TWI900112B - Energy-saving control circuit of inverter and method thereof - Google Patents

Abstract

The present disclosure is an energy-saving control circuit of an inverter and an energy-saving control method. Energy-saving control circuits include an energy storage circuit and a charge-discharge control circuit. The charge-discharge circuit starts a charging procedure according to a starting signal of the inverter to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit. The charging procedure includes a first charging procedure and a second charging procedure, and the first charging procedure charges the energy storage circuit with a first charging current and the second charging procedure charges the energy storage circuit with a second charging current. The first charging current is less than the second charging current. When the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge-discharge control circuit charges the energy storage circuit with the first charging procedure. When the energy storage voltage of the energy storage circuit is greater than the switching voltage, the charge-discharge control circuit charges the energy storage circuit with the second charging procedure.

Description

Energy-saving control circuit and energy-saving control method of inverter

The present invention relates to a frequency converter, and more particularly to an energy-saving control circuit and an energy-saving control method for the frequency converter.

For automated warehousing systems, inverters are crucial components of various mobile equipment, such as traveling, lifting, and forklift systems. However, when driving loads, especially during braking and deceleration, the voltage rebound generated within the inverter must be properly managed. Otherwise, it can easily damage the life of the inverter's components.

Therefore, the current practice is to install a braking resistor on the inverter's DC terminal. When the inverter's load braking operation generates a rebound voltage on the DC terminal, the braking resistor absorbs this rebound energy, achieving a protective effect. However, this braking resistor converts the rebound voltage into heat, which clearly does not meet the environmental requirements of energy conservation.

The technical problem to be solved by the present invention is to provide an energy-saving control circuit and an energy-saving control method for an inverter in response to the shortcomings of the existing technology.

An embodiment of the present invention provides an energy-saving control circuit for an inverter, comprising an energy storage circuit and a charge-discharge control circuit. The energy storage circuit is connected to the inverter's DC bus. The charge-discharge control circuit is connected to the energy storage circuit and activates a charging process based on a startup signal from the inverter. The charge-discharge control circuit controls a first DC voltage of the DC bus to charge the energy storage circuit according to the charging process. The charging process includes a first charging process and a second charging process. The first charging process charges the energy storage circuit with a first charging current, and the second charging process charges the energy storage circuit with a second charging current, wherein the first charging current is less than the second charging current. When the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge and discharge control circuit charges the energy storage circuit using a first charging procedure. When the energy storage voltage of the energy storage circuit is greater than the switching voltage, the charge and discharge control circuit charges the energy storage circuit using a second charging procedure.

The present invention provides an energy-saving control method for an inverter, comprising: determining whether a start signal of the inverter is obtained by a charge-discharge control circuit; when the charge-discharge control circuit obtains the start signal, the charge-discharge control circuit starts a charging process to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit; when the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge-discharge control circuit starts a charging process to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit; when the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge-discharge control circuit starts a charging process to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit; when the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge-discharge control circuit starts a charging process to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit; when the energy storage voltage of the energy storage circuit is less than the switching voltage, the charge-discharge control circuit starts a charging process to control the first DC voltage of the DC bus of the inverter to charge the energy storage circuit. The energy storage circuit is charged using a first charging procedure in the charging procedure; and when the energy storage voltage of the energy storage circuit is greater than the switching voltage, the charge and discharge control circuit charges the energy storage circuit using a second charging procedure in the charging procedure; wherein the first charging procedure charges the energy storage circuit with a first charging current, and the second charging procedure charges the energy storage circuit with a second charging current, and the first charging current is less than the second charging current.

In summary, the energy-saving control circuit and method for an inverter provided by the embodiments of the present invention can reduce the configuration of the inverter's primary-side input power capacity through the provision of a charge-discharge control circuit. Furthermore, the energy storage circuit absorbs the rebound voltage for subsequent power supply, and the charge-discharge control circuit provides a safe charging and discharging protection mechanism for the energy storage circuit. Thus, the energy-saving control circuit meets the requirements of energy conservation and safe operation.

To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only used for reference and description and are not used to limit the present invention.

The following describes the implementation of the present invention through specific embodiments. Those skilled in the art will understand the advantages and effects of the present invention from the content provided in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can be modified and altered based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are for simple schematic illustration only and are not depicted in actual size. Please note that the following embodiments will further explain the relevant technical content of the present invention in detail, but the content provided is not intended to limit the scope of protection of the present invention.

