Energy storage converter test system

Abstract

The invention provides an energy storage converter test system. The energy storage converter test system comprises a first energy storage converter unit, a second energy storage converter unit, a first switching unit and a first energy storage unit, the first switching unit is provided with a first output end, a second output end, a first input end and a second input end, a first switch is connected between the first output end and the first input end, a second switch is connected between the second output end and the second input end, and a third switch is connected between the first input end and the second input end; a fourth switch is connected between the first output end and the second output end; the first input end and the second input end are connected to the first energy storage unit, the first output end and the second output end are connected to the first energy storage converter unit and the second energy storage converter unit respectively, and the first energy storage converter unit and the second energy storage converter unit are jointly connected to a power supply. The system is beneficial to independent and parallel test and operation of the energy storage converter, and is high in test efficiency and automation degree.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of energy storage systems, and in particular to an energy storage converter testing system. Background Art

[0002] Energy storage inverters play a crucial role in energy storage systems. They bridge the gap between the grid and energy storage components (such as battery cells), ensuring bidirectional energy transmission. Advances in battery technology are driving increasing cell capacity in centralized energy storage systems. In recent years, battery cell capacity has grown from 280Ah to 314Ah, with a trend toward even larger capacities (e.g., 500Ah to 700Ah). This has led to increasing capacity requirements for energy storage components. Currently, the most popular capacity is 5MWh, while the next generation is expected to reach 6MWh to 8MWh. Advances in battery technology pose significant challenges for energy storage inverters, requiring them to achieve ever-increasing power. While the power of a single centralized energy storage inverter typically ranges from 1.25MW to 1.725MW, larger capacity inverters have already reached 2.5MW to 3.2MW.

[0003] At the same time, the market has demand for energy storage systems with different charge and discharge rates. For example, a 2-hour system corresponds to a 0.5C charge and discharge rate, a 4-hour system corresponds to a 0.25C charge and discharge rate, and an 8-hour system corresponds to a 0.125C charge and discharge rate. To accommodate energy storage systems with different charge and discharge rates, energy storage converters need to have the dual functions of independent and parallel operation. Energy storage converters with parallel AC side connection and separate DC side connection can well meet these requirements. When the energy storage converter needs to operate independently, the DC side of this energy storage converter is connected to its own battery compartment. When the energy storage converters need to be connected in parallel to form a higher-power energy storage converter, the DC sides of each energy storage converter are connected in parallel to the same DC compartment. However, commonly used energy storage converter test systems are all for single energy storage converters. On the one hand, they are difficult to adapt to the overall needs of single and parallel units. On the other hand, in order to adapt to different test items, the test system generally requires frequent manual wiring and line changes, which is inefficient. It is necessary to verify whether the wiring is correct before testing. Once a wiring error occurs, it will cause a power short circuit or damage to the energy storage converter. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an energy storage converter test system, which is beneficial to the independent and parallel testing and operation of the energy storage converter, has high testing efficiency and high degree of automation.

[0005] The energy storage converter test system provided by the present invention includes: a first energy storage converter unit, a second energy storage converter unit, a first switching unit and a first energy storage unit; wherein the first switching unit has a first output end, a second output end, a first input end and a second input end, a first switch is connected between the first output end and the first input end, a second switch is connected between the second output end and the second input end, a third switch is connected between the first input end and the second input end, and a fourth switch is connected between the first output end and the second output end; the first input end and the second input end are connected to the first energy storage unit, the first output end and the second output end are respectively connected to the first energy storage converter unit and the second energy storage converter unit, and the first energy storage converter unit and the second energy storage converter unit are commonly connected to a power supply.

[0006] Optionally, a control unit is further included, which is connected to the first switching unit and is used to control the closing and opening of each switch in the first switching unit.

[0007] Optionally, the control unit includes a micro-control circuit and a digital output circuit connected to the micro-control circuit, and the signal output end of the digital output circuit is respectively connected to each switch in the first switching unit.

