Energy storage system and energy storage management system

Abstract

The application provides an energy storage system and an energy storage management system. The energy storage system comprises an energy storage unit, a DC / DC conversion circuit, a controllable switch tube, an energy storage converter and a control unit. The control unit is configured to control the controllable switch tube to be bidirectionally conducted to stop the DC / DC conversion circuit from working when the voltage of the energy storage unit is greater than the voltage peak of one end of the energy storage converter connected to a grid point, and the energy storage converter is configured to charge and discharge the energy storage unit through the controllable switch tube; and the control unit is further configured to control the controllable switch tube to be turned off to charge and discharge the energy storage unit through the DC / DC conversion circuit and the energy storage converter when the voltage of the energy storage unit is less than the voltage peak of one end of the energy storage converter connected to the grid point. The energy storage system has improved working efficiency.

Description

Technical Field

[0001] This application relates to the field of battery energy storage technology, specifically to an energy storage system and an energy storage management system. Background Technology

[0002] With the increasing proportion of new energy sources, the configuration of energy storage systems is becoming increasingly important. Energy storage systems can achieve grid frequency regulation and peak shaving through charging and discharging control. An energy storage system mainly consists of battery clusters and uses a power conversion system (PCS) to control the charging and discharging process of the battery clusters via AC-DC conversion, and can directly supply power to AC loads in the absence of a grid. Because the power conversion system is used to connect to the grid, the voltage at the grid-connected end of the power conversion system will fluctuate significantly during charging and discharging. If this voltage exceeds the voltage that the battery clusters can provide, the power conversion system will fail to operate, reducing the efficiency of the energy storage system. Summary of the Invention

[0003] This application provides an energy storage system that can improve the working efficiency of the energy storage system.

[0004] In a first aspect, this application provides an energy storage system, which includes an energy storage unit, a DC / DC converter circuit, a controllable switching transistor, an energy storage converter, and a control unit.

[0005] The first end of the aforementioned controllable switching transistor is connected to the aforementioned energy storage unit, the second end of the aforementioned controllable switching transistor is connected to the first end of the aforementioned energy storage converter, the first end of the aforementioned DC / DC conversion circuit is connected to the aforementioned energy storage unit, the second end of the aforementioned DC / DC conversion circuit is connected to the first end of the aforementioned energy storage converter, the second end of the aforementioned energy storage converter is used to connect to the grid connection point, and the aforementioned energy storage converter is used to connect to the power grid or load through the aforementioned grid connection point.

[0006] The aforementioned control unit is used to, during a first time period, when the output voltage of the aforementioned energy storage unit is continuously greater than the peak voltage of the second terminal of the aforementioned energy storage converter, control the aforementioned controllable switch to turn on during a second time period so that the aforementioned DC / DC conversion circuit stops working, so as to charge and discharge the aforementioned energy storage unit through the aforementioned energy storage converter.

[0007] The aforementioned control unit is used to control the aforementioned controllable switch to disconnect when the output voltage of the aforementioned energy storage unit is less than the peak voltage of the second terminal of the aforementioned energy storage converter during the third time period, so as to charge and discharge the aforementioned energy storage unit through the aforementioned energy storage converter and the aforementioned DC / DC conversion circuit, wherein the aforementioned time sequence is from the aforementioned first time period to the aforementioned second time period and then to the aforementioned third time period.

[0008] Optionally, the aforementioned controllable switching transistor is an insulated-gate bipolar transistor (IGBT), a relay, a contactor, or a circuit formed by connecting an IGBT and a diode in parallel. Optionally, the aforementioned energy storage unit is a battery cluster.

[0009] Optionally, the aforementioned DC / DC converter circuit is a bidirectional DC / DC converter circuit, and / or the aforementioned energy storage converter is a bidirectional energy storage converter. The aforementioned DC / DC converter circuit includes a boost circuit or a buck-boost circuit.

[0010] In this scheme, the second terminal of the energy storage converter receives AC power, which has a voltage peak. When the voltage of the energy storage unit exceeds the peak voltage at the second terminal of the energy storage converter, a controllable switch is turned on, allowing the voltage of the energy storage unit to be output to the bidirectional energy storage converter through the controllable switch. Since the resistance of this controllable switch is very small, the additional power consumption is also very small, even negligible, thus saving power consumption in the circuit. Furthermore, because this controllable switch is bidirectional, the bidirectional energy storage converter can not only discharge but also charge the energy storage unit. This allows for full utilization of the bidirectional energy storage converter, maintaining its rated output voltage at a higher value, operating in a more efficient mode, and improving the overall efficiency of the energy storage system.

[0011] Furthermore, when the voltage of the energy storage unit is lower than the peak voltage at the second terminal of the energy storage converter, the controllable switch is turned off, allowing the DC / DC converter circuit to boost the voltage output from the energy storage unit. This boosted voltage is then output to the bidirectional energy storage converter, enabling it to operate normally. In this embodiment, the energy storage unit can still operate even when its voltage is low, fully utilizing its energy. Furthermore, the bidirectional energy storage converter can still operate even when its voltage is low, fully utilizing its capabilities and improving the efficiency of the energy storage system.

[0012] In contrast to existing solutions where the energy storage unit cannot operate when its voltage is lower than the peak voltage at the second terminal of the energy storage converter, thus reducing the efficiency of the energy storage system, this solution ensures normal operation of the energy storage system regardless of whether the energy storage unit's voltage is higher or lower than the peak voltage at the second terminal of the energy storage converter, thereby improving the system's efficiency. Furthermore, charging and discharging of the energy storage unit are possible regardless of whether the energy storage unit's voltage is higher or lower than the peak voltage at the second terminal of the energy storage converter, further optimizing the system's efficiency.

[0013] In one possible implementation, the aforementioned control unit is further configured to, when the aforementioned controllable switch is turned on during the aforementioned second time period, control the aforementioned energy storage converter to rectify and transform the voltage at the second terminal of the aforementioned energy storage converter, so that the voltage at the second terminal of the aforementioned controllable switch is greater than the output voltage of the aforementioned energy storage unit, so as to charge the aforementioned energy storage unit through the aforementioned controllable switch.

[0014] Optionally, when the output voltage of the aforementioned energy storage unit is less than the voltage at the second terminal of the aforementioned controllable switch and the voltage at the second terminal of the aforementioned controllable switch is less than the voltage at the first terminal of the aforementioned energy storage converter, the aforementioned energy storage converter is used to charge the aforementioned energy storage unit.

[0015] In another possible implementation, the aforementioned control unit is further configured to, when the aforementioned controllable switch is turned on during the aforementioned second time period, control the aforementioned energy storage converter to perform an inverter transformation on the voltage at the first terminal of the aforementioned energy storage converter, so that the output voltage of the aforementioned energy storage unit is greater than the voltage at the second terminal of the aforementioned controllable switch, so as to achieve discharge of the aforementioned energy storage unit through the aforementioned controllable switch.

[0016] Optionally, when the output voltage of the aforementioned energy storage unit is greater than the voltage at the second terminal of the aforementioned controllable switch and the voltage at the second terminal of the aforementioned controllable switch is greater than the voltage at the first terminal of the aforementioned energy storage converter, the aforementioned energy storage converter is used to discharge the aforementioned energy storage unit.

[0017] In this scheme, when the output voltage of the energy storage unit exceeds the peak voltage at the second terminal of the energy storage converter, the voltage of the energy storage unit is output to the bidirectional energy storage converter through the controllable switch. Since the controllable switch is bidirectional, the bidirectional energy storage converter can not only discharge but also charge the energy storage unit. This allows for timely replenishment of the energy storage unit when its energy is insufficient, or for the recovery and storage of excess power from the grid, effectively achieving a balance between energy use and storage.

[0018] In one possible implementation, the aforementioned control unit is further configured to, when the aforementioned controllable switch is turned off during the aforementioned third time period, control the aforementioned DC / DC conversion circuit to step down the voltage at the first terminal of the aforementioned energy storage converter and output the reduced voltage to the aforementioned energy storage unit, so as to charge the aforementioned energy storage unit.

[0019] Optionally, when the voltage at the second terminal of the aforementioned DC / DC converter is less than the voltage at the first terminal of the aforementioned energy storage converter, the aforementioned energy storage converter is used to charge the aforementioned energy storage unit.

[0020] The aforementioned control unit is also used to, when the aforementioned controllable switch is turned off during the aforementioned third time period, control the aforementioned DC / DC conversion circuit to boost the output voltage of the aforementioned energy storage unit and output the boosted voltage to the aforementioned energy storage converter, so as to realize the discharge of the aforementioned energy storage unit.

[0021] Optionally, when the voltage at the second terminal of the aforementioned DC / DC converter is greater than the voltage at the first terminal of the aforementioned energy storage converter, the aforementioned energy storage converter is used to discharge the aforementioned energy storage unit.

[0022] In this scheme, when the voltage of the energy storage unit is lower than the voltage at the second terminal of the energy storage converter, the DC / DC converter circuit increases the output voltage of the energy storage unit to a level higher than the voltage at the second terminal of the energy storage converter. This allows the energy storage converter to operate normally, ensuring that it can still output energy to the grid even when the energy storage unit is at a low voltage, thus ensuring sufficient power supply to the grid. Furthermore, by increasing the output voltage of the energy storage unit to a level higher than the voltage at the second terminal of the energy storage converter through the DC / DC converter circuit, the energy storage converter can also charge the energy storage unit. Specifically, the voltage at the first terminal of the energy storage converter is stepped down and the reduced voltage is output to the aforementioned energy storage unit to charge it. This allows for timely replenishment of the energy storage unit's electrical energy or recovery of grid energy for storage, achieving a balance between energy use and storage, thereby effectively meeting the grid's power demand.

