DC-DC exchanger, energy storage unit and energy storage system

Abstract

The utility model provides a DC-DC exchanger, an energy storage unit and an energy storage system, and the DC-DC exchanger comprises a bridge circuit, one end of the bridge circuit is used as one end of the exchanger, and the other end of the bridge circuit is used as the other end of the exchanger. The primary side of the transformer is connected with the other end of the bridge circuit, and the secondary side of the transformer comprises a center tap; one end of the cyclic wave conversion circuit is connected with the secondary side of the transformer, and the other end of the cyclic wave conversion circuit and a center tap of the transformer are led out to serve as the other end of the exchanger.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and in particular to a DC-DC converter, an energy storage unit, and an energy storage system. Background Technology

[0002] In existing technologies, batteries or battery clusters are connected in series with a bidirectional DC-DC converter, which regulates the output voltage and current. Furthermore, in energy storage systems, multiple batteries or battery clusters are connected in parallel to an energy storage converter. The output voltage is regulated by the bidirectional DC-DC converter corresponding to each battery or battery cluster, thereby controlling the output voltage balance of multiple batteries or battery clusters and controlling the state of charge (SOX) balance of multiple batteries or battery clusters (SOX includes at least one of the following: State of Charge (SOC), State of Health (SOH), State of Power (SOP), and State of Function (SOF)). This prevents problems such as battery mismatch and short battery life leading to high maintenance difficulty. Currently, bidirectional DC-DC converters only output positive or only negative voltage, resulting in a limited range of output voltage regulation. Utility Model Content

[0003] In view of this, the purpose of this application is to provide a DC-DC converter, an energy storage unit and an energy storage system, which can be composed of a bridge circuit, a transformer and a frequency conversion circuit connected in series in sequence. This solves the technical problem in the prior art that the inability to output positive and negative voltages results in a small adjustable voltage range, and achieves the technical effect of improving the adjustable voltage range.

[0004] In a first aspect, embodiments of this application provide a DC-DC converter, the converter comprising: a bridge circuit, one end of which serves as one end of the converter; a transformer, the primary side of which is connected to the other end of the bridge circuit, the secondary side of which includes a center tap; and a frequency conversion circuit, one end of which is connected to the secondary side of the transformer, the other end of which and the center tap of the transformer being led out as the other end of the converter.

[0005] Optionally, the bridge circuit includes a first bridge arm, a second bridge arm, a first capacitor, and a second capacitor. One end of the first capacitor is connected to one end of the first bridge arm, and the other end of the first bridge arm is connected to one end of the second bridge arm. The other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the other end of the second bridge arm. The first end of the first bridge arm and the other end of the second bridge arm serve as one end of the bridge circuit. The connection between the first capacitor and the second capacitor, and the connection between the first bridge arm and the second bridge arm, are respectively led out as the other end of the bridge circuit.

[0006] Optionally, the first bridge arm includes a first control switch, a second control switch, and a first diode; the second bridge arm includes a third control switch, a fourth control switch, and a second diode. One end of the first control switch serves as one end of the first bridge arm; the other end of the first control switch is connected to one end of the second control switch; the other end of the second control switch serves as the other end of the first bridge arm; the other end of the second control switch is connected to one end of the third control switch; one end of the third control switch serves as one end of the second bridge arm; the other end of the third control switch is connected to one end of the fourth control switch; the other end of the fourth control switch serves as the other end of the second bridge arm; the connection between the first and second control switches is connected to one end of the first diode; the other end of the first diode is connected to one end of the second diode; the other end of the second diode is connected to the connection between the third and fourth control switches; and the connection between the first and second diodes is connected to the connection between the first and second capacitors.

[0007] Optionally, the control switch is configured as a transistor, wherein the transistor includes any of the following: a field-effect transistor and an insulated-gate bipolar transistor.

[0008] Optionally, the frequency conversion circuit includes a third bridge arm and a fourth bridge arm, wherein one end of the third bridge arm and one end of the fourth bridge arm serve as one end of the frequency conversion circuit, and the other end of the third bridge arm and the other end of the fourth bridge arm are connected to serve as the other end of the frequency conversion circuit.

