Voltage discharge control method, electronic devices, storage medium and energy storage system

Abstract

Disclosed is an energy storage system, comprising an electronic device. Also disclosed are a voltage discharge control method and a storage medium. The voltage discharge control method comprises: determining that a direct current bus capacitor meets a voltage discharge condition; and controlling an inverter circuit to output a target voltage so as to discharge the voltage of the direct current bus capacitor, the direct current bus capacitor being connected between a positive direct current bus and a negative direct current bus, and the inverter circuit being used for converting a direct current of the direct current bus into an alternating current.

Description

Voltage discharge control method, electronic device, storage medium and energy storage system

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202411087798.8, filed on August 9, 2024, and entitled "Voltage discharge control method, electronic device, storage medium and energy storage system", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of energy storage, in particular to a voltage discharge control method, an electronic device, a non-volatile readable storage medium and an energy storage system. BACKGROUND

[0004] In the prior art, the voltage discharge control method of an electronic device such as a power conversion system (PCS) is mainly achieved by a DC side voltage equalization resistor (usually 5KΩ level) or by inputting a special discharge resistor after the system is shut down. However, both methods have some problems. When discharging through the DC side voltage equalization resistor, the discharge speed is very slow, and this slow discharge speed will prolong the existence time of high voltage, which seriously threatens the safety of equipment maintenance personnel and increases the operation risk. As for the method of discharging by inputting a discharge resistor, due to the high level of DC bus voltage, in order to meet the requirement of fast discharge, a discharge resistor of large power level is needed. Such discharge resistor has a large volume, which seriously occupies the space of main circuit design arrangement. At the same time, due to the large power level required by the discharge resistor, its cost is also relatively high.

[0005] SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to propose a voltage discharge control method, which can consume the residual electricity in the DC bus capacitor faster, realize the fast discharge of the voltage of the DC bus capacitor, and save the hardware cost and circuit design arrangement space without the need of additionally designing and installing a discharge resistor of large power.

[0007] A second object of the present application is to propose an electronic device.

[0008] A third object of the present application is to propose a non-volatile readable storage medium.

[0009] A fourth object of the present application is to propose an electronic device.

[0010] A fifth object of the present application is to propose an energy storage system.

[0011] To achieve the above object, the voltage discharge control method according to an embodiment of the present application comprises: determining that a DC bus capacitor meets a voltage discharge condition; and controlling an inverter circuit to output a target voltage to discharge the voltage of the DC bus capacitor, the DC bus capacitor being connected between a positive DC bus and a negative DC bus, and the inverter circuit being configured to convert DC power of the DC bus into AC power.

[0012] According to the voltage discharge control method, when the DC bus capacitor meets the voltage discharge condition, the inverter circuit is controlled to output the target voltage based on the inverter circuit configured to convert the DC power of the DC bus into the AC power. The inverter circuit is thus turned on and turned off in a certain manner, and outputs a stable AC voltage signal at the target voltage. The power semiconductor devices in the inverter circuit generate additional switching loss in the process of being turned on and turned off. The residual power in the DC bus capacitor is consumed by the switching loss, thereby achieving rapid discharge of the voltage of the DC bus capacitor. The voltage discharge control method does not require an additional high-power discharge resistor, thereby saving hardware cost and circuit design space.

[0013] In some embodiments, the voltage discharge condition comprises that a DC side contactor on the DC side of the inverter circuit and an AC side contactor on the AC side of the inverter circuit are both turned off.

[0014] In some embodiments, the voltage discharge condition further comprises that a cabinet door of a device in which the inverter circuit is located is closed.

[0015] In some embodiments, the target voltage is less than or equal to a human body safety voltage.

[0016] In some embodiments, the voltage discharge control method further comprises: obtaining a DC bus voltage value on the DC side of the inverter circuit; and controlling the inverter circuit to stop working when the DC bus voltage value is less than or equal to a first preset voltage threshold.

[0017] In some embodiments, the first preset voltage threshold is a human body safety voltage.

[0018] In some embodiments, the voltage discharge control method further comprises: in response to the inverter circuit stopping working, controlling a DC discharge circuit to be turned on to discharge the voltage of the DC bus capacitor through a discharge resistor in the DC discharge circuit, the DC discharge circuit being connected between the positive DC bus and the negative DC bus and being connected in parallel with the DC bus capacitor.

[0019] In some embodiments, the voltage bleed control method further comprises: when the DC bus voltage value is less than or equal to a second preset voltage threshold, controlling the DC bleed circuit to be turned off, the second preset voltage threshold being less than the first preset voltage threshold.

[0020] In some embodiments, the second preset voltage threshold is a human body safety voltage.

[0021] In some embodiments, the voltage bleed control method further comprises: when the inverter circuit satisfies a shutdown protection triggering condition, controlling the inverter circuit to perform shutdown protection.

[0022] In some embodiments, the shutdown protection triggering condition comprises at least one of: a voltage value output by the inverter circuit being greater than a voltage protection threshold; a current value output by the inverter circuit being greater than a current protection threshold; a temperature of the inverter circuit being greater than a temperature protection threshold; and a cabinet door of a device in which the inverter circuit is located being opened.

[0023] In some embodiments, controlling the inverter circuit to output a target voltage comprises: controlling the inverter circuit to work according to a first control instruction to output the target voltage, wherein the first control instruction is obtained according to a DC bus voltage and a DC bus current of a DC side of the inverter circuit.

[0024] In some embodiments, controlling the inverter circuit to output a target voltage comprises: controlling the inverter circuit to work according to a second control instruction to output the target voltage, wherein the second control instruction is obtained according to a DC bus voltage and a DC bus current of an AC side of the inverter circuit and an AC voltage and an AC current of an AC output side of the inverter circuit.

[0025] To achieve the above object, the electronic device of the second aspect embodiment of the present application comprises: at least one processor; a memory in communication connection with the at least one processor; the memory has a computer program which can be executed by the at least one processor, and the at least one processor realizes the voltage bleed control method described in the above embodiments when executing the computer program.

[0026] According to the electronic device of the present application, the processor can consume the residual electricity in the DC bus capacitor by the switching loss of the power semiconductor device in the inverter circuit by executing the computer program realizing the voltage bleed control method described in the above embodiments, so as to realize the rapid bleed of the voltage of the DC bus capacitor, without the need of additionally designing and installing a large-power bleed resistor, thereby saving the hardware cost and circuit design arrangement space.

[0027] To achieve the above object, the non-volatile readable storage medium of the third aspect of the present application stores a computer program, which is executed to implement the voltage discharge control method described in the above embodiments.

[0028] According to the non-volatile readable storage medium of the present application, by using the voltage discharge control method described in the above embodiments, the residual power in the DC bus capacitor can be consumed by the switching loss of the power semiconductor device in the inverter circuit, so that the voltage of the DC bus capacitor can be quickly discharged without the need of designing and installing a large-power discharge resistor, thereby saving the hardware cost and circuit design arrangement space.

[0029] To achieve the above object, the electronic device of the fourth aspect of the present application comprises: a DC bus comprising a positive DC bus and a negative DC bus; a DC bus capacitor connected between the positive DC bus and the negative DC bus; and an inverter circuit, an input end of which is connected with the positive DC bus and the negative DC bus, for converting the DC power of the DC bus into AC power, the inverter circuit being further configured to output a target voltage to discharge the voltage of the DC bus capacitor when the DC bus capacitor meets a voltage discharge condition.

[0030] According to the electronic device of the present application, when the DC bus capacitor meets the voltage discharge condition, the power semiconductor device in the inverter circuit is turned on and turned off in a certain manner, so that the inverter circuit outputs a stable AC voltage signal at the set target voltage, and the power semiconductor device generates additional switching loss in the process of turning on and turning off, so that the residual power in the DC bus capacitor can be consumed by the switching loss of the power semiconductor device, thereby achieving the quick discharge of the voltage of the DC bus capacitor. This control method does not need to design and install a large-power discharge resistor, thereby saving the hardware cost and circuit design arrangement space.