[0023] In one possible implementation, in the event of a transient overvoltage at the second terminal of the aforementioned energy storage converter, the aforementioned control unit is used to control the aforementioned controllable switch to disconnect. Exemplarily, the aforementioned DC / DC converter circuit is further used to increase the voltage output by the aforementioned energy storage unit and output the increased voltage to the aforementioned energy storage converter, which is used to charge and discharge the aforementioned energy storage unit based on the increased voltage.

[0024] In this scheme, when a transient overvoltage occurs at the second terminal of the energy storage converter, the controllable switch is quickly turned off. This prevents the voltage at the second terminal of the energy storage converter from backfeeding energy to the energy storage unit, while also allowing the voltage output by the energy storage unit to be increased via the DC / DC converter circuit. The increased voltage is then output to the energy storage converter, enabling it to operate normally. In other words, this embodiment achieves high-voltage ride-through through the cooperation of the controllable switch and the DC / DC converter circuit. This means the energy storage system can still maintain normal operation and output power under transient overvoltage conditions, meeting the compliance requirement of not disconnecting from the grid during abnormal grid fluctuations.

[0025] In one possible implementation, the aforementioned energy storage system further includes a voltage detection circuit;

[0026] The aforementioned voltage detection circuit is used to detect the voltage of the aforementioned energy storage unit and the voltage at the second terminal of the aforementioned energy storage converter;

[0027] The aforementioned voltage detection circuit is also used to output the detected voltage to the aforementioned control unit.

[0028] In this solution, the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter are quickly detected by the detection circuit, which facilitates a rapid control response based on the magnitude of these two voltages, ensuring the normal operation of the energy storage system.

[0029] In one possible implementation, the aforementioned energy storage system further includes a fault detection circuit; the fault detection circuit is used to detect short-circuit faults in the aforementioned energy storage unit, and after detecting the aforementioned short-circuit fault, instructs the aforementioned controllable switch to disconnect the aforementioned controllable switch. Optionally, the aforementioned fault detection circuit is a desaturation detection circuit. Exemplarily, the aforementioned controllable switch is an insulated-gate bipolar transistor (IGBT) or a device formed by connecting an IGBT and a diode in parallel, and the aforementioned fault detection circuit is a desaturation detection circuit; when the voltage between the collector and emitter of the aforementioned IGBT is greater than a preset voltage threshold, the aforementioned controllable switch is used to control the aforementioned IGBT to disconnect.

[0030] In this scheme, a short circuit fault is detected by a fault detection circuit, which then instructs the controllable switch to be turned off quickly. This allows the main circuit to be cut off quickly when a short circuit fault occurs, reducing the spread of the fault's impact and mitigating other dangers caused by the fault.

[0031] In one possible implementation, the aforementioned energy storage system further includes a second DC / DC converter circuit and a second controllable switch; the aforementioned second DC / DC converter circuit and the aforementioned second controllable switch are connected in parallel to form a second parallel circuit, which is used to connect between the second energy storage unit and the aforementioned energy storage converter.

[0032] In this solution, the energy storage system, which improves the working efficiency of the energy storage converter by cooperating with controllable switching transistors and DC / DC conversion circuits, can realize energy conversion between multiple energy storage units and the power grid, expand the application scenarios, and has strong practicality.

[0033] Secondly, this application provides an energy storage management system, which includes a DC / DC converter circuit, a controllable switching transistor, an energy storage converter, and a control unit;

[0034] The first end of the aforementioned controllable switching transistor is used to connect to the energy storage power supply, the second end of the aforementioned controllable switching transistor is connected to the first end of the aforementioned energy storage converter, the first end of the aforementioned DC / DC conversion circuit is connected to the aforementioned energy storage power supply, the second end of the aforementioned DC / DC conversion circuit is connected to the first end of the aforementioned energy storage converter, the second end of the aforementioned energy storage converter is used to connect to the grid connection point, and the aforementioned energy storage converter is used to connect to the power grid or load through the aforementioned grid connection point.

[0035] The aforementioned control unit is used to, during a first time period, when the output voltage of the aforementioned energy storage power supply is continuously greater than the peak voltage of the second terminal of the aforementioned energy storage converter, control the aforementioned controllable switch to turn on during a second time period so that the aforementioned DC / DC conversion circuit stops working, so as to charge and discharge the aforementioned energy storage power supply through the aforementioned energy storage converter.

[0036] The aforementioned control unit is used to control the aforementioned controllable switch to disconnect when the output voltage of the aforementioned energy storage power supply is less than the peak voltage of the second terminal of the aforementioned energy storage converter during the third time period, so as to charge and discharge the aforementioned energy storage power supply through the aforementioned energy storage converter and the aforementioned DC / DC conversion circuit, wherein the aforementioned time sequence is from the aforementioned first time period to the aforementioned second time period and then to the aforementioned third time period.

[0037] In one possible implementation, the aforementioned control unit is further configured to, when the aforementioned controllable switch is turned on during the aforementioned second time period, control the aforementioned energy storage converter to rectify and transform the voltage at the second terminal of the aforementioned energy storage converter, so that the voltage at the second terminal of the aforementioned controllable switch is greater than the output voltage of the energy storage power supply, so as to charge the aforementioned energy storage unit through the aforementioned controllable switch.

[0038] The beneficial effects of the second aspect can be referred to the description of the first aspect above, and will not be repeated here. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the energy storage system.

[0040] Figure 2 This is a schematic diagram of voltage fluctuations;

[0041] Figures 3 to 7 This is a schematic diagram of the energy storage system structure provided in the embodiments of this application;

[0042] Figure 8 A flowchart illustrating an embodiment of this application;

[0043] Figure 9 A diagram illustrating the boost effect provided in an embodiment of this application;

[0044] Figure 10 A flowchart illustrating an embodiment of this application;

[0045] Figure 11 A diagram illustrating the boost effect provided in an embodiment of this application;

[0046] Figures 12 to 14 This is a schematic diagram of the energy storage system structure provided in the embodiments of this application;

[0047] Figures 15 to 31 This is a schematic diagram of the circuit structure of the energy storage system provided in the embodiments of this application;

[0048] Figure 32 This is a schematic diagram of the energy storage management system provided in an embodiment of this application. Detailed Implementation

[0049] In this application embodiment, "multiple" refers to two or more. In this application embodiment, "and / or" is used to describe the association relationship of related objects, indicating three relationships that can exist independently. For example, A and / or B can mean: A exists alone, B exists alone, or A and B exist simultaneously. The description methods used in this application embodiment, such as "at least one of a1, a2, ... and an", include the case where any one of a1, a2, ... and an exists alone, as well as the case where any combination of any multiple of a1, a2, ... and an exists alone. Each case can exist alone. For example, the description method of "at least one of a, b and c" includes the cases where a, b, and c exist alone, a and b combined, a and c combined, b and c combined, or a, b, and c combined.

[0050] In this embodiment of the application, the connection between C and D represents the circuit connection between C and D, indicating that electrical signal transmission can be realized between C and D.

[0051] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions between the various embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0052] The embodiments of this application are described below with reference to the accompanying drawings.

[0053] See, for example Figure 1 The diagram shows a schematic representation of the energy storage system provided in an embodiment of this application. Figure 1 The energy storage system 100 shown includes an energy storage unit 110 and an energy storage converter 120. The energy storage unit 110 is connected to the energy storage converter 120 and is charged and discharged through the energy storage converter 120.

[0054] For example, the energy storage converter 120 can be connected to the power grid 200. Specifically, the energy storage converter 120 can convert the DC power from the energy storage unit 110 into AC power and output AC power to the power grid 200 to supply power to the power grid 200. Alternatively, the energy storage converter 120 can convert the AC power from the power grid 200 into DC power and output DC power to the energy storage unit 110 to charge the energy storage unit 110.

[0055] For example, the energy storage unit 110 may be a battery cluster. The battery cluster may include one or more batteries connected in series or in parallel. The battery may include, for example, a lithium-ion battery (e.g., a lithium iron phosphate battery or a ternary lithium battery), a lead-acid battery (or lead-acid storage battery), or a sodium battery, etc. This application does not specifically limit the specific type of battery.

[0056] In its specific implementation, the aforementioned energy storage converter 120 converts the DC voltage Vbat of the energy storage unit 110 and the voltage Vac at the end of the energy storage converter connected to the power grid, thereby enabling the storage and release of electrical energy in the energy storage unit 110, i.e., charging and discharging the energy storage unit 110. However, during the charging and discharging process, the voltage Vac will fluctuate within a large range. For example, see the example provided. Figure 2 When the voltage Vbat of energy storage unit 110 is less than the voltage Vac (see, for example, see...) Figure 2 In the risk zone (of the system), the energy storage converter 120 cannot operate, reducing its efficiency. To address this issue, this application provides an energy storage system, which can be exemplarily referred to... Figure 3 .

[0057] For example, in Figure 3In this system, the energy storage system 300 may include an energy storage unit 310, a DC / DC converter circuit 320, a controllable switch 330, an energy storage converter 340, and a control unit 350. The DC / DC converter circuit 320 and the controllable switch 330 are connected in parallel to form a parallel circuit. This parallel circuit is used to connect between the energy storage unit 310 and the energy storage converter 340. Specifically, one end of the DC / DC converter circuit 320 (referred to as the first end of the DC / DC converter circuit) is connected to the energy storage unit 310, and the other end of the DC / DC converter circuit 320 (referred to as the second end of the DC / DC converter circuit) is connected to the energy storage converter 340. One end of the controllable switch 330 (referred to as the first end of the controllable switch) is connected to the energy storage unit 310, and the other end of the controllable switch 330 (referred to as the second end of the controllable switch) is connected to one end of the energy storage converter 340 (referred to as the first end of the energy storage converter). The other end of the energy storage converter 340 (referred to as the second end of the energy storage converter) is also used to connect to the grid connection point 400. The energy storage converter 340 is connected to the power grid 200 and / or the load 500 through the grid connection point 400. The control unit 350 can be connected to the DC / DC converter circuit 320, the controllable switch 330, and the energy storage converter 340.