[0009] Optionally, the third bridge arm includes a fifth control switch and a sixth control switch, and the fourth bridge arm includes a seventh control switch and an eighth control switch, wherein one end of the fifth control switch is connected to one end of the sixth control switch, one end of the seventh control switch is connected to one end of the eighth control switch, and the other end of the fifth control switch serves as one end of the third bridge arm, the other end of the seventh control switch serves as one end of the fourth bridge arm, the other end of the sixth control switch serves as another end of the third bridge arm, and the other end of the eighth control switch serves as another end of the fourth bridge arm.

[0010] Optionally, the control switch is configured as a transistor, wherein for each of the third and fourth bridge arms, the two transistors on that bridge arm are connected through the same connection terminal, wherein the transistor includes any of the following: field-effect transistor, insulated-gate bipolar transistor.

[0011] Optionally, the switch further includes a filter circuit, wherein one end of the filter circuit is connected to the other end of the frequency conversion circuit, and the other end of the filter circuit serves as the other end of the switch.

[0012] Optionally, the filter circuit includes an inductor and a third capacitor. One end of the inductor is connected to the other end of the frequency conversion circuit, and the other end of the inductor is connected to one end of the third capacitor. The other end of the third capacitor is connected to the center tap of the transformer. The connection between the inductor and the third capacitor and the connection between the third capacitor and the center tap of the transformer serve as the other end of the exchange.

[0013] Secondly, embodiments of this application also provide an energy storage unit, the energy storage unit comprising: a first external interface and a second external interface; a battery pack, wherein a first connection point of the battery pack is connected to a connection point at the other end of the switch, and a second connection point of the battery pack is led out as the first external interface; and a switch as described in the first aspect or any possible implementation thereof, wherein another connection point at the other end of the switch is led out as the second external interface, and one end of the switch is connected to a power supply.

[0014] Optionally, the battery pack serves as a power supply terminal connected to one end of the switch, wherein the first connection point and the second connection point of the battery pack are connected to one end of the switch.

[0015] Secondly, embodiments of this application also provide an energy storage system, the energy storage system comprising: an energy storage converter; a first bus and a second bus, the first bus being connected to a first connection terminal of the energy storage converter, and the second bus being connected to a second connection terminal of the energy storage converter; a plurality of energy storage units, each energy storage unit having a first external interface connected to the first bus and a second external interface connected to the second bus; wherein, the energy storage unit comprises: a first external interface and a second external interface; a battery pack, the first connection point of the battery pack being connected to a connection point at the other end of the converter, and the second connection point of the battery pack being extended as the first external interface; and a converter as described in the first aspect or any possible embodiment of the first aspect, wherein another connection point at the other end of the converter is extended as the second external interface.

[0016] This application provides a DC-DC converter, energy storage unit, and energy storage system. The converter includes: a bridge circuit, one end of which serves as one end of the converter; a transformer, the primary side of which is connected to the other end of the bridge circuit, and the secondary side of which includes a center tap; and a frequency conversion circuit, one end of which is connected to the secondary side of the transformer, and the other end of which, along with the center tap of the transformer, serves as the other end of the converter. By sequentially connecting the bridge circuit, the transformer, and the frequency conversion circuit in series to form the DC-DC converter, the technical problem of the inability to output positive and negative voltages, resulting in a small adjustable voltage range, is solved, thus improving the adjustable voltage range.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A circuit diagram of a DC-DC converter provided in an embodiment of this application is shown.

[0020] Figure 2 A circuit diagram of another DC-DC converter provided in an embodiment of this application is shown.

[0021] Figure 3 A circuit diagram of an energy storage unit provided in an embodiment of this application is shown.