[0031] In some embodiments, the electronic device further comprises a DC discharge circuit connected in parallel with the DC bus capacitor, the DC discharge circuit comprising a discharge resistor, the DC discharge circuit being configured to be turned on to discharge the voltage of the DC bus capacitor through the discharge resistor in response to the inverter circuit stopping working.

[0032] In some embodiments, the electronic device further comprises a controller connected with the inverter circuit and the DC discharge circuit respectively, for executing the voltage discharge control method described in the above embodiments.

[0033] In some embodiments, the electronic device further comprises: a first voltage sensor connected to the controller, configured to detect a voltage across the DC bus capacitor as a DC bus voltage of a DC side of the inverter circuit; a first current sensor connected to the controller, configured to detect a DC bus current; a second voltage sensor connected to the controller, configured to detect an AC voltage of an AC side of an output of the inverter circuit; and a second current sensor connected to the controller, configured to detect an AC current of the AC side of the output of the inverter circuit.

[0034] In some embodiments, the electronic device further comprises: a DC side contactor located between a DC side interface of the electronic device and the DC bus capacitor, configured to control a connection state of the DC bus capacitor and the DC side interface; and an AC side contactor located between an AC end of the inverter circuit and an AC side interface of the electronic device, configured to control an AC output of the electronic device.

[0035] In some embodiments, the electronic device further comprises: a DC disconnector located between the DC side contactor and the DC side interface; and an AC disconnector located between the AC side contactor and the AC side interface.

[0036] In some embodiments, the electronic device further comprises: a filter circuit located between the inverter circuit and the AC side contactor.

[0037] To achieve the above object, the energy storage system of the fifth aspect embodiment of the present application comprises the electronic device of the above embodiments, or the energy storage system comprises an energy storage module and the electronic device of the above embodiments.

[0038] According to the energy storage system of the embodiments of the present application, the energy storage module is used for storing electric energy, and the electronic device is used for converting the stored DC power into AC power. Through the voltage discharge control method of the above embodiments, the output of the inverter circuit is controlled to generate a stable AC voltage signal, and the residual power in the DC bus capacitor is consumed by the switching loss of the power semiconductor device in the inverter circuit, so that the voltage of the DC bus capacitor is rapidly discharged, without the need for additional design and installation of a large-power discharge resistor, thereby saving the hardware cost and circuit design arrangement space.

[0039] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0040] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings in which:

[0041] FIG. 1 is a schematic diagram of an electronic device, according to one embodiment of the present application;

[0042] FIG. 2 is a schematic diagram of an electronic device, according to yet another embodiment of the present application;

[0043] FIG. 3 is a block diagram of an energy storage system, according to one embodiment of the present application;

[0044] FIG. 4 is a block diagram of an energy storage system, according to yet another embodiment of the present application;

[0045] FIG. 5 is a flowchart of a voltage bleed-off control method, according to one embodiment of the present application;

[0046] FIG. 6 is a flowchart of a voltage bleed-off control method, according to one embodiment of the present application;

[0047] FIG. 7 is a flowchart of a voltage bleed-off control method, according to yet another embodiment of the present application;

[0048] FIG. 8 is a simulation result diagram of voltage bleed-off by a voltage equalization resistor only, according to the prior art;

[0049] FIG. 9 is a simulation result diagram of voltage bleed-off by an inverter circuit only, according to one embodiment of the present application;

[0050] FIG. 10 is a simulation result diagram of a first stage of voltage bleed-off by a combination of a voltage equalization resistor and a bleed-off resistor, according to the prior art;

[0051] FIG. 11 is a simulation result diagram of a second stage of voltage bleed-off by a combination of a voltage equalization resistor and a bleed-off resistor, according to the prior art;

[0052] FIG. 12 is a simulation result diagram of a first stage of voltage bleed-off by a combination of an inverter circuit and a bleed-off resistor, according to one embodiment of the present application;

[0053] FIG. 13 is a simulation result diagram of a second stage of voltage bleed-off by a combination of an inverter circuit and a bleed-off resistor, according to one embodiment of the present application;

[0054] FIG. 14 is a block diagram of an electronic device, according to one embodiment of the present application.

[0055] Reference signs: energy storage system 110; electronic device 1; energy storage module 2; DC bus 10; DC bus capacitor 11; DC discharge circuit 12; inverter circuit 13; controller 14; DC side contactor 15; AC side contactor 16; DC disconnector 17; AC disconnector 18; filter circuit 19; discharge resistor 121; discharge switch 122; pre-charge resistor 151; pre-charge switch 152; processor 201; memory 202. DETAILED DESCRIPTION

[0056] Embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0057] The existing DC bus voltage discharge control method has the following problems: when discharging through the DC side voltage balancing resistor, the discharging speed is very slow, which seriously affects the safety of equipment maintenance personnel. When discharging through the discharge resistor, due to the high DC bus voltage level, in order to meet the requirement of fast discharge, a high-power discharge resistor is needed. Such discharge resistor is large in size, which seriously occupies the main circuit design arrangement space. At the same time, due to the large power level required by the discharge resistor, its cost is also relatively high. The embodiments of the present application propose a voltage discharge control method, which can consume the voltage on the DC bus capacitor faster, realize the fast discharge of the voltage on the DC bus capacitor, and save the hardware cost and circuit design arrangement space without additional design and installation of high-power discharge resistor.

[0058] For the convenience of description of the technical solutions, the electronic device 1 of the embodiments of the present application will be described below with reference to FIG. 1 and FIG. 2. In the embodiments, the electronic device 1 can include energy storage converters and vehicle chargers, etc.

[0059] FIG. 1 is a schematic diagram of an electronic device 1 according to an embodiment of the present application, and FIG. 2 is a schematic diagram of an electronic device 1 according to another embodiment of the present application. As shown in FIG. 1 and FIG. 2, the electronic device 1 can include a DC bus 10, a DC bus capacitor 11 and an inverter circuit 13.

[0060] In some embodiments, the DC bus 10 is a conductive path for transmitting DC power in the electronic device 1, such as an energy storage converter. The DC bus 10 can be connected with an external DC power supply, and the DC bus 10 connects various circuit parts of the electronic device 1 and provides DC power for them, ensuring effective transmission and distribution of electric energy. The DC bus 10 can include a positive DC bus and a negative DC bus.

[0061] In some embodiments, as shown in FIG. 1, the DC bus capacitor 11 can be formed by two groups of capacitors in series, and the DC bus capacitor 11 is connected across the DC bus 10, i.e., the DC bus capacitor 11 is connected between the positive DC bus and the negative DC bus, for smoothing the voltage fluctuation on the DC bus 10. Specifically, the DC bus capacitor 11 releases electrical energy at the peak of electrical energy demand and stores electrical energy at the trough, and through the storage and release of electrical energy, the voltage fluctuation on the DC bus 10 can be reduced, a stable DC voltage output can be provided, and thus the stability and reliability of the system can be improved.

[0062] In some embodiments, the inverter circuit 13 is a key component in the electronic device 1, such as an energy storage converter, and the input end of the inverter circuit 13 is connected to the positive DC bus and the negative DC bus, for converting the DC power of the DC bus into AC power.

[0063] In some embodiments, the inverter circuit 13 can adopt a three-phase IGBT (Insulated Gate Bipolar Transistor) bridge, including but not limited to an NPC type inverter bridge, a TNPC type inverter bridge, and an ANPC type inverter bridge. The inverter circuit 13 can include power semiconductor devices, such as IGBTs and the like. The inverter circuit 13 can realize the conversion from DC to AC by controlling the conduction and blocking of the devices such as IGBTs.

[0064] In the embodiments of the present application, the inverter circuit 13 is also used to output a target voltage to discharge the voltage of the DC bus capacitor 11 when the DC bus capacitor meets the voltage discharge condition, so as to realize the voltage discharge of the DC bus capacitor 11 through the switching loss of the inverter circuit 13 itself.

[0065] According to the electronic device 1 of the embodiments of the present application, when the DC bus capacitor 11 meets the voltage discharge condition, the power semiconductor devices in the inverter circuit 13 are turned on and off in a certain manner, so that the inverter circuit 13 outputs a stable AC voltage signal according to the set target voltage, and the power semiconductor devices will generate additional switching loss in the process of conduction and blocking. Therefore, the remaining electrical energy in the DC bus capacitor 11 can be consumed by using the switching loss itself, so as to realize the rapid discharge of the voltage of the DC bus capacitor 11. This control method does not need to additionally design and install a large-power discharge resistor, and saves the hardware cost and the circuit design arrangement space.

[0066] In addition, if it is necessary to further improve the discharge speed of the voltage of the DC bus capacitor 11, the electronic device 1 can also select to increase the DC discharge circuit 12, as shown in FIG. 2. The main function of the DC discharge circuit 12 is to quickly and safely discharge the residual charge on the DC bus capacitor 11 to ensure safety during system maintenance and prevent high voltage from causing danger to equipment maintenance personnel.

[0067] In some embodiments, the DC discharge circuit 12 is connected in parallel with the DC bus capacitor 11, and the DC discharge circuit 12 can include a discharge resistor 121 and a discharge switch 122. The DC discharge circuit 12 is used to conduct in response to the inverter circuit 13 stopping working, so as to discharge the voltage of the DC bus capacitor 11 through the discharge resistor 121.

[0068] The discharge resistor 121 can convert electrical energy into heat energy through resistance heating, so as to consume the electrical energy on the DC bus capacitor 11, so as to achieve the purpose of quickly discharging the voltage of the DC bus capacitor 11. The discharge switch 122 can control the conduction of the DC discharge circuit 12.

[0069] In some embodiments, compared with the discharge resistor of a large power level in the prior art, the discharge resistor 121 used in the present application can be a resistor of a smaller power level. Such a discharge resistor 121 is small in size and does not occupy too much space, thereby saving hardware costs and cabinet space of the electronic device 1.

[0070] In some embodiments, the electronic device 1 further includes a controller 14. The controller 14 is a core control unit of the entire electronic device 1, responsible for managing and coordinating the operation of each circuit part. The controller 14 is connected with the inverter circuit 13, and is used to execute the voltage discharge control method described in the following embodiments.

[0071] Specifically, the controller 14 can generate appropriate drive waveforms through PWM modulation, where PWM is a technology for controlling output voltage by adjusting pulse width and frequency. These waveforms can cause the IGBT switches in the inverter circuit 13 to conduct and cut off in a certain way, thereby generating the required alternating voltage signal. The IGBT switches will generate additional switching losses during conduction and cut-off, and therefore the residual electrical energy in the DC bus capacitor 11 can be consumed by using the switching losses of the IGBT, thereby achieving the quick discharge of the voltage of the DC bus capacitor 11.

[0072] In some embodiments, the controller 14 can also be connected with the DC discharge circuit 12 for performing the voltage discharge control method described in the following embodiments. That is, the controller 14 starts the inverter circuit 13 to output a stable AC voltage signal through PWM modulation, and uses the switching loss of IGBT to quickly discharge the voltage of the DC bus capacitor 11. When the voltage of the DC bus capacitor 11 decreases to a certain value, the discharge switch 122 is closed to complete the discharge of the remaining voltage in the DC bus capacitor 11 by using the discharge resistor 121.

[0073] In some embodiments, the electronic device 1 further comprises a first voltage sensor, a first current sensor, a second voltage sensor, and a second current sensor.

[0074] The first voltage sensor is connected with the controller 14 for detecting the voltage across the DC bus capacitor 11 as the DC bus voltage on the DC side of the inverter circuit 13. The first voltage sensor monitors the voltage across the DC bus capacitor 11 and feeds the detected voltage signal to the controller 14, so that the controller 14 can know the change of the voltage of the DC bus capacitor 11 in real time and whether the discharge operation is needed.

[0075] In some embodiments, the first current sensor is connected with the controller 14 for detecting the DC bus current. The monitoring of the DC bus current can help the controller 14 to know the flow of energy in the system, such as the current change in the charging or discharging state, and the condition of the load. These information are very important for the operation and safety of the system.

[0076] In some embodiments, the second voltage sensor is connected with the controller 14 for detecting the AC voltage on the AC side of the inverter circuit 13. Specifically, the second voltage sensor detects the AC voltage output by the inverter circuit 13 and feeds the voltage signal to the controller 14 for real-time monitoring of the waveform and stability of the output voltage of the inverter circuit 13, to ensure that the AC voltage meets the requirements. Therefore, the detection of the AC voltage can help the controller 14 to adjust the working state of the inverter circuit 13 in real time to ensure that the output voltage meets the set target value, while ensuring the stability and safety of the system.

[0077] In some embodiments, a second current sensor is connected to the controller 14 for detecting the AC current on the AC side of the inverter circuit 13. Specifically, the second current sensor feeds back the current signal to the controller 14 by detecting the AC current output by the inverter circuit 13, for real-time monitoring of the load condition of the inverter circuit 13 output current, so that the controller 14 can adjust and protect the inverter circuit 13. Therefore, the monitoring of the AC current can help the controller 14 to understand the status of the load in real time, such as the current change under different loads, and the running state of the load. These information are very important for the load management and fault diagnosis of the system.

[0078] In some embodiments, the electronic device 1 further comprises a temperature sensor connected to the controller 14 for detecting the temperature of the inverter circuit 13, so as to take timely measures to avoid damage or safety risks caused by overheating.

[0079] In some embodiments, as shown in FIG. 1 and FIG. 2, the electronic device 1 further comprises a DC side contactor 15 and an AC side contactor 16.

[0080] The DC side contactor 15 can be a switching device located between the DC side interface of the electronic device 1, such as an energy storage inverter, and the DC bus capacitor 11, for controlling the connection state of the DC bus capacitor 11 and the DC side interface. Specifically, the main function of the DC side contactor 15 is to control the on-off state of the circuit when it is necessary to disconnect or connect the DC side circuit. When maintenance, troubleshooting or other operations are needed, the DC circuit can be isolated by controlling the DC side contactor 15 to ensure the safety of the operators and the stability of the equipment.

[0081] In some embodiments, the DC side contactor 15 can include a pre-charge resistor 151 and a pre-charge switch 152. The pre-charge resistor 151 and the pre-charge switch 152 can be used to limit the sudden change of current when connecting the DC side, reduce the damage to the equipment, and protect the safety of the system.

[0082] Specifically, when the system starts or reconnects, the pre-charge resistor 151 is used to limit the current increase rate in the DC circuit before the DC side contactor 15 is closed, to prevent excessive current impact, while the pre-charge switch 152 is used to control the connection or disconnection of the pre-charge resistor 151, to ensure a smooth start-up process of the system.

[0083] In some embodiments, the AC side contactor 16 is located between the AC end of the inverter circuit 13 and the AC side interface of the electronic device 1, and is used to control the AC output of the electronic device 1. Specifically, the AC side contactor 16 can realize the connection or disconnection of the AC output of the inverter circuit 13 and the AC side interface of the electronic device 1 according to the input of the control signal, so as to control the delivery or stop of the AC power output by the inverter circuit 13, so as to ensure the stability and safety of the system.

[0084] In some embodiments, when the inverter circuit 13 adopts a three-phase IGBT bridge, the AC side contactor 16 can adopt a parallel connection of three switches, and each switch corresponds to each phase (A phase, B phase and C phase) of the output of the inverter circuit 13. The purpose of this design is to be able to cut off or connect each phase respectively when it is necessary to isolate the AC side circuit, so as to ensure the isolation and connection of the entire AC side circuit. Each switch controls one phase respectively, and by combining different switch states, the isolation and connection of single-phase or multi-phase can be realized, thereby improving the flexibility and controllability of the system.

[0085] As shown in FIGS. 1 and 2, the electronic device 1 further comprises a DC isolation switch 17 and an AC isolation switch 18. The DC isolation switch 17 is located between the DC side contactor 15 and the DC side interface, and the DC isolation switch 17 is used to cut off the connection between the DC side contactor 15 and the DC side interface when it is necessary to isolate the DC side circuit, so as to ensure the safety and reliability of the system. The DC isolation switch 17 can include two switches, which can be respectively connected to the positive and negative poles of the DC side interface, so as to more flexibly control the disconnection and connection of the DC circuit.

[0086] For example, in the energy storage system, the DC side may need to be periodically maintained or overhauled. By connecting the DC isolation switch 17 to the positive and negative poles of the DC side interface respectively, the operator can more conveniently control the isolation and connection of the DC side circuit, thereby improving the convenience and flexibility of operation; in addition, the DC isolation switch 17 composed of two switches can also enhance the safety of the system. For example, when emergency shutdown or troubleshooting is performed, the operator can simultaneously cut off the positive and negative connections of the DC side, so as to ensure that the DC side circuit is completely isolated, thereby reducing the occurrence of unexpected events.

[0087] In some embodiments, the AC isolation switch 18 is located between the AC side contactor 16 and the AC side interface. The AC isolation switch 18 is used to cut off the connection between the AC side contactor 16 and the AC side interface when it is necessary to isolate the AC side circuit, so as to ensure the safety and reliability of the system.

[0088] For example, in the energy storage system, a three-phase inverter bridge can be used to convert DC power into AC power. Therefore, the AC disconnect switch 18 can correspond to a three-phase AC interface, i.e., phase A, phase B, and phase C. By connecting the AC disconnect switch 18 with the three-phase AC interface, the isolation and connection of the entire AC side circuit can be achieved, ensuring the safety and stability of the system. Therefore, when maintenance or repair of the AC side is required, the operator can control the AC disconnect switch 18 to cut off phase A, phase B, and phase C, respectively, to isolate the three-phase circuit, prevent accidental start-up of the circuit or harm to personnel, and thus improve the flexibility and safety of the operation.

[0089] As shown in FIGS. 1 and 2, the electronic device 1 further includes a filter circuit 19 located between the inverter circuit 13 and the AC side contactor 16. The main function of the filter circuit 19 is to filter out high-frequency noise and harmonic components output by the inverter circuit 13, so that the AC signal is more pure and stable.

[0090] Specifically, in the electronic device 1, such as an energy storage converter, the inverter circuit 13 is used to convert DC power into AC power. This process is prone to introduce some high-frequency noise and harmonic components, which can interfere with the power grid or other devices. In order to reduce these disturbances, a filter circuit 19 can be added between the output of the inverter circuit 13 and the AC side contactor 16. The filter circuit 19 can include filter capacitors, filter inductors, and other elements, which can provide low-pass filtering function, i.e., by applying different impedances to signals of different frequencies, high-frequency noise and harmonic components are filtered out, while the fundamental frequency components of the AC signal are retained.

[0091] In some embodiments, the filter circuit 19 can include, but is not limited to, an LC filter or an LCL filter, and the specific type can be designed according to system requirements and design standards to ensure that when the electronic device 1, such as an energy storage converter, outputs AC power, the filtering effect is good, most of the high-frequency noise and harmonic components are filtered out, and the quality of the output electrical signal meets the specified standard requirements.

[0092] The energy storage system 110 of the embodiments of the present application is described below with reference to FIGS. 3 and 4.

[0093] FIG. 3 is a block diagram of an energy storage system 110 according to an embodiment of the present application, and FIG. 4 is a block diagram of an energy storage system 110 according to another embodiment of the present application. As shown in FIGS. 3 and 4, the energy storage system 110 includes the electronic device 1 described in the embodiments below, or the energy storage system 110 includes the energy storage module 2 and the electronic device 1 described in the embodiments above.

[0094] In some embodiments, the energy storage system of the embodiments of the present application, such as a vehicle, a drone, etc., can include the electronic device 1 of the embodiments above.

[0095] In some embodiments, the energy storage module 2 can include energy storage units, control systems and other auxiliary devices for storing electrical energy. The energy storage units can be batteries, supercapacitors and the like, which function to store electrical energy when it is abundant and release it when needed. The control systems can monitor and manage the charging and discharging process of the energy storage units to ensure the safe and reliable operation of the energy storage module 2; other auxiliary devices can include electrical connectors, protection devices and sensors, etc., to improve the performance and reliability of the system.

[0096] In some embodiments, the electronic device 1, such as the energy storage inverter, is a key component connecting the energy storage module 2 with the external power grid or load. The electronic device 1, such as the energy storage inverter, can control the flow of electrical energy, convert the direct current in the energy storage module 2 into alternating current, or convert the external alternating current into direct current for storage. The electronic device 1, such as the energy storage inverter, can also have a voltage discharge control function of the DC bus capacitor 11, which outputs a target voltage by controlling the inverter circuit 13 when the voltage discharge condition is met, to achieve rapid discharge of the voltage of the DC bus capacitor 11.

[0097] In some embodiments, the energy storage system 110 can be a device for storing electrical energy and releasing it when needed, used for balancing grid load, responding to frequent changes in the grid and responding to power demand peaks, etc. In practical applications, the energy storage system 110 can be applied in multiple fields, such as smart grid, renewable energy integration and electric vehicle charging stations, etc. For smart grid, the energy storage system 110 can be used for peak shaving and frequency regulation, etc. For renewable energy integration, the energy storage system 110 can smooth the fluctuations of renewable energy. For electric vehicle charging stations, the energy storage system 110 can provide fast charging and discharging services to alleviate the peak demand for charging. Therefore, the design and application of the energy storage system 110 have wide prospects and practical value.

[0098] According to the energy storage system 110 of the embodiments of the present application, the energy storage module 2 and the electronic device 1 described in the above embodiments are adopted, the energy storage module 2 is used to store electrical energy, and the electronic device 1 is used to convert the stored direct current into alternating current. By using the voltage discharge control method described in the following embodiments, the output of the inverter circuit 13 is controlled to generate a stable alternating voltage signal, and the residual electricity in the DC bus capacitor 11 is consumed by the switching loss of the power semiconductor devices in the inverter circuit 13, thereby achieving rapid discharge of the voltage of the DC bus capacitor 11, without the need for additional design and installation of a large-power discharge resistor, saving hardware costs and circuit design arrangement space.

[0099] Based on the electronic device 1 and the energy storage system 110 described in the above embodiments, a voltage bleed control method according to an embodiment of the present application is described below with reference to FIG. 5. The method can be used for the electronic device such as the energy storage converter in the above embodiments, which includes an inverter circuit for converting direct current to alternating current, and the inverter circuit is connected to a DC bus.

[0100] FIG. 5 is a flow chart of a voltage bleed control method according to an embodiment of the present application. As shown in FIG. 5, the voltage bleed control method includes at least steps S1-S2. S1, determine that the DC bus capacitor meets a voltage bleed condition.

[0101] In some embodiments, the voltage bleed of the DC bus capacitor is to ensure that the voltage of the DC bus capacitor can be quickly reduced to a safe level during system maintenance and repair, so as to ensure the safety of the equipment maintenance personnel. In addition, high voltage can cause damage to electronic components inside the equipment. By timely bleeding the voltage of the DC bus capacitor, damage to the electronic device such as the energy storage converter and other connected devices caused by high voltage can be prevented, thereby prolonging the service life of the equipment and reducing maintenance costs.

[0102] In some embodiments, the voltage bleed condition can refer to one or more specific conditions that need to be met when the device where the inverter circuit is located, such as the energy storage converter, needs to quickly reduce the voltage of the DC bus capacitor. The setting of these conditions helps to ensure safety and operational reliability when bleeding the voltage of the DC bus capacitor.

[0103] In some embodiments, the voltage bleed condition includes that the DC side contactor of the inverter circuit DC side and the AC side contactor of the inverter circuit AC side are both open. Only when it is confirmed that these conditions are all met, the controller can start the voltage bleed program of the DC bus capacitor to quickly reduce the voltage of the DC bus capacitor to a safe level, avoiding affecting the normal operation of the electronic device.

[0104] Wherein, the DC side contactor being open means that the DC bus capacitor of the electronic device is disconnected from the external DC power supply. In this way, it can be prevented that the external power supply continues to provide power to the DC bus capacitor, thereby ensuring that there is no additional power input when bleeding the voltage. The AC side contactor being open means that the output of the electronic device such as the energy storage converter is disconnected from the external grid or load. This ensures that the energy discharged during voltage bleeding will not be accidentally transmitted to the external load or grid, preventing interference and impact on the external system during the bleeding process. At the same time, it also prevents external current from flowing back to the electronic device such as the energy storage converter, affecting the bleeding process.

[0105] In some embodiments, the voltage bleed condition also includes that the cabinet door of the device where the inverter circuit is located, such as the energy storage converter, is closed, to prevent high voltage from causing harm to the system and personnel.

[0106] The closing of the cabinet door of the device in which the inverter circuit is located, such as the energy storage converter, is to ensure that the device is in a closed and safe state during the voltage discharge process of the DC bus capacitor, preventing the operator from directly contacting the internal high-voltage components during the voltage discharge of the DC bus capacitor. At the same time, the closing of the cabinet door can also prevent dust and other foreign matter from entering the internal electronic equipment, protecting the equipment from the influence of the external environment.

[0107] In some embodiments, the closing of the cabinet door of the electronic device, such as the energy storage converter, can be detected and confirmed by a door lock or an induction device, and the system will only allow the voltage discharge operation of the DC bus capacitor after confirming that the cabinet door has been closed.

[0108] In some embodiments, a safety interlocking mechanism can be provided to detect the states of the DC side contactor, the AC side contactor, and the cabinet door. When all conditions are met, the controller will only allow the voltage discharge operation of the DC bus capacitor. The safety interlocking mechanism can include a contactor state sensor, a door state sensor, and a controller. The contactor state sensor is used to detect the open state of the DC side contactor and the AC side contactor. The door state sensor is used to detect whether the cabinet door of the energy storage converter is closed. The controller can trigger the voltage discharge process of the DC bus capacitor only when all sensors feedback that the conditions are met.

[0109] S2, control the output target voltage of the inverter circuit to discharge the voltage of the DC bus capacitor connected between the positive and negative DC buses, and the inverter circuit is used to convert the DC power of the DC bus into AC power.

[0110] The input end of the inverter circuit can be connected to the positive and negative DC buses, and the inverter circuit is used to convert the DC power of the DC bus into AC power.

[0111] Specifically, when the DC bus voltage discharge condition is met, the controller can generate an inverter PWM drive waveform through the physical quantity information such as voltage and current detected by the sampling circuit in the electronic device, and through a series of processing and control algorithms. The power semiconductor devices (such as IGBT) in the inverter circuit will conduct and cut off according to the set PWM drive waveform to output a specific AC voltage signal. This control can be achieved through constant AC voltage mode open-loop control or closed-loop control, and the specific method depends on the system design. Through the frequent conduction and cutoff of the power semiconductor devices, the switching loss can quickly consume the remaining energy on the DC bus capacitor, thereby rapidly reducing the voltage of the DC bus capacitor.

[0112] In some embodiments, the sampling circuit in the electronic device, such as the energy storage converter, can include a current transformer circuit for detecting the output current of the inverter circuit, a voltage transformer circuit for detecting the output voltage of the inverter circuit, and a circuit for detecting the DC voltage and current across the bus capacitor.

[0113] According to the voltage discharge control method, when the DC bus capacitor meets the voltage discharge condition, the inverter circuit is controlled to output a target voltage, so that the inverter circuit is turned on and turned off in a certain manner, and the inverter circuit outputs a stable AC voltage signal according to the set target voltage. However, the power semiconductor devices in the inverter circuit will generate additional switching loss during the process of turning on and turning off. The residual electricity in the DC bus capacitor can be consumed by using the switching loss, thereby realizing the rapid discharge of the voltage of the DC bus capacitor. This control method does not need to design and install a large-power discharge resistor, thereby saving the hardware cost and the circuit design arrangement space.

[0114] In some embodiments, the target voltage is less than or equal to a human body safety voltage. The target voltage can be the final voltage value set by the controller during the voltage discharge of the DC bus capacitor. The target voltage can be set by the controller according to system requirements and safety standards. The human body safety voltage can be the voltage level that the human body can safely withstand, for example, 36V. The voltage exceeding the human body safety voltage can cause an electric shock hazard to the human body.

[0115] In some embodiments, during the voltage discharge of the DC bus capacitor, the controller adjusts the output of the inverter circuit according to the target voltage setting value, so that the output target voltage does not exceed the human body safety voltage. The controller can adjust the PWM signal of the inverter circuit to control the size and stability of the output target voltage, and ensure that the voltage is maintained within the safety range during the discharge process.

[0116] In some embodiments, the voltage discharge control method further includes obtaining a DC bus voltage value on the DC side of the inverter circuit, and controlling the inverter circuit to stop working when the DC bus voltage value is less than or equal to a first preset voltage threshold.

[0117] The DC bus voltage value on the DC side of the inverter circuit can be obtained by a first voltage sensor or other measuring device. The first voltage sensor detects the DC bus voltage value on the DC side of the inverter circuit in real time and transmits it to the controller. The controller can determine whether the system needs to perform the voltage discharge operation of the DC bus capacitor according to the data.

[0118] In some embodiments, the first preset voltage threshold can be a voltage threshold preset by the system during runtime. When the DC bus voltage value is less than or equal to the first preset voltage threshold, it indicates that the voltage has been reduced to a certain extent, and the operation of the inverter circuit needs to be stopped to avoid system instability or damage. That is, the controller will send a signal to stop the operation of the inverter circuit, and stopping the operation of the inverter circuit helps to reduce the power consumption of the system and protects the inverter circuit and related equipment from damage when the voltage is low.

[0119] In some embodiments, stopping the operation of the inverter circuit can be achieved by controlling the PWM signal or other related control means, so that the inverter circuit no longer outputs a voltage signal to the AC side.

[0120] In some embodiments, the first preset voltage threshold is a human body safety voltage (e.g., 36V). When the DC bus voltage drops to or below the human body safety voltage, the controller will start the operation of stopping the inverter circuit to ensure that the operating personnel will not be harmed during the voltage discharge process of the DC bus capacitor.

[0121] In some embodiments, in addition to using the switching loss of the power semiconductor device in the inverter circuit to quickly discharge the voltage of the DC bus capacitor, a combination of the switching loss of the power semiconductor device in the inverter circuit and a discharge resistor with a small power level can also be used to discharge the voltage of the DC bus capacitor. The advantage of this method is that it can further improve the discharge speed of the voltage of the DC bus capacitor. At the same time, since the discharge resistor has a small power level, it does not need to occupy too much space in the electronic equipment cabinet.

[0122] In some embodiments, the electronic device, such as an energy storage converter, further includes a DC discharge circuit connected across the DC bus, and the AC discharge circuit includes a discharge resistor. The voltage discharge control method further includes: in response to the inverter circuit stopping operating, controlling the DC discharge circuit to be turned on to discharge the voltage of the DC bus capacitor through the discharge resistor in the DC discharge circuit, and the DC discharge circuit is connected between the positive and negative DC buses and connected in parallel with the DC bus capacitor.

[0123] Specifically, taking the energy storage converter as an example, when the DC bus capacitor meets the voltage discharge condition, the system can generate PWM drive waveforms, which can cause the power semiconductor devices in the inverter circuit to turn on and off in a certain way, and through continuous on and off, additional switching loss can be generated to quickly discharge the voltage of the DC bus capacitor. When the DC bus voltage drops to the first preset voltage threshold, the inverter circuit stops working, and the controller can control the DC discharge circuit to be turned on, that is, first control the pre-charge switch in the DC discharge circuit to be closed, and then use the pre-charge resistor to prevent sudden current impact, and then open the pre-charge switch. The voltage across the DC bus capacitor will be discharged through the discharge resistor in the DC discharge circuit, thereby further improving the discharge speed of the voltage of the DC bus capacitor.

[0124] In some embodiments, the voltage discharge control method further comprises: when the DC bus voltage value is less than or equal to a second preset voltage threshold, controlling the DC discharge circuit to be turned off, the second preset voltage threshold being less than the first preset voltage threshold.

[0125] Wherein, the first preset voltage threshold here can be a target setting value reached by the first stage of voltage discharge of the DC bus capacitor through the inverter circuit, for example, 700V. The first preset voltage threshold can be set according to system design and operation requirements. The second preset voltage threshold can be a target setting value reached by the second stage of voltage discharge of the DC bus capacitor through the inverter resistor of the DC discharge circuit.

[0126] Specifically, when the DC bus voltage value drops below the second preset voltage threshold, it indicates that the voltage of the DC bus capacitor has been reduced to a certain extent, and the controller sends a signal to the DC discharge circuit to turn off, stopping the voltage discharge in time to prevent the voltage from being too low to cause system damage or failure.

[0127] In some embodiments, the second preset voltage threshold is a human body safety voltage, for example, 36V. The second preset voltage threshold is set to a human body safety voltage to ensure that in any case, even in the event of system abnormalities or failures, the operating personnel will not be harmed.

[0128] In some embodiments, the voltage discharge control method further comprises: when the inverter circuit meets a shutdown protection trigger condition, controlling the inverter circuit to perform shutdown protection. Wherein, the shutdown protection trigger condition can refer to when a system failure, overload or other abnormal condition occurs, the electronic device such as the energy storage converter needs to stop working immediately to avoid further damage or dangerous situations. These conditions can include excessive temperature, overcurrent and short circuit, etc.

[0129] Specifically, when the shutdown protection trigger condition is monitored, the system will issue a command to stop the operation of the electronic device, such as the energy storage converter. This can be achieved by controlling the inverter circuit to shut down, disconnecting the DC power supply, and performing other necessary safety measures. Shutdown protection is an important measure to protect equipment and personnel safety. It can help avoid damage to equipment due to failure or abnormal conditions, while reducing the risk of personnel injury caused by equipment failure. By automatically executing the shutdown protection program, the system can respond to abnormal conditions in a timely manner and avoid accidents when possible.

[0130] In some embodiments, the shutdown protection trigger condition includes at least one of the following: the voltage value of the inverter circuit output is greater than the voltage protection threshold; the current value of the inverter circuit output is greater than the current protection threshold; the temperature of the inverter circuit is greater than the temperature protection threshold; and the cabinet door of the device where the inverter circuit is located is open.

[0131] The voltage protection threshold can be a condition set to trigger shutdown protection when the voltage at the output of the inverter circuit exceeds the threshold. When the voltage at the output of the inverter exceeds the pre-set voltage protection threshold, it can indicate that the system voltage is abnormal. This may be caused by an overvoltage situation, which can cause equipment damage or safety risks, so shutdown protection needs to be triggered.

[0132] In some embodiments, the current protection threshold can be a condition set to trigger shutdown protection when the current at the output of the inverter exceeds the threshold. If the current at the output of the inverter exceeds the pre-set current protection threshold, it can indicate that the system current is abnormal, which may be caused by overloading or short circuit, etc. Immediate action is needed to protect equipment and personnel safety.

[0133] In some embodiments, the temperature protection threshold can be a condition set to trigger shutdown protection when the internal temperature of the inverter circuit exceeds the threshold. If the temperature of the inverter exceeds the pre-set temperature protection threshold, it can indicate that the system has a risk of overheating. Overheating can cause equipment failure or even cause serious consequences such as fire, so shutdown protection needs to be triggered in time.

[0134] In some embodiments, when the cabinet door of the device where the inverter circuit is located is open, it is easy to expose the internal circuit elements to the external environment and increase the risk of electric shock or other dangers to personnel. Therefore, the cabinet door open state can also be one of the conditions to trigger shutdown protection.

[0135] In some embodiments, controlling the target voltage output by the inverter circuit includes controlling the inverter circuit to operate according to a first control instruction to output the target voltage, wherein the first control instruction is obtained according to the DC bus voltage value and the DC bus current at the DC side of the inverter circuit.

[0136] Specifically, the system can monitor the DC bus voltage and DC bus current of the DC side of the inverter circuit in real time. This can be done by a first voltage sensor and a first current sensor. These sensors can be connected to the controller so that the controller obtains the values of the DC bus voltage and DC bus current in real time.

[0137] Further, the controller uses the DC bus voltage and DC bus current obtained from the first voltage sensor and the first current sensor to calculate the required target voltage through a specific algorithm. The target voltage can be dynamically adjusted according to the system requirements, therefore, the controller needs to calculate the target voltage according to the real-time DC bus state.

[0138] Further, once the target voltage is calculated, the control system generates a first control instruction. This instruction is generated according to the DC bus voltage and DC bus current and the pre-set control strategy, the purpose is to adjust the working parameters of the inverter circuit to make it output the required target voltage.

[0139] Further, the controller adjusts the working parameters of the inverter circuit according to the generated first control instruction. This can involve adjusting the PWM signal in the inverter and other operations, so that the inverter circuit outputs the required target voltage. By adjusting the working parameters of the inverter circuit, the inverter circuit will output an alternating voltage signal that meets the target voltage, so that the inverter circuit successfully adjusts the inverter circuit according to the first control instruction, and realizes the output of the required target voltage.

[0140] In some embodiments, controlling the inverter circuit to output the target voltage further includes controlling the inverter circuit to output the target voltage according to a second control instruction, wherein the second control instruction is obtained according to the DC bus voltage and DC bus current of the AC side of the inverter circuit and the AC voltage and AC current of the AC side output by the inverter circuit.

[0141] Specifically, the system can monitor the DC bus voltage and DC bus current of the AC side of the inverter circuit in real time, as well as the AC voltage and AC current output by the inverter circuit, these parameters can be obtained in real time by a second voltage sensor and a second current sensor, the sensors can be connected to the controller so that the controller obtains the values of the DC bus voltage and DC bus current of the AC side of the inverter circuit in real time.

[0142] Further, the controller uses the monitored DC bus and AC side parameters to generate a second control instruction through a specific algorithm, this instruction is generated according to the real-time DC bus state and the AC side state output by the inverter circuit, the purpose is to adjust the working parameters of the inverter circuit to realize the output of the required target voltage.

[0143] Further, the controller adjusts the working parameters of the inverter circuit according to the generated second control instruction. This involves adjusting the PWM signal of the inverter circuit and the like to make the inverter circuit output the required target voltage. By adjusting the working parameters of the inverter circuit, the inverter circuit will output an alternating voltage signal that meets the target voltage, so that the inverter circuit successfully adjusts the working of the inverter circuit according to the second control instruction and achieves the output of the required target voltage.

[0144] The specific flow of the two voltage bleed control methods according to the embodiments of the present application is described below with reference to FIGS. 6-7.

[0145] Taking an energy storage converter as an example, FIG. 6 is a flowchart of a voltage bleed control method according to an embodiment of the present application. As shown in FIG. 6, the overall flow of the voltage bleed control method at least includes steps S10-S16.

[0146] S10, the energy storage converter receives a shutdown instruction and has completed the shutdown action, the controller detects the system check signal to ensure that the DC side contactor and the AC side contactor have been disconnected, and the cabinet door of the energy storage converter is closed, and the controller controls the energy storage converter to enter a "DC bleed state".

[0147] S11, the energy storage converter operates in a constant AC voltage mode, outputs a target voltage through open-loop control, drives power semiconductor devices in the inverter circuit through PWM modulation, and consumes the residual voltage of the DC bus capacitor by using the switching loss of the power semiconductor devices.

[0148] S12, the controller detects the voltage value and current value of the inverter circuit output, the temperature of the inverter circuit, and the cabinet door of the energy storage converter in real time.

[0149] S13, it is determined whether the voltage value of the inverter circuit output is less than or equal to the voltage protection threshold, whether the current value of the inverter circuit output is less than or equal to the current protection threshold, whether the temperature of the inverter circuit is less than or equal to the temperature protection threshold, and whether the cabinet door of the energy storage converter is closed. If yes, go to step S14, if not, go to step S16.

[0150] S14, the inverter circuit continuously outputs an AC voltage signal, and the controller detects the DC bus voltage value in real time.

[0151] S15, it is determined whether the DC bus voltage value is less than or equal to a first preset voltage threshold (36V). If yes, go to step S16, if not, return to step S11.

[0152] S16, turn off the PWM modulation drive and control the energy storage converter to perform shutdown protection, and exit the "DC bleed state".

[0153] In general, the voltage discharge control method of the embodiments of the present application can discharge the voltage of the DC bus capacitor by outputting a target voltage of the inverter circuit. That is, when the DC bus capacitor meets the voltage discharge condition, the system can generate appropriate drive waveforms through PWM modulation. These waveforms can cause the power semiconductor devices in the inverter circuit to turn on and off in a certain way, so that the inverter circuit outputs a stable AC voltage signal according to the set target voltage. The power semiconductor devices will generate additional switching losses during the process of turning on and off, and the residual electricity in the DC bus capacitor can be consumed by using the switching losses, thereby achieving rapid discharge of the voltage of the DC bus capacitor.

[0154] Taking the energy storage converter as an example, FIG. 7 is a flowchart of the overall process of the voltage discharge control method according to another embodiment of the present application. As shown in FIG. 7, the overall process of the voltage discharge control method at least includes steps S100-S109.

[0155] S100, the energy storage converter receives a shutdown instruction, and has completed the shutdown action. The controller detects the system check signal to ensure that the DC side contactor and the AC side contactor have been disconnected, and the cabinet door of the energy storage converter is closed. The controller controls the energy storage converter to enter the "DC discharge state".

[0156] S101, the energy storage converter operates in a constant AC voltage mode, outputs a target voltage through open-loop control, drives the power semiconductor devices in the inverter circuit through PWM modulation, and consumes the residual voltage of the DC bus capacitor by using the switching losses of the power semiconductor devices.

[0157] S102, the controller detects the voltage value and current value output by the inverter circuit, the temperature of the inverter circuit, and the cabinet door of the energy storage converter in real time.

[0158] S103, it is determined whether the voltage value output by the inverter circuit is less than or equal to the voltage protection threshold value, whether the current value output by the inverter circuit is less than or equal to the current protection threshold value, whether the temperature of the inverter circuit is less than or equal to the temperature protection threshold value, and whether the cabinet door of the energy storage converter is closed. If yes, go to step S104, if not, go to step S109.

[0159] S104, the inverter circuit continuously outputs an AC voltage signal, and the controller detects the DC bus voltage value in real time.

[0160] S105, it is determined whether the DC bus voltage value is less than or equal to the first preset voltage threshold value (36V). If yes, go to step S106, if not, return to step S101.

[0161] S106, the PWM modulation drive is closed, and the controller controls the direct current discharge circuit to be turned on, and the residual voltage of the direct current bus capacitor is discharged through the discharge resistor.

[0162] S107, it is judged whether the direct current bus voltage value is less than or equal to a second preset voltage threshold (36V), if yes, step S108 is entered, if not, step S106 is returned.

[0163] S108, the direct current discharge circuit is turned off.

[0164] S109, the PWM modulation drive is closed, the energy storage converter is controlled to perform shutdown protection, and the "direct current discharge state" is exited.

[0165] In general, the voltage discharge control method of the embodiment of the application can discharge the voltage of the direct current bus capacitor by using the discharge resistor with a smaller target voltage and power level output by the inverter circuit. That is, when the direct current bus capacitor meets the voltage discharge condition, the system can generate PWM drive waveforms, which can cause the power semiconductor devices in the inverter circuit to turn on and turn off in a certain way, so that the inverter circuit outputs a stable alternating voltage signal according to the set target voltage. The power semiconductor devices will generate additional switching loss in the process of turning on and turning off, so the energy in the direct current bus capacitor can be consumed by using the switching loss itself. At the same time, a discharge resistor with a smaller power level can be installed in the direct current discharge circuit, so that the discharge speed of the voltage of the direct current bus capacitor depends not only on the energy loss of the power semiconductor devices, thereby further improving the discharge speed of the voltage of the direct current bus capacitor.

[0166] The effects of the two voltage discharge control methods of the embodiment of the application under Simulink simulation are compared below.

[0167] In some embodiments, it is set that the two direct current bus capacitors in FIG. 1 are both 150mF (wherein the voltage equalizing resistor is 100kΩ), and the direct current bus voltage Udc is 1500V. The direct current disconnecting switch is closed at t=1s, the direct current bus capacitors are charged, and the voltage on both sides rises to 1500V. The discharge starts at t=10s.

[0168] FIG. 8 is a simulation effect schematic diagram of the prior art voltage discharge only through the voltage equalizing resistor. As shown in FIG. 8, the discharge to the human body safety voltage 36V is completed at t=1896.4s, and the total time of the direct current discharge is 1886.4s.

[0169] Figure 9 is a simulation effect diagram of voltage discharge only through the inverter circuit according to one embodiment of the present application. As shown in Figure 9, the DC bus capacitor voltage is discharged, the DC disconnecting switch and the AC disconnecting switch are disconnected, the energy storage converter is open-loop to send a target voltage of 36V amplitude, the IGBT consumes the residual electricity in the DC bus capacitor, and the voltage is discharged to the human body safety voltage of 36V at t=290.3s, with a total time of 280.3s, and the discharge speed is increased by 85.1%.

[0170] In some embodiments, the two DC bus capacitors in Figure 2 are set to 150mF (wherein the voltage balancing resistor is 100kΩ), and the DC bus voltage Udc=1500V. The discharge resistor is 3kΩ / 100W specification. The simulation sets the DC side disconnecting switch to be closed at t=1s, the DC bus capacitor is charged, and the voltage on both sides is increased to 1500V. The discharge starts at t=10s.

[0171] Figure 10 is a simulation effect diagram of the first stage of discharge through the combination of the voltage balancing resistor and the discharge resistor according to the prior art, and Figure 11 is a simulation effect diagram of the second stage of discharge through the combination of the voltage balancing resistor and the discharge resistor according to the prior art. In which, the first stage of discharge from 1500V to 700V is through the voltage balancing resistor, and the second stage of discharge from 700V to the human body safety voltage of 36V is through the discharge resistor. The first stage of discharge effect is shown in Figure 10, and the voltage is discharged to 700V at t=391.05s, with a total time of 381.05s. The discharge resistor is connected, the second stage of discharge effect is shown in Figure 11, and the voltage is discharged to the human body safety voltage of 36V at t=455.01s, with a total time of 63.96s. The total time of DC discharge is 445.01s.

[0172] Figure 12 is a simulation effect diagram of the first stage of discharge through the combination of the inverter circuit and the discharge resistor according to one embodiment of the present application, and Figure 13 is a simulation effect diagram of the second stage of discharge through the combination of the inverter circuit and the discharge resistor according to one embodiment of the present application. In which, the first stage of discharge from 1500V to 700V is through the IGBT of the inverter circuit to consume the residual electricity in the DC bus capacitor (the DC disconnecting switch and the AC disconnecting switch are disconnected when the DC bus capacitor voltage is discharged, and the energy storage converter is open-loop to send a target voltage of 36V amplitude). The second stage of discharge from 700V to the human body safety voltage of 36V is achieved through the discharge resistor. The first stage of discharge effect is shown in Figure 12, and the voltage is discharged to 700V at t=108.8s, with a total time of 98.8s. The discharge resistor is connected, the second stage of discharge effect is shown in Figure 13, and the voltage is discharged to the human body safety voltage of 36V at t=172.8s, with a total time of 64s. The total time of DC discharge is 162.8s, and the discharge speed is increased by 63.4%. All the simulation results are shown in Table 1 as follows:

[0173] Table 1 Comparison of simulation results of two DC bus voltage discharge control methods and prior art

[0174] The electronic device 1 of the embodiments of the present application is described below with reference to FIG. 14.

[0175] FIG. 14 is a block diagram of the electronic device 1 according to an embodiment of the present application. As shown in FIG. 14, the electronic device 1 includes a memory 202 and at least one processor 201.

[0176] The at least one processor 201 can be one processor 201, two processors 201, three processors 201, five processors 201, eight processors 201, ten processors 201, or the like. The processor 201 can be a general-purpose processor (such as a central processing unit, CPU) or a special-purpose processor, depending on the application and requirements of the electronic device 1.

[0177] In some embodiments, the memory 202 can include random access memory (RAM), read-only memory (ROM), and flash memory, etc. The RAM is used to temporarily store runtime data and programs, the ROM is used to store read-only data, and the flash memory is usually used for long-term storage, such as storing operating systems, application programs, and user data.

[0178] In some embodiments, the memory 202 stores a computer program executable by the at least one processor 201, and the at least one processor 201 implements the DC bus voltage discharge control method described in the above embodiments when executing the computer program. By executing the computer program stored in the memory 202 by the processor 201, the processor 201 can implement the discharge process of the DC bus voltage and perform shutdown protection according to the preset conditions.

[0179] According to the electronic device 1 of the embodiments of the present application, the processor 201 can consume the residual power in the DC bus capacitor 11 by the switching loss of the power semiconductor device in the inverter circuit 13 by executing the computer program implementing the voltage discharge control method described in the above embodiments, thereby achieving rapid discharge of the voltage of the DC bus capacitor 11, without the need for additional design and installation of a large-power discharge resistor 121, saving hardware costs and circuit design arrangement space.

[0180] In some embodiments, the energy storage system 110 of the embodiments of the present application, such as a vehicle and a drone, can include the electronic device 1 of the above embodiments.

[0181] The embodiment of the present application further provides a non-volatile readable storage medium, which stores a computer program, and the computer program is executed to realize the voltage leakage control method described in the above embodiment. The specific implementation process of the voltage leakage control method can refer to the description of the above embodiment.

[0182] According to the non-volatile readable storage medium of the embodiment of the present application, by using the voltage leakage control method described in the above embodiment, the residual power in the DC bus capacitor 11 is consumed by the switching loss of the power semiconductor device in the inverter circuit 13, the voltage of the DC bus capacitor 11 can be quickly discharged, and a large-power leakage resistor 121 does not need to be additionally designed and installed, thereby saving the hardware cost and the circuit design arrangement space.

[0183] The computer readable storage medium of the embodiment of the present application can include, but is not limited to, a phase change memory (PRAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), other types of random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory or other optical and magnetic storage medium, which will not be described one by one here.

[0184] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example.

[0185] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A voltage discharge control method, characterized in that, include: Ensure that the DC bus capacitor meets the voltage discharge condition; and The inverter circuit outputs a target voltage to discharge the voltage of the DC bus capacitor, which is connected between the positive and negative DC buses. The inverter circuit is used to convert the DC power from the DC bus into AC power.

2. The voltage discharge control method according to claim 1, characterized in that, The voltage discharge condition includes the disconnection of both the DC-side contactor on the DC side of the inverter circuit and the AC-side contactor on the AC side of the inverter circuit.

3. The voltage discharge control method according to claim 2, characterized in that, The voltage discharge condition also includes the cabinet door of the device containing the inverter circuit being closed.

4. The voltage discharge control method according to any one of claims 1-3, characterized in that, The target voltage is less than or equal to the safe voltage for the human body.

5. The voltage discharge control method according to any one of claims 1-4, characterized in that, The voltage discharge control method further includes: Obtain the DC bus voltage value on the DC side of the inverter circuit; and When the DC bus voltage is less than or equal to a first preset voltage threshold, the inverter circuit is controlled to stop working.

6. The voltage discharge control method according to claim 5, characterized in that, The first preset voltage threshold is a human safety voltage.

7. The voltage discharge control method according to claim 5 or 6, characterized in that, The voltage discharge control method further includes: In response to the inverter circuit stopping operation, the DC discharge circuit is controlled to conduct, so as to discharge the voltage of the DC bus capacitor through the discharge resistor in the DC discharge circuit. The DC discharge circuit is connected between the positive and negative DC buses and is connected in parallel with the DC bus capacitor.

8. The voltage discharge control method according to claim 7, characterized in that, The voltage discharge control method further includes: When the DC bus voltage is less than or equal to the second preset voltage threshold, the DC discharge circuit is controlled to disconnect, and the second preset voltage threshold is less than the first preset voltage threshold.

9. The voltage discharge control method according to claim 8, characterized in that, The second preset voltage threshold is a human safety voltage.

10. The voltage discharge control method according to any one of claims 1-9, characterized in that, The voltage discharge control method further includes: When the inverter circuit meets the shutdown protection trigger condition, the inverter circuit is controlled to perform shutdown protection.

11. The voltage discharge control method according to claim 10, characterized in that, The shutdown protection triggering condition includes at least one of the following: The voltage output by the inverter circuit is greater than the voltage protection threshold. The current value output by the inverter circuit is greater than the current protection threshold. The temperature of the inverter circuit is greater than the temperature protection threshold; and The cabinet door of the device containing the inverter circuit is opened.

12. The voltage discharge control method according to any one of claims 1-11, characterized in that, Controlling the output target voltage of the inverter circuit includes: The inverter circuit is controlled to operate according to a first control command in order to output the target voltage, wherein the first control command is obtained based on the DC bus voltage and DC bus current on the DC side of the inverter circuit.

13. The voltage discharge control method according to any one of claims 1-12, characterized in that, Controlling the output target voltage of the inverter circuit includes: The inverter circuit is controlled to operate according to a second control command to output the target voltage, wherein the second control command is obtained based on the DC bus voltage and DC bus current on the AC side of the inverter circuit and the AC voltage and AC current on the AC side of the inverter circuit.

14. An electronic device (1), characterized in that, include: At least one processor (201); and A memory (202) communicatively connected to the at least one processor (201); The memory (202) stores a computer program that can be executed by the at least one processor (201), which, when executing the computer program, implements the voltage discharge control method according to any one of claims 1-13.

15. A non-volatile readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the voltage discharge control method according to any one of claims 1-13.

16. An electronic device (1), characterized in that, include: DC bus (10), the DC bus (10) includes a positive DC bus (10) and a negative DC bus (10); A DC bus capacitor (11) is connected between the positive DC bus (10) and the negative DC bus (10); and The inverter circuit (13) is connected to the positive DC bus (10) and the negative DC bus (10) at its input terminal. It is used to convert the DC power of the DC bus (10) into AC power. The inverter circuit (13) is also used to output a target voltage when the DC bus capacitor (11) meets the voltage discharge condition, so as to discharge the voltage of the DC bus capacitor (11).

17. The electronic device (1) according to claim 16, characterized in that, The electronic device (1) further includes: A DC discharge circuit (12) is connected in parallel with the DC bus capacitor (11). The DC discharge circuit (12) includes a discharge resistor (121). The DC discharge circuit (12) is turned on in response to the inverter circuit (13) stopping operation, so as to discharge the voltage of the DC bus capacitor (11) through the discharge resistor (121).

18. The electronic device (1) according to claim 17, characterized in that, The electronic device (1) further includes: A controller (14) is connected to the inverter circuit (13) and the DC discharge circuit (12) respectively, and is used to execute the voltage discharge control method according to any one of claims 1-13.

19. The electronic device (1) according to claim 18, characterized in that, The electronic device (1) further includes: The first voltage sensor is connected to the controller (14) and is used to detect the voltage across the DC bus capacitor (11) as the DC bus (10) voltage on the DC side of the inverter circuit (13). The first current sensor is connected to the controller (14) and is used to detect the current of the DC bus (10); A second voltage sensor, connected to the controller (14), is used to detect the AC voltage on the AC side of the inverter circuit (13) output; and The second current sensor is connected to the controller (14) and is used to detect the AC current on the AC side of the inverter circuit (13).

20. The electronic device (1) according to any one of claims 16-19, characterized in that, The electronic device (1) further includes: A DC-side contactor (15), located between the DC-side interface of the electronic device (1) and the DC bus capacitor (11), is used to control the connection state between the DC bus capacitor (11) and the DC-side interface; and An AC-side contactor (16) is located between the AC terminal of the inverter circuit (13) and the AC-side interface of the electronic device (1) and is used to control the AC output of the electronic device (1).

21. The electronic device (1) according to claim 20, characterized in that, The electronic device (1) further includes: A DC disconnect switch (17) is located between the DC-side contactor (15) and the DC-side interface; and An AC disconnect switch (18) is located between the AC side contactor (16) and the AC side interface.

22. The electronic device (1) according to claim 20 or 21, characterized in that, The electronic device (1) further includes: A filter circuit (19) is located between the inverter circuit (13) and the AC side contactor (16).

23. An energy storage system (110), characterized in that, The energy storage system (110) includes the electronic device (1) of claim 14, or The energy storage system (110) includes an energy storage module (2) and an electronic device (1) according to any one of claims 16-22.

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