[0058] The aforementioned DC / DC converter circuit 320 can be used to increase the output voltage of the energy storage unit 310. In specific implementations, the DC / DC converter circuit 320 can be any type of DC-DC converter circuit, and this application embodiment does not impose any limitations on it.

[0059] In one possible implementation, the DC / DC converter circuit may further include a buck converter for stepping down the input DC voltage before outputting it; that is, the DC / DC converter circuit includes a buck-boost converter. Exemplarily, the DC / DC converter circuit may be a bidirectional DC / DC converter circuit.

[0060] The aforementioned controllable switch 330 can be used to bypass the aforementioned DC / DC converter circuit 320. Exemplarily, the controllable switch 330 can be a switching device, and after being turned on, the current can flow bidirectionally, i.e., it can be bidirectionally conductive. For example, it can be a bidirectional field-effect transistor, relay, or contactor. In one possible implementation, the field-effect transistor can be, for example, an insulated-gate bipolar transistor (IGBT). It is understood that the description herein is merely illustrative and does not constitute a limitation on the embodiments of this application.

[0061] Another possible implementation can be exemplified by [example to be provided]. Figure 4The aforementioned controllable switch 330 can be a parallel circuit of an IGBT and a diode D. Specifically, the emitter (E) of the IGBT is connected to the anode of the diode, the collector (C) of the IGBT is connected to the cathode of the diode D, and the gate (G) of the IGBT is connected to the control unit 350. The emitter of the IGBT and the anode of the diode are also connected to the energy storage unit 310 and the DC / DC converter circuit. The collector of the IGBT and the cathode of the diode D are also connected to the DC / DC converter circuit and the energy storage inverter 340.

[0062] The aforementioned energy storage converter 340 can be used to convert DC power into AC power, or to convert AC power into DC power. For example, the energy storage converter 340 is a bidirectional energy storage converter.

[0063] The control unit 350 can be used to control the operating status of the DC / DC converter circuit 320, the controllable switching transistor 330, and the energy storage converter 340.

[0064] It is understandable that the above Figure 3 and Figure 4 The structure of the energy storage system 100 shown is merely an example. In specific implementations, other circuits or components may also be included, and this application does not limit this.

[0065] The following is combined with the above Figure 3 or Figure 4 The working principle of the energy storage system 300 described above is illustrated by example.

[0066] In one possible implementation, when the output voltage of the energy storage unit 310 is greater than the peak voltage at the second terminal of the energy storage converter 340, the control unit 350 is used to control the controllable switch 330 to turn on.

[0067] When the second terminal of the energy storage converter 340 is used to connect to the power grid 200, the voltage at the second terminal of the energy storage converter 340 can also be regarded as the voltage of the power grid 200.

[0068] For example, when the output voltage of the energy storage unit 310 is continuously greater than the peak voltage of the second terminal of the energy storage converter 340 during the first time period, the controllable switch 330 is turned on during the second time period to stop the DC / DC conversion circuit 320 from working, so that the energy storage unit 310 can be charged and discharged through the energy storage converter 340.

[0069] For example, the first time period may be a power frequency cycle, or a preset duration, such as 0.5 seconds or 1 second, etc., and this application embodiment does not limit it. The second time period may be the response time of the controllable switch 330, or a preset duration, such as 1 millisecond or 2 milliseconds, etc., and this application embodiment does not limit it.

[0070] For example, in a specific implementation, the control unit 350 can acquire the voltage of the energy storage unit 310 and the peak voltage of the second terminal of the energy storage converter 340. Then, it compares the magnitudes of the two voltages and controls the on / off state of the controllable switch 330 based on the comparison result.

[0071] One possible implementation can be exemplified by [example shown]. Figure 5 The aforementioned energy storage system 300 includes a voltage detection circuit 360. This voltage detection circuit 360 can detect the voltage of the energy storage unit 310 and the voltage at the second terminal of the energy storage converter 340. Then, it sends the detected voltages of the energy storage unit 310 and the second terminal of the energy storage converter 340 to the control unit 350. The voltage detection circuit 360 can be implemented in any possible manner, and this application embodiment does not limit this. In one possible implementation, the control unit 350 and the voltage detection circuit can be integrated into a single chip, or they can be designed and implemented separately, and this application embodiment does not limit this.

[0072] In another possible implementation, the DC / DC converter circuit 320 may include a voltage detection circuit. This voltage detection circuit can be used to detect the voltage of the energy storage unit 310 and send the detected voltage to the control unit 350. Furthermore, the energy storage converter 340 may also include a voltage detection circuit. This voltage detection circuit can be used to detect the voltage at the second terminal of the energy storage converter 340 and send the detected voltage to the control unit 350. In this solution, the voltage is detected using the voltage detection circuit built into the DC / DC converter circuit 320 and / or the energy storage converter 340, eliminating the need for... Figure 5 An additional voltage detection circuit is also included, thereby saving costs and reducing chip area.

[0073] In one possible implementation, the voltage of the energy storage unit 310 being greater than the voltage at the second terminal of the energy storage converter 340 can be the maximum value of the voltage of the energy storage unit 310 being greater than the voltage at the second terminal of the energy storage converter. Because the voltage at the second terminal of the energy storage converter is an AC voltage, it fluctuates, and therefore has a maximum voltage. This maximum voltage could, for example, be... Figure 2 Vac_max is shown in the figure.

[0074] As described above, the controllable switch 330 is a switching device, and the control unit 350 can send a control signal to the controllable switch 330 to control its on / off state. When the control unit 350 determines that the voltage of the energy storage unit 310 is greater than the voltage at the second terminal of the energy storage converter 340, it sends a control signal to the controllable switch 330 to control its conduction.

[0075] Since the controllable switch 330 and the DC / DC converter circuit 320 are connected in parallel, and the controllable switch 330 is a switching device with very low resistance after being turned on, it is equivalent to a wire. Therefore, after the controllable switch 330 is turned on, it can be seen by example... Figure 6 If current flows through the controllable switch 330 but not through the DC / DC converter circuit 320, then the DC / DC converter circuit 320 stops working. In another possible implementation, when the control unit 350 controls the controllable switch 330 to turn on, it can also send a control signal to the DC / DC converter circuit 320 to instruct it to stop working.

[0076] After the controllable switch 330 is turned on, the energy storage converter 340 can charge and discharge the energy storage unit 310 through the controllable switch 330. In one possible implementation, when the control unit 350 controls the controllable switch 330 to turn on, it can also send a control signal to the energy storage converter 340 to instruct the energy storage converter 340 to start working.

[0077] For example, in a specific implementation, after the controllable switch 330 is turned on, the voltage of the energy storage unit 310 is output to the energy storage converter 340 through the controllable switch 330. Since the voltage of the energy storage unit 310 is greater than the peak voltage at the second terminal of the energy storage converter 340, the energy storage converter 340 can operate normally. Furthermore, since the controllable switch 330 can be bidirectionally turned on, the energy storage converter 340 can not only discharge the energy storage unit 310, that is, convert the DC power in the energy storage unit 310 into AC power for output to the grid 200 or the load 500, but also charge the energy storage unit 310, that is, convert the AC power from the grid 200 or the load 500 into DC power to charge the energy storage unit 310.

[0078] In the above implementation, when the voltage of the energy storage unit 310 is greater than the peak voltage at the second terminal of the energy storage converter 340, the voltage of the energy storage unit 310 is output to the energy storage converter 340 by turning on the controllable switch 330. Since the resistance of the turned-on controllable switch 330 is very small, the additional power consumption is also very small, even negligible, thus saving power consumption in the circuit. Furthermore, since the controllable switch 330 is bidirectional, the energy storage converter 340 can not only discharge but also charge the energy storage unit 310. This allows for full utilization of the energy storage converter 340, maintaining its rated output operating voltage at a higher value, operating in a more efficient mode, and improving the efficiency of the energy storage system.

[0079] In one possible implementation, when the voltage of the energy storage unit 310 is less than the peak voltage at the second terminal of the energy storage converter 340, the control unit 350 controls the controllable switch 330 to turn off.

[0080] For example, when the output voltage of the energy storage unit 310 is less than the peak voltage at the second terminal of the energy storage converter 340 during the third time period, the controllable switch 330 is turned off to charge and discharge the energy storage unit 310 through the energy storage converter 340 and the DC / DC conversion circuit 320.

[0081] For example, the third time period may be a power frequency cycle, or it may be a preset duration, such as 0.5 seconds or 1 second, etc. This application embodiment does not limit this.

[0082] In one possible implementation, the order of the first time period, the second time period, and the third time period is: the first time period is followed by the second time period, and then the third time period.

[0083] For example, in a specific implementation, after the control unit 350 obtains the voltage of the energy storage unit 310 and the voltage of the second terminal of the energy storage converter 340, if the control unit 350 compares and finds that the voltage of the energy storage unit 310 is less than the voltage of the second terminal of the energy storage converter 340, it sends a control signal to the controllable switch 330 to control its turn-off.

[0084] After the controllable switch 330 is turned off, see the example provided. Figure 7 The voltage output of the energy storage unit 310 is sent to the DC / DC converter circuit 320, and current flows through the DC / DC converter circuit 320, thus the DC / DC converter circuit 320 starts to work. In another possible implementation, when the control unit 350 controls the controllable switch 330 to turn off, it can also send a control signal to the DC / DC converter circuit 320 to instruct the DC / DC converter circuit 320 to start working.