It should be understood that while terms such as "first," "second," and "third" may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein may include any one or more combinations of the associated listed items, as appropriate.

Embodiments of the present invention provide an energy-saving control circuit and method for an inverter. The energy-saving control circuit features large-capacity energy storage to assist the inverter in powering the load when driving heavy-load equipment (e.g., during load acceleration), or to store the recovered energy generated by the inverter (e.g., during load deceleration). This energy-saving control circuit reduces the inverter's primary power supply burden and protects the inverter from damage caused by the recovered energy.

[Embodiment of Energy Saving Control Circuit]

Please refer to Figures 1 and 2. Figure 1 is a schematic diagram of the automated warehousing system architecture according to an embodiment of the present invention, and Figure 2 is a schematic diagram of the connection between mobile devices and an energy-saving control circuit according to an embodiment of the present invention. The automated warehousing system described in this embodiment includes, for example, one or more mobile devices and an energy-saving control circuit 1. The mobile devices shown in Figure 1 are illustrated as three examples. Each mobile device includes an inverter 2 and a load M (e.g., a motor). The primary side of each inverter 2 receives an AC power source Vac input and the output terminal is connected to the load M. The DC terminals of each inverter 2 are connected together to form a parallel DC bus Vbus. The number of mobile devices can be flexibly adjusted according to actual usage requirements, and the mobile devices can be, for example but not limited to, walking mobile devices, lifting mobile devices, or fork arm mobile devices according to different functional operations.

It is worth noting that the energy-saving control circuit 1 includes an energy storage circuit 10 and a charge-discharge control circuit 12. The energy storage circuit 10 is connected in parallel to the DC bus Vbus, and the charge-discharge control circuit 12 is connected to the energy storage circuit 10. The energy storage circuit 10 can store energy from the voltage of the DC bus Vbus, or it can also supply power to the DC bus Vbus.

The inverter 2 includes a rectifier 20, an intermediate stage circuit 22, and an inverter 24. The input of the rectifier 20 is connected to the AC power source Vac, the output of the rectifier 20 is connected to the intermediate stage circuit 22, the input of the inverter 24 is connected to the intermediate stage circuit 22, and the output of the inverter 24 is connected to the load M. The intermediate stage circuit 22 receives the DC voltage (hereinafter referred to as the first DC voltage) output by the rectifier 20. In addition to the capacitor, the intermediate stage circuit 22 also includes a control circuit (not shown). The control circuit generates the drive signal (such as a three-phase pulse width modulated voltage) required to control the operation of the inverter 24, as well as the start signal Vr. The start signal Vr is a signal that indicates that the DC bus Vbus in the intermediate stage circuit 22 is functioning properly.

The charge-discharge control circuit 12 can control the energy storage circuit 10 to operate in different charging or discharging modes. For example, when the voltage of the DC bus Vbus is greater than the energy storage voltage of the energy storage circuit 10, the charge-discharge control circuit 12 controls the voltage of the DC bus Vbus to charge the energy storage circuit 10. Furthermore, when the energy storage voltage of the energy storage circuit 10 has been successfully charged to equal the voltage of the DC bus Vbus, if the voltage on the DC bus Vbus increases according to the operating requirements of the load M, the stored energy in the energy storage circuit 10 can be output to the DC bus Vbus to meet the power requirements of the load.

In one embodiment, the charge-discharge control circuit 12 activates a charging process based on a start signal Vr from the inverter 2. Upon receiving the start signal Vr, the charge-discharge control circuit 12 initiates a charging process, controlling the first DC voltage of the DC bus Vbus to charge the energy storage circuit 10. The charging process further includes a first charging process and a second charging process.

Specifically, when the charge/discharge control circuit 12 executes the first charging process, it charges the energy storage circuit 10 with a first charging current. When the charge/discharge control circuit 12 executes the second charging process, it charges the energy storage circuit 10 with a second charging current. The first charging current is less than the second charging current, and the charge/discharge control circuit 12 executes the first charging process before the second charging process. This ensures that the energy storage element used in the energy storage circuit 10 is protected from excessive current shock when the battery is unloaded. The energy storage element is, for example, a supercapacitor.

