotonic mapping relationship is the second duty ratio parameter d ₂. Implementations of the monotonic mapping relationship may include, but are not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be represented by an increase in the second duty cycle parameter d ₂ when the output variation trend of the power module 11 is increasing in the positive direction, and a decrease in the second duty cycle parameter d ₂ when the output variation trend of the power module 11 is decreasing in the negative direction. For example, in the case where the monotonic mapping relationship is a differential formula, the second duty ratio parameter d ₂ is a value obtained by differentiating the amount of change between the first signal and the second signal, and it should be noted that the specific implementation manner of the monotonic mapping relationship may be determined according to the actual application scenario, which is not limited herein.

Further, the controller 10 may further output the third duty ratio parameter d ₃ based on a monotonic mapping relationship between the variation between the first temperature and the second temperature and the fan rotation speed, that is, the input parameter of the monotonic mapping relationship is the variation between the first temperature and the second temperature, and the output parameter of the monotonic mapping relationship is the third duty ratio parameter d ₃. The implementation of the monotonic mapping relationship may include, but is not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be represented by an increase in the third duty cycle parameter d ₃ when the temperature variation trend of the power module 11 is positive, and a decrease in the third duty cycle parameter d ₃ when the temperature variation trend of the power module 11 is negative. For example, in the case where the monotonic mapping relationship is an integral formula, the third duty ratio parameter d ₃ is a value obtained by integrating the amount of change between the first temperature and the second temperature, and it should be noted that the specific implementation manner of the monotonic mapping relationship may be determined according to the actual application scenario, which is not limited herein.

In some possible embodiments, the controller 10 may adjust the target fan duty cycle d _out based on the first duty cycle parameter d ₁, the second duty cycle parameter d ₂, and the third duty cycle parameter d ₃. Because the first duty cycle parameter d ₁ is a steady state adjustment amount reflecting the fan rotation speed, and the second duty cycle parameter d ₂ and the third duty cycle parameter d ₃ are dynamic adjustment amounts reflecting the fan rotation speed, the target fan duty cycle d _out can reflect the steady state adjustment amount and the dynamic adjustment amount of the fan rotation speed at the same time, thereby improving the accuracy of the target fan duty cycle d _out. At this time, the controller 10 controls the rotation speed of each cooling fan based on the target fan duty ratio d _out, so that the number of temperature cycles and the magnitude of the temperature cycles of the power module 11 can be reduced, thereby effectively inhibiting the temperature cycles of the power module 11, further improving the safety of the power module 11, and having strong applicability.

Specifically, the controller 10 may further obtain the weighting coefficients of each of the first duty cycle parameter d ₁, the second duty cycle parameter d ₂, and the third duty cycle parameter d ₃, and adjust the target fan duty cycle d _out based on each of the duty cycle parameters and the weighting coefficients thereof. The weighting coefficient may be greater than or equal to 0 and less than or equal to 1, where the weighting coefficient may be a preset parameter set by the inverter 1 in a factory, a parameter set by a user, or a parameter dynamically adjusted according to a specific working condition of the inverter 1, and may specifically be determined according to an actual application scenario, and is not limited herein. The target fan duty ratio d _out may be a value obtained by performing weighted summation on each duty ratio parameter and its weighting coefficient. It can be understood that the controller 10 realizes flexible control of the parameter proportion of each duty ratio through the weighting coefficient, thereby reducing the temperature cycle times and the temperature cycle amplitude of the power module 11 to inhibit the temperature cycle of the power module 11, improving the safety of the power module 11, and having strong applicability.

In some possible embodiments, after adjusting the target fan duty ratio d _out, the controller 10 controls the rotation speed of one part of the cooling fans 15a to 15n to be 0 and the rotation speed of the other part of the cooling fans to be the first rotation speed in the case where the target fan duty ratio d _out is less than the preset duty ratio threshold. The number of the other part of the cooling fans and the first rotating speed are determined by the second temperature and the second signal, the first rotating speed is smaller than a preset rotating speed threshold value, the number of the other part of the cooling fans can be understood as the running number of the cooling fans, the number of the other part of the cooling fans can be represented as N and N is larger than or equal to 1, and the first rotating speed can be understood as the running rotating speed of the cooling fans. The preset duty ratio threshold is a parameter of factory configuration of the inverter 1 or a parameter set by a user, and the preset rotation speed threshold is a maximum rotation speed value of the cooling fan running in a low-speed section. When the rotation speed of one part of the cooling fans is 0, one part of the cooling fans can be obtained to not run, and when the rotation speed of the other part of the cooling fans is the first rotation speed, the other part of the cooling fans can be obtained to run in a low-speed section.