[0085] For example, in a specific implementation, after the DC / DC converter circuit 320 starts working, it can boost the voltage output by the energy storage unit 310 and output it to the energy storage converter 340. The boosted voltage is greater than the voltage at the second terminal of the energy storage converter 340.

[0086] In one possible implementation, the voltage output by the energy storage unit 310 can be increased to be equal to the bus voltage.

[0087] Alternatively, in another possible implementation, the control unit 350 may record the highest voltage at the second terminal of the energy storage converter 340 (e.g., it could be...). Figure 2 (Vac_max shown). Then, if the voltage of the newly detected energy storage unit 310 is found to be less than the voltage at the second terminal of the newly detected energy storage converter 340, the DC / DC converter circuit 320 is controlled to increase the voltage output by the energy storage unit 310. The increased voltage is greater than the recorded peak voltage at the second terminal of the energy storage converter 340.

[0088] After the DC / DC converter circuit 320 outputs the increased voltage to the energy storage converter 340, the energy storage converter 340 can operate normally because the increased voltage is greater than the highest voltage at the second terminal of the energy storage converter 340. In one possible implementation, when the control unit 350 controls the controllable switch 330 to turn off, it can also send a control signal to the energy storage converter 340 to instruct the energy storage converter 340 to start working.

[0089] In one possible implementation, the DC / DC converter circuit 320 is a bidirectional DC / DC converter circuit, meaning it can conduct in both directions. Therefore, the energy storage converter 340 can charge and discharge the energy storage unit 310.

[0090] For example, during the process of the energy storage converter 340 discharging the energy storage unit 310, the voltage of the energy storage unit 310 is output to the DC / DC conversion circuit 320, the DC / DC conversion circuit 320 outputs the increased voltage to the energy storage converter 340, and the energy storage converter 340 converts the DC power from the DC / DC conversion circuit 320 into AC power and outputs it to the grid 200 or the load 500.

[0091] Exemplarily, during the charging process of the energy storage unit 310 by the energy storage converter 340, the energy storage converter 340 converts AC power from the grid 200 or the load 500 into DC power. Then, this DC power is input to the energy storage unit 310 via the DC / DC converter circuit 320 to charge the energy storage unit 310. Exemplarily, the DC / DC converter circuit 320 may perform a voltage boost operation on the DC power, or it may not perform a voltage boost operation; this embodiment of the application does not limit this.

[0092] In one possible implementation, the energy storage converter 340 can charge and discharge the energy storage unit 310 through the DC / DC conversion circuit.

[0093] For example, during the discharge process of the energy storage unit 310 by the energy storage converter 340, the voltage of the energy storage unit 310 is output to the DC / DC conversion circuit. The DC / DC conversion circuit increases the voltage output by the energy storage unit 310 through the DC / DC conversion circuit 320. The DC / DC conversion circuit outputs the increased voltage to the energy storage converter 340, and the energy storage converter 340 converts the DC power from the DC / DC conversion circuit into AC power and outputs it to the grid 200 or the load 500.

[0094] For example, during the charging process of the energy storage unit 310 by the energy storage converter 340, the energy storage converter 340 converts AC power from the grid 200 or the load 500 into DC power. Then, this DC power is input to the energy storage unit 310 via a DC / DC converter circuit to charge the energy storage unit 310. For example, the DC / DC converter circuit can perform DC power conversion on the DC power and output it to the energy storage unit 310.

[0095] In the above implementation, when the voltage of the energy storage unit 310 is lower than the peak voltage at the second terminal of the energy storage converter 340, the controllable switch 330 is turned off, allowing the DC / DC converter circuit 320 to boost the voltage output by the energy storage unit 310. The boosted voltage is then output to the energy storage converter 340, enabling it to operate normally. In other words, this embodiment ensures that the energy storage unit can still operate even when the voltage is low, fully utilizing its energy. Furthermore, it ensures that the energy storage converter can still operate even when the voltage is low, fully utilizing its energy and improving the efficiency of the energy storage system.

[0096] To facilitate understanding of the above implementation plan, the following is combined with... Figure 8 Exemplary introduction. Figure 8An exemplary flowchart of the above-described energy storage system is shown. Specifically, after the energy storage system starts working, it detects the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter, and determines whether the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter. If the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter, it enters the bypass working mode. The specific implementation is described above for the case where the voltage of the energy storage unit is greater than the voltage at the second terminal of the energy storage converter, and will not be repeated here. If the voltage of the energy storage unit is not greater than the maximum value of the voltage at the second terminal of the energy storage converter, it enters the boost working mode. The specific implementation is described above for the case where the voltage of the energy storage unit is less than the voltage at the second terminal of the energy storage converter, and will not be repeated here. After the energy storage system enters the bypass working mode or the boost working mode, it continues to detect the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter in real time, and determines whether the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter. Then, based on the determination result, it enters the corresponding working mode, which will not be repeated here.

[0097] A possible implementation, illustrated by a diagram of the boost mode's effect, can be found here. Figure 9 .exist Figure 9 In the diagram, state 1 represents the state before voltage boosting. It can be seen that the voltage Vbat of the energy storage unit is less than the maximum value Vac_max of the voltage Vac at the second terminal of the energy storage converter. Then, the state after voltage boosting via the DC / DC converter circuit is shown in state 2. In state 2, Vbus is the boosted voltage, which could be, for example, the bus voltage. It can be seen that Vbus is greater than the maximum value Vac_max of the voltage Vac at the second terminal of the energy storage converter. Inputting this Vbus into the energy storage converter allows it to operate normally.

[0098] In one possible implementation, in the event of a transient overvoltage at the second terminal of the energy storage converter 340, the control unit 350 controls the controllable switch 330 to turn off.

[0099] For example, in a specific implementation, a transient overvoltage occurs when a grid fault or disturbance causes the voltage to rise rapidly beyond the maximum voltage at the second terminal of the energy storage converter. If the increase in voltage after the rapid rise is within a preset proportion compared to the maximum voltage at the second terminal of the energy storage converter, and the energy storage system can still operate within a preset duration, this situation can be called high-voltage ride-through. The preset proportion could be, for example, 25% or 30%, etc. The preset duration could be, for example, 1 minute or 2 minutes, etc. This application embodiment does not limit the values ​​of the preset proportion and the preset duration.

[0100] For example, in a specific implementation, after the control unit 350 obtains the voltage at the second terminal of the energy storage converter 340, it can determine that a transient overvoltage has occurred at the second terminal of the energy storage converter 340. For instance, it can compare the voltage at the second terminal of the energy storage converter 340 with the pre-stored maximum voltage value of the second terminal of the energy storage converter. If the voltage at the second terminal of the energy storage converter 340 is greater than the maximum voltage value of the second terminal of the energy storage converter, it is determined that a transient overvoltage has occurred at the second terminal of the energy storage converter 340. Then, the control unit 350 sends a control signal to the controllable switch 330 to control its turn-off.

[0101] In one possible implementation, the controllable switch 330 can be an IGBT. Since transient overvoltage conditions are caused by a rapid voltage rise, a fast response is required. This IGBT has a fast response speed, reaching the millisecond level. Therefore, upon receiving the control signal sent by the control unit 350, it can quickly turn off, ensuring that the voltage at the second terminal of the energy storage converter does not backflow energy into the energy storage unit. It is understood that this IGBT is merely an example; in specific implementations, other fast-response switching devices can be used, and this application does not limit this.

[0102] After the controllable switch 330 is turned off, the voltage output of the energy storage unit 310 is sent to the DC / DC converter circuit 320, and current flows through the DC / DC converter circuit 320, thus the DC / DC converter circuit 320 begins to operate. In another possible implementation, when the control unit 350 controls the controllable switch 330 to turn off, it can also send a control signal to the DC / DC converter circuit 320 to instruct the DC / DC converter circuit 320 to start operating.

[0103] For example, in a specific implementation, after the DC / DC converter circuit 320 starts working, it can boost the voltage output by the energy storage unit 310 and output it to the energy storage converter 340. This boosted voltage is greater than the voltage at the second terminal of the energy storage converter 340 at which a transient overvoltage is detected. In one possible implementation, this boosted voltage can be, for example, a voltage that increases by a preset proportion compared to the maximum voltage at the second terminal of the energy storage converter. That is, the DC / DC converter circuit 320 boosts the voltage output by the energy storage unit 310 to a voltage that is higher than the maximum voltage at the second terminal of the energy storage converter by a preset proportion. The description of the case where the voltage of the energy storage unit 310 is less than the voltage at the second terminal of the energy storage converter 340 after the DC / DC converter circuit 320 outputs the boosted voltage to the energy storage converter 340 can be referenced above, and will not be repeated here.

[0104] To facilitate understanding of the above implementation plan, the following is combined with... Figure 10 Exemplary introduction. Figure 10An exemplary flowchart of the above-described energy storage system is shown. Specifically, after the energy storage system starts working, it detects the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter, and determines whether the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter. If the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter, it enters the bypass working mode. The specific implementation is described above for the case where the voltage of the energy storage unit is greater than the voltage at the second terminal of the energy storage converter, and will not be repeated here. If the voltage of the energy storage unit is not greater than the maximum value of the voltage at the second terminal of the energy storage converter, it enters the boost working mode. The specific implementation is described above for the case where the voltage of the energy storage unit is less than the voltage at the second terminal of the energy storage converter, and will not be repeated here. After the energy storage system enters the bypass working mode or the boost working mode, it continues to detect the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter in real time, and determines whether the voltage of the energy storage unit is greater than the maximum value of the voltage at the second terminal of the energy storage converter. Then, based on the determination result, it enters the corresponding working mode, which will not be repeated here. Furthermore, after the energy storage system enters bypass or boost mode, it also determines in real time whether a transient overvoltage has occurred at the second terminal of the energy storage converter based on the detected voltage. If no transient overvoltage occurs, the original operating mode is maintained. If a transient overvoltage occurs, the system enters boost mode. For specific implementation details, please refer to the description above regarding the case of a transient overvoltage at the second terminal of the energy storage converter 340, which will not be repeated here.

