Auxiliary power supply circuit of energy storage system and energy storage system

Abstract

The utility model discloses an auxiliary power supply circuit of an energy storage system and the energy storage system, the auxiliary power supply circuit comprises a DC bus input end, a diode, an AC input end, a first auxiliary power supply module and a second auxiliary power supply module, the DC bus input end is used for accessing a DC energy storage device; the diode is connected with the direct-current bus input end through an anode end; the AC input end is used for accessing an AC power grid; the first auxiliary power supply module is connected with an AC input end and is used for reducing voltage of an input power supply and converting the input power supply into DC power supply output. The input end of the second auxiliary power supply module is connected with the output end of the first auxiliary power supply module and the cathode end of the diode for reducing the voltage of the input power supply and supplying power to the load. According to the embodiment of the utility model, the auxiliary power supply circuit can be effectively simplified, and the stability of circuit output during mode switching is improved.

Description

Technical Field

[0001] This utility model relates to the field of power supply circuit technology, and in particular to an auxiliary power supply circuit and energy storage system for an energy storage system. Background Technology

[0002] Energy storage systems require a series of power sources to operate. The energy in an energy storage system typically comes from batteries (representing DC input) and the power grid (representing AC input). An auxiliary power supply converts the energy from the batteries and grid into corresponding power sources to meet the voltage and current requirements for normal operation. Because energy storage systems switch between operating modes, the auxiliary power supply needs to be compatible with each operating condition and ensure that each mode does not interfere with the others. Current auxiliary power supplies are designed separately for DC and AC input, i.e., a DC auxiliary power supply and an AC auxiliary power supply, connected in parallel for voltage output. However, separate, independent designs require two complete power supply systems, resulting in higher costs, larger circuit sizes, and potential voltage fluctuations due to the coupling between the two auxiliary power supplies during mode switching. Utility Model Content

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide an auxiliary power supply circuit and an energy storage system for an energy storage system, which can effectively simplify the auxiliary power supply circuit and improve the stability of the circuit output during mode switching.

[0004] In a first aspect, this utility model provides an auxiliary power supply circuit for an energy storage system, comprising: a DC bus input terminal, a diode, an AC input terminal, a first auxiliary power supply module, and a second auxiliary power supply module. The DC bus input terminal is used to connect to a DC energy storage device; the diode is connected to the DC bus input terminal via its anode; the AC input terminal is used to connect to an AC power grid; the first auxiliary power supply module is connected to the AC input terminal and is used to step down the input power supply and convert it into DC power output; the input terminal of the second auxiliary power supply module is connected to the output terminal of the first auxiliary power supply module and the cathode terminal of the diode, respectively, and is used to step down the input power supply and supply power to the load.

[0005] The auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention has at least the following beneficial effects: The first auxiliary power supply module is connected to the AC power grid through the AC input terminal, and the AC power provided by the AC power grid is stepped down and rectified into DC power before being output to the second auxiliary power supply module. Simultaneously, the DC energy storage device provides DC power to the second auxiliary power supply module through the DC bus input terminal and a diode. Therefore, the rectified AC power from the first auxiliary power supply module and the DC power input from the DC bus input terminal can be jointly input to the second auxiliary power supply module to supply power to the load, which effectively reduces voltage fluctuations during mode switching. Furthermore, the diode isolates the DC bus input terminal and the output terminal of the first auxiliary power supply module, avoiding direct electrical connection between the two and preventing the power output of the first auxiliary power supply module from affecting the voltage of the DC bus. Compared to the related art's scheme of designing two auxiliary power supplies independently and connecting their outputs in parallel, this embodiment of the present invention combines the first and second auxiliary power supply modules by isolating the AC input and DC input through a diode. This design not only allows for the sharing of some circuit components, simplifying circuit design and reducing circuit costs, but also reduces voltage fluctuations during mode switching, thereby improving circuit reliability.

[0006] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the voltage level of the output voltage of the first auxiliary power supply module is higher than the voltage level of the output voltage of the second auxiliary power supply module.