[0022] Figure 4 A circuit diagram of an energy storage system provided in an embodiment of this application is shown. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0024] In existing technologies, multiple batteries or battery clusters in an energy storage system are connected in parallel to an energy storage converter. The output voltage is regulated by a bidirectional DC-DC converter corresponding to each battery or battery cluster, thereby controlling the output voltage balance of the multiple batteries or battery clusters and balancing the state of energy (SOX) among them. This prevents the problems of high maintenance difficulty and cost caused by battery mismatch and short battery life. Currently, bidirectional DC-DC converters only output positive or only negative voltage, resulting in a limited range of output voltage regulation.

[0025] To address the aforementioned problems, this application provides a DC-DC converter, an energy storage unit, and an energy storage system. The DC-DC converter is constructed by sequentially connecting a bridge circuit, a transformer, and a frequency conversion circuit in series. This solves the technical problem in the prior art where the inability to output both positive and negative voltages results in a limited adjustable voltage range, thus achieving a significant improvement in the adjustable voltage range. Specifically:

[0026] Please see Figure 1 , Figure 1 This is a circuit diagram of a DC-DC converter provided as an embodiment of this application. Figure 1 As shown, the DC-DC converter provided in this embodiment includes: a bridge circuit 101, one end of which serves as one end of the converter; a transformer T, the primary side of which is connected to the other end of the bridge circuit, and the secondary side of which includes a center tap; and a frequency conversion circuit 102, one end of which is connected to the secondary side of the transformer, and the other end of which, along with the center tap of the transformer, serves as the other end of the converter.

[0027] The bridge circuit is used to change the positive or negative voltage supplied to the primary side of the transformer. The transformer is used to change the voltage value and output the changed voltage value to the frequency conversion circuit through the secondary side. The transformer also acts as an isolation device. The frequency conversion circuit is used to change the positive or negative value of the voltage output at the other end of the switch. In this way, by connecting the bridge circuit, the transformer and the frequency conversion circuit in series, the output of the switch can output both positive and negative voltage.

[0028] like Figure 1 As shown, the bridge circuit 101 includes a first bridge arm, a second bridge arm, a first capacitor C1, and a second capacitor C2. One end of the first capacitor is connected to one end of the first bridge arm, and the other end of the first bridge arm is connected to one end of the second bridge arm. The other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the other end of the second bridge arm. The first end of the first bridge arm and the other end of the second bridge arm serve as one end of the bridge circuit. The connection between the first capacitor and the second capacitor, and the connection between the first bridge arm and the second bridge arm, are respectively led out as the other end of the bridge circuit.

[0029] Specifically, the first bridge arm includes a first control switch Q1, a second control switch Q2, and a first diode D1; the second bridge arm includes a third control switch Q3, a fourth control switch Q4, and a second diode D2. One end of the first control switch serves as one end of the first bridge arm; the other end of the first control switch is connected to one end of the second control switch; the other end of the second control switch serves as the other end of the first bridge arm; the other end of the second control switch is connected to one end of the third control switch; one end of the third control switch serves as one end of the second bridge arm; the other end of the third control switch is connected to one end of the fourth control switch; the connection point between the first and second control switches is connected to one end of the first diode; the other end of the first diode is connected to one end of the second diode; the other end of the second diode is connected to the connection point between the third and fourth control switches; and the connection point between the first and second diodes is connected to the connection point between the first and second capacitors.

[0030] In a bridge circuit, the sign of the voltage output at the other end is changed by altering the on / off state of a control switch. The on / off state includes a conducting state and an open-circuit state.

[0031] For example, if one end of the first control switch is connected to the positive terminal of the power supply, and the other end of the fourth control switch is connected to the negative terminal of the power supply, then when both the first and second control switches are in the ON state, and both the third and fourth control switches are in the OFF state, the same-named terminal of the primary side of the transformer is connected to the positive terminal through the first and second control switches, and the opposite-named terminal of the primary side of the transformer is connected to the negative terminal through the second capacitor. Furthermore, the positive voltage between the first and second control switches does not flow into the opposite-named terminal due to the cutoff effect of the first diode. Therefore, the voltage difference between the same-named and opposite-named terminals of the primary side of the transformer is positive, meaning the primary side of the transformer is connected to a positive voltage.