[0105] In one possible implementation, a schematic diagram illustrating the effect of the boost mode under transient overvoltage conditions can be found here. Figure 11 .exist Figure 11 In the diagram, state 1 represents the state before the transient overvoltage occurs. In this state, the voltage Vbus input to the energy storage converter can be made greater than the maximum value Vac_max of the voltage Vac at the second terminal of the energy storage converter through the bypass operating mode or boost operating mode described above. The transient overvoltage begins at point A. Then, the voltage output from the energy storage unit is rapidly boosted by the DC / DC converter circuit, making the boosted voltage greater than the maximum voltage after the transient overvoltage occurs (see state 2). Inputting the boosted Vbus into the energy storage converter allows it to operate normally.

[0106] In the above implementation, when a transient overvoltage occurs at the second terminal of the energy storage converter, the controllable switch is quickly turned off. This prevents the voltage at the second terminal of the energy storage converter from backfeeding energy to the energy storage unit, while also allowing the voltage output by the energy storage unit to be increased via the DC / DC converter circuit. The increased voltage is then output to the energy storage converter, enabling it to operate normally. In this embodiment, the cooperation between the controllable switch and the DC / DC converter circuit achieves high-voltage ride-through, meaning the energy storage system can still maintain normal operation and output power even under transient overvoltage conditions, meeting the compliance requirement of not disconnecting from the grid during abnormal grid fluctuations.

[0107] Furthermore, if the aforementioned controllable switch 330 is Figure 4 The device shown, with the IGBT and diode D connected in parallel, has the IGBT turned on by the control unit 350 when the voltage of the energy storage unit 310 is greater than the voltage at the second terminal of the energy storage converter 340. In this case, during the discharge of the energy storage unit 310, current flows from the energy storage unit 310 towards the grid 200, and the diode D also turns on. Since both the diode D and the IGBT have voltage drops, their parallel connection reduces the voltage drop, thereby reducing losses and improving efficiency. Similarly, during the charging of the energy storage unit 310, current flows from the grid 200 through the IGBT towards the energy storage unit 310, thus ensuring normal charging function of the energy storage unit and improving operating efficiency.

[0108] One possible implementation can be exemplified by [example provided]. Figure 12 The energy storage system 300 may further include a fault detection circuit 370. This fault detection circuit 370 can detect the current of the controllable switch 330 and determine whether the current exceeds a threshold. If the current exceeds the threshold, it indicates a fault in the energy storage unit 310 causing a short circuit. When the fault detection circuit 370 determines that the current of the controllable switch 330 exceeds the threshold, it can send an indication signal to the control unit 350 to turn off the controllable switch 330. Then, the control unit 350 sends a control signal to the controllable switch 330 based on this indication to control its shutdown. This allows for rapid disconnection of the main circuit in the event of a short circuit fault, reducing the spread of the fault's impact and mitigating other hazards caused by the fault.

[0109] In one possible implementation, if the controllable switch 330 is an IGBT, the fault detection circuit 370 can be, for example, a desaturation detection circuit. This desaturation detection circuit can determine if a short circuit has occurred in the energy storage unit 310 by detecting the desaturation status of the IGBT. For example, the desaturation detection circuit can detect the voltage between the collector and emitter of the IGBT (CE voltage). If the CE voltage is greater than a preset threshold, it indicates that a short circuit has occurred in the energy storage unit 310. In this case, the desaturation detection circuit can send an indication signal to the control unit 350 to turn off the IGBT. Then, the control unit 350 sends a control signal to the IGBT based on this indication to control its turn-off. This allows for rapid disconnection of the main circuit in the event of a short circuit fault, reducing the spread of the fault's impact and mitigating other hazards caused by the fault.

[0110] In another possible implementation, the energy storage system 300 described above may include multiple energy storage units 310, multiple DC / DC conversion circuits 320, and multiple controllable switching transistors 330. See, for example, [link to relevant documentation]. Figure 13 Taking two energy storage units 310, two DC / DC converter circuits 320, and two controllable switching transistors 330 as an example, it can be seen that in Figure 13 Compared to the above Figure 3 A new energy storage unit (referred to as energy storage unit 310' for ease of description), a DC / DC converter circuit (referred to as DC / DC converter circuit 320' for ease of description), and a controllable switch (referred to as controllable switch 330' for ease of description) are added. The DC / DC converter circuit 320' and the controllable switch 330' are connected in parallel to form a parallel circuit, which is used to connect between the energy storage unit 310' and the energy storage converter 340. The energy storage unit 310', the DC / DC converter circuit 320', and the controllable switch 330' are also connected to the control unit 350.

[0111] In this implementation, the control unit can detect the voltages output by multiple energy storage units, and then compare these detected voltages with the voltage at the second terminal of the energy storage converter. Based on the comparison results, the operating states of the corresponding controllable switches and DC / DC converter circuits are controlled respectively. For ease of understanding, let's take... Figure 13For example, the control unit 350 detects the voltage output by the energy storage unit 310 (hereinafter referred to as voltage A) and the voltage output by the energy storage unit 310' (hereinafter referred to as voltage B). Then, voltage A and voltage B are compared with the voltage at the second terminal of the energy storage converter 340. Based on the comparison result of voltage A and the voltage at the second terminal of the energy storage converter 340, the operating state of the controllable switch 330 and the DC / DC converter circuit 320 is controlled. For specific implementation details, please refer to the aforementioned description, which will not be repeated here. Similarly, based on the comparison result of voltage B and the voltage at the second terminal of the energy storage converter 340, the operating state of the controllable switch 330' and the DC / DC converter circuit 320' is controlled. For specific implementation details, please refer to the aforementioned description, which will not be repeated here.

[0112] In another possible implementation, the energy storage system 300 described above may include multiple energy storage units 310, as well as multiple DC / DC conversion circuits 320, multiple controllable switching transistors 330, and multiple energy storage converters 340. See also the exemplary embodiments. Figure 14 Taking two energy storage units 310, two DC / DC converter circuits 320, two controllable switching transistors 330, and two energy storage converters 340 as an example, it can be seen that... Figure 14 Compared to the above Figure 3 A new energy storage unit (referred to as energy storage unit 310” for ease of description), a DC / DC converter circuit (referred to as DC / DC converter circuit 320” for ease of description), a controllable switch (referred to as controllable switch 330” for ease of description), and an energy storage converter (referred to as energy storage converter 340” for ease of description) are added. The DC / DC converter circuit 320” and the controllable switch 330” are connected in parallel to form a parallel circuit, which is used to connect between the energy storage unit 310” and the energy storage converter 340”. The energy storage unit 310”, the DC / DC converter circuit 320”, the controllable switch 330”, and the energy storage converter 340” are also connected to the control unit 350. The energy storage converter 340” is also connected to the grid 200 and the load 500 through the grid connection point 400. In another possible implementation, a control unit 350 can be added to control the energy storage unit 310”, DC / DC converter circuit 320”, controllable switch 330”, and energy storage converter 340”, etc., depending on actual needs. This application embodiment does not impose any limitations on this. Figure 14 The newly added DC / DC converter circuit 320", controllable switch 330", and energy storage converter 340" are used to realize energy conversion between the energy storage unit 310" and the power grid 200 based on the control unit 350. Please refer to the above description for details. Figure 3 The implementation process will not be described here.

[0113] In this embodiment, the energy storage system, which improves the working efficiency of the energy storage converter by cooperating with controllable switching transistors and DC / DC conversion circuits, can realize energy conversion between multiple energy storage units and the power grid, expanding the application scenarios and making it highly practical.

[0114] To better understand the working principle of the energy storage system described above, some possible circuit topologies of the energy storage system will be introduced below as examples.

[0115] See Figure 15 This figure illustrates a possible circuit topology diagram for an energy storage system. As shown, the energy storage unit can be a battery cluster. The DC / DC conversion circuit may include inductor L1, switching modules T1, T2, T3, and T4, capacitor C1, and capacitor C2. The switching modules T1 to T4 can be, for example, transistors, field-effect transistors, IGBTs, or modules consisting of an IGBT and a diode connected in parallel (referred to as IGBT switching modules), etc. This application does not limit the specific types of modules used. Figure 15 The following example illustrates the IGBT switching modules, T1 to T4. The controllable switching transistor includes switching module T5, which is also illustrated as an IGBT switching module. The energy storage converter includes capacitor C3, capacitor C4, diodes D1 and D2, switching modules T6, T7, T8, and T9, and inductor L2. Switching modules T6 to T9 can be, for example, transistors, field-effect transistors, IGBTs, or the aforementioned IGBT switching modules, etc. This application does not impose limitations on these specific types of modules. Figure 15 The example shown is the aforementioned IGBT switching module, with switching modules T6 to T9 as examples.

[0116] For example, the above Figure 15 The switching modules shown are all based on IGBT switching modules. In this IGBT switching module, the emitter (E) of the IGBT is connected to the anode of the diode, and the collector (C) of the IGBT is connected to the cathode of the diode D. For ease of description later, the end where the emitter (E) of the IGBT is connected to the anode of the diode is called the first connection terminal of the IGBT switching module, and the end where the collector (C) of the IGBT is connected to the cathode of the diode D is called the second connection terminal of the IGBT switching module. Therefore, in... Figure 15In this configuration, the positive terminal of the battery cluster is connected to the first connection terminal of IGBT switching module T5, and also to one end of inductor L1. The other end of inductor L1 is connected to the first connection terminal of IGBT switching module T2, and also to the second connection terminal of IGBT switching module T3. The second connection terminal of IGBT switching module T2 is connected to the first connection terminal of IGBT switching module T1. The second connection terminal of IGBT switching module T1 is connected to the second connection terminal of IGBT switching module T5.