It can be understood that, when the duty ratio d _out of the target fan is smaller than the preset duty ratio threshold, the controller 10 can flexibly control the operation number and the operation rotation speed of the cooling fan in the low-speed section, for example, flexibly control different operation number combinations and different operation rotation speed combinations of the cooling fan, so that the cooling efficiency range of the cooling system in the inverter 1 can be expanded, that is, the equivalent efficiency adjusting range of the cooling system is improved, thereby effectively inhibiting the temperature cycle times of the power module 11, greatly reducing the loss of the inverter 1, and having stronger applicability.

For convenience of description, taking the radiator fan 15a, the radiator fan 15b, and the radiator fan 15n as examples, the different operation number combinations corresponding to the respective radiator fans of the radiator fan 15a, the radiator fan 15b, and the radiator fan 15n may be represented as 011, 101, 110, or 010, wherein 1 may represent that the rotation speed of the radiator fan is a first rotation speed, that is, the radiator fan is operated at a first rotation speed, and 0 may represent that the rotation speed of the radiator fan is 0, that is, the radiator fan is not operated. For example, when the combination of the different operation numbers corresponding to the respective heat radiation fans is 011, the heat radiation fan 15a is not operated, the heat radiation fan 15b is operated at the first rotation speed, and the heat radiation fan 15n is operated at the first rotation speed. The different operation rotation speed combinations corresponding to the respective heat radiation fans may be represented as (D1-D2-D3), wherein D1 is used to represent the rotation speed of the heat radiation fan 15a, D2 is used to represent the rotation speed of the heat radiation fan 15b, D3 is used to represent the rotation speed of the heat radiation fan 15n, and any one of D1, D2, and D3 is 0 or the first rotation speed.

In some possible embodiments, the controller 10 may control the rotational speeds of the cooling fans 15a to 15n to be the second rotational speed based on the target fan duty ratio d _out in the case where the target fan duty ratio d _out is greater than or equal to the preset duty ratio threshold. The second rotating speed is greater than the first rotating speed, and the second rotating speed refers to any rotating speed value of the cooling fan running in the high-speed section. The second rotational speed may be determined by the target fan duty cycle d _out, the second temperature, and the second signal. It can be appreciated that, when the duty ratio d _out of the target fan is greater than or equal to the preset duty ratio threshold, the controller 10 controls all the heat dissipation fans to operate simultaneously to quickly dissipate heat of the power module 11, so that the heat dissipation efficiency of the inverter 1 is improved, and the applicability is strong. In summary, the controller 10 may compare the target fan duty ratio d _out with the preset duty ratio threshold, and flexibly control the cooling fans 15a to 15n to operate in the low-speed section or the high-speed section according to the comparison result, so as to widen the working range of the cooling system to improve the cooling efficiency, and have stronger applicability.

For convenience of description, the first signal and the second signal will be described below as examples of output power. In an embodiment, the controller 10 controls the rotation speed of each of the heat dissipation fans 15a to 15n based on the target fan duty ratio d _out, wherein the rotation speed may be 0, the first rotation speed or the second rotation speed, and the effect of suppressing the temperature cycle of the power module 11 may refer to fig. 3A, and fig. 3A is a schematic diagram of an effect of suppressing the temperature cycle of the power module according to the present application. In another embodiment, the controller 10 obtains the fan duty ratio according to the current temperature of the power module 11 only, and controls the rotation speed of each of the cooling fans 15a to 15n according to the fan duty ratio, and the effect of suppressing the temperature cycle of the power module 11 can be seen in fig. 3B, and fig. 3B is a schematic diagram of another effect of suppressing the temperature cycle of the power module according to the present application.

As can be obtained by comparing the effect diagrams shown in fig. 3A and 3B, in the case that the power variation trend is consistent, the fluctuation range and the fluctuation amplitude of the temperature of the power module 11 shown in fig. 3A are smaller, so that the controller 10 can quickly reflect the power variation trend and the temperature variation trend by controlling the rotation speed of each cooling fan based on the target fan duty ratio d _out, thereby effectively inhibiting the temperature cycle times and the temperature cycle amplitude of the power module 11, improving the reliability of the inverter 1, and reducing the market failure rate of the inverter 1.

In some possible embodiments, the specific structure of the inverter 1 may also be referred to fig. 4, and fig. 4 is another schematic structural diagram of the inverter provided by the present application. As shown in fig. 4, the power module 11 includes power units 110a to 110m, and the inverter 1 shown in fig. 2 further includes a heat sink 16 and silicone grease 17a to 17m. The power units 110a to 110m may be mounted on the surface of the heat sink 16, respectively, and silicone grease is disposed between each of the power units 110a to 110m and the heat sink 16, for example, silicone grease 17a is disposed between the power unit 110a and the heat sink 16, silicone grease 17b is disposed between the power unit 110b and the heat sink 16. The power units 110a to 110m, the heat dissipation fans 15a to 15n, the heat sink 16, and the silicone grease 17a to 17m may constitute a heat dissipation system in the inverter 1, and the heat dissipation system further includes, but is not limited to, heat pipes and air ducts, and the number and arrangement positions of various types of devices in the heat dissipation system may be determined by the specific types of the inverter 1 described above, which is not limited herein. The heat pipe is a heat transfer element, and the air duct is a channel for air circulation, which is built by concrete, bricks and other materials.