In one embodiment, the charge-discharge control circuit 12 determines when to switch from the first charging process to the second charging process based on the energy storage voltage of the energy storage circuit 10. Furthermore, the charge-discharge control circuit 12 compares the energy storage voltage of the energy storage circuit 10 with the switching voltage. When the energy storage voltage of the energy storage circuit 10 is less than the switching voltage, the charge-discharge control circuit 12 charges the energy storage circuit 10 using the first charging procedure. When the energy storage voltage of the energy storage circuit 10 exceeds the switching voltage after being charged through the first charging procedure, the charge-discharge control circuit 12 switches from the first charging procedure to the second charging procedure and continues to charge the energy storage circuit 10 until the energy storage voltage of the energy storage circuit 10 equals the first DC voltage of the DC bus Vbus.

Simply put, the energy-saving control circuit 1 determines whether to activate the charge-discharge control circuit 12 to charge the energy storage circuit 10 based on the startup signal Vr from the inverter 2. This ensures that the energy storage circuit 10 can successfully complete the charging process during the initial startup phase of the inverter 2 and can subsequently respond to the potential power demand when the inverter 2 actually drives the load M. For example, if the power demand of the load M exceeds the supply capacity of the primary power supply of the inverter 2, the stored energy in the energy storage circuit 10 can actively supply power to the DC bus Vbus. When the load M generates a rebound voltage on the DC bus Vbus due to deceleration, the rebound voltage can directly charge the energy storage circuit 10. Therefore, the energy storage circuit 10 absorbs the energy of the rebound voltage to protect the inverter 2.

Please refer to Figure 3, which provides a block diagram of an energy-saving control circuit according to an embodiment of the present invention. The charge-discharge control circuit 12 includes a first-stage switching circuit 120, a DC power conversion circuit 122, a second-stage switching circuit 124, and a power detection circuit 126. The first-stage switching circuit 120 is connected to the DC power conversion circuit 122 and the DC bus Vbus. The second-stage switching circuit 124 is connected to the DC power conversion circuit 122 and the power detection circuit 126. The power detection circuit 126 is connected to the energy storage circuit 10.

Specifically, the first-stage switching circuit 120 operates at a first DC voltage. The DC power conversion circuit 122 converts the first DC voltage into a second DC voltage that is less than the first DC voltage. The power detection circuit 126 detects the energy storage voltage of the energy storage circuit 10. The second-stage switching circuit 124 operates at the second DC voltage.

In one embodiment, after receiving the activation signal Vr, the second-stage switching circuit 124 can control the first-stage switching circuit 120 to charge the energy storage circuit 10 using a first charging process. Furthermore, when the power detection circuit 126 detects that the energy storage voltage of the energy storage circuit 10 is greater than the switching voltage, the second-stage switching circuit 124 can control the first-stage switching circuit 120 to charge the energy storage circuit 10 using a second charging process.

Please refer to Figures 4 and 5. Figure 4 is a circuit diagram of a first-stage switching circuit according to an embodiment of the present invention, and Figure 5 is a circuit diagram of a second-stage switching circuit according to an embodiment of the present invention.

In one embodiment, the first-stage switching circuit 120 includes a first auxiliary contact switch C1/S1 of the first relay, a second auxiliary contact switch C2/S2 of the second relay, a first resistor R1, and a third normally closed switch S3A of the third relay. A first terminal of the first auxiliary contact switch C1/S1 is connected to the positive terminal P of the first DC voltage. A first terminal of the second auxiliary contact switch C2/S2 is connected to the second terminal of the first auxiliary contact switch C1/S1, and a second terminal of the second auxiliary contact switch C2/S2 is connected to the first terminal of the energy storage circuit 10. The second terminal of the energy storage circuit 10 is connected to the negative terminal N of the first DC voltage. A first end of a first resistor R1 is connected to the second end of the first auxiliary contact switch C1/S1 and the first end of the second auxiliary contact switch C2/S2. A second end of the first resistor R1 is connected to the second end of the second auxiliary contact switch C2/S2. A first end of a third normally closed switch S3A is connected to the second end of the first resistor R1. A first end of a second resistor R2 is connected to the second end of the third normally closed switch S3A. A second end of the second resistor R2 is connected to the negative terminal N of the first DC voltage.