[0032] For example, if one end of the first control switch is connected to the positive terminal of the power supply, and the other end of the fourth control switch is connected to the negative terminal of the power supply, then when both the first and second control switches are in an open-circuit state, and both the third and fourth control switches are in a closed-circuit state, the same-name terminal of the primary side of the transformer is connected to the negative terminal through the third and fourth control switches, and the opposite-name terminal of the primary side of the transformer is connected to the positive terminal through the first capacitor. Furthermore, the cutoff effect of the second diode prevents the positive voltage at the connection point between the first and second capacitors from flowing between the third and fourth control switches, and thus from flowing to the same-name terminal. Therefore, the voltage difference between the same-name and opposite-name terminals of the primary side of the transformer is negative, meaning the primary side of the transformer is connected to a negative voltage.

[0033] like Figure 1 As shown, the frequency conversion circuit 102 includes a third bridge arm and a fourth bridge arm, wherein one end of the third bridge arm and one end of the fourth bridge arm serve as one end of the frequency conversion circuit, and the other end of the third bridge arm and the other end of the fourth bridge arm are connected to serve as the other end of the frequency conversion circuit.

[0034] Specifically, the third bridge arm includes a fifth control switch Q5 and a sixth control switch Q6, and the fourth bridge arm includes a seventh control switch Q7 and an eighth control switch Q8. One end of the fifth control switch is connected to one end of the sixth control switch, and one end of the seventh control switch is connected to one end of the eighth control switch. The other end of the fifth control switch serves as one end of the third bridge arm, the other end of the seventh control switch serves as one end of the fourth bridge arm, the other end of the sixth control switch serves as another end of the third bridge arm, and the other end of the eighth control switch serves as another end of the fourth bridge arm.

[0035] In this design, the secondary winding of the transformer is divided into a first winding and a second winding by a center tap. One end of the first winding and one end of the second winding are both connected to the center tap. The other ends of both the first and second windings serve as the secondary winding of the transformer, connecting to one end of the frequency conversion circuit. Furthermore, the other end of the first winding serves as the same-name terminal of the first winding, and one end of the first winding serves as the opposite-name terminal of the first winding. Similarly, one end of the second winding serves as the same-name terminal of the second winding, and the other end of the second winding serves as the opposite-name terminal of the second winding.

[0036] like Figure 1 As shown, the other end of the first winding is connected to the other end of the fifth control switch, and the other end of the second winding is connected to the other end of the seventh control switch. The voltage value at the other end of the frequency conversion circuit is the voltage difference between the connection point between the sixth and eighth control switches and the center tap.

[0037] For example, if one end of the first control switch is connected to the positive terminal of the power supply, the other end of the fourth control switch is connected to the negative terminal of the power supply, and the voltage value at the other end of the control frequency conversion circuit is positive, then the on / off states of the fifth and seventh control switches are both in the on state, and only the on / off states of the sixth and eighth control switches are changed, so as to reduce the number of times the control switches are operated, thereby increasing the usage time of the control switches.

[0038] Specifically, if one end of the first control switch is connected to the positive terminal of the power supply and the other end of the fourth control switch is connected to the negative terminal of the power supply, and both the first and second control switches are in the ON state, while both the third and fourth control switches are in the OFF state, the primary side of the transformer is connected to a positive voltage, the sixth control switch is in the ON state, and the eighth control switch is in the OFF state. At this time, the first winding is on while the second winding is not on, the other end of the sixth control switch is positive, and the middle tap is negative. Consequently, the voltage at the other end of the frequency conversion circuit is positive. Conversely, if both the third and fourth control switches are on, and both the first and second control switches are in the OFF state, the primary side of the transformer is connected to a negative voltage, the sixth control switch is in the OFF state, and the eighth control switch is on. At this time, the first winding is not on while the second winding is on, the other end of the eighth control switch is positive, and the middle tap is negative. Consequently, the voltage at the other end of the frequency conversion circuit is positive.