In some possible embodiments, the power units 110a to 110m may perform ac-dc conversion on the dc input signal to output the first signal or the second signal, and heat is continuously generated from the power units 110a to 110m during the output process. At this time, the heat dissipation fans 15a to 15n may be operated at a certain rotation speed to draw external air into the heat sink 16 through the air duct, so that heat generated from the power units 110a to 110m is dissipated by heat exchange between the air flow and the heat sink 16, thereby ensuring reliability and safety of the power module 11.

In some possible embodiments, in order to quickly dissipate heat from the power module 11, the controller 10 may control the rotational speeds of the heat dissipation fans 15a to 15n in real time. As shown in fig. 4, the controller 10 shown in fig. 2 described above may include, but is not limited to, an output signal sampling unit 101 and a fan speed regulation control unit 102, and alternatively, the output signal sampling unit 101 may be disposed outside the controller 10. Where the output signal of the power module 11 is output power, the output signal sampling unit 101 may include, but is not limited to, a power detection circuit or a power meter, and where the output signal of the power module 11 is output current, the output signal sampling unit 101 may include, but is not limited to, a current detection circuit or a current meter.

In some possible embodiments, wired or wireless communication may be established between the temperature detection device 14 and the output signal sampling unit 101 and the fan speed control unit 102, thereby transmitting temperature data and signal data. In the process of controlling the rotation speed of each cooling fan, the temperature detecting device 14 can detect a first temperature when the power module 11 outputs a first signal and a second temperature when the power module 11 outputs a second signal, and output the first temperature and the second temperature to the fan speed regulation control unit 102, and the output signal sampling unit 101 can detect the first signal and the second signal output from the power units 110a to 110m through the output port 13, and output the first signal and the second signal to the fan speed regulation control unit 102.

Further, the fan speed control unit 102 may adjust the target fan duty d _out according to the second signal, the amount of change between the first signal and the second signal, the second temperature, and the amount of change between the first temperature and the second temperature to generate a duty command, and output the duty command to the cooling fans 15a to 15n, thereby controlling the rotation speeds of the cooling fans 15a to 15 n. The specific calculation process of the target fan duty d _out included in the duty command may be referred to as a fan speed control command, and the description of the target fan duty d _out in the embodiment corresponding to fig. 2 is omitted herein. After the duty ratio command is obtained, each of the heat dissipation fans 15a to 15n can be operated according to the duty ratio command to dissipate heat of the power module 11, so that temperature fluctuation of the radiator 16 and the power module 11 is reduced, temperature circulation of the power module 11 is effectively suppressed, and applicability is strong.

In the inverter 1 provided by the application, the controller 10 can dynamically adjust the duty ratio of the target fan according to the second signal, the variation between the first signal and the second signal, the second temperature and the variation between the first temperature and the second temperature so as to rapidly control the rotating speed of each cooling fan, and can reduce the temperature cycle times and the temperature cycle amplitude of the power module 11, thereby improving the safety of the power module 11, and in addition, the service life damage of the power module 11 is reduced, and the reliability of the power module 11 is improved. Further, the controller 10 may compare the target fan duty ratio d _out with the preset duty ratio threshold, and flexibly control the cooling fans 15a to 15n to operate in the low-speed section or the high-speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency, and having stronger applicability.

Next, an example of a photovoltaic system including an inverter will be described, and referring to fig. 5, fig. 5 is a schematic structural diagram of the photovoltaic system provided by the present application. As shown in fig. 5, the photovoltaic system 2 includes a photovoltaic array 20 and an inverter 30 (such as the inverter 1 described above) connected (e.g., directly connected or indirectly connected) to the photovoltaic array 20, and the output terminal of the inverter 30 may be connected (e.g., directly connected or indirectly connected) to an ac power grid. During the process of powering the ac power grid, the inverter 30 may convert the dc voltage provided by the photovoltaic array 20 to an ac voltage and power the ac power grid based on the ac voltage. In the case that the inverter 30 includes the cooling fan and the controller, the controller can control the rotation speed of the cooling fan in real time to ensure reliable operation of the inverter 30, so that the power supply reliability and the power supply safety of the inverter 30 are higher, thereby improving the power supply efficiency and the power supply safety of the photovoltaic system 2, and having strong adaptability.