[0008] Optionally, an auxiliary power supply is further included, and the auxiliary power supply is respectively connected to the first switching unit, the digital output circuit and the micro-control circuit.

[0009] Optionally, a communication unit is further included, wherein the communication unit is connected to the micro-control circuit.

[0010] Optionally, the communication unit includes an RS485 communication circuit and / or a CAN communication circuit.

[0011] Optionally, a host computer is further included, and the host computer is connected to the communication unit.

[0012] Optionally, the first energy storage unit includes a first battery compartment and a second battery compartment, wherein the first input end is connected to the first battery compartment, and the second input end is connected to the second battery compartment.

[0013] Optionally, a DC / DC converter is connected between the first battery compartment and the second battery compartment.

[0014] Optionally, the first energy storage unit includes a first AC / DC power supply and a second AC / DC power supply, wherein the first input end is connected to the first AC / DC power supply, and the second input end is connected to the second AC / DC power supply.

[0015] Optionally, it also includes a third energy storage converter unit, a fourth energy storage converter unit, a second switching unit and a second energy storage unit, the structure of the second switching unit is the same as that of the first switching unit, the two input ends of the second switching unit are connected to the second energy storage unit, and the two output ends of the second switching unit are respectively connected to the third energy storage converter unit and the fourth energy storage converter unit; the first energy storage converter unit, the second energy storage converter unit, the third energy storage converter unit and the fourth energy storage converter unit are commonly connected to the power supply; one output end of the first switching unit is connected to one output end of the second switching unit through a fifth switch.

[0016] Optionally, a fifth energy storage converter unit and a sixth energy storage converter unit are also included, and the first energy storage converter unit, the second energy storage converter unit, the fifth energy storage converter unit and the sixth energy storage converter unit are commonly connected to the power supply; the output ends of the fifth energy storage converter unit and the sixth energy storage converter unit are also connected to the first energy storage unit.

[0017] Compared with the prior art, the present invention has the following advantages: the first energy storage converter unit and the second energy storage converter unit are respectively connected through the switching unit, and the closing or opening of the first switch, the second switch, the third switch and the fourth switch in the switching unit can be combined to form the required energy storage path, which is beneficial to the independent and parallel testing and operation of the energy storage converter, with high testing efficiency and high degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present application. They are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the accompanying drawings:

[0019] Figure 1 1 is a schematic structural diagram of an energy storage converter test system according to an embodiment of the present invention;

[0020] Figure 2 1 is a schematic structural diagram of an energy storage converter test system according to a second embodiment of the present invention;

[0021] Figure 3 1 is a schematic structural diagram of an energy storage converter test system according to a third embodiment of the present invention;

[0022] Figure 4 1 is a schematic structural diagram of a fourth energy storage converter test system according to an embodiment of the present invention;

[0023] Figure 5 1 is a structural diagram of a fifth energy storage converter test system according to an embodiment of the present invention;

[0024] Figure 6 It is a structural diagram of the energy storage converter test system according to the sixth embodiment of the present invention. DETAILED DESCRIPTION

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0026] As used in this application and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0027] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0028] It should be understood that when a component is referred to as being “on another component,” “connected to another component,” “coupled to another component,” or “contacting another component,” it can be directly on, connected to, coupled to, or contacting the other component, or intervening components may be present. In contrast, when a component is referred to as being “directly on another component,” “directly connected to,” “directly coupled to,” or “directly contacting” another component, there are no intervening components. Similarly, when a first component is referred to as being “electrically in contact with” or “electrically coupled to” a second component, an electrical path exists between the first and second components that allows current to flow. This electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between the conductive components.