In one embodiment, the second-stage switching circuit 124 includes a third normally-open switch S3B of the third relay, a fourth switch S4 of the fourth relay, a fourth coil C4 of the fourth relay, a second coil C2 of the second relay, a fifth A switch S5A of the fifth relay, a third coil C3 of the third relay, a fifth B switch S5B of the fifth relay, a sixth coil C6 of the sixth relay, a sixth switch S6 of the sixth relay, and a fifth coil C5 of the fifth relay.

Among them, the first end of the third normally open switch S3B is connected to the positive terminal PA of the second DC voltage; the first end of the fourth switch S4 is connected to the second end of the third normally open switch S3B; the first end of the fourth coil C4 is connected to the positive terminal PA of the second DC voltage, and the second end of the fourth coil C4 is connected to the power detection circuit 126; the first end of the second coil C2 is connected to the second end of the fourth switch S4, and the second end of the second coil C2 is connected to the negative terminal NA of the second DC voltage; the first end of the fifth A switch S5A is connected to the positive terminal PA of the second DC voltage; the first end of the third coil C3 is connected to the second end of the fifth A switch S5A, and the second end of the third coil C3 is connected to the negative terminal NA of the second DC voltage. The first end of the fifth B-switch S5B is connected to the negative terminal NA of the second DC voltage; the first end of the fifth B-switch S5B is connected to the second terminal of the third normally-open switch S3B; the first end of the first coil C1 is connected to the second end of the fifth B-switch S5B, and the second end of the first coil C1 is connected to the negative terminal NA of the second DC voltage; the first end of the sixth coil C6 is connected to the inverter 2 to receive the start signal Vr, and the second end of the sixth coil C6 is connected to the negative terminal NA of the second DC voltage; the first end of the sixth switch S6 is connected to the positive terminal PA of the second DC voltage; the first end of the fifth coil C5 is connected to the second end of the sixth switch S6, and the second end of the fifth coil C5 is connected to the negative terminal NA of the second DC voltage.

Next, please refer to Figure 6, which is a control timing diagram of the energy-saving control circuit according to an embodiment of the present invention. When the power of the automated warehousing system is turned on, the operation of the first-stage switching circuit 120 and the second-stage switching circuit 124 in the energy-saving control circuit 1 is described as follows. Here, the first auxiliary contact switch C1/S1, the second auxiliary contact switch C2/S2, the third normally open switch S3B, the fourth switch S4, the fifth A switch S5A, the fifth B switch S5B, and the sixth switch S6 are all normally open switches (i.e., contact a), and the third normally closed switch S3A is a normally closed switch (i.e., contact b).

First, after the inverter 2 receives system power, the sixth coil C6 in the second-stage switching circuit 124 is energized upon receiving the start signal Vr. Simultaneously, the sixth switch S6 is turned on in response to the energization of the sixth coil C6.

When the sixth switch S6 is turned on, the fifth coil C5 is energized by the second DC voltage. Simultaneously, the fifth A switch S5A and the fifth B switch S5B are turned on according to the excitation of the fifth coil C5.

When the fifth A-type switch S5A is turned on, the third coil C3 is energized by the second DC voltage. The third normally-open switch S3B is turned on in response to the excitation of the third coil C3, and the third normally-closed switch S3A is turned off (i.e., non-conductive) in response to the excitation of the third coil. As shown in FIG6 , at time T1, the third normally-closed switch S3A switches from on to off.

When the third normally-open switch S3B and the fifth B-switch S5B are turned on, the first coil C1 is energized by the second DC voltage. The first auxiliary contact switch C1/S1 is then turned on in response to the excitation of the first coil C1. Therefore, the first DC voltage can charge the energy storage circuit 10 with the first charging current via the first auxiliary contact switch C1/S1 and the first resistor R1. At this time, as shown in FIG6 , at time T1, the first auxiliary contact switch C1/S1 switches from off to on. It should be noted that the first resistor R1 is used as a current-limiting resistor. That is, the first DC voltage charges the energy storage circuit 10 in a buffered manner to protect the energy storage circuit 10 and the inverter 2 from damage. On the other hand, the second resistor R2 does not form a conducting loop and has no function.