In some possible embodiments, the specific structure of the photovoltaic system 2 may also be referred to fig. 6, and fig. 6 is another schematic structural diagram of the photovoltaic system provided by the present application. As shown in fig. 6, the photovoltaic system 2 further includes a dc combiner box 40, and the photovoltaic array 20 may be connected to the input end of the inverter 30 through the dc combiner box 40, and the output end of the inverter 30 may be connected (e.g., directly connected or indirectly connected) to an ac power grid. In the process of supplying power to the ac power grid, the dc combiner box 40 can combine the dc voltages provided by the photovoltaic strings in the photovoltaic array 20 and output the combined dc voltages to the inverter 30, and at this time, the inverter 30 (e.g., a centralized photovoltaic inverter) can supply power to the ac power grid based on the combined dc voltages. In this power supply process, since the power supply reliability and the power supply safety of the inverter 30 are higher, the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

Optionally, as shown in fig. 6, the photovoltaic system 2 further includes a box transformer 50, and the output end of the inverter 30 may be connected to an ac power grid through the box transformer 50, where the box transformer 50 refers to a transformer substation (or a power distribution station) that combines a high-voltage switching device, a distribution transformer, and a low-voltage distribution device according to a certain wiring scheme, and is installed in a box housing. In the process of supplying power to the ac power grid, the inverter 30 (e.g., a centralized photovoltaic inverter) may output an ac voltage to the box-type transformer 50 based on the dc voltage after the confluence, and at this time, the box-type transformer 50 may supply power to the ac power grid based on the ac voltage input from the inverter 30. In this power supply process, since the power supply reliability and the power supply safety of the inverter 30 are higher, the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

In some possible embodiments, the specific structure of the photovoltaic system 2 may also be referred to fig. 7, and fig. 7 is another schematic structural diagram of the photovoltaic system provided by the present application. As shown in fig. 7, the photovoltaic system 2 shown in fig. 5 further includes an ac combiner box 60, where the photovoltaic array 20 may be connected to an input end of the ac combiner box 60 through the inverter 30, and an output end of the ac combiner box 60 may be connected (e.g., directly connected or indirectly connected) to an ac power grid. In the process of supplying power to the ac power grid, the inverter 30 may provide ac voltage to the ac combiner box 60 based on dc voltage provided by the photovoltaic array 20, and the ac combiner box 60 may supply ac voltage input from the inverter 30 (e.g., a string-type photovoltaic inverter) to the ac power grid. In this power supply process, since the power supply reliability and the power supply safety of the inverter 30 are higher, the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

Optionally, as shown in fig. 7, the photovoltaic system 2 further includes a box transformer 51, and the output end of the ac combiner box 60 may be connected to an ac power grid through the box transformer 51. In the process of supplying power to the ac power grid, the ac combiner box 60 may combine the ac voltages input from the inverter 30 (e.g., the string-type photovoltaic inverter) and output the combined ac voltages to the box-type transformer 51, and at this time, the box-type transformer 51 may supply power to the ac power grid based on the combined ac voltages. In this power supply process, since the power supply reliability and the power supply safety of the inverter 30 are higher, the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the adaptability is higher.

In some possible embodiments, the specific structure of the photovoltaic system 2 may also be referred to fig. 8, and fig. 8 is another schematic structural diagram of the photovoltaic system provided by the present application. As shown in fig. 8, the photovoltaic system 2 shown in fig. 5 further includes a DC/DC converter 70 and a DC bus 80, and the photovoltaic array 20 may be connected to an input end of the inverter 30 through the DC/DC converter 70 and the DC bus 80, and an output end of the inverter 30 may be connected to an ac power grid, where the DC bus 80 may include a positive DC bus and a negative DC bus (such as the positive DC bus and the negative DC bus shown in fig. 1). During the process of powering the ac power grid, the DC/DC converter 70 may convert the DC voltage provided by the photovoltaic array 20 to a target DC voltage and output the target DC voltage to the inverter 30 via the DC bus 80. At this time, the inverter 30 may convert the target direct current voltage into an alternating current voltage and supply power to the alternating current grid based on the alternating current voltage. In this power supply process, since the power supply reliability and the power supply safety of the inverter 30 are higher, the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the adaptability is higher.

In the photovoltaic system 2 provided by the application, the power supply reliability and the power supply safety of the inverter 30 are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system 2 can be improved, and the system has stronger power supply flexibility and stronger adaptability.