[0117] Then, the first connection terminal of IGBT switching module T3 is connected to the second connection terminal of IGBT switching module T4, and also to one end of capacitor C1. That is, one end of capacitor C1 is connected between the first connection terminal of IGBT switching module T3 and the second connection terminal of IGBT switching module T4. The other end of capacitor C1 is connected to the second connection terminal of IGBT switching module T2 and the first connection terminal of IGBT switching module T1. The first connection terminal of IGBT switching module T4 is connected to the negative terminal of the battery cluster, and also to one end of capacitor C2. The other end of capacitor C2 is connected to point A at the second connection terminals of IGBT switching module T1 and IGBT switching module T5.

[0118] Then, point A is connected to one end of capacitor C3. The other end of capacitor C3 is connected to one end of capacitor C4, and also to the anode of diode D1 and the cathode of diode D2. The other end of capacitor C4 is connected to the negative terminal of the battery cluster, and also to the first connection terminal of IGBT switching module T9. The second connection terminal of IGBT switching module T9 is connected to the anode of diode D2, and also to the first connection terminal of IGBT switching module T8. The cathode of diode D2 is connected to the anode of diode D1. The second connection terminal of IGBT switching module T8 is connected to the first connection terminal of IGBT switching module T7. The second connection terminal of IGBT switching module T7 is connected to the cathode of diode D1. The second connection terminal of IGBT switching module T7 and the cathode of diode D1 are also connected to the first connection terminal of IGBT switching module T6. The second connection terminal of IGBT switching module T6 is connected to one end of the aforementioned capacitor C3 at point B. Between points A and B is a wire used to connect the DC / DC converter circuit and the energy storage converter. This wire is also the wire connecting the controllable switching transistor and the energy storage converter. The conductor can be, for example, an electrical wire or cable.

[0119] Then, the second connection terminal of the aforementioned IGBT switching module T8 and the first connection terminal of the IGBT switching module T7 are also connected to one end of inductor L2. The other end of inductor L2 is connected to the power grid. Furthermore, the power grid is also connected to point C. As shown in the figure, point C is located where the other end of the aforementioned capacitor C3 is connected to the anode of diode D1. That is, the power grid can also be connected to this location to form a loop.

[0120] The above Figure 15 The diagram only illustrates the circuit structure of the energy storage unit, DC / DC converter circuit, controllable switch, and energy storage converter in the energy storage system; the specific circuit structures of the control unit, voltage detection circuit, and fault detection circuit 370 are not shown. It is understood that the unshown circuit structure can be any circuit structure capable of implementing the functions described above, and this application embodiment does not impose any limitations on it. Although the specific circuit structure of the control unit is not shown, the above... Figure 15 The individual switch modules (T1 to T9) shown are controlled by a control unit. Further details are omitted. Figure 15 Taking the connection of energy storage converters to the power grid as an example, it can be understood that there is a grid connection point between the energy storage converter and the power grid. Figure 15 (Not shown in the diagram). In the actual implementation, the energy storage converter can also be connected to the load, which will not be elaborated further.

[0121] Based on the above description, if the voltage of the energy storage unit is greater than the peak voltage at the second terminal of the energy storage converter during the first time period, the control unit controls the controllable switch to turn on during the second time period, the DC / DC conversion circuit stops working, and the energy storage converter is used to charge and discharge the energy storage unit through the controllable switch. For example, as... Figure 15 As shown, the voltage at point A is denoted as Vbus1, the voltage at point B is denoted as Vbus2, and the battery voltage is still denoted as Vbat. For example, if... Figure 15 The energy storage system shown is the aforementioned energy storage system 300. Therefore, point A is the second terminal of the aforementioned controllable switch, and also the second terminal of the aforementioned DC / DC converter circuit. Point B is the first terminal of the aforementioned energy storage converter. The terminal of the energy storage converter used to connect to the power grid is the second terminal of the energy storage converter, for example... Figure 15 Point D in the diagram represents the second terminal of the energy storage converter.

[0122] In one possible implementation, when the voltage of the energy storage unit is greater than the voltage at the second terminal of the energy storage converter, and when Vbat > Vbus1 > Vbus2, the energy storage converter is used to discharge the energy storage unit. It is understood that the magnitudes of voltage Vbus1 at point A and voltage Vbus2 at point B can be controlled by a control module (not shown in the figure) in the energy storage system. Specific control methods are conventional in the art, and this application does not limit the scope of the embodiments.

[0123] For example, when the controllable switch is turned on during the second time period, the energy storage converter is controlled to invert the voltage at the first terminal of the energy storage converter, so that the output voltage of the energy storage unit is greater than the voltage at the second terminal of the controllable switch, thereby discharging the energy storage unit through the controllable switch. The following is in conjunction with... Figures 16 to 19The specific implementation of this discharge operation state is illustrated by example.

[0124] Should Figures 16 to 19 The circuit structure and the above Figure 15 The difference is that a current flow diagram has been added to facilitate the description of the specific implementation under the discharge working state, and in order not to interfere with the rapid identification of the current flow, the specific energy storage unit, DC / DC conversion circuit, controllable switching transistor and energy storage converter are not marked.

[0125] See examples Figure 16 .exist Figure 16 In the process, because the output voltage of the energy storage unit, i.e., the battery cluster, is greater than the voltage at the second terminal of the energy storage converter, the controllable switch, i.e., the IGBT switching module T5, is turned on, and the switching modules (T1 to T4) in the DC / DC converter circuit are turned off. Then, because the battery cluster voltage Vbat is greater than Vbus1, current flows from the positive terminal of the battery cluster to point A, and then through point A to capacitor C2 to charge capacitor C2. Capacitor C2 is then connected to the negative terminal of the battery cluster to form a current loop, such as... Figure 16 As shown. Furthermore, after the current flows from the positive terminal of the battery cluster to point A, it also flows through point B (due to the voltage drop between points A and B, Vbus1 > Vbus2) to charge capacitors C3 and C4. Similarly, capacitor C4 is connected to the negative terminal of the battery cluster, forming a current loop. During the charging process of capacitor C2 by the battery cluster, since Vbus1 > Vbus2, capacitor C2 also charges capacitors C3 and C4. The current flows from capacitor C2 to capacitors C3 and C4, and then back to capacitor C2, forming a current loop, as shown. Figure 16 As shown. In addition, capacitor C3 also discharges to supply power to the grid during the charging process. Specifically, as shown... Figure 16 As shown, during the discharge process, switch modules T6 and T7 are turned on, and the discharge current of capacitor C3 reaches the power grid through point B, switch modules T6 and T7, and inductor L2. The power grid connects to point C to form a current loop with the energy storage converter.

[0126] Energy storage converters are used to convert direct current (DC) to alternating current (AC) to supply power to the grid. AC includes both forward and reverse currents, as described above. Figure 16 The operating state shown (discharge bypass operating state 1) is the state in which the energy storage converter converts DC power into positive AC power. Furthermore, since the voltage of the AC power changes at every moment, see, for example, the above... Figure 2 The diagram shows an AC sinusoidal waveform. To avoid such sudden voltage changes, a freewheeling current is needed during the DC-AC conversion process of the energy storage converter to ensure smooth voltage and current changes. This freewheeling current is typically achieved through the combination of a freewheeling diode and an inductor. See the example provided. Figure 17 , Figure 17The shown operating state (discharge bypass operating state 2) belongs to the state of freewheeling during the process of the energy storage converter converting direct current into positive alternating current. This freewheeling is achieved through the cooperation of diode D1 and inductor L2. Specifically, in this state, switch module T7 is turned on. When there is a sudden change in the current of inductor L2, it can flow through the power grid to diode D1 and then back to inductor L2 through switch module T7, forming a current loop to consume this sudden change.

[0127] See Figure 18 , Figure 18 The shown operating state (discharge bypass operating state 3) belongs to the state of the energy storage converter converting direct current into reverse alternating current. In this state, switch module T8 and switch module T9 are turned on, and power is supplied to the power grid by discharging capacitor C4. Specifically, the discharge current of capacitor C4 reaches the power grid through point C, and then flows through inductor L2, switch module T8, switch module T9 and back to capacitor C4 to form a loop. Thus, reverse alternating current power supply to the power grid is achieved. It can be understood that in the above Figure 18 shown state, the battery cluster is still charging capacitors C2, C3 and C4, and capacitor C2 is also charging capacitors C3 and C4. For specific reference, see the above Figure 16 related description, which will not be elaborated here. In addition, similar to the above positive alternating current power supply, freewheeling is also required during this reverse alternating current power supply process. For example, see <000033​​​​​​​​​​​​​​​​The shown operating state (charging bypass operating state 1) belongs to the state where the energy storage converter converts positive alternating current into direct current. In Figure 20 , since the voltage of the energy storage unit, i.e., the battery cluster, is greater than the voltage at the second terminal of the energy storage converter, the controllable switch tube, i.e., the IGBT switch module T5, conducts, and the switch modules (T1 to T4) in the DC / DC conversion circuit are turned off. However, although the voltage of the battery cluster is greater than the voltage at the second terminal of the energy storage converter, due to the voltage of the battery cluster itself being less than the preset threshold, or due to an excess of energy in the power grid, or for reasons such as planned power recovery from the power grid, the power grid can charge the battery cluster. Specifically, as Figure 20 shown, first, the switch module T6 and the switch module T7 conduct. The current of the power grid charges the capacitor C3 through point C, and then flows through point B, the switch module T6, the switch module T7, and the inductor L2 back to the power grid to form a charging loop. During the process of the power grid charging the capacitor C3, the capacitor C3 discharges to charge the capacitor C2. The discharge current of the capacitor C3 flows from point B to point A to the capacitor C2, and then flows back to the capacitor C3 through the capacitor C4 to form a current loop, as Figure 20 shown. The charging of the capacitor C2 by the capacitor C3 causes the voltage at point A to increase. At this time, Vbat < Vbus1 < Vbus2. Then, the capacitor C2 starts to discharge to charge the battery cluster. Specifically, the charging current flows through the switch module T5 to the battery cluster to charge the battery. Then, the current flows from the negative terminal of the battery cluster to the capacitor C2 to form a charging loop.