Next, when the power detection circuit 126 detects that the energy storage voltage of the energy storage circuit 10 is greater than the switching voltage, the power detection circuit 126 outputs a signal to excite the fourth coil C4, and the fourth switch S4 is turned on according to the excitation of the fourth coil C4.

When both the third normally-open switch S3B and the fourth switch S4 are turned on, the second coil C2 is energized by the second DC voltage, and the second auxiliary contact switch C2/S2 is turned on in response to the excitation of the second coil C2. Therefore, the first DC voltage can now charge the energy storage circuit 10 with the second charging current via the first auxiliary contact switch C1/S1 and the second auxiliary contact switch C2/S2. As shown in Figure 6, at time T2, the second auxiliary contact switch C2/S2 switches from off to on. It should be noted that the current of the first DC voltage bypasses the first resistor R1 and directly charges the energy storage circuit 10 with a second charging current that is higher than the first charging current.

Subsequently, when the automated warehousing system is shut down or powered off, inverter 2 will no longer output the start signal Vr to the sixth coil C6 due to the shutdown or power outage. This demagnetizes the first coil C1, second coil C2, third coil C3, fourth coil C4, fifth coil C5, and sixth coil C6, and restores the relays to their initial states. As shown at time T3 in Figure 6, the first auxiliary contact switch C1/S1 and the second auxiliary contact switch C2/S2 return to their initial off states, and the third normally closed switch S3A returns to its initial on state. It should be noted that at this point, the stored energy within the energy storage circuit 10 is discharged through the second resistor R2 to ensure the safety of subsequent maintenance personnel.

[Energy-saving control method of inverter]

Please refer to Figure 7, which is a flow chart of the energy-saving control method for the inverter according to an embodiment of the present invention. The flow chart shown in Figure 7 includes, but is not limited to, the following steps, and can be used in conjunction with the structure of the energy-saving control circuit 1 of the aforementioned embodiment.

In step S701, a startup signal Vr is received. The energy-saving control circuit 1 determines whether the inverter 2's DC bus Vbus is functioning properly by determining whether the startup signal Vr has been received. Therefore, upon receiving the startup signal Vr, the charge-discharge control circuit 12 within the energy-saving control circuit 1 initiates the charging process, initially charging the energy storage circuit 10 using the voltage of the DC bus Vbus.

In step S703, a first charging process is executed. After initiating the charging process, the charge-discharge control circuit 12 first charges the energy storage circuit 10 using the first charging process. It should be noted that the charging current used by the charge-discharge control circuit 12 during the charging process of the energy storage circuit 10 using the first DC voltage of the DC bus Vbus is a first charging current. This first charging current flows through a current-limiting resistor (e.g., first resistor R1) to buffer the energy storage circuit 10 using a current-limiting charging method.

In step S705, a determination is made as to whether the stored voltage is greater than the switching voltage. During the first charging process, the charge-discharge control circuit 12 determines whether the stored voltage of the energy storage circuit 10 has reached the switching voltage level to determine whether to switch to the second charging process. If the determination in step S705 is yes, step S707 is executed; if the determination in step S705 is no, step S703 is executed.

In step S707, a second charging process is executed. When the energy storage voltage of the energy storage circuit 10 is greater than the switching voltage, the charge-discharge control circuit 12 charges the energy storage circuit 10 using the second charging process. It should be noted that during this process, when the charge-discharge control circuit 12 charges the energy storage circuit 10 using the first DC voltage of the DC bus Vbus, the charging current is a second charging current. This second charging current is greater than the first charging current. In other words, the second charging current no longer flows through the current-limiting resistor and instead charges the energy storage circuit 10 at a normal charging rate.

In step S709, discharge or charge is performed based on the load's operating status. When the charge-discharge control circuit 12 successfully completes the charging process (including the first and second charging processes), the energy storage circuit 10's stored voltage has reached a level sufficient to assist the inverter 2 in supplying power to the load M. For example, when the load M is accelerating, the inverter 2's output current demand increases. Therefore, the energy stored in the energy storage circuit 10 can be supplied to the inverter 2 via the DC bus Vbus to meet the load M's maximum instantaneous current demand. On the other hand, when the load M driven by the inverter 2 is in a decelerating operation state, the boosted voltage generated by the DC bus Vbus is higher than the energy storage voltage of the energy storage circuit 10 , so the boosted voltage will charge the energy storage circuit 10 .