Next, an example of a method for adjusting the speed of the inverter cooling fan will be described, referring to fig. 9, fig. 9 is a schematic flow chart of the method for adjusting the speed of the inverter cooling fan provided by the application. The method is applicable to a controller in an inverter (such as the inverter 1 shown in fig. 2-4 above) further comprising a power module and at least one radiator fan. As shown in fig. 9, the method includes the following steps S101 to S102:

Step S101, detecting a first temperature when the power module outputs a first signal and a second temperature when the power module outputs a second signal.

In some possible embodiments, each of the first and second signals may include, but is not limited to, an output power or an output current, the detection time of the first temperature being before the detection time of the second temperature. Specifically, the controller can detect the first temperature and the second temperature of the power module through the temperature detection device, so that the accuracy and the instantaneity of temperature sampling can be ensured. The temperature sensing means herein may include, but is not limited to, thermocouples, positive temperature coefficient thermistors, negative temperature coefficient thermistors, silicon resistance temperature sensors, I C temperature sensors, or other temperature sensitive devices. The first temperature or the second temperature may be understood as a temperature of the inverter, and the first temperature or the second temperature includes, but is not limited to, a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink. For convenience of description, the temperature of the power module is taken as an example of the first temperature or the second temperature, and the description is omitted. At this time, the second temperature may be understood as a current temperature of the power module, and the second signal may be understood as a current output signal of the power module.

In some possible embodiments, the controller may detect the first temperature and the second temperature of the power module through the temperature detection device, and detect the first signal and the second signal of the power module, thereby completing the real-time detection process of the operation state of the inverter. In an embodiment, when each of the first signal and the second signal is output power, the controller may detect the first output power and the second output power of the power module through the power detection circuit or the power meter, so that accuracy and instantaneity of power sampling may be ensured. In another embodiment, when each signal is an output current, the controller may detect the first output current and the second output current of the power module through the current detection circuit or the ammeter, so that accuracy and real-time performance of current sampling may be ensured.

Step S102, the duty ratio of the target fan is adjusted according to the second signal, the variation between the first signal and the second signal, the second temperature and the variation between the first temperature and the second temperature so as to control the rotating speed of each cooling fan in at least one cooling fan.

In some possible embodiments, the amount of change between the first temperature and the second temperature includes at least one of a difference between the first temperature and the second temperature, a rate of change, a direction of change, and a time difference. Wherein the rate of change is the ratio between the difference between the first temperature and the second temperature and the difference in detection time. The change direction is the temperature change trend of the power module, and the change direction comprises positive increase or negative decrease. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and the detection time difference is larger than 0. In the case that the first temperature is greater than the second temperature, the difference and the change rate between the first temperature and the second temperature are smaller than 0, and the change direction between the first temperature and the second temperature is decreased in a negative direction, that is, the temperature change trend of the power module is decreased in a negative direction. Under the condition that the first temperature is smaller than the second temperature, the difference value and the change rate between the first temperature and the second temperature are larger than 0, the change direction between the first temperature and the second temperature is positive increase, namely the temperature change trend of the power module is positive increase.

In some possible embodiments, the amount of change between the first signal and the second signal includes, but is not limited to, at least one of a difference between the first signal and the second signal, a rate of change, a direction of change, a time difference. Wherein the rate of change is the ratio between the difference between the first signal and the second signal and the time difference. The change direction is the output change trend of the power module, the change direction comprises positive increase or negative decrease, the output change trend of the power module is the power change trend when each of the first signal and the second signal is output power, and the output change trend of the power module is the current change trend when each of the first signal and the second signal is output current. The time difference is the difference between the detection time of the first signal and the detection time of the second signal, and the time difference is greater than 0. When the first signal is larger than the second signal, the difference value and the change rate between the first signal and the second signal are smaller than 0, and the change direction between the first signal and the second signal is reduced in the negative direction, namely the output change trend of the power module is reduced in the negative direction. When the first signal is smaller than the second signal, the difference value and the change rate between the first signal and the second signal are larger than 0, and the change direction between the first signal and the second signal is positive increase, namely the output change trend of the power module is positive increase.

In some possible embodiments, the operations performed by the controller in controlling the rotational speed of each cooling fan may be refer to fig. 10, and fig. 10 is another flow chart of the speed regulation method of the inverter cooling fan provided by the present application. As shown in fig. 10, the method includes the following steps S1021 to S1026:

step S1021, obtaining the first duty cycle parameter d ₁ based on the second signal and the second temperature.

In some possible embodiments, the controller may output the first duty cycle parameter d ₁ based on a monotonic mapping between the second signal and the second temperature and the fan speed, i.e., the input parameter of the monotonic mapping is the second temperature and the second signal, and the output parameter of the monotonic mapping is the first duty cycle parameter d ₁. Implementations of the monotonic mapping relationship include, but are not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be manifested by an increase in the first duty cycle parameter d ₁ if the temperature of the power module increases or the output signal of the power module increases, and a decrease in the first duty cycle parameter d ₁ if the temperature of the power module decreases or the output signal of the power module decreases. The first duty ratio parameter d ₁ may be understood as a fan speed control amount, and the first duty ratio parameter d ₁ is a steady-state adjustment amount reflecting the fan speed.

