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WO2025082171A1 - 直流变换器以及光伏系统 - Google Patents

直流变换器以及光伏系统 Download PDF

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Publication number
WO2025082171A1
WO2025082171A1 PCT/CN2024/121093 CN2024121093W WO2025082171A1 WO 2025082171 A1 WO2025082171 A1 WO 2025082171A1 CN 2024121093 W CN2024121093 W CN 2024121093W WO 2025082171 A1 WO2025082171 A1 WO 2025082171A1
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WO
WIPO (PCT)
Prior art keywords
voltage
circuit
output
converter
safety
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2024/121093
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English (en)
French (fr)
Inventor
刘永泉
顾桂磊
张世勇
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Huawei Digital Power Technologies Co Ltd
Original Assignee
Huawei Digital Power Technologies Co Ltd
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Filing date
Publication date
Application filed by Huawei Digital Power Technologies Co Ltd filed Critical Huawei Digital Power Technologies Co Ltd
Publication of WO2025082171A1 publication Critical patent/WO2025082171A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02J2101/24—

Definitions

  • the present application relates to the technical field of photovoltaic power generation, and in particular to a direct current converter and a photovoltaic system.
  • a photovoltaic optimizer is a component-level power electronic device with DC input and DC output, which is used to convert the DC power provided by the photovoltaic module into voltage and then output it.
  • a photovoltaic optimizer will adopt the predicted current and voltage technology to solve the impact of photovoltaic modules on the power generation of the photovoltaic system due to shadow obstruction, inconsistent orientation or differences in the electrical specifications of the modules, so as to achieve the maximum power output of the photovoltaic modules, thereby increasing the power generation of the photovoltaic system.
  • the photovoltaic optimizer When the wiring between the photovoltaic optimizer and the photovoltaic module is abnormal, the photovoltaic optimizer will be unable to output DC power, and the power supply reliability of the photovoltaic optimizer will be poor. Therefore, in order to avoid the impact of abnormal wiring problems on the power supply reliability of the photovoltaic optimizer, it is particularly important to identify in advance whether the wiring between the photovoltaic optimizer and the photovoltaic module is abnormal.
  • the present application provides a DC converter and a photovoltaic system, which can reduce the detection error of the safety voltage at the output end of the DC converter, thereby improving the accuracy of wiring abnormality detection and having strong applicability.
  • the present application provides a DC converter, which includes a DC conversion circuit, an auxiliary power supply, and a safety voltage output circuit, wherein the input end of the DC conversion circuit is connected in parallel with the input end of the auxiliary power supply as the input end of the DC converter, the input end of the DC converter is used to connect the DC power supply, the output end of the auxiliary power supply is connected to the input end of the safety voltage output circuit, and the output end of the safety voltage output circuit is connected in parallel with the output end of the DC conversion circuit as the output end of the DC converter.
  • the auxiliary power supply is used to output a second voltage to the safety voltage output circuit based on the first voltage provided by the DC power supply when the DC conversion circuit does not perform voltage conversion, wherein the second voltage is less than the first voltage. Since the auxiliary power supply can output stable electric energy to the outside, the voltage amplitude of the second voltage is basically unchanged. Further, the safety voltage output circuit is used to output a safety voltage based on the second voltage, that is, the voltage at the output end of the DC converter is a safety voltage at this time, wherein the safety voltage is less than the second voltage. The safety voltage is used to compare with a preset safety voltage threshold, so as to determine the connection state between the DC converter and the DC power supply.
  • the connection state between the DC converter and the DC power supply is a normal state.
  • the connection state between the DC converter and the DC power supply is abnormal.
  • the preset safety voltage threshold is a theoretical value of the safety voltage.
  • the voltage amplitude of the second voltage is substantially unchanged and the output voltage accuracy of the safety voltage output circuit is high
  • the voltage amplitude of the safety voltage is also substantially unchanged.
  • the safety voltage at the output end of the DC converter has no voltage ripple or the voltage ripple is very small, thereby reducing the detection error of the safety voltage at the output end of the DC converter, thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the wiring state between the DC converter and the DC power supply can be identified in advance when the DC conversion circuit does not perform voltage conversion, thereby ensuring that the DC converter can continuously output DC power to the outside, thereby improving the power supply reliability of the DC converter.
  • the safety voltage output circuit includes a voltage divider circuit and a switch
  • the first connection end of the voltage divider circuit is connected to the output end of the auxiliary power supply
  • the second connection end of the voltage divider circuit is connected to the first output end of the DC conversion circuit
  • the third connection end of the voltage divider circuit is connected to the second output end of the DC conversion circuit.
  • the switch can be arranged between the first connection end of the voltage divider circuit and the output end of the auxiliary power supply, or the switch can also be arranged between the second connection end of the voltage divider circuit and the first output end of the DC conversion circuit, and the specific circuit position of the switch is not limited here.
  • the DC converter also includes a controller for controlling the switch to be in a conducting state (i.e., normally on) when the DC conversion circuit does not perform voltage conversion, so that the voltage divider circuit divides the second voltage and outputs a safety voltage, and the safety voltage output circuit is in a working state at this time.
  • the switch can be controlled to be normally on to make the voltage divider circuit output a stable safety voltage to the outside, so that the voltage amplitude of the safety voltage at the output end of the DC converter is basically unchanged under ideal conditions, thereby reducing the detection error of the safety voltage, thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the above-mentioned controller is used to control the switch to be in an on state when the power-on command of the DC converter is not received, so that the voltage divider circuit outputs a stable safety voltage to the outside, thereby reducing the detection error of the safety voltage, and further improving the accuracy of wiring abnormality detection, and has strong applicability.
  • the controller is further used to control the switch to be in an off state when receiving a power-on instruction of the DC converter.
  • the safety voltage output circuit stops outputting the safety voltage and disconnects the connection between the auxiliary power supply and the DC conversion circuit, thereby preventing the DC conversion circuit from being interfered by the signal of the auxiliary power supply during operation, and also preventing the high-power current output by the DC conversion circuit from flowing through the auxiliary power supply and thus burning the auxiliary power supply, which is safer and more applicable.
  • the safety voltage output circuit includes a voltage divider circuit and a power chip
  • the first connection end of the voltage divider circuit is connected to the output end of the auxiliary power supply through the power chip
  • the second connection end of the voltage divider circuit is connected to the first output end of the DC conversion circuit
  • the third connection end of the voltage divider circuit is connected to the second output end of the DC conversion circuit.
  • the above-mentioned DC converter also includes a controller for sending a first enable signal to the power chip when the DC conversion circuit does not perform voltage conversion.
  • the power chip is used to respond to the first enable signal and output a second voltage to the voltage divider circuit, so that the voltage divider circuit divides the second voltage and outputs a safety voltage, and the safety voltage output circuit is in a working state.
  • the first level can be a high level or a low level, which is not specifically limited here.
  • the voltage divider circuit can be controlled to output a stable safety voltage to the outside by enabling the power chip, thereby reducing the detection error of the safety voltage, thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the controller is used to send a second enable signal to the power chip when receiving a power-on instruction of the DC converter.
  • the power chip is used to stop outputting the second voltage to the voltage divider circuit in response to the second enable signal.
  • the safety voltage output circuit stops outputting the safety voltage and disconnects the connection between the auxiliary power supply and the DC conversion circuit, thereby preventing the DC conversion circuit from being interfered by the signal of the auxiliary power supply during operation, and also preventing the high-power current output by the DC conversion circuit from flowing through the auxiliary power supply and burning the auxiliary power supply, which is safer and more applicable.
  • the first enable signal is a first level
  • the second enable signal is a second level, wherein the first level and the second level are relative levels.
  • the first level is a high level
  • the second level is a low level
  • the second level is a high level
  • the above-mentioned safety voltage output circuit also includes a protection circuit, wherein the protection circuit can be arranged between the second connection end of the voltage divider circuit and the first output end of the DC conversion circuit, and when the safety voltage output circuit also includes the above-mentioned switch, the protection circuit and the switch can be connected in series between the second connection end of the voltage divider circuit and the first output end of the DC conversion circuit.
  • the above-mentioned protection circuit is used to perform circuit protection on the voltage divider circuit, and the circuit protection is mainly to protect the voltage divider resistor in the voltage divider circuit from being damaged under the conditions of overvoltage, overcurrent, surge and electromagnetic interference, so as to ensure the safety of the voltage divider resistor and extend its service life, and it has stronger applicability.
  • the protection circuit includes a current limiting resistor or a diode, wherein the current limiting resistor or the diode is arranged between the second connection end of the voltage divider circuit and the first output end of the DC conversion circuit, thereby realizing current limiting protection or overvoltage protection of the voltage divider circuit.
  • the output current of the DC conversion circuit is large, and the current limiting resistor is used to limit the current flowing through the voltage divider circuit, thereby preventing the DC conversion circuit from outputting a large current to the voltage divider circuit and burning the voltage divider resistor, and the use is safer.
  • the output voltage of the DC conversion circuit is high, and the diode is in a cut-off state at this time, thereby preventing the DC conversion circuit from outputting a high voltage to the voltage divider circuit and causing the voltage divider resistor to fail, thereby extending the service life of the voltage divider resistor.
  • the above-mentioned protection circuit includes a current limiting resistor and a diode, wherein the current limiting resistor and the diode are connected in series between the second connection end of the voltage divider circuit and the first output end of the DC conversion circuit, thereby realizing current limiting protection and overvoltage protection of the voltage divider circuit.
  • the DC converter further includes a controller for controlling the DC conversion circuit to convert the first voltage and then output it upon receiving a power-on command of the DC converter, thereby ensuring that the DC converter outputs stable DC power and providing higher power supply reliability.
  • the present application provides a photovoltaic system, which includes a plurality of DC converters and photovoltaic inverters as provided in the first aspect and any one of its possible implementations.
  • the input end of each of the plurality of DC converters is used to connect to a photovoltaic component
  • the output ends of the plurality of DC converters are connected in series and then connected to the input end of the photovoltaic inverter
  • the output end of the photovoltaic inverter is used to connect to a power grid.