[0007] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the first auxiliary power supply module includes a first rectifier and filter branch connected to the AC input terminal.

[0008] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the utility model, the first auxiliary power supply module further includes a first switching transistor, a first transformer and a first feedback branch. The first switching transistor is connected to the first rectifier and filter branch and the primary winding of the first transformer, respectively. The secondary winding of the first transformer is connected to the input terminals of the second auxiliary power supply module and the first feedback branch, respectively. The output terminal of the first feedback branch is connected to the control terminal of the first switching transistor.

[0009] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the higher the voltage at the input terminal of the first feedback branch, the shorter the conduction time of the first switching transistor.

[0010] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the first auxiliary power supply module further includes a second rectifier and filter branch, and the secondary winding of the first transformer is connected to the input terminals of the second auxiliary power supply module and the first feedback branch through the second rectifier and filter branch respectively.

[0011] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the second auxiliary power supply module further includes a second switching transistor, a second transformer, and a second feedback branch. One end of the second switching transistor is connected to the output terminal of the first auxiliary power supply module, the cathode of the diode, and the primary winding of the second transformer, respectively. The secondary winding of the second transformer is connected to the load and the input terminal of the second feedback branch, respectively. The output terminal of the second feedback branch is connected to the control terminal of the second switching transistor.

[0012] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the second auxiliary power supply module further includes a third rectifier and filter branch, and the secondary winding of the second transformer is connected to the load and the input terminal of the second feedback branch respectively through the third rectifier and filter branch.

[0013] In the auxiliary power supply circuit of the energy storage system provided in this embodiment of the present invention, the second auxiliary power supply module further includes a multi-stage step-down circuit for supplying power to different loads, and the multi-stage step-down circuit is connected to the secondary winding of the second transformer.

[0014] Secondly, embodiments of the present invention provide an energy storage system, including the auxiliary power supply circuit of the energy storage system described in the first aspect embodiment above.

[0015] The energy storage system provided according to the embodiments of this utility model has at least the following beneficial effects: The first auxiliary power module is connected to the AC power grid through the AC input terminal, and outputs the AC power provided by the AC power grid as DC power after stepping down and rectifying it to the second auxiliary power module. At the same time, the DC energy storage device provides DC power to the second auxiliary power module through the DC bus input terminal and a diode. Therefore, the AC power rectified by the first auxiliary power module and the DC power input at the DC bus input terminal can be jointly input to the second auxiliary power module to supply power to the load, which can effectively reduce voltage fluctuations during mode switching. In addition, the diode can isolate the DC bus input terminal and the output terminal of the first auxiliary power module, avoiding direct electrical connection between the two and preventing the power supply at the output terminal of the first auxiliary power module from affecting the voltage of the DC bus. Compared with the related technology of designing two auxiliary power supplies independently and connecting their outputs in parallel, the embodiments of this utility model combine the first auxiliary power module and the second auxiliary power module by isolating the input of the AC part and the input of the DC part with a diode. This design can not only share some circuit components, simplify circuit design, and reduce circuit costs, but also reduce voltage fluctuations during mode switching, thereby improving circuit reliability.

[0016] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this utility model to explain the technical solution of this utility model, and do not constitute a limitation on the technical solution of this utility model.

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0019] Figure 1 This is a schematic diagram of the charging and discharging control circuit provided in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the charging and discharging control circuit provided in another embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the charging and discharging control circuit provided in another embodiment of the present invention. Detailed Implementation

[0022] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0023] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, while "above," "below," "within," etc. are understood to include the number itself. "Any one" refers to one or more, and "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or multiple items. If the terms "first" and "second" are used in the description, they are only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] It should be noted that the terms "setting," "installing," and "connecting" in the embodiments of this utility model should be interpreted broadly. Those skilled in the art can reasonably determine the specific meaning of the above terms in the embodiments of this utility model in conjunction with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or a connection that allows for mutual communication; it can be a direct connection or an indirect connection through an intermediate medium.