Optionally, the controller may further obtain a first duty cycle parameter d ₁₁ based on the second signal and another first duty cycle parameter d ₁₂ based on the second temperature, where the first duty cycle parameter d ₁₁ and the first duty cycle parameter d ₁₂ may be understood as fan speed control amounts, and the first duty cycle parameter d ₁₁ is a steady state adjustment amount reflecting the fan speed associated with the second signal, and the first duty cycle parameter d ₁₂ is a steady state adjustment amount reflecting the fan speed associated with the second temperature. For convenience of description, the first duty cycle parameter d ₁ will be described as an example, and will not be described in detail.

Step S1022 obtains a second duty cycle parameter d ₂ based on the amount of change between the first signal and the second signal.

Specifically, the controller may further output the second duty ratio parameter d ₂ based on a monotonic mapping relationship between the variation between the first signal and the second signal and the fan rotation speed, that is, the input parameter of the monotonic mapping relationship is the variation between the first signal and the second signal, and the output parameter of the monotonic mapping relationship is the second duty ratio parameter d ₂. The implementation of the monotonic mapping relationship may include, but is not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be represented by an increase in the second duty cycle parameter d ₂ when the output variation trend of the power module is increasing in a positive direction, and a decrease in the second duty cycle parameter d ₂ when the output variation trend of the power module is decreasing in a negative direction. For example, in the case where the monotonic mapping relationship is a differential formula, the second duty ratio parameter d ₂ is a value obtained by differentiating the amount of change between the first signal and the second signal, and it should be noted that the specific implementation manner of the monotonic mapping relationship may be determined according to the actual application scenario, which is not limited herein.

The second duty ratio parameter d ₂ can be understood as a fan rotation speed control amount, and the second duty ratio parameter d ₂ is a dynamic adjustment amount reflecting the fan rotation speed, so that the influence of illumination and load mutation on the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, and the temperature cycle of the power module is effectively inhibited.

Step S1023, obtaining a third duty ratio parameter d ₃ based on the amount of change between the first temperature and the second temperature.

Specifically, the controller may further output the third duty cycle parameter d ₃ based on a monotonic mapping relationship between the variation between the first temperature and the second temperature and the fan rotation speed, that is, the input parameter of the monotonic mapping relationship is the variation between the first temperature and the second temperature, and the output parameter of the monotonic mapping relationship is the third duty cycle parameter d ₃. The implementation of the monotonic mapping relationship may include, but is not limited to, a function, a formula, a graph, or a curve, and the monotonic mapping relationship may be represented by an increase in the third duty cycle parameter d ₃ when the temperature variation trend of the power module increases in a positive direction, and a decrease in the third duty cycle parameter d ₃ when the temperature variation trend of the power module decreases in a negative direction. For example, in the case where the monotonic mapping relationship is an integral formula, the third duty ratio parameter d ₃ is a value obtained by integrating the amount of change between the first temperature and the second temperature, and it should be noted that the specific implementation manner of the monotonic mapping relationship may be determined according to the actual application scenario, which is not limited herein.

The third duty ratio parameter d ₃ can be understood as a fan rotation speed control amount, and the third duty ratio parameter d ₃ is a dynamic adjustment amount reflecting the fan rotation speed, so that the influence of the start and stop of the cooling fan and the ambient temperature on the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, and the temperature cycle amplitude of the power module in a power fluctuation scene can be reduced, namely, the temperature cycle amplitude of the power module in the power fluctuation scene is prevented from greatly fluctuating.

In step S1024, the target fan duty cycle d _out is adjusted based on the first duty cycle parameter d ₁, the second duty cycle parameter d ₂, and the third duty cycle parameter d ₃.

The first duty ratio parameter d ₁ is a steady state adjustment amount reflecting the fan rotation speed, and the second duty ratio parameter d ₂ and the third duty ratio parameter d ₃ are dynamic adjustment amounts reflecting the fan rotation speed, so that the target fan duty ratio d _out can reflect the steady state adjustment amount and the dynamic adjustment amount of the fan rotation speed at the same time, thereby improving the accuracy of the target fan duty ratio d _out.