[0131] In addition, since the current for the power grid to charge the capacitor is alternating current, a freewheeling current is also required during the charging process. For example, refer to Figure 21 , Figure 21 The shown operating state (charging bypass operating state 2) belongs to the state of freewheeling during the process of the energy storage converter converting reverse alternating current into direct current. The specific implementation of this freewheeling can refer to the description in the foregoing Figure 17 , and will not be elaborated here.

[0132] Refer to Figure 22 , Figure 22 The shown operating state (charging bypass operating state 3) belongs to the state where the energy storage converter converts reverse alternating current into direct current. In this state, the switch module T8 and the switch module T9 conduct, which is achieved by charging the capacitor C4. Specifically, the current of the power grid reaches the capacitor C4 through the inductor L2, the switch module T8, and the switch module T9 to charge it, and then flows back to the power grid through point C to form a charging loop. During the process of the power grid charging the capacitor C4, the capacitor C4 also discharges to charge the capacitor C2. The discharge current of the capacitor C4 flows through the capacitor C3, then to the capacitor C2, and then flows back to the capacitor C4 to form a current loop, as Figure 22As shown, capacitor C4 charges capacitor C2, causing the voltage at point A to rise. At this time, Vbat < Vbus1 < Vbus2. Then, capacitor C2 starts to discharge to charge the battery cluster. Specifically, the discharge current flows through the switch module T5 to the battery cluster to charge the battery. Then, the current flows from the negative electrode of the battery cluster to capacitor C2 to form a charging loop.

[0133] In addition, since the current for charging the capacitor by the power grid is alternating current, a freewheeling current is also required during the charging process. For example, reference can be made to Figure 23 , Figure 23 The working state shown (charging bypass working state 4) belongs to the state of freewheeling during the process of the energy storage converter converting reverse alternating current into direct current. The specific implementation of this freewheeling can refer to the description above Figure 19 and will not be elaborated here.

[0134] In another possible implementation, when the voltage of the energy storage unit is less than the voltage of the second terminal of the energy storage converter, the control unit is used to control the controllable switch tube to disconnect. The DC / DC conversion circuit is used to increase the voltage output by the energy storage unit and output the increased voltage to the energy storage converter. The energy storage converter is used to charge and discharge the energy storage unit based on the increased voltage. Exemplarily, when the voltage of the energy storage unit is less than the voltage of the second terminal of the energy storage converter, and, when Vbat <vbus1>In the case of Vbus2, the energy storage converter is used to discharge the energy storage unit. For example, when the controllable switch is off during the third time period mentioned above, the DC / DC converter circuit is controlled to boost the output voltage of the energy storage unit and output the boosted voltage to the energy storage converter to achieve energy storage unit discharge. The following section combines... Figures 24 to 27 The specific implementation of this discharge operation state is illustrated by example.

[0135] exist Figures 24 to 27 In this process, because the voltage of the energy storage unit, i.e., the battery cluster, is lower than the voltage at the second terminal of the energy storage converter, the controllable switch, i.e., the IGBT switch module T5, is turned off, and the DC / DC converter circuit starts working. Specifically, the DC / DC converter circuit is used to boost the voltage of the battery cluster, making Vbus1 > Vbus2, thereby enabling power supply to the grid. The entire voltage boosting process can include four operating states, which can be referred to separately. Figures 24 to 27 .

[0136] exist Figure 24 In the state shown (boost and discharge operation state 1), switching modules T2 and T4 in the DC / DC converter circuit are turned on, while switching modules T1 and T3 are turned off. This allows the battery pack to store energy in inductor L1 and charge capacitor C1. The specific current loop is as follows: Figure 24 As shown. Then, switching modules T2 and T1 in the DC / DC converter circuit are turned on, while switching modules T3 and T4 are turned off, allowing the battery pack to charge capacitor C2. The charging circuit is as follows. Figure 25 As shown, Figure 25 The state shown is referred to as boost discharge state 2. In this state, the voltage at point A is the sum of the voltage of the battery cluster and the voltage of inductor L1, which is greater than the voltage of the battery cluster, thus achieving a voltage boost. Furthermore, the voltage Vbus1 at point A is greater than Vbus2 at point B. This causes capacitor C2 to discharge and supply power to the grid. The process of capacitor C2 discharging to supply power to the grid can be found above. Figures 16 to 19 The relevant descriptions are not repeated here.

[0137] After completing the boost operation and discharge operation state 2, the aforementioned DC / DC converter circuit enters the following state: Figure 26 The state shown is (boost operation and discharge operation state 3). Specifically, in the DC / DC converter circuit, switching modules T3 and T1 are turned on, and switching modules T2 and T4 are turned off, allowing the battery pack to store energy for inductor L1 and charge capacitors C1 and C2. The specific current loop is as follows: Figure 26 As shown in the figure. Similarly, in this state, the voltage at point A is the voltage of the battery cluster plus the voltages of inductor L1 and capacitor C1, which is greater than the voltage of the battery cluster, thus achieving voltage boost. And at this time, the voltage Vbus1 at point A is greater than Vbus2 at point B, causing capacitor C2 to discharge to supply power to the power grid. The process of capacitor C2 discharging to supply power to the power grid can refer to the relevant description above Figures 16 to 19 and will not be elaborated here. The boosted voltage is greater than the maximum voltage of the grid alternating current, enabling the energy storage converter to operate normally throughout the alternating current cycle and improving the working efficiency.

[0138] After the above DC / DC conversion circuit completes the above boost operation and discharge working state 3, it enters the state shown in Figure 27 (boost operation discharge working state 4). This boost operation discharge working state 4 is the same as the boost operation discharge working state 2 shown in Figure 25 above. For specific reference, refer to the above description and will not be elaborated here. Then, the DC / DC conversion circuit operates in a cycle according to the above four working states of boost operation discharge working states 1 to 4 to achieve the boost of the above battery cluster, which will not be elaborated here.

[0139] In a possible implementation, when the voltage of the energy storage unit is less than the voltage at the second end of the energy storage converter, and when Vbat < Vbus1 < Vbus2, the energy storage converter is used to charge the energy storage unit. Exemplarily, when the controllable switch tube is disconnected during the above third time period, the DC / DC conversion circuit is controlled to step down the voltage at the first end of the energy storage converter and output the reduced voltage to the energy storage unit to charge the energy storage unit. The following combines Figures 28 to 31 to exemplarily introduce the specific implementation in this charging working state.

[0140] In Figures 28 to 31 , since the voltage of the energy storage unit, i.e., the battery cluster, is less than the voltage at the second end of the energy storage converter, the controllable switch tube, i.e., IGBT switch module T5, is turned off, and the DC / DC conversion circuit starts to work. Specifically, the DC / DC conversion circuit is used to boost the voltage of the battery cluster. If the voltage is boosted and Vbus1 < Vbus2 is controlled, then the power grid charges the battery cluster. The entire process of boosting the voltage can include four working states, which can be respectively referred to Figures 28 to 31 .

[0141] In Figure 28 the state shown (boost operation charging working state 1), the power grid charges capacitor C2 through the energy storage converter. The specific implementation can refer to the above Figures 20 to 23 The relevant descriptions are not repeated here. Furthermore, during the charging process of capacitor C2, capacitor C2 also discharges to charge the battery cluster. Specifically, in the DC / DC converter circuit, switching modules T3 and T1 are turned on, while switching modules T2 and T4 are turned off. This allows the discharge current of capacitor C2 to pass through switching module T1, capacitor C1, switching module T3, and inductor L1, reaching the battery cluster. Then, it flows back to capacitor C2 through the negative terminal of the battery cluster, forming a loop, as shown below. Figure 28 As shown in the diagram, in this state, the voltage at point A is the voltage of the battery cluster plus the voltage of inductor L1 and capacitor C1, which is greater than the voltage of the battery cluster, thus achieving a voltage boost. This boosted voltage is greater than the maximum AC voltage of the power grid, allowing the energy storage converter to operate normally throughout the entire AC cycle, improving its efficiency.

[0142] After completing the boost charging operation state 1, the aforementioned DC / DC converter circuit enters the following state: Figure 29 The state shown is (boost charging operation state 2). This state is a freewheeling state. Specifically, in the DC / DC converter circuit, switching modules T3 and T4 are turned on, and the remaining switching modules are turned off. Then, the current in inductor L1 flows back to inductor L1 through the battery cluster, switching module T4, and switching module T3, forming a current loop. This dissipates the sudden voltage change in inductor L1, preventing sudden voltage and current changes that could cause device losses.

[0143] After completing the boost charging operation state 2, the aforementioned DC / DC converter circuit enters the following state: Figure 30 The state shown is (boost-up operation and charging operation state 3). The power grid charges capacitor C2 through the energy storage converter. For details, please refer to the above. Figures 20 to 23 The relevant descriptions are not repeated here. Furthermore, during the charging process of capacitor C2, capacitor C2 also discharges to charge the battery cluster. Specifically, in the DC / DC converter circuit, switching modules T2 and T1 are turned on, while switching modules T3 and T4 are turned off. This allows the discharge current of capacitor C2 to pass through switching modules T1 and T2 and inductor L1, reaching the battery cluster. Then, it flows back to capacitor C2 through the negative terminal of the battery cluster, forming a loop, as shown below. Figure 30 As shown in the diagram, in this state, the voltage at point A is the sum of the voltage of the battery cluster and the voltage of inductor L1, which is greater than the voltage of the battery cluster, thus achieving a voltage boost. This boosted voltage is greater than the maximum AC voltage of the power grid, allowing the energy storage converter to operate normally throughout the entire AC cycle, improving its efficiency.

[0144] After completing the boost charging operation state 3, the aforementioned DC / DC converter circuit enters the following state: Figure 31 The state shown is boost charging state 4. This state is a freewheeling state. Specifically, in the DC / DC converter circuit, switching modules T2 and T4 are turned on, and the remaining switching modules are turned off. Then, the current in inductor L1 flows back to inductor L1 through the battery cluster, switching module T4, capacitor C1, and switching module T2, forming a current loop. This dissipates the sudden voltage change in inductor L1, preventing sudden voltage and current changes that could cause device losses. Then, the DC / DC converter circuit operates cyclically according to the four working states 1 to 4 described above to achieve the boost of the battery cluster, which will not be elaborated further here.

[0145] This application also provides an energy storage management system, which can be exemplarily referred to as such. Figure 32 The energy storage management system includes a DC / DC converter circuit, a controllable switching transistor, an energy storage converter, and a control unit.

[0146] The first end of the controllable switching transistor is used to connect to the energy storage power supply, and the second end of the controllable switching transistor is connected to the first end of the energy storage converter. The first end of the DC / DC conversion circuit is connected to the energy storage power supply, and the second end of the DC / DC conversion circuit is connected to the first end of the energy storage converter. The second end of the energy storage converter is used to connect to the grid connection point, and the energy storage converter is used to connect to the power grid or load through the grid connection point.

[0147] The control unit is used to, during a second time period, control the controllable switch to turn on so that the DC / DC conversion circuit stops working when the output voltage of the energy storage power supply is continuously greater than the peak voltage of the second terminal of the energy storage converter during a first time period, so that the energy storage power supply can be charged and discharged through the energy storage converter.

[0148] The control unit is used to control the controllable switch to disconnect when the output voltage of the energy storage power supply is less than the peak voltage of the second terminal of the energy storage converter during the third time period, so that the energy storage power supply can be charged and discharged through the energy storage converter and the DC / DC conversion circuit, wherein the time sequence is from the first time period to the second time period and then to the third time period.

[0149] In one possible implementation, the control unit is further configured to, during the second time period when the controllable switch is turned on, control the energy storage converter to rectify and transform the voltage at the second terminal of the energy storage converter, so that the voltage at the second terminal of the controllable switch is greater than the output voltage of the energy storage power supply, so as to charge the energy storage unit through the controllable switch.

[0150] The specific implementation and working principle of this energy storage management system can be referred to the aforementioned... Figure 3 The relevant descriptions of the energy storage system and its possible implementations are not elaborated here.

[0151] In this application, the terms "first," "second," etc., are used to distinguish identical or similar items that have substantially the same function. It should be understood that there is no logical or temporal dependency between "first," "second," and "nth," nor does it limit the quantity or order of execution. It should also be understood that although the following description uses the terms "first," "second," etc., to describe various elements, these elements should not be limited by the terms. These terms are merely used to distinguish one element from another.

[0152] It should also be understood that, in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0153] It should also be understood that the term "comprising" (also known as "includes", "including", "comprises" and / or "comprising") as used in this specification specifies the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0154] It should also be understood that the phrases "an embodiment," "a possible implementation," and "an embodiment" used throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment or implementation is included in at least one embodiment of this application. Therefore, the phrases "in an embodiment," "a possible implementation," and "an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An energy storage system, characterized by, The energy storage system includes an energy storage unit, a DC / DC converter circuit, a controllable switching transistor, an energy storage converter, and a control unit; The first end of the controllable switching transistor is connected to the energy storage unit, the second end of the controllable switching transistor is connected to the first end of the energy storage converter, the first end of the DC / DC conversion circuit is connected to the energy storage unit, the second end of the DC / DC conversion circuit is connected to the first end of the energy storage converter, the second end of the energy storage converter is used to connect to the grid connection point, and the energy storage converter is used to connect to the power grid or load through the grid connection point. The control unit is configured to, during a second time period, control the controllable switch to turn on so that the DC / DC conversion circuit stops working when the output voltage of the energy storage unit is continuously greater than the peak voltage of the second terminal of the energy storage converter during a first time period, so that the energy storage unit can be charged and discharged through the energy storage converter. The control unit is configured to, during a third time period, when the output voltage of the energy storage unit is less than the peak voltage at the second terminal of the energy storage converter, control the controllable switch to disconnect so that the energy storage unit can be charged and discharged through the energy storage converter and the DC / DC conversion circuit, wherein the time sequence is from the first time period to the second time period and then to the third time period.

2. The energy storage system according to claim 1, characterized in that, The control unit is further configured to, during the second time period, when the controllable switch is turned on, control the energy storage converter to rectify and transform the voltage at the second terminal of the energy storage converter, so that the voltage at the second terminal of the controllable switch is greater than the output voltage of the energy storage unit, so as to charge the energy storage unit through the controllable switch.

3. The energy storage system of claim 2, wherein, When the output voltage of the energy storage unit is less than the voltage at the second terminal of the controllable switch and the voltage at the second terminal of the controllable switch is less than the voltage at the first terminal of the energy storage converter, the energy storage converter is used to charge the energy storage unit.

4. The energy storage system of claim 1, wherein, The control unit is further configured to, during the second time period, when the controllable switch is turned on, control the energy storage converter to perform an inverter transformation on the voltage at the first terminal of the energy storage converter, so that the output voltage of the energy storage unit is greater than the voltage at the second terminal of the controllable switch, so as to discharge the energy storage unit through the controllable switch.

5. The energy storage system of claim 4, wherein, When the output voltage of the energy storage unit is greater than the voltage at the second terminal of the controllable switch and the voltage at the second terminal of the controllable switch is greater than the voltage at the first terminal of the energy storage converter, the energy storage converter is used to discharge the energy storage unit.

6. The energy storage system of claim 1, wherein, The control unit is further configured to, when the controllable switch is disconnected during the third time period, control the DC / DC conversion circuit to step down the voltage at the first terminal of the energy storage converter and output the reduced voltage to the energy storage unit, so as to charge the energy storage unit.

7. The energy storage system of claim 6, wherein, When the voltage at the second terminal of the DC / DC converter is less than the voltage at the first terminal of the energy storage converter, the energy storage converter is used to charge the energy storage unit.

8. The energy storage system of claim 1, wherein, The control unit is further configured to, when the controllable switch is turned off during the third time period, control the DC / DC converter circuit to boost the output voltage of the energy storage unit and output the boosted voltage to the energy storage converter, so as to realize the discharge of the energy storage unit.

9. The energy storage system of claim 8, wherein, When the voltage at the second terminal of the DC / DC converter is greater than the voltage at the first terminal of the energy storage converter, the energy storage converter is used to discharge the energy storage unit.

10. The energy storage system of claim 1, wherein, In the event of a transient overvoltage at the second terminal of the energy storage converter, the control unit is used to control the controllable switch to disconnect.

11. The energy storage system of any one of claims 1-10, wherein, The energy storage system also includes a voltage detection circuit; The voltage detection circuit is used to detect the voltage of the energy storage unit and the voltage at the second terminal of the energy storage converter; The voltage detection circuit is also used to output the detected voltage to the control unit.

12. The energy storage system of any one of claims 1-10, wherein, The energy storage system also includes a fault detection circuit; the fault detection circuit is used to detect short-circuit faults in the energy storage unit, and after detecting the short-circuit fault, instructs the control unit to disconnect the controllable switch tube.

13. The energy storage system of claim 12, wherein, The controllable switching transistor is an insulated gate bipolar transistor (IGBT) or a device formed by connecting an IGBT and a diode in parallel; the fault detection circuit is a desaturation detection circuit. When the voltage between the collector and emitter of the IGBT is greater than a preset voltage threshold, the control unit controls the IGBT to disconnect.

14. The energy storage system of any one of claims 1-10, wherein, The controllable switching transistor is an insulated gate bipolar transistor (IGBT), a relay, a contactor, or a device formed by connecting an IGBT and a diode in parallel.

15. An energy storage management system, characterized by, The energy storage management system includes a DC / DC converter circuit, a controllable switching transistor, an energy storage converter, and a control unit; The first end of the controllable switching transistor is used to connect to the energy storage power supply, the second end of the controllable switching transistor is connected to the first end of the energy storage converter, the first end of the DC / DC conversion circuit is connected to the energy storage power supply, the second end of the DC / DC conversion circuit is connected to the first end of the energy storage converter, the second end of the energy storage converter is used to connect to the grid connection point, and the energy storage converter is used to connect to the power grid or load through the grid connection point. The control unit is used to, during a second time period, control the controllable switch to turn on so that the DC / DC conversion circuit stops working when the output voltage of the energy storage power supply is continuously greater than the peak voltage of the second terminal of the energy storage converter during a first time period, so that the energy storage power supply can be charged and discharged through the energy storage converter. The control unit is configured to, during a third time period, when the output voltage of the energy storage power supply is less than the peak voltage at the second terminal of the energy storage converter, control the controllable switch to disconnect so that the energy storage power supply can be charged and discharged through the energy storage converter and the DC / DC conversion circuit, wherein the time sequence is from the first time period to the second time period and then to the third time period.

16. The energy storage management system of claim 15, wherein, The control unit is further configured to, during the second time period, when the controllable switch is turned on, control the energy storage converter to rectify and transform the voltage at the second terminal of the energy storage converter, so that the voltage at the second terminal of the controllable switch is greater than the output voltage of the energy storage power supply, so as to charge the energy storage power supply through the controllable switch.

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