[0025] It should be noted that the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0026] Energy storage systems require a series of power sources to operate. The energy in an energy storage system typically comes from batteries (representing DC input) and the power grid (representing AC input). An auxiliary power supply converts the energy from the batteries and grid into corresponding power sources to meet the voltage and current requirements for normal operation. Because energy storage systems switch between operating modes, the auxiliary power supply needs to be compatible with each operating condition and ensure that each mode does not interfere with the others. Current auxiliary power supplies are designed separately for DC and AC input, i.e., a DC auxiliary power supply and an AC auxiliary power supply, connected in parallel for voltage output. However, separate, independent designs require two complete power supply systems, resulting in higher costs, larger circuit sizes, and potential voltage fluctuations due to the coupling between the two auxiliary power supplies during mode switching.

[0027] Based on this, this utility model embodiment proposes an auxiliary power supply circuit and energy storage system for an energy storage system. The first auxiliary power module is connected to the AC power grid via its AC input terminal, stepping down and rectifying the AC power supplied by the grid into DC power before outputting it to the second auxiliary power module. Simultaneously, the DC energy storage device provides DC power to the second auxiliary power module via its DC bus input terminal and a diode. Therefore, the rectified AC power from the first auxiliary power module and the DC power input from the DC bus input terminal can be jointly input to the second auxiliary power module to supply power to the load, effectively reducing voltage fluctuations during mode switching. Furthermore, the diode isolates the DC bus input terminal from the output terminal of the first auxiliary power module, avoiding direct electrical connection between them and preventing the power supply at the output terminal of the first auxiliary power module from affecting the voltage of the DC bus. Compared to related technologies that design two auxiliary power supplies independently and connect their outputs in parallel, this utility model embodiment uses diodes to isolate the input of the AC section from the input of the DC section, thereby combining the first auxiliary power supply module and the second auxiliary power supply module. This design not only allows for the sharing of some circuit components, simplifying circuit design and reducing circuit costs, but also reduces voltage fluctuations during mode switching, thereby improving circuit reliability.

[0028] The embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0029] Reference Figure 1 The first aspect of this utility model provides an auxiliary power supply circuit for an energy storage system. This auxiliary power supply circuit is not a backup power source, but rather a power source used to maintain the stability of the control circuits in the energy storage system. It is responsible for managing key functions such as battery charging and discharging, AC grid connection and switching. By providing a stable operating power supply, the auxiliary power supply circuit ensures that these control circuits can issue commands correctly and accurately, thereby maintaining the stability and reliability of the entire energy storage system. In an energy storage system, the auxiliary power supply circuit needs to have good compatibility to adapt to the needs of different operating conditions. For example, in a photovoltaic energy storage system, the auxiliary power supply circuit needs to be able to smoothly switch between different energy sources such as photovoltaic panels, batteries, and the AC grid to ensure stable operation of the energy storage system under various power supply modes. Specifically, the auxiliary power supply circuit of the energy storage system includes two power supply sections: an AC power supply section and a DC power supply section. The AC power supply section includes an AC input terminal 300 and a first auxiliary power supply module 100. The AC input terminal 300 is connected to the input terminal of the first auxiliary power supply module 100. The AC input terminal 300 can be connected to the AC power grid, so the first auxiliary power supply module 100 can obtain AC power from the AC power grid through the AC input terminal 300. The first auxiliary power supply module 100 has the functions of stepping down the input power and rectifying the input power. Specifically, the first auxiliary power supply module 100 can convert the AC power input from the AC power grid into DC power, step down the voltage, and then output the stepped-down DC power to the second auxiliary power supply module 200. Unlike the auxiliary power supply in related technologies, the first auxiliary power supply module 100, i.e. the AC power supply section, in this embodiment of the utility model has only one output, which is output to the second auxiliary power supply module 200, i.e. the DC power supply section. This integrates the AC power supply section and the DC power supply section, saving the power supply circuit to the downstream load set in the AC power supply section, i.e. the AC auxiliary power supply section, in related technologies, simplifying the circuit design and saving circuit costs.

[0030] The DC input section includes a DC bus input terminal 400, a diode 500, and a second auxiliary power module 200. The DC bus input terminal 400 is connected to the second auxiliary power module 200 through the diode 500. At the same time, the output terminal of the first auxiliary power module 100 is also connected to the connection point between the diode 500 and the second auxiliary power module 200. The DC bus input terminal 400 can be connected to a DC energy storage device to obtain DC power. For example, the DC energy storage device may include at least one of a photovoltaic panel and a battery. The DC bus terminal is connected to the anode of diode 500, and the cathode of diode 500 and the output terminal of the first auxiliary power module 100 are simultaneously connected to the input terminal of the second auxiliary power module 200. Therefore, the unidirectional conductivity of diode 500 can isolate the first auxiliary power module 100 from the DC bus input terminal 400, preventing the power output of the first auxiliary power module from affecting the voltage of the DC bus. Moreover, during mode switching, the power-on sequence of the first auxiliary power module 100 and the DC bus input terminal 400 may be inconsistent. If the two are directly connected, it may cause voltage fluctuations or current surges, which may damage the circuit.

[0031] The second auxiliary power module 200 also has a step-down function, capable of reducing the input power to a voltage level suitable for the load and distributing the stepped-down power to the load. This module can support various load devices, including but not limited to devices with rated voltages of 12V, 10V, 5V, or 3.8V. The input power source for the second auxiliary power module 200 can be the AC grid or a DC energy storage device, depending on the operating mode. For example, when the DC energy storage device has sufficient power, the system can switch to DC power supply mode. In this case, the power provided by the DC energy storage device through the DC bus input terminal 400 becomes the input of the second auxiliary power module 200 and is responsible for powering the load. Conversely, when the DC energy storage device has insufficient power, the system adopts AC power supply mode. In this case, the power provided by the AC grid through the first auxiliary power module 100 becomes the input power source for the second auxiliary power module 200.

[0032] During mode switching, the power output from the first auxiliary power module 100 and the power output from the DC bus input 400 both serve as the input power for the second auxiliary module. However, the power output from the first auxiliary power module 100 and the power output from the DC bus input 400 gradually change in an inverse relationship. That is, the voltage of the power output from the first auxiliary power module 100 gradually decreases (increases), while the voltage of the power output from the DC bus input 400 gradually increases (decreases) to maintain the voltage stability of the input power for the second auxiliary module. Therefore, combining the first auxiliary power module 100 and the second auxiliary power module 200 simplifies the circuit design and reduces voltage fluctuations during mode switching, thereby improving the reliability of the circuit.

[0033] Understandably, referring to Figure 2 , Figure 2 This is an auxiliary power supply circuit for an energy storage system provided in another embodiment of the present invention. The first auxiliary power supply module 100 includes a first rectifier and filter branch 110, which can convert the input AC signal into a DC signal and reduce output fluctuations. The input terminal of the first rectifier and filter branch 110 is connected to the AC input terminal 300, thereby converting the AC power input from the AC grid into DC power. The first auxiliary power supply module 100 can then step down the DC power and provide the stepped-down DC power to the second auxiliary power supply module 200. The first rectifier and filter branch 110 may include a rectifier bridge and a filter unit. The rectifier bridge may be a bridge structure consisting of four diodes. Through the unidirectional conduction characteristics of the diodes, the negative half-cycle of the AC power input from the AC grid is flipped to the positive half-cycle, thereby realizing the conversion from AC to DC. The input terminal of the filter circuit is connected to the output terminal of the rectifier bridge, which can filter out the ripples of the rectified DC power, making the rectified output voltage smoother and more stable. The filter circuit may include reactive components such as capacitors and inductors.

[0034] It is understandable that, such as Figure 2 As shown, the first auxiliary power supply module 100 also includes a first switching transistor 120, a first transformer 130, and a first feedback branch 140, which together constitute a single-transistor flyback topology. Specifically, one end of the first switching transistor 120 is connected to the first rectifier-filter branch 110, and the other end is connected to the primary winding of the first transformer 130. Furthermore, the first rectifier-filter branch 110 is also connected to the primary winding of the first transformer 130. The secondary winding of the first transformer 130 is connected to the second auxiliary power supply module 200, using the stepped-down power output from the first transformer 130 as the input to the subsequent second auxiliary power supply module 200.

[0035] When the first switch 120 is turned on, current flows through the primary winding of the first transformer 130, and magnetic energy is stored in the core of the first transformer 130. Subsequently, when the first switch 120 is turned off, the energy stored in the magnetic field is released, resulting in a reverse voltage related to the turns ratio on the secondary winding of the first transformer 130. The DC current output from the first rectifier-filter branch 110 generates a changing current in the primary winding of the first transformer 130 during the periodic turning of the first switch 120 on and off, thereby inducing a corresponding output voltage in the secondary winding. Since the first auxiliary power module 100 and the second auxiliary power module 200 are combined, the function of the first auxiliary power module 100 is to convert the AC power provided by the AC power grid into DC power and to perform preliminary voltage reduction on the DC power. The second auxiliary power module 200 can accept higher DC voltage, that is to say, the first auxiliary power module 100 can output higher DC voltage. The voltage level of the output voltage of the first auxiliary power module 100 can be higher than the voltage level of the output voltage of the second auxiliary power module 200, thereby reducing the number of winding turns of the first transformer 130 and reducing the design difficulty of the first transformer 130.

[0036] It is worth noting that the control terminal of the first switching transistor 120 is connected to the first control chip, which is responsible for adjusting the on-time of the first switching transistor 120. In the single-transistor flyback topology, there is a direct correlation between the on-time of the first switching transistor 120 and the output voltage of the first transformer 130. Specifically, the longer the on-time of the first switching transistor 120, the higher the output voltage of the first transformer 130. Therefore, by adjusting the on-time, i.e., the duty cycle, of the first switching transistor 120, the output voltage of the first auxiliary power module 100 can be controlled. Furthermore, the secondary winding of the first transformer 130 is connected to the input terminal of the first feedback branch 140, and the output terminal of the first feedback branch 140 is connected to the first control chip, which in turn connects to the control terminal of the first switching transistor 120. This design allows for feedback regulation of the output voltage of the first auxiliary power module 100 through the first feedback branch 140, ensuring that the first auxiliary power module 100 can stably output the required voltage. Therefore, when the input voltage of the first feedback branch 140 increases, it indicates that the conduction time of the first switch 120 is too long. At this time, the conduction time of the first switch 120 will be shortened to stabilize the output voltage of the first auxiliary power supply module 100.

[0037] The voltage supplied through the DC bus input terminal 400 will be higher than the voltage supplied by the first auxiliary power module 100 (e.g., 100V). In this case, diode 500 will conduct, allowing the DC energy storage device to supply power to the second auxiliary power module 200 through the DC bus input terminal 400. At this time, the sampling voltage of the first feedback branch 140 will increase accordingly, causing the conduction time of the first switch 120 to gradually shorten. As the voltage supplied by the DC energy storage device to the second auxiliary power module 200 continues to increase, the conduction time of the first switch 120 will also continue to decrease until the first switch 120 is completely turned off. This process ensures that the input voltage of the second auxiliary power module 200 remains stable when switching from AC power supply mode to DC power supply mode, effectively reducing voltage fluctuations.

[0038] When the DC energy storage device's power is insufficient, the voltage supplied to the second auxiliary power module 200 gradually decreases, and the voltage sampled by the first feedback branch 140 is also affected and decreases. This causes the conduction time of the first switch 120 to gradually increase. As the voltage supplied by the DC energy storage device to the second auxiliary power module 200 through the DC bus input terminal 400 continuously decreases, the conduction time of the first switch 120 also continuously increases until the voltage supplied by the DC bus input terminal 400 is lower than the output voltage of the first auxiliary power module 100. At this point, the diode 500 will turn off, and the DC bus input terminal 400 will stop supplying power to the second auxiliary power module 200. This process ensures that the input voltage of the second auxiliary power module 200 remains stable when switching from DC power supply mode to AC power supply mode, effectively reducing voltage fluctuations.

[0039] In other words, the power supply of the second auxiliary power module 200 is determined by the voltage of the DC bus input terminal 400. When the voltage of the DC bus input terminal 400 is high, the power supply of the second auxiliary power module 200 is the power provided by the DC bus input terminal 400. If the voltage provided by the DC bus input terminal 400 is low, the power supply of the second auxiliary power module 200 is the power provided by the first auxiliary power module 100. That is, in the auxiliary power circuit provided in this embodiment of the present invention, power is preferentially drawn from the DC energy storage device connected to the DC bus input terminal 400, and the power draw priority of the DC energy storage device is higher than the power draw priority of the AC grid.

[0040] It is understandable that, such as Figure 3 As shown, Figure 3This is a schematic diagram of the auxiliary power supply circuit proposed in another embodiment of the present invention. The first auxiliary power supply module 100 also includes a second rectifier and filter branch 150. The input terminal of the second rectifier and filter branch 150 is connected to the secondary winding of the first transformer 130, and the output terminal is connected to the second auxiliary power supply module 200, the DC bus input terminal 400 and the input terminal of the first feedback branch 140. The second rectifier and filter branch 150 can convert the AC voltage output from the secondary winding of the first transformer 130 into DC voltage and then send it to the second auxiliary power supply module 200.

[0041] It is understandable that, such as Figure 3 As shown, the second auxiliary power module 200 also includes a second switching transistor 210, a second transformer 220, and a second feedback branch 230. The second switching transistor 210 can be connected to the output terminal of the first auxiliary power module 100, the DC bus input terminal 400, and the primary winding of the second transformer 220, respectively. The secondary winding of the second transformer 220 is used to supply power to the load in the next stage.

[0042] When the second switch 210 is turned on, the current supplied by the output terminal and DC bus input terminal 400 of the first auxiliary power supply module 100 can pass through the primary winding of the second transformer 220, and magnetic energy is stored in the magnetic core of the second transformer 220. When the second switch 210 is turned off, the energy stored in the magnetic field is released, generating a reverse voltage on the secondary winding of the second transformer 220. This reverse voltage is related to the turns ratio of the second transformer 220, and the secondary winding of the second transformer 220 can induce a corresponding reverse voltage according to the turns ratio. Therefore, the DC current supplied by the output terminal and DC bus input terminal 400 of the first auxiliary power supply module 100 will form a changing current in the primary winding of the second transformer 220 during the periodic turning on and off of the first switch 120, thereby inducing a corresponding output voltage in the secondary winding. Therefore, the input voltage can be stepped down using the second transformer 220, and the stepped-down power supply can then be provided to the subsequent load.

[0043] A second control chip can be connected to the control terminal of the second switch 210. The second control chip can adjust the conduction time of the second switch 210. The secondary winding of the second transformer 220 is connected to the input terminal of the second feedback branch 230, and the output terminal of the second feedback branch 230 is connected to the second control chip. By connecting the second control chip to the control terminal of the second switch 210, the output voltage of the second auxiliary power module 200 can be adjusted by feedback through the second feedback branch 230.

[0044] It is understood that the second auxiliary power supply module 200 may also include a third rectifier and filter branch 240. The secondary winding of the second transformer 220 is connected to the third rectifier and filter branch 240, so that the AC voltage output by the second transformer 220 can be rectified and converted into DC voltage through the third rectifier and filter branch 240, which facilitates the provision of the required power to the downstream load. At the same time, the input terminal of the second feedback branch 230 can be connected to the output terminal of the third rectifier and filter branch 240, using the rectified output voltage as a parameter for feedback regulation.

[0045] It is understood that the second auxiliary power module 200 also includes a multi-stage step-down circuit 250. The multi-stage step-down circuit 250 can step down the voltage output from the secondary winding of the second transformer 220 to multiple voltage levels, providing the required voltage for different loads in the subsequent stages. In other words, the first auxiliary power module 100 can share some circuit components with the second auxiliary power module 200, saving the multi-stage step-down circuit 250 in the AC power supply section of related technologies.

[0046] Secondly, embodiments of the present invention provide an energy storage system, including the auxiliary power supply circuit of the energy storage system described in the first aspect embodiment above.

[0047] The energy storage system provided according to the embodiments of this utility model has at least the following beneficial effects: The first auxiliary power module is connected to the AC power grid through the AC input terminal, and outputs the AC power provided by the AC power grid as DC power after stepping down and rectifying it to the second auxiliary power module. At the same time, the DC energy storage device provides DC power to the second auxiliary power module through the DC bus input terminal and a diode. Therefore, the AC power rectified by the first auxiliary power module and the DC power input at the DC bus input terminal can be jointly input to the second auxiliary power module to supply power to the load, which can effectively reduce voltage fluctuations during mode switching. In addition, the diode can isolate the DC bus input terminal and the output terminal of the first auxiliary power module, avoiding direct electrical connection between the two and preventing the power supply at the output terminal of the first auxiliary power module from affecting the voltage of the DC bus. Compared with the related technology of designing two auxiliary power supplies independently and connecting their outputs in parallel, the embodiments of this utility model combine the first auxiliary power module and the second auxiliary power module by isolating the input of the AC part and the input of the DC part with a diode. This design can not only share some circuit components, simplify circuit design, and reduce circuit costs, but also reduce voltage fluctuations during mode switching, thereby improving circuit reliability.

[0048] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. An auxiliary power supply circuit for an energy storage system, characterized in that, include: The DC bus input terminal is used to connect to DC energy storage devices; The diode is connected to the DC bus input terminal via its anode end; AC input terminal, used for connecting to the AC power grid; The first auxiliary power module is connected to the AC input terminal and is used to step down the input power and convert it into DC power output. The second auxiliary power module has its input terminal connected to the output terminal of the first auxiliary power module and the cathode terminal of the diode, respectively, and is used to step down the input power supply and supply power to the load.

2. The auxiliary power supply circuit according to claim 1, characterized in that, The output voltage level of the first auxiliary power module is higher than that of the second auxiliary power module.

3. The auxiliary power supply circuit according to claim 1, characterized in that, The first auxiliary power supply module includes a first rectifier and filter branch connected to the AC input terminal.

4. The auxiliary power supply circuit according to claim 3, characterized in that, The first auxiliary power supply module further includes a first switching transistor, a first transformer, and a first feedback branch. The first switching transistor is connected to the first rectifier and filter branch and the primary winding of the first transformer, respectively. The secondary winding of the first transformer is connected to the input terminals of the second auxiliary power supply module and the first feedback branch, respectively. The output terminal of the first feedback branch is connected to the control terminal of the first switching transistor.

5. The auxiliary power supply circuit according to claim 4, characterized in that, The higher the voltage at the input terminal of the first feedback branch, the shorter the conduction time of the first switch.

6. The auxiliary power supply circuit according to claim 4, characterized in that, The first auxiliary power supply module further includes a second rectifier and filter branch, and the secondary winding of the first transformer is connected to the input terminals of the second auxiliary power supply module and the first feedback branch through the second rectifier and filter branch.

7. The auxiliary power supply circuit according to claim 1, characterized in that, The second auxiliary power module further includes a second switching transistor, a second transformer, and a second feedback branch. One end of the second switching transistor is connected to the output terminal of the first auxiliary power module, the cathode of the diode, and the primary winding of the second transformer. The secondary winding of the second transformer is connected to the load and the input terminal of the second feedback branch. The output terminal of the second feedback branch is connected to the control terminal of the second switching transistor.

8. The auxiliary power supply circuit according to claim 7, characterized in that, The second auxiliary power module also includes a third rectifier and filter branch, and the secondary winding of the second transformer is connected to the load and the input terminal of the second feedback branch through the third rectifier and filter branch.

9. The auxiliary power supply circuit according to claim 7, characterized in that, The second auxiliary power module also includes a multi-stage step-down circuit for supplying power to different loads, the multi-stage step-down circuit being connected to the secondary winding of the second transformer.

10. An energy storage system, characterized in that, Includes the auxiliary power supply circuit as described in any one of claims 1 to 9.

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