Specifically, the controller may further obtain a weighting coefficient of each of the first duty cycle parameter d ₁, the second duty cycle parameter d ₂, and the third duty cycle parameter d ₃, and adjust the target fan duty cycle d _out based on each of the duty cycle parameters and the weighting coefficients thereof. The weighting coefficient may be greater than or equal to 0 and less than or equal to 1, where the weighting coefficient may be a preset parameter set by the inverter from factory, a parameter set by a user, or a parameter dynamically adjusted according to a specific working condition of the inverter, and may be specifically determined according to an actual application scenario, which is not limited herein. The target fan duty ratio d _out may be a value obtained by performing weighted summation on each duty ratio parameter and its weighting coefficient. It can be understood that the controller realizes flexible control of the parameter proportion of each duty ratio through the weighting coefficient, thereby reducing the temperature cycle times and the temperature cycle amplitude of the power module to inhibit the temperature cycle of the power module, improving the safety of the power module and having strong applicability.

In step S1025, when the target fan duty ratio d _out is smaller than the preset duty ratio threshold, the rotation speed of a part of the at least one cooling fan is controlled to be 0, and the rotation speed of another part of the at least one cooling fan is controlled to be the first rotation speed.

The number of the other part of the cooling fans and the first rotating speed are determined by the second temperature and the second signal, the first rotating speed is smaller than a preset rotating speed threshold value, the number of the other part of the cooling fans can be understood as the running number of the cooling fans, the number of the other part of the cooling fans can be represented as N and N is larger than or equal to 1, and the first rotating speed can be understood as the running rotating speed of the cooling fans. The preset duty ratio threshold is a parameter of factory configuration of the inverter or a parameter set by a user, and the preset rotating speed threshold is a maximum rotating speed value of the cooling fan in a low-speed section. When the rotation speed of one part of the cooling fans is 0, one part of the cooling fans can be obtained to not run, and when the rotation speed of the other part of the cooling fans is the first rotation speed, the other part of the cooling fans can be obtained to run in a low-speed section.

Under the condition that the duty ratio d _out of the target fan is smaller than the preset duty ratio threshold, the controller can flexibly control the running number and the running rotating speed of the cooling fan at a low speed section, for example, flexibly control different running number combinations and different running rotating speed combinations, so that the cooling efficiency range of the cooling system in the inverter can be expanded, namely, the equivalent efficiency adjusting range of the cooling system is improved, the temperature cycle times of the power module are effectively restrained, the loss of the inverter is greatly reduced, and the applicability is stronger.

In step S1026, in the case that the target fan duty ratio d _out is greater than or equal to the preset duty ratio threshold, the rotational speed of at least one cooling fan is controlled to be the second rotational speed based on the target fan duty ratio.

The second rotating speed is greater than the first rotating speed, and the second rotating speed refers to any rotating speed value of the cooling fan running in the high-speed section. The second rotational speed may be determined by the target fan duty cycle d _out, the second temperature, and the second signal. Under the condition that the duty ratio d _out of the target fan is larger than or equal to a preset duty ratio threshold, the controller can control all the cooling fans to run simultaneously so as to quickly cool the power module, so that the cooling efficiency of the inverter is improved, and the applicability is strong. In summary, the controller may compare the target fan duty ratio d _out with the preset duty ratio threshold, and flexibly control at least one cooling fan to operate in the low-speed section or the high-speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency, and having stronger applicability.

In a specific implementation, more operations executed by the controller in the speed regulation method of the inverter cooling fan provided by the present application can be referred to the above-mentioned implementation manner executed by the controller 10 in the inverter 1 and the working principle thereof shown in fig. 2 to 4, and are not described herein again.

In the method provided by the application, the controller can dynamically adjust the duty ratio of the target fan according to the second signal, the variation between the first signal and the second signal, the second temperature and the variation between the first temperature and the second temperature so as to rapidly control the rotating speed of each cooling fan, and the temperature cycle times and the temperature cycle amplitude of the power module can be reduced, thereby improving the safety of the power module, in addition, the service life damage of the power module is reduced, and the reliability of the power module is improved. Further, the controller can compare the duty ratio of the target fan with a preset duty ratio threshold value, and flexibly control at least one cooling fan to run in a low-speed section or a high-speed section according to a comparison result, so that the working range of the cooling system can be widened to improve the cooling efficiency, and the applicability is stronger.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An inverter, characterized in that the inverter comprises a controller, a power module, a temperature detection device, at least one cooling fan, a power board and a radiator;

the power board is used for bearing the power module;

the radiator is used for radiating heat of the power module;

The power module is used for performing alternating-current/direct-current conversion on the direct-current input signal to output power or output current;

The temperature detection device is used for detecting a first temperature when the power module outputs power or current at a first moment and a second temperature when the power module outputs power or current at a second moment, and the first moment when the first temperature is detected is before the second moment when the second temperature is detected;

the controller is configured to adjust a target fan duty ratio according to the output current or output power at the second time, the variation between the output current or output power at the first time and the output current or output power at the second time, the second temperature, and the variation between the first temperature and the second temperature, so as to control the rotation speed of each cooling fan in the at least one cooling fan, so as to dissipate heat of the power module;

The first temperature or the second temperature includes a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

2. The inverter according to claim 1, wherein the amount of change between the output current or output power at the first time and the output current or output power at the second time includes at least one of a difference, a rate of change, a direction of change, and a time difference between the output current or output power at the first time and the output current or output power at the second time, and the amount of change between the first temperature and the second temperature includes at least one of a difference, a rate of change, a direction of change, and a detection time difference between the first temperature and the second temperature.