[0029] An energy storage converter test system according to one embodiment of the present invention includes a first energy storage converter unit, a second energy storage converter unit, a first switching unit, and a first energy storage unit. The first switching unit has a first output terminal, a second output terminal, a first input terminal, and a second input terminal. A first switch is connected between the first output terminal and the first input terminal, a second switch is connected between the second output terminal and the second input terminal, a third switch is connected between the first input terminal and the second input terminal, and a fourth switch is connected between the first output terminal and the second output terminal. The first input terminal and the second input terminal are connected to the first energy storage unit, the first output terminal and the second output terminal are connected to the first energy storage converter unit and the second energy storage converter unit, respectively, and the first energy storage converter unit and the second energy storage converter unit are jointly connected to a power supply.

[0030] refer to Figure 1 As shown, the switching unit includes four switches, namely K1, K2, K3, and K4, and also includes four ports, namely input terminal 1, input terminal 2, output terminal 1, and output terminal 2. Switch K1 is connected to the path between input terminal 1 and output terminal 1, switch K2 is connected to the path between input terminal 2 and output terminal 2, switch K3 is connected to the path between input terminal 1 and input terminal 2, and switch K4 is connected to the path between output terminal 1 and output terminal 2. Switches K1, K2, K3, and K4 are all switches with positive and negative terminals. Switches K1, K2, K3, and K4 are closed or opened to form corresponding energy storage paths, which are suitable for independent testing and parallel testing of energy storage converter units, and can also adapt to independent or parallel operation testing of battery compartments of different capacities. The test efficiency is high, the degree of automation is high, labor is saved, and reliability is high.

[0031] In one example, the energy storage converter testing system further includes a control unit connected to the first switching unit and configured to control the closing and opening of each switch in the first switching unit. Furthermore, the control unit includes a microcontrol circuit and a digital output circuit connected to the microcontrol circuit, wherein a signal output terminal of the digital output circuit is connected to each switch in the first switching unit.

[0032] refer to Figure 2 As shown, the control unit includes a microcontroller (MCU) and a digital output circuit (DO). The microcontroller is connected to the digital output circuit, and the signal output terminals of the digital output circuit are connected to the control coil terminals of switches K1, K2, K3, and K4, respectively. The digital output circuit generally uses a small relay control circuit. By turning the small relay on and off, the coils of the large-capacity power switches K1, K2, K3, and K4 are energized or de-energized, thereby turning the main contacts of the switches K1, K2, K3, and K4 on and off, thereby connecting or disconnecting the corresponding power circuits. For example, the microcontroller can be an integrated circuit chip such as a single-chip microcomputer, CPLD, FPGA, or DSP.

[0033] In one example, the energy storage converter test system further includes an auxiliary power supply, which is connected to the first switching unit, the digital output circuit, and the microcontroller circuit respectively. Figure 2 As shown, the auxiliary power supply is connected to the micro-control circuit and the digital output circuit. The auxiliary power supply provides auxiliary power for the micro-control circuit and the digital output circuit. The input end of the auxiliary power supply can be connected to an external battery compartment or AC / DC power supply.

[0034] In one example, the energy storage converter test system further includes a communication unit connected to the microcontroller circuit. Furthermore, the communication unit includes an RS485 communication circuit and / or a CAN communication circuit. The energy storage converter test system further includes a host computer connected to the communication unit.

[0035] RS485 is a half-duplex asynchronous serial communication protocol that uses differential signaling over two signal lines. It is suitable for long-distance, multi-node, half-duplex communication and offers low cost. CAN (Controller Area Network) is a multi-master, half-duplex serial communication bus suitable for high-reliability, multi-device communication, offering enhanced anti-interference capabilities and higher transmission rates. The system in this embodiment can select the appropriate communication circuit to implement its communication functions based on specific usage scenarios, and this will not be discussed further here.

[0036] In this embodiment, various modes of switch control logic combinations can be embedded in the control unit through software programming. The host computer only needs to issue the mode code, and the control unit automatically outputs the corresponding on-off logic signals for each switch, which has the advantages of high reliability and strong anti-interference. This embodiment system can well adapt to the testing and operation of two independent energy storage converter units and two parallel energy storage converter units, as well as the charging and discharging testing of independent or parallel battery compartments. It has a high degree of automation and avoids frequent line changes and wiring errors during testing.