In step S711, a determination is made as to whether power is off. The charge-discharge control circuit 12 determines whether the inverter 2 is powered off by continuously receiving the start signal Vr. If the determination in step S711 is yes, step S713 is executed; if the determination in step S711 is no, step S709 is executed.

In step S713, the energy storage circuit 10 is discharged. When the charge-discharge control circuit 12 no longer receives the activation signal Vr, it provides a discharge path to discharge the energy storage circuit 10. For example, if the charge-discharge control circuit 12 loses power, the relays in the charge-discharge control circuit 12 will return to their initial state, and discharge the energy storage circuit 10 through the discharge resistor connected to it (such as the second resistor R2). This prevents the high voltage in the energy storage circuit 10 from causing harm to personnel during subsequent system maintenance.

Therefore, it can be seen from the above description that the configuration of the charge-discharge control circuit 12 can reduce the configuration of the primary-side input power capacity of the inverter 2, and the energy storage circuit 10 absorbs the rebound voltage for subsequent power supply. In addition to protecting the inverter 2 from damage, it also meets the operating requirements of energy conservation and power saving.

For example, the capacity of the supercapacitor used in the energy storage circuit 10 can be configured based on the power requirements of the load M. For example, if an automated warehousing system requires 20 kW of power, the primary input power of the inverter 2 would traditionally require a 24 kW capacity to meet safety requirements. However, by using the energy-saving control circuit 1 of the present invention, and assuming the supercapacitor used in the energy storage circuit 10 is a 3.1F DC357V, the supercapacitor can provide a 10 kW capacity. Therefore, the primary input power of the inverter 2 only needs to be 14 kW to effectively meet the power requirements of the automated warehousing system. Furthermore, when the primary side input power of the inverter 2 stops supplying power due to an accident, the energy stored in the energy storage circuit 10 can continue to supply power for a period of time, thereby preventing the automated warehousing system from shutting down abnormally due to a sudden power outage.

[Beneficial Effects of the Embodiments]

The energy-saving control circuit and method for an inverter provided by this invention, along with the energy storage circuit and charge-discharge control circuit used in the energy-saving control circuit, can effectively reduce the power capacity requirements of the inverter's primary side. The charge-discharge control circuit also provides a safe charging and discharging protection mechanism for the energy storage circuit. The energy storage circuit can also utilize the rebound voltage as a charging source to protect system equipment from high-voltage shocks. This energy-saving control circuit thus meets the requirements for both energy conservation and safe operation.

The above contents are only preferred feasible embodiments of the present invention and do not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made by using the contents of the description and drawings of the present invention are included in the scope of the patent application of the present invention.

1: Energy-saving control circuit 10: Energy storage circuit 12: Charge and discharge control circuit 120: First-stage switching circuit 122: DC power conversion circuit 124: Second-stage switching circuit 126: Power detection circuit 2: Inverter 20: Rectifier 22: Intermediate stage circuit 24: Inverter Vac: AC power source Vbus: DC bus Vr: Start signal M: Load C1/S1: First auxiliary contact switch C2/S2: Second auxiliary contact switch S3A: Third normally closed switch S3B: Third normally open switch S4: Fourth switch S5A: Fifth A switch S5B: Fifth B switch S6: Sixth switch C1: First coil C2: Second coil C3: Third coil C4: Fourth coil C5: Fifth coil C6: Sixth coil S701: Receive start signal S703: Execute first charging process S705: Energy storage voltage is greater than switching voltage S707: Execute second charging process S709: Discharge or charge according to load operation status S711: Power off S713: Discharge the energy storage circuit

FIG1 is a schematic diagram of the architecture of an automated warehousing system according to an embodiment of the present invention.

FIG2 is a schematic diagram showing the connection between a mobile device and an energy-saving control circuit according to an embodiment of the present invention.

FIG3 is a block diagram of an energy-saving control circuit according to an embodiment of the present invention.

FIG4 is a schematic circuit diagram of a first-stage switching circuit according to an embodiment of the present invention.

FIG5 is a schematic circuit diagram of a second-stage switching circuit according to an embodiment of the present invention.

FIG6 is a control timing diagram of the energy-saving control circuit according to an embodiment of the present invention.