  • the DC conversion circuit in each DC converter is used to perform voltage conversion on the DC power provided by the photovoltaic component connected to each DC converter and then output a first voltage, wherein the first voltages output by any two of the plurality of DC converters may be the same or different.
  • the photovoltaic inverter is used to invert the first series voltage of the plurality of DC converters into an AC voltage and supply power to the power grid, wherein the first series voltage is the first voltage of the output end of the plurality of DC converters. sum.
  • the output terminals of the multiple DC converters are connected in series and then output a second series voltage, wherein the second series voltage is the sum of the safety voltages of the output terminals of the multiple DC converters.
  • the second series voltage is equal to the product of the preset safety voltage threshold and the number of the multiple DC converters
  • the connection state of all the DC converters in the multiple DC converters is a normal state.
  • the second series voltage is less than the product of the preset safety voltage threshold and the number of the multiple DC converters, the connection state of some or all of the DC converters in the multiple DC converters is an abnormal state.
  • the abnormal state includes at least one of the following: the connection between the DC converter and the photovoltaic assembly connected thereto is disconnected or in poor contact, the negative pole of the output terminal of the DC converter is connected to the negative pole of the output terminal of the adjacent DC converter, the positive pole of the output terminal of the DC converter is connected to the positive pole of the output terminal of the adjacent DC converter, and the connection between the DC converter and the photovoltaic inverter is disconnected or in poor contact.
  • the detection error of the safety voltage at the output end of each DC converter can be reduced, thereby reducing the detection error of the sum of the safety voltages at the output ends of multiple DC converters (i.e., the second series voltage), thereby improving the accuracy of wiring abnormality detection and increasing the power supply reliability of the photovoltaic system.
  • the voltage amplitude of the second voltage is substantially unchanged and the output voltage accuracy of the safety voltage output circuit is high, the voltage amplitude of the safety voltage is also substantially unchanged.
  • the safety voltage at the output end of the DC converter has no voltage ripple or the voltage ripple is very small, thereby reducing the detection error of the safety voltage at the output end of the DC converter, thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the wiring state between the DC converter and the DC power supply can be identified in advance when the DC conversion circuit does not perform voltage conversion, thereby ensuring that the DC converter can continuously output DC power to the outside, thereby improving the power supply reliability of the DC converter.
  • FIG1 is a schematic diagram of an application scenario of a photovoltaic system provided by the present application.
  • FIG2 is a block diagram of a DC converter provided by the present application.
  • FIG3A is a schematic diagram of a circuit structure of a DC converter provided by the present application.
  • FIG3B is another circuit structure diagram of a DC converter provided by the present application.
  • FIG3C is another circuit structure diagram of a DC converter provided by the present application.
  • FIG4A is another schematic diagram of a circuit structure of a DC converter provided by the present application.
  • FIG4B is another circuit structure diagram of a DC converter provided by the present application.
  • FIG4C is another circuit structure diagram of a DC converter provided by the present application.
  • FIG5 is a structural block diagram of the photovoltaic system provided in the present application.
  • the DC converter provided in the present application is suitable for various application fields such as the field of new energy intelligent microgrid, the field of power transmission and distribution or the field of new energy, the field of photovoltaic power generation, the field of wind power generation, the field of energy storage power generation, the field of high-power converters, etc.
  • the specific application can be determined according to the actual application scenario and is not limited here.
  • the DC converter provided in the present application can be adapted to different application scenarios, such as photovoltaic power supply application scenarios, energy storage power supply application scenarios or other application scenarios.
  • the DC converter is a photovoltaic optimizer and the DC power supply is a photovoltaic module.
  • the DC converter is a battery optimizer and the DC power supply is an energy storage battery pack, or the DC converter is a battery cluster controller and the DC power supply is an energy storage battery cluster.
  • the photovoltaic power supply application scenario will be used as an example for explanation below, and no further details will be given below.
  • FIG. 1 is a schematic diagram of an application scenario of a photovoltaic system provided in the present application.
  • the DC converter is a photovoltaic optimizer and the DC power supply is a photovoltaic module.
  • the photovoltaic system includes photovoltaic modules 10a to 10n, photovoltaic optimizers 11a to 11n, and a photovoltaic inverter 12. Among them, photovoltaic modules 10a to 10n correspond to and are connected to photovoltaic optimizers 11a to 11n one by one.
  • the input end of the photovoltaic optimizer 11a is used to connect the photovoltaic module 10a
  • the input end of the photovoltaic optimizer 11b is used to connect the photovoltaic module 10b
  • the input end of the photovoltaic optimizer 11n is used to connect the photovoltaic module 10n
  • the output ends of the photovoltaic optimizers 11a to 11n are connected in series to the input end of the photovoltaic inverter 12, and the output end of the photovoltaic inverter 12 is used to connect the power grid 13.
  • the photovoltaic optimizer 11a to the photovoltaic optimizer 11n is used to convert the DC power provided by the photovoltaic assembly 10a to the photovoltaic assembly 10n into a first voltage.
  • the photovoltaic inverter 12 is used to invert the first series voltage of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n into an AC voltage and supply power to the power grid 13, wherein the first series voltage is the sum of the first voltages at the output ends of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n.
  • the series voltage at the output end of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n is the first series voltage.
  • any photovoltaic optimizer cannot output the first voltage externally, causing the first series voltage output by the photovoltaic optimizers 11a to 11n to the photovoltaic inverter 12 to decrease or even become zero, thereby causing the actual power generation of the photovoltaic inverter 12 to be greatly reduced, that is, the actual power generation of the photovoltaic system to be greatly reduced. Therefore, in the case where the photovoltaic optimizers 11a to 11n do not perform voltage conversion, it is usually identified in advance whether the connection status between the photovoltaic optimizers 11a to 11n and the photovoltaic components connected thereto is an abnormal state.
  • the output terminals of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n are connected in series and output a second series voltage, which is the sum of the safety voltages at the output terminals of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n.
  • the safety voltage is obtained by the newly added safety voltage output circuit (not shown in FIG. 1) inside the photovoltaic optimizer based on the voltage output by the auxiliary power supply, and the voltage amplitude of the safety voltage remains basically unchanged.
  • the series voltage at the output terminal of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n is the second series voltage.
  • the wiring status of the photovoltaic optimizer 11a to the photovoltaic optimizer 11n is normal.
  • the second series voltage of the photovoltaic optimizers 11a to 11n is less than the product of the preset safety voltage threshold and n, the connection status of some or all DC converters in the photovoltaic optimizers 11a to 11n is abnormal.
  • FIG. 2 is a block diagram of the structure of the DC converter provided by the present application.
  • the DC converter 2 includes a DC conversion circuit 20, an auxiliary power supply 21, and a safety voltage output circuit 22, wherein the input end of the DC conversion circuit 20 is connected in parallel with the input end of the auxiliary power supply 21 as the input end of the DC converter 2, the input end of the DC converter 2 is used to connect the DC power supply 3, the output end of the auxiliary power supply 21 is connected to the input end of the safety voltage output circuit 22, and the output end of the safety voltage output circuit 22 is connected in parallel with the output end of the DC conversion circuit 20 as the output end of the DC converter 2.
  • the auxiliary power supply 21 can be a low-voltage power supply that provides stable power for the controller and drive circuit in the DC converter 2.
  • the voltage output by the auxiliary power supply 21 can be between 5V and 48V.
  • the safety voltage output circuit 22 can separate the DC conversion circuit 20 and the auxiliary power supply 21 so that the DC conversion circuit 20 and the auxiliary power supply 21 work independently, that is, the DC conversion circuit 20 and the auxiliary power supply 21 will not be interfered by the signal of the other party when they work separately.
  • the auxiliary power supply 21 When the auxiliary power supply 21 is working, the auxiliary power supply 21 is used to output a second voltage to the safety voltage output circuit 22 based on the first voltage provided by the DC power supply 3 when the DC conversion circuit 20 does not perform voltage conversion.
  • the fact that the DC conversion circuit 20 does not perform voltage conversion can be understood as the DC conversion circuit 20 not outputting direct current to the outside.
  • the above second voltage is less than the first voltage.
  • the second voltage can be one of 24V, 12V, 5V, 3.3V and 1.5V. Since the auxiliary power supply 21 can output stable electric energy to the outside, the voltage amplitude of the second voltage remains basically unchanged.
  • the safety voltage output circuit 22 When the safety voltage output circuit 22 is working, the safety voltage output circuit 22 is used to output the safety voltage U sv based on the second voltage, that is, the voltage at the output end of the DC converter 2 is the safety voltage U sv .
  • the safety voltage U sv is less than the second voltage, and the safety voltage U sv is a voltage not higher than 36V.
  • the safety voltage U sv is 1V.
  • the safety voltage U sv is used to compare with the preset safety voltage threshold, so as to determine the connection state between the DC converter 2 and the DC power supply 3. In a specific implementation, when the safety voltage U sv is equal to the preset safety voltage threshold, the connection state between the DC converter 2 and the DC power supply 3 is a normal state.
  • the connection state between the DC converter 2 and the DC power supply 3 is an abnormal state, wherein the abnormal state includes the connection between the DC converter 2 and the DC power supply 3 is disconnected or the contact is poor.
  • the abnormal state is the connection between the DC converter 2 and the DC power supply 3 is disconnected.
  • the safety voltage U sv is greater than 0 and less than the preset safety voltage threshold, the abnormal state is that the connection between the DC converter 2 and the DC power supply 3 is poorly connected.
  • the preset safety voltage threshold is the theoretical value of the safety voltage U sv .
  • the preset safety voltage threshold is a fixed voltage, but in actual situations, the preset safety voltage threshold will fluctuate within a small voltage range a, and the small voltage range a is (fixed voltage-fixed voltage*output voltage accuracy of the safety voltage output circuit 22) ⁇ (fixed voltage+fixed voltage*output voltage accuracy of the safety voltage output circuit 22).