[0039] For example, if one end of the first control switch is connected to the positive terminal of the power supply, the other end of the fourth control switch is connected to the negative terminal of the power supply, and the voltage value at the other end of the frequency conversion circuit is negative, then the on / off states of the sixth and eighth control switches are both in the on state. Only the on / off states of the fifth and seventh control switches are changed, thereby reducing the number of control switch operations and increasing the usage time of the control switches. When both the first and second control switches are in the on state, and both the third and fourth control switches are in the off state, the primary side of the transformer is connected to a positive voltage. The fifth control switch is in the off state, and the seventh control switch is in the on state. At this time, the first winding is not conducting while the second winding is conducting, the middle tap is positive, and the other end of the eighth control switch is negative. Consequently, the voltage value at the other end of the frequency conversion circuit is negative. When the third and fourth control switches are both in the ON state, and the first and second control switches are both in the OFF state, the primary side of the transformer is connected to a negative voltage. This controls the fifth control switch to be in the ON state and the seventh control switch to be in the OFF state. At this time, the first winding is on while the second winding is not on, the middle tap is positive, and the other end of the eighth control switch is negative. Consequently, the voltage value at the other end of the frequency conversion circuit is negative.

[0040] In this application, the control switch can be selected as a bidirectional conduction switch to enable bidirectional flow of electrical energy to the power supply connected to the bridge circuit, i.e., the power supply can perform either discharging or charging operations. In other words, by setting a bidirectional conduction switch, both the bridge circuit and the frequency conversion circuit can perform bidirectional flow of electrical energy. Furthermore, the on / off state of the control switch is changed by sending a corresponding control signal to the control terminal of the control switch.

[0041] For example, the first, second, third, and fourth control switches in the bridge circuit can all be transistors, and the fifth, sixth, seventh, and eighth control switches in the frequency conversion circuit can also all be transistors. The transistors can be any of the following: Insulated Gate Bipolar Transistor (IGBT) or Field-Effect Transistor (FET). Specifically, the FET can be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or a SiC MOSFET (Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistor).

[0042] In other words, the on / off state is changed by receiving a control signal at the gate of the transistor.

[0043] For example, in the first and second bridge arms, the collector of the transistor serves as one end of the control switch, and the emitter of the transistor serves as the other end of the control switch. That is, the first control switch, the second control switch, the third control switch, and the fourth control switch are connected sequentially by connecting the emitter of one transistor to the collector of the next transistor.

[0044] For example, for each of the third and fourth bridge arms, the two transistors on that bridge arm are connected through the same connection terminal, that is, the collector of the transistor serves as one end of the control switch and the emitter of the transistor serves as the other end of the control switch. By connecting the emitters of the two transistors on one bridge arm, the fifth and sixth control switches and the seventh and eighth control switches are connected. Furthermore, since the body diode of the transistor can achieve reverse conduction, the frequency conversion circuit can realize bidirectional flow of electrical energy.

[0045] Please see Figure 2 , Figure 2 A circuit diagram of another DC-DC converter provided as an embodiment of this application. Figure 2 As shown, the switch also includes a filter circuit 103, wherein one end of the filter circuit is connected to the other end of the frequency conversion circuit, and the other end of the filter circuit serves as the other end of the switch.

[0046] The filter circuit includes an inductor Lf and a third capacitor Cf. One end of the inductor is connected to the other end of the frequency conversion circuit, and the other end of the inductor is connected to one end of the third capacitor. The other end of the third capacitor is connected to the center tap of the transformer. The connection between the inductor and the third capacitor and the connection between the third capacitor and the center tap of the transformer serve as the other end of the exchange.

[0047] In other words, the voltage output from the other end of the frequency converter circuit is filtered by the filter circuit to obtain a more stable voltage.

[0048] Based on the same concept, this application also provides an energy storage unit corresponding to the switch provided in the above embodiments. Since the principle of the energy storage unit in this application is similar to that of the switch in the above embodiments, the implementation of the energy storage unit can refer to the implementation of the above embodiments, and the repeated parts will not be described again.