FIG7 is a flow chart of an energy-saving control method for an inverter according to an embodiment of the present invention.

1: Energy-saving control circuit

10: Energy storage circuit

12: Charge and discharge control circuit

2: Inverter

20: Rectifier

22: Intermediate stage circuit

24: Inverter

Vac: alternating current power supply

Vbus: DC bus

Vr: Start signal

M: Load

Claims (16)

An energy-saving control circuit for an inverter includes: an energy storage circuit connected to a DC bus of the inverter; and a charge-discharge control circuit connected to the energy storage circuit. The charge-discharge control circuit starts a charging process according to a start signal of the inverter. The charge-discharge control circuit controls a first DC voltage of the DC bus to charge the energy storage circuit according to the charging process. The charging process includes a first charging process and a second charging process. The first charging process uses a first charging current to charge the energy storage circuit. The energy storage circuit is charged by the second charging procedure, the second charging current is used to charge the energy storage circuit, and the first charging current is less than the second charging current; wherein the charge-discharge control circuit charges the energy storage circuit by the first charging procedure when a storage voltage of the energy storage circuit is less than a switching voltage; wherein the charge-discharge control circuit charges the energy storage circuit by the second charging procedure when the storage voltage of the energy storage circuit is greater than the switching voltage. The energy-saving control circuit of the inverter as described in claim 1, wherein when the charge-discharge control circuit completes the charging process and a load driven by the inverter is in an accelerated operating state, the energy storage circuit supplies power to the inverter, and when the load driven by the inverter is in a decelerated operating state, a boosted voltage of the DC bus charges the energy storage circuit. The energy-saving control circuit of the inverter as described in claim 1, wherein when the charge-discharge control circuit does not receive the start signal, the charge-discharge control circuit provides a discharge path to discharge the energy storage circuit. The energy-saving control circuit of the inverter as described in claim 1, wherein the energy storage circuit is a super capacitor. The energy-saving control circuit of the inverter as claimed in claim 1, wherein the charge and discharge control circuit comprises: a first-stage switching circuit connected to the DC bus and operating at the first DC voltage; a DC power conversion circuit connected to the first-stage switching circuit and the DC bus, the DC power conversion circuit converting the first DC voltage into a second DC voltage, the second DC voltage being less than the first DC voltage; a power detection circuit connected to the energy storage circuit and detecting the energy storage voltage. and a second-stage switching circuit connected to the DC power conversion circuit and the power detection circuit and operating at the second DC voltage; wherein the second-stage switching circuit controls the first-stage switching circuit to charge the energy storage circuit using the first charging procedure according to the start signal, and when the power detection circuit detects that the energy storage voltage is greater than the switching voltage, the second-stage switching circuit controls the first-stage switching circuit to charge the energy storage circuit using the second charging procedure. An energy-saving control circuit for an inverter as described in claim 5, wherein the first-stage switching circuit includes: a first auxiliary contact switch of a first relay, a first end of the first auxiliary contact switch being connected to the positive end of the first DC voltage; a second auxiliary contact switch of a second relay, a first end of the second auxiliary contact switch being connected to a second end of the first auxiliary contact switch, a second end of the second auxiliary contact switch being connected to a first end of the energy storage circuit, and a second end of the energy storage circuit being connected to the negative end of the first DC voltage; and a first resistor, a first end of the first resistor being connected to the second end of the first auxiliary contact switch and the first end of the second auxiliary contact switch, and a second end of the first resistor being connected to the second end of the second auxiliary contact switch. An energy-saving control circuit for an inverter as described in claim 6, wherein the first-stage switching circuit further includes: a third normally closed switch of a third relay, a first end of the third normally closed switch being connected to the second end of the first resistor; and a second resistor, a first end of the second resistor being connected to a second end of the third normally closed switch, and a second end of the second resistor being connected to the negative end of the first DC voltage. The energy-saving control circuit of the inverter as claimed in claim 7, wherein the second-stage switching circuit comprises: a third normally-open switch of the third relay, a first end of the third normally-open switch being connected to the positive end of the second DC voltage; a fourth switch of the fourth relay, a first end of the fourth switch being connected to a second end of the third normally-open switch; a fourth coil of the fourth relay, a first end of the fourth coil being connected to the positive end of the second DC