  • the output voltage accuracy of the safety voltage output circuit 22 is generally within 1%. It should be understood that when the safety voltage U sv is in the above-mentioned small voltage range a, the connection state between the DC converter 2 and the DC power supply 3 is a normal state. When the safety voltage U sv is outside the above-mentioned small voltage range a, the connection state between the DC converter 2 and the DC power supply 3 is an abnormal state.
  • the voltage amplitude of the second voltage is substantially unchanged and the output voltage accuracy of the safety voltage output circuit 22 is high, Therefore, the voltage amplitude of the safety voltage U sv is also basically unchanged.
  • the safety voltage U sv at the output end of the DC converter 2 has no voltage ripple or the voltage ripple is very small, thereby reducing the detection error of the safety voltage U sv at the output end of the DC converter 2, thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the wiring state between the DC converter 2 and the DC power supply 3 can be identified in advance when the DC conversion circuit 20 does not perform voltage conversion, thereby ensuring that the DC converter 2 can continuously output DC power to the outside, thereby improving the power supply reliability of the DC converter 2.
  • the DC converter 2 when the DC converter 2 is used in a photovoltaic power supply application scenario, the DC converter 2 is a photovoltaic optimizer and the DC power supply 3 is a photovoltaic module.
  • the DC converter 2 when the DC converter 2 is used in an energy storage power supply application scenario, the DC converter 2 is a battery optimizer and the DC power supply 3 is an energy storage battery pack, or the DC converter 2 is a battery cluster controller and the DC power supply 3 is an energy storage battery cluster.
  • the DC conversion circuit 20 may be one of a boost circuit, a buck circuit, a buck-boost circuit, a flyback circuit, a forward circuit, a push-pull circuit, a half-bridge circuit, and a full-bridge circuit.
  • the DC conversion circuit 20 is taken as a step-down circuit for example.
  • the circuit topology of the DC converter 2 can be shown in FIG3A.
  • the DC conversion circuit 20 shown in FIG2 includes a switch Q1, a switch Q2, a capacitor C1, a capacitor C2, an inductor L, and a diode D1.
  • the output end of the DC conversion circuit 20 includes a first output end and a second output end.
  • the two ends of the capacitor C1 serve as the input ends of the DC conversion circuit 20, one end of the capacitor C1 is connected to the drain of the switch Q1, the source of the switch Q1 is connected to the drain of the switch Q2 and one end of the inductor L, the other end of the inductor L is connected to one end of the capacitor C2 and the cathode of the diode D1, the other end of the capacitor C1 is connected to the source of the switch Q2, the other end of the capacitor C2 and the anode of the diode D1, the cathode of the diode D1 is connected to the first output end of the DC conversion circuit 20, and the anode of the diode D1 is connected to the second output end of the DC conversion circuit 20.
  • the specific circuit topology of the DC conversion circuit 20 is not limited here.
  • the safety voltage output circuit 22 shown in FIG2 includes a voltage divider circuit 220 and a switch Q3, wherein a first connection end of the voltage divider circuit 220 is connected to an output end of the auxiliary power supply 21, a second connection end of the voltage divider circuit 220 is used to connect to a first output end of the DC conversion circuit 20, and a third connection end of the voltage divider circuit 220 is used to connect to a second output end of the DC conversion circuit 20.
  • the switch Q3 is arranged between the second connection end of the voltage divider circuit 220 and the first output end of the DC conversion circuit 20, and at this time, the first connection end of the voltage divider circuit 220 serves as an input end of the safety voltage output circuit 22, and the drain of the switch Q3 and the third connection end of the voltage divider circuit 220 serve as an output end of the safety voltage output circuit 22.
  • the switch Q3 can also be set at other positions in the safety voltage output circuit 22. As shown in Figure 3B, the switch Q3 is set between the first connection terminal of the voltage divider circuit 220 and the output terminal of the auxiliary power supply 21. At this time, the drain of the switch Q3 serves as the input terminal of the safety voltage output circuit 22, and the second connection terminal and the third connection terminal of the voltage divider circuit 220 serve as the output terminal of the safety voltage output circuit 22.
  • the switch Q3 can be any switch including an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), a triode, a relay, a contactor, a circuit breaker and other types of switches.
  • IGBT insulated gate bipolar transistor
  • MOSFET metal-oxide-semiconductor field-effect transistor
  • the switch Q3 is a MOSFET.
  • the DC converter 2 shown in FIG2 further includes a controller 23, and the controller 23 establishes wired or wireless communication with all switches in the DC conversion circuit 20, thereby controlling all switches in the DC conversion circuit 20 to be turned on or off, so that the DC conversion circuit 20 performs voltage conversion on the first voltage provided by the DC power supply 3 and then outputs it.
  • the controller 23 can also establish wired or wireless communication with the switch Q3, thereby controlling the switch Q3 to be turned on or off.
  • the controller 23 is used to control the switch Q3 to be in the on state (i.e., normally on) when the DC conversion circuit 20 does not perform voltage conversion, so that the voltage divider circuit 220 divides the second voltage and outputs the safety voltage U sv , and the safety voltage output circuit 22 is in the working state.
  • the voltage divider circuit 220 includes a voltage divider resistor R1 and a voltage divider resistor R2, and the voltage divider resistor R1 and the voltage divider resistor R2 divide the second voltage to obtain the safety voltage U sv , that is, U sv is the second voltage ⁇ R2/(R1+R2).
  • the voltage divider resistor R2 can output the safety voltage U sv to the outside.
  • the switch Q3 can be controlled to be normally on to make the voltage divider circuit 220 output a stable safety voltage U sv . Therefore, under ideal conditions, the voltage amplitude of the safety voltage U sv at the output end of the DC converter 2 remains substantially unchanged, thereby reducing the detection error of the safety voltage U sv and further improving the accuracy of wiring abnormality detection, and the applicability is strong.
  • the controller 23 is used to receive power from the auxiliary power supply 21, and output a pulse width modulation (PWM) signal to the switch Q2 and the switch Q3 through the switch drive circuit when the DC conversion circuit 20 does not perform voltage conversion, thereby controlling the switch Q2 and the switch Q3 to be turned on or off to form a voltage at the output end of the DC converter 2.
  • PWM pulse width modulation
  • the voltage contains voltage ripples and the voltage amplitude is constantly changing, which will reduce the output voltage accuracy of the DC converter 2, thereby causing the measurement error of the voltage at the output end of the DC converter 2 to become larger, and then causing the accuracy of the abnormal connection detection of the DC converter 2 to be too low.
  • the output voltage accuracy of the DC converter 2 is generally 10%.
  • the safety voltage output circuit 22 provided in the present application will output a safety voltage U sv with a substantially unchanged voltage amplitude, that is, at this time, a safety voltage U sv with a substantially unchanged voltage amplitude will be formed at the output end of the DC converter 2, which is greatly increased.
  • the output voltage accuracy of the DC converter 2 is improved, thereby reducing the detection error of the safety voltage U sv , and further improving the accuracy of the abnormal wiring detection of the DC converter 2, and the applicability is strong.
  • the conventional accuracy of the voltage control chip in the auxiliary power supply 21 is within 2%
  • the resistance accuracy of the voltage divider circuit 220 is within 1%.
  • the output voltage accuracy of the DC converter 2 is generally within 2% to 3%, which greatly improves the output voltage accuracy of the DC converter 2 compared with the prior art, thereby reducing the detection error of the voltage at the output end of the DC converter 2 (i.e., the safety voltage U sv ).
  • the controller 23 is used to control the switch Q3 to be in an on state when no power-on command is received from the DC converter 2, so that the voltage divider circuit 220 outputs a stable safety voltage U sv to the outside, thereby reducing the detection error of the safety voltage U sv , thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the controller 23 is used to control the switch Q3 to remain in the off state when receiving the power-on command of the DC converter 2.
  • the safety voltage output circuit 22 stops outputting the safety voltage U sv and disconnects the connection between the auxiliary power supply 21 and the DC conversion circuit 20, thereby preventing the DC conversion circuit 20 from being interfered by the signal of the auxiliary power supply 21 during operation, and also preventing the high-power current output by the DC conversion circuit 20 from flowing through the auxiliary power supply 21 and burning the auxiliary power supply 21, which is safer and more applicable.
  • the second connection end of the voltage divider circuit 220 is connected to the first output end of the DC conversion circuit 20, and the third connection end of the voltage divider circuit 220 is connected to the second output end of the DC conversion circuit 20.
  • the input end of the power chip 221 serves as the input end of the safety voltage output circuit 22, and the second connection end and the third connection end of the voltage divider circuit 220 serve as the output end of the safety voltage output circuit 22.
  • the controller 23 establishes wired communication or wireless communication with the power chip 221, thereby outputting an enable signal to the power chip 221.
  • the controller 23 is used to send a first enable signal to the power chip 221 when the DC conversion circuit 20 does not perform voltage conversion.
  • the power chip 221 is used to respond to the first enable signal and output the second voltage to the voltage divider circuit 220, so that the voltage divider circuit 220 divides the second voltage and outputs the safety voltage U sv .
  • the voltage divider circuit 220 can be controlled to output a stable safety voltage U sv to the outside by enabling the power chip 221, thereby reducing the detection error of the safety voltage U sv , thereby improving the accuracy of wiring abnormality detection, and having strong applicability.
  • the controller 23 is used to send a second enable signal to the power chip 221 when receiving a power-on command of the DC converter 2.
  • the power chip 221 is used to stop outputting the second voltage to the voltage divider circuit 220 in response to the second enable signal.
  • the safety voltage output circuit 22 stops outputting the safety voltage U sv and disconnects the connection between the auxiliary power supply 21 and the DC conversion circuit 20, thereby preventing the DC conversion circuit 20 from being interfered by the signal of the auxiliary power supply 21 during operation, and also preventing the high-power current output by the DC conversion circuit 20 from flowing through the auxiliary power supply 21 to burn the auxiliary power supply 21, so that the auxiliary power supply 21 is safer to use and more applicable.
  • the first enable signal is at a first level
  • the second enable signal is at a second level
  • the first level and the second level are relative levels.
  • the first level is at a high level
  • the second level is at a low level
  • the second level is at a high level
  • the above-mentioned safety voltage output circuit 22 also includes a protection circuit, which can be arranged between the second connection terminal of the voltage divider circuit 220 and the first output terminal out 11 of the DC conversion circuit 20.
  • the protection circuit 222 is used to perform circuit protection on the voltage divider circuit 220, and the circuit protection is mainly to protect the voltage divider resistor in the voltage divider circuit 220 from being damaged under the conditions of overvoltage, overcurrent, surge and electromagnetic interference, so as to ensure the safety of the use of the voltage divider resistor and extend its service life, and the applicability is stronger.
  • This application does not limit the specific circuit topology of the protection circuit.
  • the protection circuit includes a current limiting resistor or a diode, wherein the current limiting resistor or the diode is arranged between the second connection end of the voltage divider circuit 220 and the first output end of the DC conversion circuit 20, thereby realizing current limiting protection or overvoltage protection of the voltage divider circuit 220.
  • the safety voltage output circuit 22 shown in FIG. 3A above also includes a protection circuit 222, and the protection circuit 222 and the switch Q3 can be connected in series between the second connection end of the voltage divider circuit 220 and the first output end of the DC conversion circuit 20, and the circuit positions of the protection circuit 222 and the switch Q3 can be interchanged.
  • the protection circuit 222 includes a current limiting resistor R3.
  • the current limiting resistor R3 is used to limit the current flowing through the voltage divider circuit 220, thereby preventing the DC conversion circuit 20 from outputting a large current to the voltage divider circuit 220, thereby burning the voltage divider resistor, and the use safety is higher.
  • the current limiting resistor R3 can also be replaced by a diode. When the DC conversion circuit 20 is working, the output voltage of the DC conversion circuit 20 is high.
  • the diode is in the cut-off state, thereby preventing the DC conversion circuit 20 from outputting a high voltage to the voltage divider circuit 220 and causing the voltage divider resistor to fail, thereby extending the voltage divider resistor. Service life.
  • the safety voltage output circuit 22 shown in FIG3B above further includes a protection circuit 223, and the protection circuit 223 includes a current limiting resistor R4 and a diode D2, wherein the current limiting resistor R4 and the diode D2 are connected in series between the second connection end of the voltage divider circuit 220 and the first output end of the DC conversion circuit 20, thereby realizing current limiting protection and overvoltage protection of the voltage divider circuit 220.
  • the diode D2 may not be provided in the safety voltage output circuit 22, and no specific limitation is made here.
  • the safety voltage output circuit 22 shown in FIG3C above also includes a protection circuit 223, and the protection circuit 223 includes a current limiting resistor R4 and a diode D2, wherein the current limiting resistor R4 and the diode D2 are connected in series between the second connection end of the voltage divider circuit 220 and the first output end of the DC conversion circuit 20, thereby realizing current limiting protection and overvoltage protection of the voltage divider circuit 220.
  • the diode D2 may not be set in the safety voltage output circuit 22, and no specific limitation is made here.
  • the controller 23 is used to control the DC conversion circuit 20 to convert the first voltage and output it when receiving a power-on command from the DC converter 2, thereby ensuring that the DC converter 2 outputs stable DC power and providing higher power supply reliability.
  • the controller 23 is used to control the switch Q3 to remain in an off state or output a second enable signal to the power chip 221 when receiving a power-on instruction of the DC converter 2, and control the DC conversion circuit 20 to convert the first voltage and output it after the safety voltage output circuit 22 stops outputting the safety voltage U sv .
  • the auxiliary power supply 21 can be prevented from burning out, and the DC converter 2 can also be ensured to output stable DC power, with higher power supply safety and reliability.
  • FIG. 5 is a block diagram of a photovoltaic system provided by the present application.
  • the photovoltaic system 4 includes a DC converter 40a to a DC converter 40n and a photovoltaic inverter 41, wherein the input end of each DC converter in the DC converter 40a to the DC converter 40n is used to connect a photovoltaic module, thereby realizing the maximum power point tracking and fast shutdown function of the photovoltaic module.
  • the input end of the DC converter 40a is used to connect the photovoltaic module 5a
  • the input end of the DC converter 40b is used to connect the photovoltaic module 5b
  • the input end of the DC converter 40c is used to connect the photovoltaic module 5c
  • the input end of the DC converter 40n is used to connect the photovoltaic module 5n.
  • the output ends of the DC converters 40a to the DC converters 40n are connected in series and then connected to the input end of the photovoltaic inverter 41, so as to flexibly adjust the total output power of the DC converters 40a to the DC converters 40n.
  • the output terminals of the DC converters 40a to 40n are connected in series, which means that the negative pole of the output terminal of one of the DC converters in any two adjacent DC converters is connected to the positive pole of the output terminal of the other DC converter.
  • the output terminal of the photovoltaic inverter 41 is used to connect to the power grid 6 for grid-connected power generation.
  • the photovoltaic inverter 41 can be a household photovoltaic inverter or an industrial and commercial photovoltaic inverter.
  • the DC conversion circuits in the DC converters 40a to 40n perform voltage conversion
  • the DC conversion circuits in each DC converter are used to perform voltage conversion on the DC power provided by the photovoltaic assembly connected to each DC converter and then output a first voltage.
  • the first voltages output by any two DC converters in the DC converters 40a to 40n can be the same or different.
  • the photovoltaic inverter 41 is used to invert the first series voltage of the DC converters 40a to 40n into an AC voltage and supply power to the power grid 6.
  • the first series voltage is the sum of the first voltages at the output ends of the DC converters 40a to 40n.
  • the series voltage at the output ends of the DC converters 40a to 40n is the first series voltage.
  • the output terminals of the DC converter 40a to the DC converter 40n are connected in series and then output a second series voltage, which is the sum of the safety voltages of the output terminals of the DC converter 40a to the DC converter 40n.
  • the second series voltage Usc is the product of the safety voltage of the output terminal of the DC converter and n.
  • the series voltage of the output terminal of the DC converter 40a to the DC converter 40n is the second series voltage.
  • the connection status of all the DC converters in the DC converters 40a to 40n is normal.
  • the connection status of some or all of the DC converters in the DC converters 40a to 40n is abnormal.
  • the connection status of the DC converter includes the connection status between the DC converter and the photovoltaic module connected to it.
  • the abnormal state includes at least one of a connection state, a connection state between the DC converter and an adjacent DC converter, and a connection state between the DC converter and the photovoltaic inverter 41.
  • the abnormal state includes at least one of a disconnection or poor contact between the DC converter and the photovoltaic assembly connected thereto, a connection between the negative pole of the output end of the DC converter and the negative pole of the output end of the adjacent DC converter, a connection between the positive pole of the output end of the DC converter and the positive pole of the output end of the adjacent DC converter, and a disconnection or poor contact between the DC converter and the photovoltaic inverter 41.
  • the above-mentioned preset safety voltage threshold is the theoretical value of the safety voltage.
  • the product of the preset safety voltage threshold and n is a fixed voltage, while in actual situations, the product of the preset safety voltage threshold and n will fluctuate within a small voltage range b, and the small voltage range b is (fixed voltage-fixed voltage*output voltage accuracy of the safety voltage output circuit in the DC converter)*n ⁇ (fixed voltage+fixed voltage*output voltage accuracy of the safety voltage output circuit in the DC converter)*n.
  • each DC converter in DC converters 40a to 40n can refer to the description of the specific structure and working principle of DC converter 2 in the embodiments corresponding to Figures 2 to 4C above, which will not be repeated here.
  • the detection error of the safety voltage at the output end of each DC converter can be reduced, thereby reducing the detection error of the sum of the safety voltages at the output ends of the DC converters 40a to 40n (i.e., the second series voltage U sc ), thereby improving the accuracy of wiring abnormality detection, and the power supply reliability of the photovoltaic system 4 is higher.
  • the number n of the DC converters 40a to 40n is less than or equal to 20, it is possible to accurately identify whether the wiring state of the DC converter is abnormal, and when the number n is greater than or equal to 50, the detection error of the safety voltage at the output end of a DC converter is accumulated, but in actual application scenarios, so many DC converters will not be connected in series, so the accuracy of wiring abnormality detection is greatly improved, and the applicability is stronger.

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Abstract

本申请提供一种直流变换器以及光伏系统，直流变换电路的输入端与辅助电源的输入端并联后作为直流变换器的输入端，直流变换器的输入端用于连接直流电源，辅助电源的输出端连接安全电压输出电路的输入端，安全电压输出电路的输出端与直流变换电路的输出端并联后作为直流变换器的输出端。辅助电源用于在直流变换电路未进行电压转换的情况下，基于直流电源提供的第一电压向安全电压输出电路输出第二电压。安全电压输出电路用于基于第二电压输出安全电压。安全电压用于与预设安全电压阈值进行比较，从而确定直流变换器与直流电源之间的接线状态。在本申请中，可减小直流变换器的输出端的安全电压的检测误差，提高了接线异常检测的精准度。

Description

直流变换器以及光伏系统
本申请要求在2023年10月20日提交中国国家知识产权局、申请号为202311374279.5的中国专利申请的优先权，申请名称为“直流变换器以及光伏系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光伏发电技术领域，尤其涉及一种直流变换器以及光伏系统。
背景技术
光伏优化器是一种直流输入且直流输出的组件级电力电子设备，用于将光伏组件提供的直流电进行电压转换后输出。通常来说，光伏优化器会采取预测电流与电压技术来解决光伏组件由于阴影遮挡、朝向不一致或组件电气规格差异而对光伏系统的发电量造成的影响，实现光伏组件的最大功率输出，从而提升了光伏系统的发电量。
在光伏系统发电的过程中，当光伏优化器与光伏组件之间的接线出现异常时，会导致光伏优化器无法向外输出直流电，光伏优化器的供电可靠性差。因此，为了避免因为光伏优化器的接线异常问题而对光伏优化器的供电可靠性造成的影响，如何提前识别光伏优化器与光伏组件之间的接线是否异常变得尤为重要。
发明内容
本申请提供一种直流变换器以及光伏系统，可减小直流变换器的输出端的安全电压的检测误差，从而提高了接线异常检测的精准度，适用性强。
第一方面，本申请提供一种直流变换器，该直流变换器包括直流变换电路、辅助电源以及安全电压输出电路，其中，直流变换电路的输入端与辅助电源的输入端并联后作为直流变换器的输入端，直流变换器的输入端用于连接直流电源，辅助电源的输出端连接安全电压输出电路的输入端，安全电压输出电路的输出端与直流变换电路的输出端并联后作为直流变换器的输出端。辅助电源用于在直流变换电路未进行电压转换的情况下，基于直流电源提供的第一电压向安全电压输出电路输出第二电压，其中，第二电压小于第一电压。由于辅助电源可以向外输出稳定的电能，因此第二电压的电压幅值基本不变。进一步地，安全电压输出电路用于基于第二电压输出安全电压，即此时直流变换器的输出端的电压为安全电压，其中，安全电压小于第二电压。该安全电压用于与预设安全电压阈值进行比较，从而确定直流变换器与直流电源之间的接线状态。具体实现中，当安全电压等于预设安全电压阈值时，直流变换器与直流电源之间的接线状态为正常状态。而当安全电压小于预设安全电压阈值时，直流变换器与直流电源之间的接线状态为异常状态。其中，该预设安全电压阈值为安全电压的理论值。
实施本申请实施例，由于第二电压的电压幅值基本不变且安全电压输出电路的输出电压精度高，因此安全电压的电压幅值也基本不变，此时直流变换器的输出端的安全电压没有电压纹波或者电压纹波很小，从而减小了直流变换器的输出端的安全电压的检测误差，进而提高了接线异常检测的精准度，适用性强。另外，可在直流变换电路未进行电压转换的情况下提前识别直流变换器与直流电源之间的接线状态，从而保证直流变换器可以持续向外输出直流电，进而提高了直流变换器的供电可靠性。
结合第一方面，在一种可能的实施方式中，当直流变换电路的输出端包括第一输出端和第二输出端，安全电压输出电路包括分压电路和开关时，分压电路的第一连接端连接辅助电源的输出端，分压电路的第二连接端连接直流变换电路的第一输出端，分压电路的第三连接端连接直流变换电路的第二输出端。上述开关可以设置在分压电路的第一连接端和辅助电源的输出端之间，或者，开关还可以设置在分压电路的第二连接端和直流变换电路的第一输出端之间，在此不对开关的具体电路位置进行限制。上述直流变换器还包括控制器，用于在直流变换电路未进行电压转换的情况下控制开关处于导通状态(即常通)，以使分压电路对第二电压进行分压并输出安全电压，此时安全电压输出电路处于工作状态。实施本申请实施例，可控制开关常通来使分压电路向外输出稳定的安全电压，因此在理想情况下直流变换器的输出端的安全电压的电压幅值基本不变，从而减小了安全电压的检测误差，进而提高了接线异常检测的精准度，适用性强。
结合第一方面，在一种可能的实施方式中，上述控制器用于在未接收到直流变换器的开机指令的情况下，控制开关处于导通状态，从而使分压电路向外输出稳定的安全电压，从而减小了安全电压的检测误差，进而提高了接线异常检测的精准度，适用性强。
结合第一方面，在一种可能的实施方式中，上述控制器还用于在接收到直流变换器的开机指令的情况下，控制开关处于关断状态。此时，安全电压输出电路会停止输出安全电压并断开辅助电源和直流变换电路之间的连接，从而避免直流变换电路在工作时受到辅助电源的信号干扰，还可以避免直流变换电路输出的大功率电流流过辅助电源从而烧坏辅助电源，安全性更高，适用性更强。
结合第一方面，在一种可能的实施方式中，在直流变换电路的输出端包括第一输出端和第二输出端，安全电压输出电路包括分压电路和电源芯片的情况下，分压电路的第一连接端通过电源芯片连接辅助电源的输出端，分压电路的第二连接端连接直流变换电路的第一输出端，分压电路的第三连接端连接直流变换电路的第二输出端。上述直流变换器还包括控制器，用于在直流变换电路未进行电压转换的情况下向电源芯片下发第一使能信号。此时，电源芯片用于响应于第一使能信号，向分压电路输出第二电压，从而使得分压电路对第二电压进行分压并输出安全电压，此时安全电压输出电路处于工作状态。其中，第一电平可以是高电平或者低电平，在此不作具体限制。实施本申请实施例，可通过电源芯片的使能来控制分压电路向外输出稳定的安全电压，从而减小了安全电压的检测误差，进而提高了接线异常检测的精准度，适用性强。
结合第一方面，在一种可能的实施方式中，上述控制器用于在接收到直流变换器的开机指令的情况下，向电源芯片下发第二使能信号。此时，电源芯片用于响应于第二使能信号，停止向分压电路输出第二电压。此时，安全电压输出电路会停止输出安全电压并断开辅助电源和直流变换电路之间的连接，从而避免直流变换电路在工作时受到辅助电源的信号干扰，还可以避免直流变换电路输出的大功率电流流过辅助电源从而烧坏辅助电源，安全性更高，适用性更强。
结合第一方面，在一种可能的实施方式中，上述第一使能信号为第一电平，第二使能信号为第二电平，其中，第一电平和第二电平为相对电平。具体实现中，当第一电平为高电平时第二电平为低电平，或者，当第一电平为低电平时第二电平为高电平。
结合第一方面，在一种可能的实施方式中，上述安全电压输出电路还包括保护电路，其中，保护电路可以设置在分压电路的第二连接端和直流变换电路的第一输出端之间，在安全电压输出电路还包括上述开关的情况下，保护电路和开关可以串联在分压电路的第二连接端和直流变换电路的第一输出端之间。上述保护电路用于对分压电路进行电路保护，该电路保护主要是保护分压电路中的分压电阻在受到过压、过流、浪涌以及电磁干扰等情况下不受损坏，从而保证分压电阻的使用安全性并延长使用寿命，适用性更强。
结合第一方面，在一种可能的实施方式中，上述保护电路包括限流电阻或者二极管，其中，限流电阻或者二极管设置在分压电路的第二连接端和直流变换电路的第一输出端之间，从而实现分压电路的限流保护或者过压保护。在直流变换电路工作的情况下直流变换电路的输出电流较大，该限流电阻用于限制流过分压电路的电流大小，从而避免直流变换电路向分压电路输出大电流从而烧坏分压电阻，使用安全性更高。在直流变换电路工作的情况下直流变换电路的输出电压较高，此时二极管处于截止状态，从而避免直流变换电路向分压电路输出高电压而导致分压电阻失效，延长了分压电阻的使用寿命。
结合第一方面，在一种可能的实施方式中，上述保护电路包括限流电阻和二极管，其中，限流电阻和二极管串联在分压电路的第二连接端和直流变换电路的第一输出端之间，从而实现分压电路的限流保护和过压保护。
结合第一方面，在一种可能的实施方式中，上述直流变换器还包括控制器，用于在接收到直流变换器的开机指令的情况下，控制直流变换电路对第一电压进行电压转换后输出，从而保证直流变换器输出稳定的直流电，供电可靠性更高。
第二方面，本申请提供一种光伏系统，该光伏系统包括多个如上述第一方面及其可能的实施方式中任一种提供的直流变换器以及光伏逆变器。其中，多个直流变换器中的每个直流变换器的输入端用于连接光伏组件，多个直流变换器的输出端串联后连接光伏逆变器的输入端，光伏逆变器的输出端用于连接电网。在多个直流变换器中的直流变换电路进行电压转换的情况下，每个直流变换器中的直流变换电路用于对每个直流变换器连接的光伏组件提供的直流电进行电压转换后输出第一电压，其中，多个直流变换器中的任意两个直流变换器输出的第一电压可以相同，也可以不同。此时，光伏逆变器用于将多个直流变换器的第一串联电压逆变为交流电压并向电网供电，其中，第一串联电压为多个直流变换器的输出端的第一电压的 总和。
在多个直流变换器中的直流变换电路未进行电压转换的情况下，多个直流变换器的输出端串联后输出第二串联电压，其中，第二串联电压为多个直流变换器的输出端的安全电压的总和。当第二串联电压等于预设安全电压阈值与多个直流变换器的数量的乘积时，多个直流变换器中的所有直流变换器的接线状态为正常状态。而当第二串联电压小于预设安全电压阈值与多个直流变换器的数量的乘积时，多个直流变换器中的部分直流变换器或者所有直流变换器的接线状态为异常状态。该异常状态包括直流变换器与其连接的光伏组件之间的接线断开或者接触不良，直流变换器的输出端的负极与相邻直流变换器的输出端的负极连接，直流变换器的输出端的正极与相邻直流变换器的输出端的正极连接，以及直流变换器与光伏逆变器之间的接线断开或者接触不良中的至少一种。实施本申请实施例，由于安全电压的电压幅值基本不变，因此可减小每个直流变换器的输出端的安全电压的检测误差，从而减小多个直流变换器的输出端的安全电压的总和(即第二串联电压)的检测误差，进而提高了接线异常检测的精准度，光伏系统的供电可靠性更高。
在本申请中，由于第二电压的电压幅值基本不变且安全电压输出电路的输出电压精度高，因此安全电压的电压幅值也基本不变，此时直流变换器的输出端的安全电压没有电压纹波或者电压纹波很小，从而减小了直流变换器的输出端的安全电压的检测误差，进而提高了接线异常检测的精准度，适用性强。另外，可在直流变换电路未进行电压转换的情况下提前识别直流变换器与直流电源之间的接线状态，从而保证直流变换器可以持续向外输出直流电，进而提高了直流变换器的供电可靠性。
附图说明
图1是本申请提供的光伏系统的应用场景示意图；
图2是本申请提供的直流变换器的结构框图；
图3A是本申请提供的直流变换器的一种电路结构示意图；
图3B是本申请提供的直流变换器的另一种电路结构示意图；
图3C是本申请提供的直流变换器的另一种电路结构示意图；
图4A是本申请提供的直流变换器的另一种电路结构示意图；
图4B是本申请提供的直流变换器的另一种电路结构示意图；
图4C是本申请提供的直流变换器的另一种电路结构示意图；
图5是本申请提供的光伏系统的结构框图。
具体实施方式
本申请提供的直流变换器适用于新能源智能微网领域、输配电领域或者新能源领域、光伏发电领域、风力发电领域、储能发电领域、大功率变换器领域等多种应用领域，具体可根据实际应用场景确定，在此不做限制。本申请提供的直流变换器可适配不同的应用场景，比如，光伏供电应用场景、储能供电应用场景或者其它应用场景。在光伏供电应用场景下，直流变换器为光伏优化器且直流电源为光伏组件。在储能供电应用场景下，直流变换器为电池优化器且直流电源为储能电池包，或者直流变换器为电池簇控制器且直流电源为储能电池簇。下面将以光伏供电应用场景为例进行说明，以下不再赘述。
参见图1，图1是本申请提供的光伏系统的应用场景示意图。在光伏供电应用场景下，直流变换器为光伏优化器且直流电源为光伏组件，如图1所示，光伏系统包括光伏组件10a至光伏组件10n、光伏优化器11a至光伏优化器11n以及光伏逆变器12。其中，光伏组件10a至光伏组件10n与光伏优化器11a至光伏优化器11n一一对应并进行连接。示例性的，光伏优化器11a的输入端用于连接光伏组件10a，光伏优化器11b的输入端用于连接光伏组件10b，……，光伏优化器11n的输入端用于连接光伏组件10n，光伏优化器11a至光伏优化器11n的输出端串联后连接光伏逆变器12的输入端，光伏逆变器12的输出端用于连接电网13。在光伏优化器11a至光伏优化器11n中的直流变换电路进行电压转换的情况下，光伏优化器11a至光伏优化器11n用于将光伏组件10a至光伏组件10n提供的直流电分别进行电压转换后输出第一电压。光伏逆变器12用于将光伏优化器11a至光伏优化器11n的第一串联电压逆变为交流电压并向电网13供电，其中，第一串联电压为光伏优化器11a至光伏优化器11n的输出端的第一电压的总和。应当理解，当光伏优化器11a至光伏优化器11n中的直流变换电路进行电压转换，且光伏优化器11a至光伏优化器11n中的辅助电源和新增的安全电压输出电路未工作时，光伏优化器11a至光伏优化器11n的输出端的串联电压为第一串联电压。
然而，当光伏优化器11a至光伏优化器11n中的任一光伏优化器与其连接的光伏组件之间的接线出现异常时，任一光伏优化器无法向外输出第一电压，导致光伏优化器11a至光伏优化器11n输出到光伏逆变器12的第一串联电压减小甚至为零，从而导致光伏逆变器12的实际发电量大幅度降低，即光伏系统的实际发电量大幅度降低。因此，在光伏优化器11a至光伏优化器11n未进行电压转换的情况下，通常会提前识别光伏优化器11a至光伏优化器11n及其连接的光伏组件之间的接线状态是否为异常状态。
在光伏优化器11a至光伏优化器11n中的直流变换电路未进行电压转换的情况下，光伏优化器11a至光伏优化器11n的输出端串联后输出第二串联电压，该第二串联电压为光伏优化器11a至光伏优化器11n的输出端的安全电压的总和。其中，安全电压由光伏优化器内部新增的安全电压输出电路(图1中未示出)基于辅助电源输出的电压得到，并且安全电压的电压幅值基本不变。应当理解，当光伏优化器11a至光伏优化器11n中的直流变换电路未进行电压转换，且光伏优化器11a至光伏优化器11n中的辅助电源和新增的安全电压输出电路工作时，光伏优化器11a至光伏优化器11n的输出端的串联电压为第二串联电压。当第二串联电压等于光伏优化器的预设安全电压阈值与光伏优化器11a至光伏优化器11n的数量n的乘积时，光伏优化器11a至光伏优化器11n的接线状态均为正常状态。而当光伏优化器11a至光伏优化器11n的第二串联电压小于预设安全电压阈值与n的乘积时，光伏优化器11a至光伏优化器11n中的部分直流变换器或者所有直流变换器的接线状态为异常状态。
实施本申请实施例，可提前识别光伏优化器11a至光伏优化器11n的接线状态是否为异常状态，从而保证在光伏系统供电的过程中光伏优化器11a至光伏优化器11n均可以正常输出第一电压，进而提升了光伏系统的发电量，适用性强。
下面将结合图2至图5对本申请提供的直流变换器、光伏系统及其工作原理进行示例说明。
参见图2，图2是本申请提供的直流变换器的结构框图。如图2所示，直流变换器2包括直流变换电路20、辅助电源21以及安全电压输出电路22，其中，直流变换电路20的输入端与辅助电源21的输入端并联后作为直流变换器2的输入端，直流变换器2的输入端用于连接直流电源3，辅助电源21的输出端连接安全电压输出电路22的输入端，安全电压输出电路22的输出端与直流变换电路20的输出端并联后作为直流变换器2的输出端。辅助电源21可以是为直流变换器2中的控制器和驱动电路等提供稳定电能的低压电源，示例性的，辅助电源21输出的电压可以在5V至48V之间。安全电压输出电路22可以将直流变换电路20和辅助电源21分开以使直流变换电路20和辅助电源21独立工作，即直流变换电路20和辅助电源21分别工作时不会受到对方的信号干扰。
在辅助电源21工作的情况下，辅助电源21用于在直流变换电路20未进行电压转换的情况下，基于直流电源3提供的第一电压向安全电压输出电路22输出第二电压。其中，直流变换电路20未进行电压转换可以理解为直流变换电路20不会向外输出直流电。上述第二电压小于第一电压，示例性的，第二电压可以是24V、12V、5V、3.3V以及1.5V中的一种。由于辅助电源21可以向外输出稳定的电能，因此第二电压的电压幅值基本不变。
在安全电压输出电路22工作的情况下，安全电压输出电路22用于基于第二电压输出安全电压Usv，即此时直流变换器2的输出端的电压为安全电压Usv。其中，安全电压Usv小于第二电压，并且安全电压Usv为不高于36V的电压。示例性的，安全电压Usv为1V。该安全电压Usv用于与预设安全电压阈值进行比较，从而确定直流变换器2与直流电源3之间的接线状态。具体实现中，当安全电压Usv等于预设安全电压阈值时，直流变换器2与直流电源3之间的接线状态为正常状态。而当安全电压Usv小于预设安全电压阈值时，直流变换器2与直流电源3之间的接线状态为异常状态，其中，异常状态包括直流变换器2与直流电源3之间的接线断开或者接触不良。示例性的，当安全电压Usv为0，即直流变换器2的输出端检测不到电压时，异常状态为直流变换器2与直流电源3之间的接线断开。而当安全电压Usv大于0且小于预设安全电压阈值时，异常状态为直流变换器2与直流电源3之间的接线接触不良。
其中，该预设安全电压阈值为安全电压Usv的理论值。在理想情况下，预设安全电压阈值为固定电压，而在实际情况下，预设安全电压阈值会在小电压范围a内波动，小电压范围a为(固定电压-固定电压*安全电压输出电路22的输出电压精度)～(固定电压+固定电压*安全电压输出电路22的输出电压精度)。示例性的，安全电压输出电路22的输出电压精度一般在1％以内。应当理解，当安全电压Usv处于上述小电压范围a时，直流变换器2与直流电源3之间的接线状态为正常状态。而当安全电压Usv在上述小电压范围a之外时，直流变换器2与直流电源3之间的接线状态为异常状态。
实施本申请实施例，由于第二电压的电压幅值基本不变且安全电压输出电路22的输出电压精度高， 因此安全电压Usv的电压幅值也基本不变，此时直流变换器2的输出端的安全电压Usv没有电压纹波或者电压纹波很小，从而减小了直流变换器2的输出端的安全电压Usv的检测误差，进而提高了接线异常检测的精准度，适用性强。另外，可在直流变换电路20未进行电压转换的情况下提前识别直流变换器2与直流电源3之间的接线状态，从而保证直流变换器2可以持续向外输出直流电，进而提高了直流变换器2的供电可靠性。
在一些可行的实施方式中，在直流变换器2应用在光伏供电应用场景下，直流变换器2为光伏优化器且直流电源3为光伏组件。在直流变换器2应用在储能供电应用场景下，直流变换器2为电池优化器且直流电源3为储能电池包，或者直流变换器2为电池簇控制器且直流电源3为储能电池簇。
在一些可行的实施方式中，直流变换电路20可以是升压电路、降压电路、升降压电路、反激电路、正激电路、推挽电路、半桥电路以及全桥电路中的一种。
在一些可行的实施方式中，以直流变换电路20为降压电路为例进行说明，上述直流变换器2的电路拓扑可以如图3A所示，上述图2所示的直流变换电路20包括开关Q1、开关Q2、电容C1、电容C2、电感L以及二极管D1，直流变换电路20的输出端包括第一输出端和第二输出端。其中，电容C1的两端作为直流变换电路20的输入端，电容C1的一端连接开关Q1的漏极，开关Q1的源极连接开关Q2的漏极和电感L的一端，电感L的另一端连接电容C2的一端和二极管D1的阴极，电容C1的另一端连接开关Q2的源极、电容C2的另一端和二极管D1的阳极，二极管D1的阴极连接直流变换电路20的第一输出端，二极管D1的阳极连接直流变换电路20的第二输出端，在此不对直流变换电路20的具体电路拓扑进行限制。
在一些可行的实施方式中，如图3A所示，上述图2所示的安全电压输出电路22包括分压电路220和开关Q3，分压电路220的第一连接端连接辅助电源21的输出端，分压电路220的第二连接端用于连接直流变换电路20的第一输出端，分压电路220的第三连接端用于连接直流变换电路20的第二输出端。上述开关Q3设置在分压电路220的第二连接端和直流变换电路20的第一输出端之间，此时，分压电路220的第一连接端作为安全电压输出电路22的输入端，开关Q3的漏极和分压电路220的第三连接端作为安全电压输出电路22的输出端。可选的，开关Q3还可以设置在安全电压输出电路22中的其他位置，如图3B所示，开关Q3设置在分压电路220的第一连接端和辅助电源21的输出端之间，此时，开关Q3的漏极作为安全电压输出电路22的输入端，分压电路220的第二连接端和第三连接端作为安全电压输出电路22的输出端。
其中，开关Q3可以是绝缘栅双极性晶体管(insulated gate bipolar transistor，可以简称为IGBT)、金属氧化物半导体场效应晶体管(metal-oxide-semiconductor field-effect transistor，可以简称为MOSFET)、三级管、继电器、接触器、断路器以及其他类型开关中的任一种开关，示例性的，如图3A所示，开关Q3为MOSFET。
在一些可行的实施方式中，如图3A所示，上述图2所示的直流变换器2还包括控制器23，控制器23与直流变换电路20中的所有开关建立有线通信或者无线通信，从而控制直流变换电路20中的所有开关导通或者关断，从而使得直流变换电路20对直流电源3提供的第一电压进行电压转换后输出。控制器23还可与开关Q3建立有线通信或者无线通信，从而控制开关Q3导通或者关断。
在一些可行的实施方式中，控制器23用于在直流变换电路20未进行电压转换的情况下，控制开关Q3处于导通状态(即常通)，从而使得分压电路220对第二电压进行分压并输出安全电压Usv，此时安全电压输出电路22处于工作状态。示例性的，分压电路220包括分压电阻R1和分压电阻R2，分压电阻R1和分压电阻R2对第二电压进行分压得到安全电压Usv，即Usv为第二电压×R2/(R1+R2)。在开关Q3保持导通状态的情况下，分压电阻R2可以向外输出安全电压Usv。实施本申请实施例，可控制开关Q3常通来使分压电路220向外输出稳定的安全电压Usv，因此在理想情况下直流变换器2的输出端的安全电压Usv的电压幅值基本不变，从而减小了安全电压Usv的检测误差，进而提高了接线异常检测的精准度，适用性强。
应当理解，在现有技术中，控制器23用于接收辅助电源21供电，并在直流变换电路20未进行电压转换的情况下通过开关驱动电路向开关Q2和开关Q3输出脉宽调制(pulse width modulation wave，PWM)信号，从而控制开关Q2和开关Q3导通或者关断以在直流变换器2的输出端形成一个电压。然而，该电压包含电压纹波并且电压幅值不断变化，会降低直流变换器2的输出电压精度，从而导致直流变换器2的输出端的电压的测量误差变大，进而导致直流变换器2接线异常检测的精准度过低。示例性的，在现有技术中直流变换器2的输出电压精度一般为10％。而本申请提供的安全电压输出电路22则会输出电压幅值基本不变的安全电压Usv，即此时直流变换器2的输出端会形成一个电压幅值基本不变的安全电压Usv，大幅度 提高了直流变换器2的输出电压精度，从而减小了安全电压Usv的检测误差，进而提高了直流变换器2接线异常检测的精准度，适用性强。示例性的，在理想情况下，辅助电源21中的电压控制芯片的常规精度在2％以内，而分压电路220的电阻精度在1％以内，在结合安全电压输出电路22的其他电路参数误差的情况下，直流变换器2的输出电压精度一般在2％～3％以内，与现有技术相比大幅度提高了直流变换器2的输出电压精度，从而减小了直流变换器2的输出端的电压(即安全电压Usv)的检测误差。
在一些可行的实施方式中，上述控制器23用于在未接收到直流变换器2的开机指令的情况下，控制开关Q3处于导通状态，从而使分压电路220向外输出稳定的安全电压Usv，从而减小了安全电压Usv的检测误差，进而提高了接线异常检测的精准度，适用性强。
在一些可行的实施方式中，上述控制器23用于在接收到直流变换器2的开机指令的情况下，控制开关Q3保持关断状态。此时，安全电压输出电路22会停止输出安全电压Usv并断开辅助电源21和直流变换电路20之间的连接，从而避免直流变换电路20在工作时受到辅助电源21的信号干扰，还可以避免直流变换电路20输出的大功率电流流过辅助电源21从而烧坏辅助电源21，安全性更高，适用性更强。
在一些可行的实施方式中，上述图3A和图3B所示的安全电压输出电路22也可以替换为图3C所示的安全电压输出电路22，安全电压输出电路22包括分压电路220和电源芯片221，该电源芯片221是安全电压输出电路22中具有实现电能的变换、分配和检测等功能的芯片。其中，分压电路220的第一连接端通过电源芯片221连接辅助电源21的输出端，具体地，电源芯片221的输入端连接辅助电源21的输出端，电源芯片221的输出端连接分压电路220的第一连接端。分压电路220的第二连接端连接直流变换电路20的第一输出端，分压电路220的第三连接端连接直流变换电路20的第二输出端。此时，电源芯片221的输入端作为安全电压输出电路22的输入端，分压电路220的第二连接端和第三连接端作为安全电压输出电路22的输出端。
在一些可行的实施方式中，控制器23与电源芯片221建立有线通信或者无线通信，从而向电源芯片221输出使能信号。具体实现中，控制器23用于在直流变换电路20未进行电压转换的情况下，向电源芯片221下发第一使能信号。此时，电源芯片221用于响应于第一使能信号，向分压电路220输出第二电压，从而使得分压电路220对第二电压进行分压并输出安全电压Usv。实施本申请实施例，可通过电源芯片221的使能(enable)来控制分压电路220向外输出稳定的安全电压Usv，从而减小了安全电压Usv的检测误差，进而提高了接线异常检测的精准度，适用性强。
在一些可行的实施方式中，控制器23用于在接收到直流变换器2的开机指令的情况下，向电源芯片221下发第二使能信号。此时，电源芯片221用于响应于第二使能信号，停止向分压电路220输出第二电压。此时，安全电压输出电路22会停止输出安全电压Usv并断开辅助电源21和直流变换电路20之间的连接，从而避免直流变换电路20在工作时受到辅助电源21的信号干扰，还可以避免直流变换电路20输出的大功率电流流过辅助电源21以烧坏辅助电源21，辅助电源21的使用安全性更高，适用性更强。
在一些可行的实施方式中，上述第一使能信号为第一电平，第二使能信号为第二电平，其中，第一电平和第二电平为相对电平。示例性的，当第一电平为高电平时第二电平为低电平，或者，当第一电平为低电平时第二电平为高电平。
在一些可行的实施方式中，上述安全电压输出电路22还包括保护电路，该保护电路可以设置在分压电路220的第二连接端和直流变换电路20的第一输出端out11之间。其中，保护电路222用于对分压电路220进行电路保护，该电路保护主要是保护分压电路220中的分压电阻在受到过压、过流、浪涌以及电磁干扰等情况下不受损坏，从而保证分压电阻的使用安全性并延长使用寿命，适用性更强。本申请不对保护电路的具体电路拓扑进行限制。
在一些可行的实施方式中，保护电路包括限流电阻或者二极管，其中，限流电阻或者二极管设置在分压电路220的第二连接端和直流变换电路20的第一输出端之间，从而实现分压电路220的限流保护或者过压保护。如图4A所示，上述图3A所示的安全电压输出电路22还包括保护电路222，保护电路222和开关Q3可以串联在分压电路220的第二连接端和直流变换电路20的第一输出端之间，并且，保护电路222和开关Q3的电路位置可以互换。其中，保护电路222包括限流电阻R3。在直流变换电路20工作的情况下直流变换电路20的输出电流较大，该限流电阻R3用于限制流过分压电路220的电流大小，从而避免直流变换电路20向分压电路220输出大电流从而烧坏分压电阻，使用安全性更高。可选的，限流电阻R3也可以替换为二极管。在直流变换电路20工作的情况下直流变换电路20的输出电压较高，此时二极管处于截止状态，从而避免直流变换电路20向分压电路220输出高电压而导致分压电阻失效，延长了分压电阻的 使用寿命。
在一些可行的实施方式中，如图4B所示，上述图3B所示的安全电压输出电路22还包括保护电路223，保护电路223包括限流电阻R4和二极管D2，其中，限流电阻R4和二极管D2串联在分压电路220的第二连接端和直流变换电路20的第一输出端之间，从而实现分压电路220的限流保护和过压保护。可选的，当上述分压电阻R1、分压电阻R2、开关Q3以及辅助电源21在设计时所能承受的电压较高，并且在高电压场景下不具有失效风险可以正常工作时，安全电压输出电路22中也可以不设置二极管D2，在此不作具体限制。
在一些可行的实施方式中，如图4C所示,上述图3C所示的安全电压输出电路22还包括保护电路223，保护电路223包括限流电阻R4和二极管D2，其中，限流电阻R4和二极管D2串联在分压电路220的第二连接端和直流变换电路20的第一输出端之间，从而实现分压电路220的限流保护和过压保护。可选的，当上述分压电阻R1、分压电阻R2、电源芯片221以及辅助电源21在设计时所能承受的电压较高，并且在高电压场景下不具有失效风险可以正常工作时，安全电压输出电路22中也可以不设置二极管D2，在此不作具体限制。
在一些可行的实施方式中，上述控制器23用于在接收到直流变换器2的开机指令的情况下，控制直流变换电路20对第一电压进行电压转换后输出，从而保证直流变换器2输出稳定的直流电，供电可靠性更高。
在一些可行的实施方式中，上述控制器23用于在接收到直流变换器2的开机指令的情况下，控制开关Q3保持关断状态或者向电源芯片221输出第二使能信号，并在安全电压输出电路22停止输出安全电压Usv之后控制直流变换电路20对第一电压进行电压转换后输出。实施本申请实施例，可避免辅助电源21烧坏，并且还可以保证直流变换器2输出稳定的直流电，供电安全性和供电可靠性更高。
参见图5，图5是本申请提供的光伏系统的结构框图。如图5所示，光伏系统4包括直流变换器40a至直流变换器40n以及光伏逆变器41，其中，直流变换器40a至直流变换器40n中的每个直流变换器的输入端用于连接光伏组件，从而实现对光伏组件的最大功率点跟踪和快速关断功能。示例性的，直流变换器40a的输入端用于连接光伏组件5a，直流变换器40b的输入端用于连接光伏组件5b，直流变换器40c的输入端用于连接光伏组件5c，……，直流变换器40n的输入端用于连接光伏组件5n。直流变换器40a至直流变换器40n的输出端串联后连接光伏逆变器41的输入端，从而灵活调整直流变换器40a至直流变换器40n的输出功率总和。其中，直流变换器40a至直流变换器40n的输出端串联是指任意两个相邻直流变换器中的其中一个直流变换器的输出端的负极和另外一个直流变换器的输出端的正极连接。光伏逆变器41的输出端用于连接电网6进行并网发电。示例性的，光伏逆变器41可以是户用光伏逆变器或者工商业光伏逆变器。
在直流变换器40a至直流变换器40n中的直流变换电路进行电压转换的情况下，每个直流变换器中的直流变换电路用于对每个直流变换器连接的光伏组件提供的直流电进行电压转换后输出第一电压。其中，直流变换器40a至直流变换器40n中的任意两个直流变换器输出的第一电压可以相同，也可以不同。此时，光伏逆变器41用于将直流变换器40a至直流变换器40n的第一串联电压逆变为交流电压并向电网6供电。其中，第一串联电压为直流变换器40a至直流变换器40n的输出端的第一电压的总和。应当理解，当直流变换器40a至直流变换器40n中的直流变换电路进行电压转换，且直流变换器40a至直流变换器40n中的辅助电源和安全电压输出电路未工作时，直流变换器40a至直流变换器40n的输出端的串联电压为第一串联电压。
在直流变换器40a至直流变换器40n中的直流变换电路未进行电压转换的情况下，直流变换器40a至直流变换器40n的输出端串联后输出第二串联电压，该第二串联电压为直流变换器40a至直流变换器40n的输出端的安全电压的总和。示例性的，在理想情况下，第二串联电压Usc为直流变换器的输出端的安全电压与n的乘积。应当理解，当直流变换器40a至直流变换器40n中的直流变换电路未进行电压转换，且直流变换器40a至直流变换器40n中的辅助电源和安全电压输出电路工作时，直流变换器40a至直流变换器40n的输出端的串联电压为第二串联电压。
当第二串联电压Usc等于预设安全电压阈值与直流变换器40a至直流变换器40n的数量n的乘积时，直流变换器40a至直流变换器40n中的所有直流变换器的接线状态均为正常状态。而当第二串联电压Usc小于预设安全电压阈值与n的乘积时，直流变换器40a至直流变换器40n中的部分直流变换器或者所有直流变换器的接线状态为异常状态。其中，直流变换器的接线状态包括直流变换器与其连接的光伏组件之间的 接线状态、直流变换器与相邻直流变换器之间的接线状态、以及直流变换器与光伏逆变器41之间的接线状态中的至少一种。异常状态包括直流变换器与其连接的光伏组件之间的接线断开或者接触不良，直流变换器的输出端的负极与相邻直流变换器的输出端的负极连接，直流变换器的输出端的正极与相邻直流变换器的输出端的正极连接，以及直流变换器与光伏逆变器41之间的接线断开或者接触不良中的至少一种。
其中，上述预设安全电压阈值为安全电压的理论值。在理想情况下，预设安全电压阈值与n的乘积为固定电压，而在实际情况下，预设安全电压阈值与n的乘积会在小电压范围b内波动，小电压范围b为(固定电压-固定电压*直流变换器中的安全电压输出电路的输出电压精度)*n～(固定电压+固定电压*直流变换器中的安全电压输出电路的输出电压精度)*n。应当理解，当第二串联电压Usc处于上述小电压范围b时，所有直流变换器的接线状态均为正常状态。而当第二串联电压Usc在上述小电压范围b之外时，部分直流变换器或者所有直流变换器的接线状态为异常状态。
具体实现中，直流变换器40a至直流变换器40n中的每个直流变换器的具体结构和工作原理可以参见上述图2至图4C对应的实施例中关于直流变换器2的具体结构和工作原理的描述，在此不再赘述。
实施本申请实施例，由于安全电压的电压幅值基本不变，因此可减小每个直流变换器的输出端的安全电压的检测误差，从而减小直流变换器40a至直流变换器40n的输出端的安全电压总和(即第二串联电压Usc)的检测误差，进而提高了接线异常检测的精准度，光伏系统4的供电可靠性更高。示例性的，当直流变换器40a至直流变换器40n的数量n小于或等于20时，可以准确识别直流变换器的接线状态是否异常，而当数量n大于或者等于50时才会累计出一个直流变换器的输出端的安全电压的检测误差，然而在实际应用场景中不会串联如此多的直流变换器，因此大幅度提高了接线异常检测的准确性，适用性更强。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (12)

  1. 一种直流变换器，其特征在于，所述直流变换器包括直流变换电路、辅助电源以及安全电压输出电路，其中，所述直流变换电路的输入端与所述辅助电源的输入端并联后作为所述直流变换器的输入端，所述直流变换器的输入端用于连接直流电源，所述辅助电源的输出端连接所述安全电压输出电路的输入端，所述安全电压输出电路的输出端与所述直流变换电路的输出端并联后作为所述直流变换器的输出端；
    所述辅助电源用于在所述直流变换电路未进行电压转换的情况下，基于所述直流电源提供的第一电压向所述安全电压输出电路输出第二电压，所述第二电压小于所述第一电压；
    所述安全电压输出电路用于基于所述第二电压输出安全电压，所述安全电压小于所述第二电压。
  2. 根据权利要求1所述的直流变换器，其特征在于，所述直流变换电路的输出端包括第一输出端和第二输出端，所述安全电压输出电路包括分压电路和开关，所述分压电路的第一连接端连接所述辅助电源的输出端，所述分压电路的第二连接端连接所述直流变换电路的所述第一输出端，所述分压电路的第三连接端连接所述直流变换电路的所述第二输出端；所述开关设置在所述分压电路的第一连接端和所述辅助电源的输出端之间，或者，所述开关设置在所述分压电路的第二连接端和所述直流变换电路的所述第一输出端之间；所述直流变换器还包括控制器；
    所述控制器用于在所述直流变换电路未进行电压转换的情况下控制所述开关处于导通状态，以使所述分压电路对所述第二电压进行分压并输出所述安全电压。
  3. 根据权利要求2所述的直流变换器，其特征在于，所述控制器用于在未接收到所述直流变换器的开机指令的情况下，控制所述开关处于导通状态。
  4. 根据权利要求2所述的直流变换器，其特征在于，所述控制器还用于在接收到所述直流变换器的开机指令的情况下，控制所述开关处于关断状态。
  5. 根据权利要求1所述的直流变换器，其特征在于，所述直流变换电路的输出端包括第一输出端和第二输出端，所述安全电压输出电路包括分压电路和电源芯片，所述分压电路的第一连接端通过所述电源芯片连接所述辅助电源的输出端，所述分压电路的第二连接端连接所述直流变换电路的所述第一输出端，所述分压电路的第三连接端连接所述直流变换电路的所述第二输出端；所述直流变换器还包括控制器；
    所述控制器用于在所述直流变换电路未进行电压转换的情况下向所述电源芯片下发第一使能信号；
    所述电源芯片用于响应于所述第一使能信号，向所述分压电路输出所述第二电压，以使所述分压电路对所述第二电压进行分压并输出所述安全电压。
  6. 根据权利要求5所述的直流变换器，其特征在于，所述控制器用于在接收到所述直流变换器的开机指令的情况下，向所述电源芯片下发第二使能信号；
    所述电源芯片用于响应于所述第二使能信号，停止向所述分压电路输出所述第二电压。
  7. 根据权利要求5所述的直流变换器，其特征在于，所述第一使能信号为第一电平，所述第二使能信号为第二电平，其中，所述第一电平为高电平且所述第二电平为低电平，或者，所述第一电平为低电平且所述第二电平为高电平。
  8. 根据权利要求2-7任一项所述的直流变换器，其特征在于，所述安全电压输出电路还包括保护电路，所述保护电路设置在所述分压电路的第二连接端和所述直流变换电路的所述第一输出端之间；
    所述保护电路用于对所述分压电路进行电路保护。
  9. 根据权利要求8所述的直流变换器，其特征在于，所述保护电路包括限流电阻或者二极管，其中，所述限流电阻或者所述二极管设置在所述分压电路的第二连接端和所述直流变换电路的所述第一输出端之间。
  10. 根据权利要求8所述的直流变换器，其特征在于，所述保护电路包括限流电阻和二极管，其中，所述限流电阻和所述二极管串联在所述分压电路的第二连接端和所述直流变换电路的所述第一输出端之间。
  11. 根据权利要求1-10任一项所述的直流变换器，其特征在于，所述直流变换器还包括控制器；
    所述控制器用于在接收到所述直流变换器的开机指令的情况下，控制所述直流变换电路对所述第一电压进行电压转换后输出。
  12. 一种光伏系统，其特征在于，所述光伏系统包括多个如权利要求1-11任一项所述的直流变换器以及光伏逆变器，多个所述直流变换器中的每个所述直流变换器的输入端用于连接光伏组件，多个所述直流变换器的输出端串联后连接所述光伏逆变器的输入端，所述光伏逆变器的输出端用于连接电网；
    在多个所述直流变换器中的所述直流变换电路进行电压转换的情况下，每个所述直流变换器中的所述直流变换电路用于对所述光伏组件提供的直流电进行电压转换后输出第一电压；所述光伏逆变器用于将多个所述直流变换器的第一串联电压逆变为交流电压并向所述电网供电，其中，所述第一串联电压为多个所述直流变换器的输出端的所述第一电压的总和；
    在多个所述直流变换器中的所述直流变换电路未进行电压转换的情况下，多个所述直流变换器的输出端串联后输出第二串联电压，所述第二串联电压为多个所述直流变换器的输出端的所述安全电压的总和。
PCT/CN2024/121093 2023-10-20 2024-09-25 直流变换器以及光伏系统 Pending WO2025082171A1 (zh)

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