[0049] Please see Figure 3 , Figure 3 This is a circuit diagram of an energy storage unit provided in an embodiment of this application. Figure 3As shown, the energy storage unit includes: a first external interface J1 and a second external interface J2; a battery pack BAT, wherein a first connection point of the battery pack is connected to a connection point at the other end of the switch, and a second connection point of the battery pack is led out as the first external interface; and a switch as described in any of the above possible embodiments, wherein another connection point at the other end of the switch is led out as the second external interface, and one end of the switch is connected to the power supply.

[0050] The battery pack serves as the power supply terminal connected to one end of the switch, wherein the first connection point and the second connection point of the battery pack are connected to one end of the switch.

[0051] In other words, the battery pack is connected to one end of the switch as the power supply terminal of the switch, and the battery pack is also connected in series with the switch so that the voltage of the battery pack is combined with the voltage of the other end of the switch to form the voltage value between the first external interface and the second external interface of the energy storage unit. For example, if the voltage range of the other end of the switch is [+U, -U], and the voltage value of the battery pack is U... P Then the voltage range between the first external interface and the second external interface of the energy storage unit is [U P +U,U P -U]. In existing technology, the voltage range at the other end of the switch can only be 0 to +U, and the voltage range between the first and second external interfaces of the energy storage unit is only [U]. P U P +U]; or, the voltage range at the other end of the switch can only be -U to 0, and the voltage range between the first and second external interfaces of the energy storage unit can only be [U]; P -U, U P Furthermore, the voltage range of the first and second external interfaces of the energy storage unit is increased through the switch of this application.

[0052] Based on the same concept, this application also provides an energy storage system corresponding to the exchanger provided in the above embodiments. Since the principle of the energy storage system in this application is similar to that of the exchanger in the above embodiments, the implementation of the energy storage system can refer to the implementation of the above embodiments, and the repeated parts will not be described again.

[0053] Please see Figure 4 , Figure 4 This is a circuit diagram of an energy storage system provided as an embodiment of this application. Figure 4As shown, the energy storage system includes: an energy storage converter PCS; a first bus BUS1 and a second bus BUS2, the first bus being connected to a first connection terminal of the energy storage converter, and the second bus being connected to a second connection terminal of the energy storage converter; multiple energy storage units, each energy storage unit having a first external interface connected to the first bus, and each energy storage unit having a second external interface connected to the second bus; wherein, the energy storage unit includes: a first external interface and a second external interface; a battery pack, the first connection point of which is connected to a connection point at the other end of the converter, and the second connection point of which is led out as the first external interface; and a converter as described in any of the above possible embodiments, wherein another connection point at the other end of the converter is led out as the second external interface.

[0054] One end of the energy storage converter is connected to the first busbar and the second busbar of multiple energy storage units, and the other end of the energy storage converter can be connected to external power equipment or charging equipment, so as to enable multiple energy storage units to supply power or charge externally.

[0055] In other words, as the voltage regulation range between the first and second external interfaces of each energy storage unit increases, the voltage flowing into the first and second connection terminals of the energy storage converter also increases accordingly.

[0056] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0057] It should also be noted that, unless otherwise explicitly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A DC-DC converter, characterized in that, The switch includes: A bridge circuit, one end of which serves as one end of the switch; A transformer, wherein the primary side of the transformer is connected to the other end of the bridge circuit, and the secondary side of the transformer includes a center tap; A frequency conversion circuit is provided, one end of which is connected to the secondary side of the transformer, and the other end of the frequency conversion circuit is led out from the middle tap of the transformer as the other end of the exchange.

2. The switch according to claim 1, characterized in that, The bridge circuit includes a first bridge arm, a second bridge arm, a first capacitor, and a second capacitor. In this configuration, one end of the first capacitor is connected to one end of the first bridge arm, the other end of the first bridge arm is connected to one end of the second bridge arm, the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the other end of the second bridge arm. One end of the first bridge arm and the other end of the second bridge arm serve as one end of the bridge circuit, and the connection between the first capacitor and the second capacitor, as well as the connection between the first bridge arm and the second bridge arm, are respectively led out as the other end of the bridge circuit.

3. The switch according to claim 2, characterized in that, The first bridge arm includes a first control switch, a second control switch, and a first diode; the second bridge arm includes a third control switch, a fourth control switch, and a second diode. In this configuration, one end of the first control switch serves as one end of the first bridge arm, the other end of the first control switch is connected to one end of the second control switch, the other end of the second control switch serves as the other end of the first bridge arm, and the other end of the second control switch is connected to one end of the third control switch. One end of the third control switch serves as one end of the second bridge arm, and the other end of the third control switch is connected to one end of the fourth control switch, which serves as the other end of the second bridge arm. The connection between the first control switch and the second control switch is connected to one end of the first diode, the other end of the first diode is connected to one end of the second diode, the other end of the second diode is connected to the connection between the third control switch and the fourth control switch, and the connection between the first diode and the second diode is connected to the connection between the first capacitor and the second capacitor.

4. The switch according to claim 3, characterized in that, The control switch is configured as a transistor, wherein the transistor includes any one of the following: a field-effect transistor or an insulated-gate bipolar transistor.

5. The switch according to claim 1, characterized in that, The frequency conversion circuit includes a third bridge arm and a fourth bridge arm. Wherein, one end of the third bridge arm and one end of the fourth bridge arm serve as one end of the frequency conversion circuit, and the other end of the third bridge arm and the other end of the fourth bridge arm are connected and serve as the other end of the frequency conversion circuit.

6. The switch according to claim 5, characterized in that, The third bridge arm includes a fifth control switch and a sixth control switch, and the fourth bridge arm includes a seventh control switch and an eighth control switch. Wherein, one end of the fifth control switch is connected to one end of the sixth control switch, and one end of the seventh control switch is connected to one end of the eighth control switch. The other end of the fifth control switch serves as one end of the third bridge arm, the other end of the seventh control switch serves as one end of the fourth bridge arm, the other end of the sixth control switch serves as the other end of the third bridge arm, and the other end of the eighth control switch serves as the other end of the fourth bridge arm.

7. The switch according to claim 6, characterized in that, The control switch is configured as a transistor, wherein for each of the third and fourth bridge arms, the two transistors on that bridge arm are connected via the same terminal. The transistor includes any one of the following: a field-effect transistor and an insulated-gate bipolar transistor.

8. The switch according to claim 1, characterized in that, The switch also includes a filtering circuit. One end of the filter circuit is connected to the other end of the frequency conversion circuit, and the other end of the filter circuit serves as the other end of the switch.

9. The switch according to claim 8, characterized in that, The filter circuit includes an inductor and a third capacitor. One end of the inductor is connected to the other end of the frequency conversion circuit, and the other end of the inductor is connected to one end of the third capacitor. The other end of the third capacitor is connected to the center tap of the transformer. The connection between the inductor and the third capacitor, and the connection between the third capacitor and the center tap of the transformer, serve as the other end of the exchange.

10. An energy storage unit, characterized in that, The energy storage unit includes: First external interface and second external interface; A battery pack, wherein a first connection point of the battery pack is connected to a connection point at the other end of the switch, and a second connection point of the battery pack is led out as the first external interface; The switch as described in any one of claims 1 to 9, wherein another connection point at the other end of the switch is led out as the second external interface, and one end of the switch is connected to the power supply.

11. The energy storage unit according to claim 10, characterized in that, The battery pack serves as the power supply terminal connected to one end of the switch. The first connection point and the second connection point of the battery pack are connected to one end of the switch.

12. An energy storage system, characterized in that, The energy storage system includes: Energy storage converter; A first busbar and a second busbar, wherein the first busbar is connected to the first connection terminal of the energy storage converter, and the second busbar is connected to the second connection terminal of the energy storage converter; Multiple energy storage units, each with a first external interface connected to the first busbar and a second external interface connected to the second busbar; The energy storage unit includes: First external interface and second external interface; A battery pack, wherein a first connection point of the battery pack is connected to a connection point at the other end of the switch, and a second connection point of the battery pack is led out as the first external interface; The switch as claimed in any one of claims 1 to 9, wherein, Another connection point at the other end of the switch is led out as the second external interface.

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