3. The inverter according to any one of claims 1or 2, wherein the controller is configured to:

obtaining a first duty cycle parameter based on the output current or output power at the second time and the second temperature;

obtaining a second duty ratio parameter based on the variation between the output current or output power at the first moment and the output current or output power at the second moment, and obtaining a third duty ratio parameter based on the variation between the first temperature and the second temperature;

And adjusting the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter and the third duty cycle parameter.

4. The inverter of claim 3, wherein the controller is configured to:

And acquiring the weighting coefficient of each duty ratio parameter in the first duty ratio parameter, the second duty ratio parameter and the third duty ratio parameter, and adjusting the duty ratio of the target fan based on each duty ratio parameter and the weighting coefficient thereof, wherein the weighting coefficient is greater than or equal to 0 and less than or equal to 1.

5. The inverter of any one of claims 1-4, wherein the controller is configured to:

Controlling the rotation speed of one part of the at least one cooling fan to be 0 and the rotation speed of the other part of the at least one cooling fan to be a first rotation speed under the condition that the target fan duty ratio is smaller than a preset duty ratio threshold, wherein the number of the other part of cooling fans and the first rotation speed are determined by the second temperature and the output current or the output power at the second moment, and the first rotation speed is smaller than the preset rotation speed threshold;

And controlling the rotating speed of the at least one cooling fan to be a second rotating speed based on the target fan duty ratio under the condition that the target fan duty ratio is larger than or equal to the preset duty ratio threshold, wherein the second rotating speed is larger than the first rotating speed.

6. The speed regulating method of the radiator fan of the inverter is suitable for a controller in the inverter, the inverter further comprises a power module and at least one radiator fan, and the method comprises the following steps:

Detecting a first temperature when the power module outputs an output current or output power at a first moment and a second temperature when the power module outputs an output current or output power at a second moment, each signal of the output current or output power at the first moment and the output current or output power at the second moment comprising the output power or the output current, the detection time of the first temperature being before the detection time of the second temperature;

And adjusting a target fan duty ratio according to the output current or output power at the second moment, the variation between the output current or output power at the first moment and the output current or output power at the second moment, the second temperature and the variation between the first temperature and the second temperature so as to control the rotating speed of each cooling fan in the at least one cooling fan.

7. The method of claim 6, wherein the inverter further comprises a power board and a heat sink, wherein the power board is configured to carry the power module and the heat sink is configured to dissipate heat from the power module;

8. The method according to claim 6 or 7, wherein the amount of change between the output current or output power at the first time and the output current or output power at the second time includes at least one of a difference, a rate of change, a direction of change, and a time difference between the output current or output power at the first time and the output current or output power at the second time, and wherein the amount of change between the first temperature and the second temperature includes at least one of a difference, a rate of change, a direction of change, and a detection time difference between the first temperature and the second temperature.

9. The method of claim 7 or 8, wherein said adjusting the target fan duty cycle based on the output current or output power at the second time, the amount of change between the output current or output power at the first time and the output current or output power at the second time, the second temperature, and the amount of change between the first temperature and the second temperature, comprises:

Obtaining a first intermediate fan duty cycle based on the output current or output power at the second time and the second temperature;

Obtaining a second intermediate fan duty cycle based on an amount of change between the output current or output power at the first time and the output current or output power at the second time, and obtaining a third intermediate fan duty cycle based on an amount of change between the first temperature and the second temperature;

And adjusting a target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter and the third duty cycle parameter.

10. The method of claim 9, wherein said adjusting a target fan duty cycle in accordance with said first duty cycle parameter, said second duty cycle parameter, and said third duty cycle parameter comprises:

And obtaining the weighting coefficient of each duty ratio parameter in the first duty ratio parameter, the second duty ratio parameter and the third duty ratio parameter, and adjusting the duty ratio of the target fan based on each duty ratio parameter and the weighting coefficient thereof, wherein the weighting coefficient is greater than or equal to 0 and less than or equal to 1.

11. The method of any of claims 7-10, wherein after said adjusting a target fan duty cycle based on said output current or output power at said second time, said change between said output current or output power at said first time and said output current or output power at said second time, said second temperature, and said change between said first temperature and said second temperature, said method further comprises: