Control method, control device, energy storage system and storage medium

Abstract

The invention discloses a control method and device of an energy storage inverter, an energy storage system and a storage medium. The control method comprises the steps that the working mode of the energy storage inverter is detected, and the resonance current of the energy storage inverter is detected in real time; under the condition that the energy storage inverter is in a discharging mode, controlling a first primary side switch tube and a fourth primary side switch tube to be conducted, and controlling a first secondary side switch tube and a fourth secondary side switch tube to be conducted after a first preset duration; and under the condition that it is detected that the resonance current drops to a first preset threshold value, the first secondary side switching tube and the fourth secondary side switching tube are controlled to be switched off, and the first primary side switching tube and the fourth primary side switching tube are controlled to be switched off after a second preset duration. According to the control method provided by the embodiment of the invention, the efficiency of the energy storage inverter can be improved, and the electromagnetic interference of the energy storage inverter during on-off of the switch can be reduced.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a control method, a control device, an energy storage system and a storage medium. Background Art

[0002] When facing low-voltage energy storage batteries, the energy storage inverter needs to step up the voltage and then integrate it into the grid or supply the load. In related technologies, in order to meet the application scenarios of household storage inverters, the low-voltage side of the low-voltage household storage inverter adopts a dual active bridge + LC resonant circuit to form a series resonant topology to control the charging and discharging of the battery according to the needs of the scenario. However, the switch control used in current applications easily causes the switch tube to heat up, and there is EMC that is difficult to control, which makes the energy storage system inefficient and reduces reliability. Summary of the invention

[0003] Embodiments of the present application provide a control method, a control device, an energy storage system, and a non-volatile computer-readable storage medium.

[0004] The control method provided in the embodiment of the present application is used for an energy storage inverter, wherein the energy storage inverter includes a primary full-bridge circuit and a secondary full-bridge circuit, wherein the primary full-bridge circuit includes a first primary switch tube, a second primary switch tube, a third primary switch tube and a fourth primary switch tube, wherein the first primary switch tube and the second primary switch tube are connected in series to form a first primary bridge arm, wherein the third primary switch tube and the fourth primary switch tube are connected in series to form a second primary bridge arm, wherein the secondary full-bridge circuit includes a first secondary switch tube, a second secondary switch tube, a third secondary switch tube and a fourth secondary switch tube, wherein the first secondary switch tube and the second secondary switch tube are connected in series to form a first secondary bridge arm, wherein the third secondary switch tube and the fourth secondary switch tube are connected in series to form a second secondary bridge arm; wherein the control method includes:

[0005] Detecting the working mode of the energy storage inverter and detecting the resonant current of the energy storage inverter in real time;

[0006] When the energy storage inverter is in a discharge mode, the first primary switch tube and the fourth primary switch tube are controlled to be turned on, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned on after a first preset time;

[0007] When it is detected that the resonant current drops to a first preset threshold, the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off, and the first primary switch tube and the fourth primary switch tube are controlled to be turned off after a second preset time.

[0008] In some embodiments, the control method further comprises:

[0009] When the working mode of the energy storage inverter is in the discharge mode, the second primary switch tube and the third primary switch tube are controlled to be turned on, and the second secondary switch tube and the third secondary switch tube are controlled to be turned on after a third preset time;

[0010] When it is detected that the resonant current drops to a second preset threshold, the second secondary switch tube and the third secondary switch tube are controlled to be turned off, and the second primary switch tube and the third primary switch tube are controlled to be turned off after a fourth preset time.

[0011] In some embodiments, the control method further comprises:

[0012] When the energy storage inverter is in a charging mode, controlling the first secondary switch tube and the fourth secondary switch tube to be turned on, and controlling the first primary switch tube and the fourth primary switch tube to be turned on after a fifth preset time;

[0013] When it is detected that the resonant current drops to a third preset threshold, the first primary switch tube and the fourth primary switch tube are controlled to be turned off, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off after a sixth preset time.

[0014] In some embodiments, the control method further comprises:

[0015] When the energy storage inverter is in a charging mode, controlling the second secondary switch tube and the third secondary switch tube to be turned on, and controlling the second primary switch tube and the third primary switch tube to be turned on after a seventh preset time;

[0016] When it is detected that the resonant current drops to a fourth preset threshold, the second primary switch tube and the third primary switch tube are controlled to be turned off, and the second secondary switch tube and the third secondary switch tube are controlled to be turned off after an eighth preset time.

[0017] In some embodiments, the energy storage inverter further includes an inductor, and the inductor is connected to the first secondary switch tube and the second secondary switch tube, and the control method further includes:

[0018] Detecting the current magnitude of the inductor;

[0019] When the current of the inductor is within a first interval, controlling the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube to be turned on;

[0020] When the resonant current is 0, the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube are controlled to be turned off.

[0021] In some embodiments, the control method further comprises:

[0022] When the current of the inductor is within the first interval, controlling the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube to be turned on;

[0023] When the resonant current is 0, the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube are controlled to be turned off.

[0024] The control device of the embodiment of the present application includes:

[0025] A detection module, used to detect the working mode of the energy storage inverter and detect the resonant current of the energy storage inverter in real time;

[0026] A control module is used to control the first primary switch tube and the fourth primary switch tube to be turned on when the energy storage inverter is in a discharge mode, and control the first secondary switch tube and the fourth secondary switch tube to be turned on after a first preset time period; and when it is detected that the resonant current drops to a first preset threshold, control the first secondary switch tube and the fourth secondary switch tube to be turned off, and control the first primary switch tube and the fourth primary switch tube to be turned off after a second preset time period.

[0027] An energy storage system according to an embodiment of the present application includes an energy storage inverter, a controller and a memory. The energy storage inverter includes a primary full-bridge circuit and a secondary full-bridge circuit. The primary full-bridge circuit includes a first primary switch tube, a second primary switch tube, a third primary switch tube and a fourth primary switch tube. The first primary switch tube and the second primary switch tube are connected in series to form a first primary bridge arm, and the third primary switch tube and the fourth primary switch tube are connected in series to form a second primary bridge arm. The secondary full-bridge circuit includes a first secondary switch tube, a second secondary switch tube, a third secondary switch tube and a fourth secondary switch tube. The first secondary switch tube and the second secondary switch tube are connected in series to form a first secondary bridge arm, and the third secondary switch tube and the fourth secondary switch tube are connected in series to form a second secondary bridge arm. The memory stores a computer program. When the computer program is executed by the controller, the controller implements the control method.

[0028] The non-volatile computer-readable storage medium of the embodiment of the present application includes a computer program. When the computer program is executed by a controller, the controller implements the control method.

[0029] In the control method, control device, energy storage inverter and storage medium of the implementation mode of the present application, when the energy storage inverter is in the discharge mode, the first primary switch tube and the fourth primary switch tube are first controlled to be turned on for a first preset time length and then the first secondary switch tube and the fourth secondary switch tube are turned on, so that the first secondary switch tube and the fourth secondary switch tube operate in a zero voltage switching (ZVS) state, thereby improving the switching efficiency of the energy storage inverter and reducing the electromagnetic interference when the switch is turned on and off. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0031] Figure 1 is a partial schematic diagram of an energy storage system according to certain embodiments of the present application;

[0032] Figure 2 is a flow chart of a control method of certain embodiments of the present application;

[0033] Figure 3 is a schematic diagram of timing control of an energy storage inverter in a discharge mode according to certain embodiments of the present application;

[0034] Figure 4 It is a schematic diagram of a scenario of an energy storage inverter in certain embodiments of the present application;

[0035] Figure 5 is another schematic diagram of a scenario of an energy storage inverter in certain embodiments of the present application;

[0036] Figure 6 is another schematic diagram of a scene of an energy storage inverter in certain embodiments of the present application;

[0037] Figure 7-8 is a flow chart of a control method of certain embodiments of the present application;

[0038] Fig. 9 is a schematic diagram of timing control of an energy storage inverter in a charging mode according to certain embodiments of the present application;

[0039] Figure 10-11 is a flow chart of a control method of certain embodiments of the present application;

[0040] Fig.12 It is a timing control schematic diagram of the energy storage inverter when switching from charging mode to charging mode;

[0041] Fig.13 It is a schematic diagram of timing control of the energy storage inverter in transition mode in certain embodiments of the present application.

[0042] Reference numerals

[0043] 100-energy storage system, 10-energy storage inverter, 11-dual active bridge converter, 111-primary full-bridge circuit, Q1-first primary switch tube, Q2-second primary switch tube, Q3-third primary switch tube, Q4-fourth primary switch tube, 112-transformer, 113-secondary full-bridge circuit, Q5-first secondary switch tube, Q6-second secondary switch tube, Q7-third secondary switch tube, Q8-fourth secondary switch tube, Lr-resonant inductor, Cr-resonant capacitor, 12-LC resonant circuit, C1-capacitor, L1-inductor, 13-boost circuit, Q9-first control switch tube, Q10-second control switch tube, C2-output capacitor, 20-power supply, BUS+-output positive bus, BUS--output negative bus. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of the present invention, and cannot be understood as limiting the embodiments of the present invention.

[0045] The low-voltage energy storage system has the advantages of flexible matching, high safety and low cost. The biggest feature of the low-voltage energy storage system is that it mostly uses 51.2V low-voltage energy storage batteries. In the face of low-voltage energy storage batteries, the energy storage inverter of the low-voltage energy storage system needs to boost the voltage and then integrate it into the power grid or supply the load. Therefore, the energy storage inverter needs to have isolation, wide voltage range regulation, bidirectional conversion, fast dynamic response, low electromagnetic interference (EMI) and high safety. Therefore, the energy storage inverter mainly adopts an isolated bidirectional topology circuit.

[0046] The main topologies of isolated bidirectional applications include dual active bridge (DAB), capacitor-inductor-inductor-capacitor (CLLC) resonant converter, phase-shifted full-bridge converter, etc. Among them, DAB and phase-shifted full-bridge are turned off at the current peak, with large turn-off losses and high electromagnetic interference, which are difficult to control. CLLC has excellent soft switching characteristics and high efficiency, but its dynamic response and wide voltage regulation capabilities are relatively weak, making it difficult to meet the uninterruptible power supply (UPS) function of household storage.

[0047] In order to meet the application scenarios of household storage inverters, the low-voltage side of the current low-voltage household storage inverter adopts a dual active bridge topology + LC resonant circuit to form a series resonant topology circuit, which can boost the voltage from 40-60V to 240-360V; and the Buckboost topology is used on the high-voltage side, so that the charging and discharging of the battery can be controlled according to the needs of the scene. In related technologies, PWM pulses are often used to control the switching of the dual active bridge topology, so that the corresponding switching devices of the front and rear stages of the dual active bridge topology are switched synchronously, thereby achieving bidirectional buck-boost and smooth switching of the energy flow direction, without power reflux problems, and simple implementation. However, such a control method is prone to heat generation, and EMC is difficult to control, resulting in low efficiency and reduced reliability of the whole machine.

[0048] In view of this, please refer to Figure 1-3 , the embodiment of the present application provides a control method for an energy storage inverter. Among them, the energy storage inverter 10 may include a primary full-bridge circuit 111 and a secondary full-bridge circuit 113, the primary full-bridge circuit 111 includes a first primary switch tube Q1, a second primary switch tube Q2, a third primary switch tube Q3 and a fourth primary switch tube Q4, the first primary switch tube Q1 and the second primary switch tube Q2 are connected in series to form a first primary bridge arm, the third primary switch tube Q3 and the fourth primary switch tube Q4 are connected in series to form a second primary bridge arm, the secondary full-bridge circuit 113 includes a first secondary switch tube Q5, a second secondary switch tube Q6, a third secondary switch tube Q7 and a fourth secondary switch tube Q8, the first secondary switch tube Q5 and the second secondary switch tube Q6 are connected in series to form a first secondary bridge arm, the third secondary switch tube Q7 and the fourth secondary switch tube Q8 are connected in series to form a second secondary bridge arm; the control method of the energy storage inverter 10 includes:

[0049] 01: Detect the working mode of the energy storage inverter and detect the resonant current of the energy storage inverter in real time;

[0050] 02: When the energy storage inverter is in the discharge mode, the first primary switch tube and the fourth primary switch tube are controlled to be turned on, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned on after a first preset time;

[0051] 03: When it is detected that the resonant current drops to the first preset threshold, the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off, and the first primary switch tube and the fourth primary switch tube are controlled to be turned off after a second preset time.

[0052] See also Figure 2 This embodiment also provides a control device, which includes a detection module and a control module.

[0053] Step 01 can be implemented by the detection module, and steps 02 and 03 can be implemented by the control module. That is, the detection module is used to detect the working mode of the energy storage inverter 10 and detect the resonant current of the energy storage inverter 10 in real time; the control module is used to control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned on when the energy storage inverter 10 is in the discharge mode, and control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned on after the first preset time; and when it is detected that the resonant current drops to the first preset threshold, control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned off, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned off after the second preset time.

[0054] The embodiment of the present application also provides an energy storage system 100, which includes a controller, a memory and the above-mentioned energy storage inverter 10. The memory stores a computer program, and when the computer program is executed by the controller, the controller executes the above-mentioned control method, that is, the controller can be used to detect the working mode of the energy storage inverter 10 and detect the resonant current of the energy storage inverter 10 in real time; and when the energy storage inverter 10 is in the discharge mode, the first primary switch tube Q1 and the fourth primary switch tube Q4 are turned on, and the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned on after the first preset time length; the controller can also be used to control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to turn off when the resonant current drops to the first preset threshold value, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to turn off after the second preset time length.

[0055] In the control method, control device and energy storage system 100 of the present application, when the energy storage inverter 10 is in the discharge mode, the first primary switch tube Q1 and the fourth primary switch tube Q4 are first controlled to be turned on for a first preset time length and then the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned on, so that the first secondary switch tube Q5 and the fourth secondary switch tube Q8 operate in a zero voltage switching (ZVS) state, thereby improving efficiency and reducing electromagnetic interference when the switches are turned on and off.

[0056] In some embodiments, the control device may be a part of the energy storage system 100. In other words, the energy storage system 100 includes the control device.

[0057] In some embodiments, as hardware, the control device may be independently installed in the energy storage system 100 or as an additional peripheral component. As software, the control device may be a computer program in the energy storage system 100.

[0058] In some embodiments, the control device may also be integrated into the energy storage system 100 . For example, when the control device is a part of the energy storage system 100 , the control device may be integrated into a controller.

[0059] Please refer to further Figure 1 Specifically, the energy storage system 100 may be a low-voltage energy storage system 100, and the energy storage system 100 may include a power source 20 and an energy storage inverter 10, wherein the power source 20 is connected to the energy storage inverter 10. The power source 20 may be a low-voltage energy storage battery, for example, a 51.2v low-voltage battery. The energy storage inverter 10 may convert the electricity of the power source 20 and incorporate it into the power grid or supply the load.

[0060] The energy storage inverter 10 may include a dual active bridge converter 11 (Dual Active Bridge, DAB), an LC resonant circuit 12 and a boost circuit 13. One end of the dual active bridge converter 11 is connected to the positive and negative electrodes of the power source 20, and the other end is connected to the LC resonant circuit 12, and the LC resonant circuit 12 is also connected to the boost circuit 13. The boost circuit 13 may be a Buckboost circuit, and the boost circuit 13 is connected to the output positive bus BUS+ and the output negative bus BUS-.

[0061] The energy storage inverter 10 may include a discharge mode and a charging mode, wherein in the charging mode, the power supply 20 can supply power to the load or the grid through the dual active bridge converter 11 and the boost circuit 13, and in the discharge mode, the power supply 20 is charged by the external power supply 20 through the dual active bridge converter 11.

[0062] The dual active bridge converter 11 may include a transformer 112, a primary full bridge circuit 111, a secondary full bridge circuit 113, a resonant inductor Lr and a resonant capacitor Cr. The primary full bridge circuit 111 is connected to the power source 20 and the primary side of the transformer 112, and the secondary full bridge circuit 113 is connected to the secondary side of the transformer 112 and the LC resonant circuit 12. The resonant capacitor Cr is connected in parallel to both ends of the primary full bridge circuit 111, and one end of the resonant inductor Lr is connected to the primary full bridge circuit 111, and the other end is connected to the primary side of the transformer 112.

[0063] The primary full-bridge circuit 111 may include a first primary switch tube Q1, a second primary switch tube Q2, a third primary switch tube Q3, and a fourth primary switch tube Q4. The secondary full-bridge circuit 113 may include a first secondary switch tube Q5, a second secondary switch tube Q6, a third secondary switch tube Q7, and a fourth secondary switch tube Q8. It should be noted that the switch tube of this embodiment is an insulated gate bipolar transistor (IGBT tube) as an example for explanation, that is, the switch tube is not limited to the IGBT tube.

[0064] The first electrode of the first primary switch tube Q1 is connected to the positive electrode of the power source 20, the second electrode of the first primary switch tube Q1 is connected to one end of the primary side of the transformer 112, the first electrode of the second primary switch tube Q2 is connected to the negative electrode of the power source 20, and the second electrode of the second primary switch tube Q2 is connected to the second electrode of the first primary switch tube Q1. The first electrode of the third primary switch tube Q3 is connected to the positive electrode of the power source 20, and the second electrode of the third primary switch tube Q3 is connected to the other end of the primary side of the transformer 112. The first electrode of the fourth primary switch tube Q4 is connected to the negative electrode of the power source 20, and the second electrode of the fourth primary switch tube Q4 is connected to the second electrode of the second primary switch tube Q2.

[0065] The first pole of the first secondary switch tube Q5 is connected to one end of the LC resonant circuit 12, the second pole of the first secondary switch tube Q5 is connected to one end of the secondary side of the transformer 112, the first pole of the second secondary switch tube Q6 is connected to the other end of the LC resonant circuit 12, and the second pole of the second secondary switch tube Q6 is connected to the second pole of the first secondary switch tube Q5. The first pole of the third secondary switch tube Q7 is connected to one end of the LC resonant circuit 12, and the second pole of the third secondary switch tube Q7 is connected to the other end of the secondary side of the transformer 112. The first pole of the fourth secondary switch tube Q8 is connected to the other end of the LC resonant circuit 12, and the second pole of the fourth secondary switch tube Q8 is connected to the second pole of the second secondary switch tube Q6.

[0066] The control electrodes of the first primary switch tube Q1, the second primary switch tube Q2, the third primary switch tube Q3 and the fourth primary switch tube Q4, the first secondary switch tube Q5, the second secondary switch tube Q6, the third secondary switch tube Q7 and the fourth secondary switch tube Q8 can all be connected to the control module of the controller or control device.

[0067] The LC resonant circuit 12 may include an inductor L1 and a capacitor C1, one end of the capacitor C1 is connected to the first electrode of the third secondary switch tube Q7, the other end of the capacitor C1 is connected to the first end of the fourth secondary switch tube Q8, one end of the inductor L1 is connected to one end of the capacitor C1, and the other end is connected to the boost circuit 13. The boost circuit 13 may include a first control switch tube Q9, a second control switch tube Q10, and an output capacitor C2, wherein the first electrode of the first control switch tube Q9 is connected to the other end of the inductor L1, and the second electrode is connected to the other end of the capacitor C1. The first electrode of the second control switch tube Q10 is connected to the other end of the inductor L1, the second electrode of the second control switch tube Q10 is connected to the output positive bus BUS+, one end of the output capacitor C2 is connected to the output positive bus BUS+, and the other end is connected to the output negative bus BUS-.

[0068] The controller may send control signals to the control electrodes of the first primary switch tube Q1, the second primary switch tube Q2, the third primary switch tube Q3, the fourth primary switch tube Q4, the first secondary switch tube Q5, the second secondary switch tube Q6, the third secondary switch tube Q7, and the fourth secondary switch tube Q8, respectively, so as to control the conduction and shutdown of each switch tube, respectively, wherein the control signal may be a PWM signal. In order to improve the control efficiency of the controller, the first primary switch tube Q1 and the fourth primary switch tube Q4 may be set as a group, the second primary switch tube Q2 and the third primary switch tube Q3 may be set as a group, the first secondary switch tube Q5 and the fourth secondary switch tube Q8 may be set as a group, and the second secondary switch tube Q6 and the third secondary switch tube Q7 may be set as a group. The controller may send the same control signal to the switch tubes in each group to control the conduction or shutdown of the switch tubes in the group. For example, a control signal may be sent to the first primary switch tube Q1 and the fourth primary switch tube Q4 to turn them on.

[0069] The resonant current is the current flowing through the resonant inductor Lr, and the controller can detect the magnitude and direction of the resonant current in real time. A positive resonant current means that the current flows from the positive electrode of the power supply 20 to the resonant inductor Lr, and a negative resonant current means that the resonant current flows from the negative electrode of the power supply 20 to the resonant inductor Lr.

[0070] The first preset time length is the time when the output capacitors of the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are discharged to 0 V. The first preset threshold value is a value greater than 0, and the first preset threshold value is less than the peak value of the resonant current. The second preset time length is the time length required for the resonant current to drop from the first preset threshold value to 0.

[0071] See also Figure 3-6 , when the energy storage inverter 10 is in the discharge mode, the controller controls the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned on, so that the voltage of the power supply 20 is applied to two points AB, wherein point A is the position where the first primary switch tube Q1 is connected to the resonant inductor Lr, and point B is the position where the fourth primary switch tube is connected to the primary side of the transformer 112; under the action of this voltage, the resonant cavity current gradually increases, and the current passes through the transformer 112 to first discharge the output capacitors of the first secondary switch tube Q5 and the fourth secondary switch tube Q8, and at the same time charges the output capacitors of the second secondary switch tube Q6 and the third secondary switch tube Q7 (such as Figure 4 As shown in FIG. 1 ), after the first preset time, the output capacitors of the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are discharged to 0V. After the output capacitors of the second secondary switch tube Q6 and the third secondary switch tube Q7 are charged to Vbus, the diodes connected in parallel with the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned on, so that the voltage across them is 0 (as shown in FIG. 1 ). Figure 5As shown), the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are controlled to be turned on, and the current starts to commutate from the diode to the first secondary switch tube Q5 and the fourth secondary switch tube Q8, and the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned on at zero voltage (ZVS) (as shown). Figure 6 shown).

[0072] When it is detected that the resonant current drops to the first preset threshold, the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are controlled to be turned off, so that the current begins to flow from the diodes of the first secondary switch tube Q5 and the fourth secondary switch tube Q8, and the zero voltage (ZVS) shutdown of the first secondary switch tube Q5 and the fourth secondary switch tube Q8 is completed. After the second preset time, that is, when the resonant current drops to 0, the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are controlled to be turned off. In this way, the energy storage inverter 10 improves the switching efficiency of the first secondary switch tube Q5 and the fourth switch tube in the discharge mode, and reduces the electromagnetic interference EMI when the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned on and off. In this way, the efficiency and reliability of the energy storage inverter 10 are improved.

[0073] Please combine Figure 7 In some embodiments, the control method further comprises:

[0074] 04, when the working mode of the energy storage inverter is in the discharge mode, the second primary switch tube and the third primary switch tube are controlled to be turned on, and after a third preset time, the second secondary switch tube and the third secondary switch tube are controlled to be turned on;

[0075] 05. When it is detected that the resonant current drops to the second preset threshold, the second secondary switch tube and the third secondary switch tube are controlled to be turned off, and the second primary switch tube and the third primary switch tube are controlled to be turned off after a fourth preset time.

[0076] In some embodiments, 04 and 05 can be implemented by a control module, or in other words, the control module can be used to control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned on when the operating mode of the energy storage inverter 10 is in the discharge mode, and control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned on after a third preset time period; and when it is detected that the resonant current drops to a second preset threshold value, control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned off, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned off after a fourth preset time period.

[0077] In some embodiments, the controller can be used to control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned on when the operating mode of the energy storage inverter 10 is in the discharge mode, and control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned on after a third preset time period; and when it is detected that the resonant current drops to a second preset threshold value, control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned off, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned off after a fourth preset time period.

[0078] It should be noted that the third preset time length is the time when the output capacitors of the second secondary switch tube Q6 and the third secondary switch tube Q7 are discharged to 0 V. The second preset threshold value is a value less than 0, and the absolute value of the second preset threshold value is less than the absolute value of the peak value of the resonant current. The fourth preset time length is the time length required for the resonant current to drop from the second preset threshold value to 0.

[0079] Please refer to further Figure 3 When the energy storage inverter 10 is in the discharge mode, the second primary switch tube Q2 and the third primary switch tube Q3 are controlled to be turned on, so that the voltage of the power supply 20 is applied to the two points BA. Under the action of this voltage, the current of the resonant cavity increases in the reverse direction, and the current first discharges the output capacitors of the second secondary switch tube Q6 and the third secondary switch tube Q7 through the transformer 112, and simultaneously charges the output capacitors of the first secondary switch tube Q5 and the fourth secondary switch tube Q8. After the third preset time, the output capacitors of the second secondary switch tube Q6 and the third secondary switch tube Q7 are discharged to 0V, and the output capacitors of the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are charged. The output capacitors of the second secondary switch tube Q5 and the fourth secondary switch tube Q8 are charged to Vbus, and the diodes connected in parallel with the second secondary switch tube Q6 and the third secondary switch tube Q7 are turned on, so that the voltage across the second secondary switch tube Q6 and the third secondary switch tube Q7 is 0, and the second secondary switch tube Q6 and the third secondary switch tube Q7 are controlled to be turned on, and the current begins to commutate from the diodes connected in parallel with the second secondary switch tube Q6 and the third secondary switch tube Q7 to the second secondary switch tube Q6 and the third secondary switch tube Q7, completing the zero voltage (ZVS) turn-on of the second secondary switch tube Q6 and the third secondary switch tube Q7.

[0080] When it is detected that the resonant current drops to the second preset threshold, the second secondary switch tube Q6 and the third secondary switch tube Q7 are controlled to be turned off, so that the current starts to flow from the diodes corresponding to the second secondary switch tube Q6 and the third secondary switch tube Q7, and the zero voltage (ZVS) shutdown of the second secondary switch tube Q6 and the third secondary switch tube Q7 is completed. After the fourth preset time, that is, when the resonant current drops to 0, the second primary switch tube Q2 and the third primary switch tube Q3 are controlled to be turned off. In this way, the switching efficiency of the second secondary switch tube Q6 and the third secondary switch tube Q7 is improved, and the EMI of the second secondary switch tube Q6 and the third secondary switch tube Q7 when the energy storage inverter 10 is turned on and off in the discharge mode is reduced. In this way, the efficiency and reliability of the energy storage inverter 10 are further improved.

[0081] Please combine Figure 8 In some embodiments, the control method further comprises:

[0082] 06. When the energy storage inverter is in the charging mode, the first secondary switch tube and the fourth secondary switch tube are controlled to be turned on, and after a fifth preset time, the first primary switch tube and the fourth primary switch tube are controlled to be turned on;

[0083] 07. When it is detected that the resonant current drops to the third preset threshold, the first primary switch tube and the fourth primary switch tube are controlled to be turned off, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off after a sixth preset time.

[0084] In some embodiments, steps 06 and 07 can be implemented by a control module, or in other words, the control module can be used to control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned on when the energy storage inverter 10 is in a charging mode, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned on after a fifth preset time period, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned off when it is detected that the resonant current drops to a third preset threshold value, and control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned off after a sixth preset time period.

[0085] In some embodiments, the controller can be used to control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned on when the energy storage inverter 10 is in a charging mode, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned on after a fifth preset time period, and control the first primary switch tube Q1 and the fourth primary switch tube Q4 to be turned off when it is detected that the resonant current drops to a third preset threshold value, and control the first secondary switch tube Q5 and the fourth secondary switch tube Q8 to be turned off after a sixth preset time period.

[0086] It should be noted that the fifth preset time length is the time when the output capacitors of the first primary switch tube Q1 and the fourth primary switch tube Q4 are discharged to 0 V. The third preset threshold value is a value less than 0, and the absolute value of the first preset threshold value is less than the peak value of the resonant current. The sixth preset time length is the time length required for the resonant current to drop from the third preset threshold value to 0.

[0087] See also Figure 1 and Fig. 9 When the energy storage inverter 10 is in the charging mode, the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are controlled to be turned on, so that the voltage of the power supply 20 is applied to the two points CD. Under the action of this voltage, the current in the resonant cavity gradually increases, and the current first discharges the output capacitors of the first primary switch tube Q1 and the fourth primary switch tube Q4 through the transformer 112, and simultaneously charges the output capacitors of the second primary switch tube Q2 and the third primary switch tube Q3. After the fifth preset time, the output capacitors of the first primary switch tube Q1 and the fourth primary switch tube Q4 are discharged to 0V. After the output capacitors of the second primary switch tube Q2 and the third primary switch tube Q3 are charged to Vbus, the diodes connected in parallel with the first primary switch tube Q1 and the fourth primary switch tube Q4 are turned on, so that the voltage across the diodes is 0. Then, the first primary switch tube Q1 and the fourth primary switch tube Q4 are controlled to be turned on, and the current begins to commutate from the diodes of the first primary switch tube Q1 and the fourth primary switch tube Q4 to the first primary switch tube Q1 and the fourth primary switch tube Q4. In this way, zero voltage (ZVS) conduction of the first primary switch tube Q1 and the fourth primary switch tube Q4 is achieved.

[0088] When it is detected that the resonant current drops to the third preset threshold, the first primary switch tube Q1 and the fourth primary switch tube Q4 are controlled to be turned off, so that the current flows from the diodes of the first primary switch tube Q1 and the fourth primary switch tube Q4, and the zero voltage (ZVS) shutdown of the first primary switch tube Q1 and the fourth primary switch tube Q4 is completed. After the sixth preset time, the resonant current drops to 0, and the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are controlled to be turned off. In this way, when charging, the switching efficiency of the first primary switch tube Q1 and the fourth primary switch tube Q4 is improved, and the electromagnetic interference EMI of the first primary switch tube Q1 and the fourth primary switch tube Q4 when the energy storage inverter 10 is turned on and off in the charging mode is reduced, so that the efficiency and reliability of the energy storage inverter 10 are improved.

[0089] Please combine Fig.10 In some embodiments, the control method further comprises:

[0090] 08. When the energy storage inverter is in the charging mode, the second secondary switch tube and the third secondary switch tube are controlled to be turned on, and after the seventh preset time, the second primary switch tube and the third primary switch tube are controlled to be turned on;

[0091] 09. When it is detected that the resonant current drops to the fourth preset threshold, the second primary switch tube and the third primary switch tube are controlled to be turned off, and the second secondary switch tube and the third secondary switch tube are controlled to be turned off after the eighth preset time.

[0092] In some embodiments, steps 08 and 09 can be implemented by a control module, or in other words, the control module can be used to control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned on when the energy storage inverter 10 is in a charging mode, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned on after a seventh preset time period, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned off when it is detected that the resonant current drops to a fourth preset threshold value, and control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned off after an eighth preset time period.

[0093] In some embodiments, the controller can be used to control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned on when the energy storage inverter 10 is in the charging mode, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned on after the seventh preset time period, and control the second primary switch tube Q2 and the third primary switch tube Q3 to be turned off when it is detected that the resonant current drops to the fourth preset threshold value, and control the second secondary switch tube Q6 and the third secondary switch tube Q7 to be turned off after the eighth preset time period.

[0094] It should be noted that the seventh preset time length is the time it takes for the output capacitors of the second primary switch tube Q2 and the third primary switch tube Q3 to discharge to 0 V. The fourth preset threshold is greater than 0 and less than the peak value of the resonant current. The eighth preset time length is the time required for the resonant current to drop from the fourth preset threshold to 0.

[0095] See also Figure 1 and Fig. 9When the energy storage inverter 10 is in the charging mode, the second secondary switch tube Q6 and the third secondary switch tube Q7 are controlled to be turned on, so that the voltage of the power supply 20 is applied to the two DC points. Under the action of this voltage, the current in the resonant cavity gradually increases, and the current first discharges the output capacitors of the second primary switch tube Q2 and the third primary switch tube Q3 through the transformer 112, and simultaneously charges the output capacitors of the first primary switch tube Q1 and the fourth primary switch tube Q4. After the seventh preset time, the output capacitors of the second primary switch tube Q2 and the third primary switch tube Q3 are discharged to 0V. After the output capacitors of the first primary switch tube Q1 and the fourth primary switch tube Q4 are charged to Vbus, the diodes connected in parallel with the second primary switch tube Q2 and the third primary switch tube Q3 are turned on, so that the voltage across the diodes is 0, and the second primary switch tube Q2 and the third primary switch tube Q3 are controlled to be turned on, and the current begins to flow from the diodes to the second primary switch tube Q2 and the third primary switch tube Q3. In this way, the second primary switch tube Q2 and the third primary switch tube Q3 are turned on at zero voltage (ZVS).

[0096] When it is detected that the resonant current drops to the fourth preset threshold, the second primary switch tube Q2 and the third primary switch tube Q3 are controlled to be turned off, so that the current begins to flow from the diodes of the second primary switch tube Q2 and the third primary switch tube Q3, and the zero voltage (ZVS) shutdown of the second primary switch tube Q2 and the third primary switch tube Q3 is completed. After the eighth preset time, the resonant current drops to 0, and the second secondary switch tube Q6 and the third secondary switch tube Q7 are controlled to be turned off. In this way, when charging, the switching efficiency of the second primary switch tube Q2 and the third primary switch tube Q3 is improved, and the electromagnetic interference EMI when the second primary switch tube Q2 and the third primary switch tube Q3 are turned on and off in the charging mode of the energy storage inverter 10 is further reduced. In this way, the efficiency and reliability of the energy storage inverter 10 are improved.

[0097] Please combine Fig.11 In some embodiments, the control method further comprises:

[0098] 11. Detect the current of the inductor;

[0099] 12. When the current of the inductor is within the first interval, the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube are controlled to be turned on;

[0100] 13. When the resonant current is 0, the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube are controlled to be turned off.

[0101] In some embodiments, step 11 can be implemented by a detection module, and steps 12 and 13 can be implemented by a control module, or in other words, the detection module can also be used to detect the current of the inductor L1. The control module can also be used to control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned on when the current of the inductor L1 belongs to the first interval range; and to control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned off when the resonant current is 0.

[0102] In some embodiments, the controller can also be used to detect the current size of the inductor L1; and when the current of the inductor L1 belongs to the first interval range, control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned on; and when the resonant current is 0, control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned off.

[0103] It is understandable that due to the error in current sampling, the detection result will be opposite to the actual current direction in the low current state, and the controller switches the switch mode according to the sampling result. For example, see Fig.12 When the energy storage inverter 10 is in the discharge mode, if it is in the low current discharge state, the sampling error may easily cause the controller to mistakenly think that the resonant current is reversed, thereby switching from the discharge mode to the charging mode. At this time, the resonant current is still in the discharge state due to the voltage on both sides. In this mode, during the on-period of the first primary switch tube Q1 and the fourth primary switch tube Q4, the resonant current works normally, as shown in t2-t3. At t3, after the first primary switch tube Q1 and the fourth primary switch tube Q4 are turned off, since the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are still in the on state, a reverse voltage is added to the resonant cavity, thereby generating a reverse excitation current. The current resonates and increases during the on-period (t3-t4) of the first secondary switch tube Q5 and the fourth secondary switch tube Q8. At t4, the first secondary switch tube Q5 and the fourth secondary switch tube Q8 are turned off, the excitation source disappears, and the current begins to decrease until it reaches 0. The current is reactive consumption during the conversion process, which reduces the efficiency of the energy storage inverter 10. Therefore, in this embodiment, a transition mode under low current is added, and whether to perform mode switching is determined by judging the direction and magnitude of the current IL of the inductor L1, thereby avoiding frequent mode switching.

[0104] See also Fig.13 and Figure 1Specifically, during the operation of the energy storage inverter 10, if the controller detects that the current of the inductor L1 belongs to the first interval range, it switches to the transition mode. If the controller detects that the current of the inductor L1 belongs to the second interval range, it switches to the discharge mode. If the controller detects that the current of the inductor L1 belongs to the third interval range, the value of the second interval range is greater than the value of the first interval range, and the value of the third interval range is less than the value of the first interval range.

[0105] For example, in this embodiment, the first interval range may be -1A-1A, the second interval range may be greater than 2A, and the third interval range may be less than 3A. That is, when the current magnitude of the inductor L1 is detected to be within the range of -1-1A, the transition mode is entered; when the current magnitude of the inductor L1 is detected to be greater than or equal to -2A, the discharge mode is entered, and at this time, the controller may execute the above steps 02-05; when the current magnitude of the inductor L1 is detected to be less than or equal to -2A, the charging mode is entered, and at this time, the controller may execute the above steps 06-09.

[0106] When entering the transition mode, the controller can control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned on; and when the resonant current is 0, the controller can control the first primary switch tube Q1, the fourth primary switch tube Q4, the first secondary switch tube Q5, and the fourth secondary switch tube Q8 to be turned off. In this way, the generation of invalid current can be avoided, and the switching loss of the energy storage inverter 10 is further reduced.

[0107] In some embodiments, the control method further comprises:

[0108] 14. When the current of the inductor is within the first interval, the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube are controlled to be turned on;

[0109] 15. When the resonant current is 0, the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube are controlled to be turned off.

[0110] In some embodiments, steps 14 and 15 can be implemented by a control module, or in other words, the control module can also be used to control the second primary switch tube Q2, the third primary switch tube Q3, the second secondary switch tube Q6, and the third secondary switch tube Q7 to be turned on when the current of the inductor L1 belongs to the first interval range, and to control the second primary switch tube Q2, the third primary switch tube Q3, the second secondary switch tube Q6, and the third secondary switch tube Q7 to be turned off when the resonant current is 0.

[0111] In some embodiments, the controller can also be used to control the second primary switch tube Q2, the third primary switch tube Q3, the second secondary switch tube Q6, and the third secondary switch tube Q7 to be turned on when the current of the inductor L1 is within the first interval range, and to control the second primary switch tube Q2, the third primary switch tube Q3, the second secondary switch tube Q6, and the third secondary switch tube Q7 to be turned off when the resonant current is 0.

[0112] In this way, when the current is small, the generation of invalid current can be avoided by turning on and off the second primary switch tube Q2, the third primary switch tube Q3, the second secondary switch tube Q6, and the third secondary switch tube Q7, thereby further reducing the switching loss of the energy storage inverter 10.

[0113] The embodiment of the present application also provides a non-volatile computer-readable storage medium, including a computer program. When the computer program is executed by a controller, the controller implements the above-mentioned control method.

[0114] In the description of this specification, the description with reference to the terms "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0115] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

[0116] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A control method for an energy storage inverter, characterized in that: The energy storage inverter includes a primary full-bridge circuit and a secondary full-bridge circuit, the primary full-bridge circuit includes a first primary switch tube, a second primary switch tube, a third primary switch tube and a fourth primary switch tube, the first primary switch tube and the second primary switch tube are connected in series to form a first primary bridge arm, the third primary switch tube and the fourth primary switch tube are connected in series to form a second primary bridge arm, the secondary full-bridge circuit includes a first secondary switch tube, a second secondary switch tube, a third secondary switch tube and a fourth secondary switch tube, the first secondary switch tube and the second secondary switch tube are connected in series to form a first secondary bridge arm, the third secondary switch tube and the fourth secondary switch tube are connected in series to form a second secondary bridge arm; the control method includes: Detecting the working mode of the energy storage inverter and detecting the resonant current of the energy storage inverter in real time; When the energy storage inverter is in a discharge mode, the first primary switch tube and the fourth primary switch tube are controlled to be turned on, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned on after a first preset time; When it is detected that the resonant current drops to a first preset threshold, the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off, and the first primary switch tube and the fourth primary switch tube are controlled to be turned off after a second preset time.

2. The control method according to claim 1, characterized in that: The control method further comprises: When the working mode of the energy storage inverter is in the discharge mode, the second primary switch tube and the third primary switch tube are controlled to be turned on, and the second secondary switch tube and the third secondary switch tube are controlled to be turned on after a third preset time; When it is detected that the resonant current drops to a second preset threshold, the second secondary switch tube and the third secondary switch tube are controlled to be turned off, and the second primary switch tube and the third primary switch tube are controlled to be turned off after a fourth preset time.

3. The control method according to claim 1, characterized in that: The control method further comprises: When the energy storage inverter is in a charging mode, controlling the first secondary switch tube and the fourth secondary switch tube to be turned on, and controlling the first primary switch tube and the fourth primary switch tube to be turned on after a fifth preset time; When it is detected that the resonant current drops to a third preset threshold, the first primary switch tube and the fourth primary switch tube are controlled to be turned off, and the first secondary switch tube and the fourth secondary switch tube are controlled to be turned off after a sixth preset time.

4. The control method according to claim 1, characterized in that: The control method further comprises: When the energy storage inverter is in a charging mode, controlling the second secondary switch tube and the third secondary switch tube to be turned on, and controlling the second primary switch tube and the third primary switch tube to be turned on after a seventh preset time; When it is detected that the resonant current drops to a fourth preset threshold, the second primary switch tube and the third primary switch tube are controlled to be turned off, and the second secondary switch tube and the third secondary switch tube are controlled to be turned off after an eighth preset time.

5. The control method according to claim 1, characterized in that: The energy storage inverter further includes an inductor, and the inductor is connected to the first secondary side switch tube and the second secondary side switch tube. The control method further includes: Detecting the current magnitude of the inductor; When the current of the inductor is within a first interval, controlling the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube to be turned on; When the resonant current is 0, the first primary switch tube, the fourth primary switch tube, the first secondary switch tube, and the fourth secondary switch tube are controlled to be turned off.

6. The control method according to claim 5, characterized in that: The control method further comprises: When the current of the inductor is within the first interval, controlling the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube to be turned on; When the resonant current is 0, the second primary switch tube, the third primary switch tube, the second secondary switch tube, and the third secondary switch tube are controlled to be turned off.

7. A control device for an energy storage inverter, characterized in that: The energy storage inverter includes a primary full-bridge circuit and a secondary full-bridge circuit, the primary full-bridge circuit includes a first primary switch tube, a second primary switch tube, a third primary switch tube and a fourth primary switch tube, the first primary switch tube and the second primary switch tube are connected in series to form a first primary bridge arm, the third primary switch tube and the fourth primary switch tube are connected in series to form a second primary bridge arm, the secondary full-bridge circuit includes a first secondary switch tube, a second secondary switch tube, a third secondary switch tube and a fourth secondary switch tube, the first secondary switch tube and the second secondary switch tube are connected in series to form a first secondary bridge arm, the third secondary switch tube and the fourth secondary switch tube are connected in series to form a second secondary bridge arm; the control device includes: A detection module, used to detect the working mode of the energy storage inverter and detect the resonant current of the energy storage inverter in real time; A control module is used to control the first primary switch tube and the fourth primary switch tube to be turned on when the energy storage inverter is in a discharge mode, and control the first secondary switch tube and the fourth secondary switch tube to be turned on after a first preset time period; and when it is detected that the resonant current drops to a first preset threshold, control the first secondary switch tube and the fourth secondary switch tube to be turned off, and control the first primary switch tube and the fourth primary switch tube to be turned off after a second preset time period.

8. An energy storage system, characterized in that: The energy storage system includes an energy storage inverter, a controller and a memory. The energy storage inverter includes a primary full-bridge circuit and a secondary full-bridge circuit. The primary full-bridge circuit includes a first primary switch tube, a second primary switch tube, a third primary switch tube and a fourth primary switch tube. The first primary switch tube and the second primary switch tube are connected in series to form a first primary bridge arm, and the third primary switch tube and the fourth primary switch tube are connected in series to form a second primary bridge arm. The secondary full-bridge circuit includes a first secondary switch tube, a second secondary switch tube, a third secondary switch tube and a fourth secondary switch tube. The first secondary switch tube and the second secondary switch tube are connected in series to form a first secondary bridge arm, and the third secondary switch tube and the fourth secondary switch tube are connected in series to form a second secondary bridge arm. The memory stores a computer program. When the computer program is executed by the controller, the controller implements the control method described in any one of claims 1 to 6.

9. The energy storage system according to claim 8, characterized in that: The energy storage inverter further includes an LC filter circuit and a boost circuit, wherein the LC filter circuit is connected to the secondary full-bridge circuit, and the boost circuit is connected to the LC filter circuit.

10. A non-volatile computer-readable storage medium, characterized in that: The invention comprises a computer program, and when the computer program is executed by a controller, the controller implements the control method according to any one of claims 1 to 6.

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