voltage, A second end of the fourth coil is connected to the power detection circuit; a second coil of the second relay, a first end of the second coil is connected to a second end of the fourth switch, and a second end of the second coil is connected to the negative end of the second DC voltage; a fifth A switch of the fifth relay, a first end of the fifth A switch is connected to the positive end of the second DC voltage; a third coil of the third relay, a first end of the third coil is connected to the A second end of the fifth A switch, a second end of the third coil is connected to the negative end of the second DC voltage; a fifth B switch of the fifth relay, a first end of the fifth B switch is connected to a second end of the third normally open switch; a first coil of the first relay, the first coil is connected to a second end of the fifth B switch, a second end of the first coil is connected to the negative end of the second DC voltage; a sixth coil of the sixth relay, the first coil of the sixth relay A first end of the sixth coil is connected to the inverter to receive the start signal, and a second end of the sixth coil is connected to the negative end of the second DC voltage. A sixth switch of the sixth relay has a first end connected to the positive end of the second DC voltage. A fifth coil of the fifth relay has a first end connected to a second end of the sixth switch, and a second end connected to the negative end of the second DC voltage. The energy-saving control circuit of the inverter as described in claim 8, wherein the sixth coil is energized upon receiving the start signal and turns on the sixth switch; when the sixth switch is turned on, the fifth coil is energized and turns on the fifth A switch and the fifth B switch; when the fifth A switch is turned on, the third coil is energized and turns on the third normally open switch and turns off the third normally closed switch; when the third normally open switch and the fifth B switch are turned on, the first coil is energized and turns on the first auxiliary contact switch, at which time the first The DC voltage charges the energy storage circuit with the first charging current via the first auxiliary contact switch and the first resistor. When the power detection circuit detects that the energy storage voltage is greater than the switching voltage, the fourth coil is energized, causing the fourth switch to conduct. When both the third normally open switch and the fourth switch are turned on, the second coil is energized, causing the second auxiliary contact switch to conduct. At this time, the first DC voltage charges the energy storage circuit with the second charging current via the first auxiliary contact switch and the second auxiliary contact switch. An energy-saving control circuit for an inverter as described in claim 8, wherein when the inverter is turned off or powered off, the first coil, the second coil, the third coil, the fourth coil, the fifth coil, and the sixth coil are demagnetized, the third normally closed switch is turned on, and the energy storage circuit is discharged through the third normally closed switch and the second resistor. An energy-saving control circuit for an inverter as described in claim 8, wherein the first auxiliary contact switch, the second auxiliary contact switch, the fourth switch, the fifth A switch, the fifth B switch and the sixth switch are all normally open switches. The energy-saving control circuit of the inverter as described in claim 1, wherein the start signal is a normal signal indicating that the DC bus can operate normally. A method for controlling energy conservation of an inverter comprises: determining whether a start signal of the inverter is obtained by a charge-discharge control circuit; when the charge-discharge control circuit obtains the start signal, the charge-discharge control circuit starts a charging process to control a first DC voltage of a DC bus of the inverter to charge an energy storage circuit; when a storage voltage of the energy storage circuit is less than a switching voltage, the charge-discharge control circuit controls the energy storage circuit to charge the energy storage circuit according to the charging process; A first charging procedure charges the energy storage circuit; and when the energy storage voltage of the energy storage circuit is greater than the switching voltage, the charge and discharge control circuit charges the energy storage circuit with a second charging procedure in the charging procedure; wherein the first charging procedure charges the energy storage circuit with a first charging current, and the second charging procedure charges the energy storage circuit with a second charging current, and the first charging current is less than the second charging current. The energy-saving control method for an inverter as described in claim 13 further includes: when the charge and discharge control circuit completes the charging process and a load driven by the inverter is in an accelerated operation state, the energy storage circuit supplies power to the inverter. The energy-saving control method for an inverter as described in claim 13 further includes: when the charge-discharge control circuit completes the charging process and a load driven by the inverter is in a deceleration operation state, charging the energy storage circuit through a boosted voltage of the DC bus. The energy-saving control method for an inverter as described in claim 13 further includes: when the charge-discharge control circuit does not receive the start signal, the charge-discharge control circuit provides a discharge path to discharge the energy storage circuit.