[0037] Still refer to Figure 2 As shown, the communication unit may include an RS485 communication circuit and a CAN communication circuit, or one of the two. The communication unit receives control instructions from a host computer (or monitoring center). After the control instructions are transmitted to the microcontroller circuit, the microcontroller circuit issues a corresponding control signal, which is then output by the digital output circuit to control the switches K1, K2, K3, and K4 in the switching unit to close or open, thereby forming a corresponding energy storage path.

[0038] In one example, in the energy storage converter test system of this embodiment, the first energy storage unit includes a first battery compartment and a second battery compartment, wherein the first input terminal is connected to the first battery compartment, and the second input terminal is connected to the second battery compartment. Furthermore, a DC / DC converter may be connected between the first battery compartment and the second battery compartment.

[0039] refer to Figure 3 As shown, the energy storage converter test system of this embodiment includes a power grid, a power grid simulator (or a transformer), two energy storage converter units, a switching unit, a battery compartment 1, a battery compartment 2 and a DC / DC converter, wherein the power grid may be a public power grid, the input end of the power grid simulator or the transformer is connected to the power grid, the output end of the power grid simulator or the transformer is connected to the AC input ends of the two energy storage converter units, the DC output end of the energy storage converter unit is connected to the output end 1 and the output end 2 of the switching unit, the input end 1 and the input end 2 are respectively connected to the output ends of the battery compartment 1 and the battery compartment 2, and the DC / DC converter is connected between the battery compartment 1 and the battery compartment 1.

[0040] based on Figure 3 The energy storage converter test system shown in the figure has the following test condition: test condition 1: when each energy storage converter unit works independently, switches K1 and K2 in the switching unit are closed, and switches K3 and K4 are disconnected; test condition 2: when energy storage converter unit 1 and energy storage converter unit 2 need to work in parallel to charge and discharge battery compartment 1, switches K1 and K4 are closed, and switches K2 and K3 are disconnected; when energy storage converter unit 1 and energy storage converter unit 2 need to work in parallel to charge and discharge battery compartment 2, switches K2 and K4 are closed, and switches K1 and K3 are disconnected; test condition 3: when battery compartment 1 and battery compartment 2 need to be connected in parallel, switch K3 is closed. At this time, if only energy storage converter unit 1 needs to work, switch K1 is closed, and if only energy storage converter unit 2 needs to work, switch K2 is closed; when energy storage converter unit 1 and energy storage converter unit 2 need to work simultaneously, switches K1 and K2 are closed. It should be noted that when battery compartment 1 and battery compartment 2 need to be connected in parallel, the DC / DC converter is first operated so that the battery compartment with higher voltage in battery compartment 1 and battery compartment 2 charges the battery compartment with lower voltage. After the voltages of the two reach a balance, the switch K3 is closed, and then the DC / DC converter stops working.

[0041] In this embodiment, voltage, current, temperature and other sensors may be installed on the corresponding paths of the switching unit to collect information such as voltage, current, temperature and other information on the corresponding paths and transmit it to the host computer for power analysis or fault diagnosis.

[0042] In one example, in the energy storage converter test system of this embodiment, the first energy storage unit includes a first AC / DC power supply and a second AC / DC power supply, wherein the first input end is connected to the first AC / DC power supply, and the second input end is connected to the second AC / DC power supply.

[0043] refer to Figure 4 As shown, the test system of the energy storage converter in this embodiment will Figure 3 In the embodiment shown, the battery compartment 1 and the battery compartment 2 are replaced by AC / DC power supply 1 and AC / DC power supply 2, respectively. An AC / DC power supply with adjustable output power, voltage and current is used to facilitate simulation of various working conditions and test conditions of the battery compartment. At the same time, energy can be circulated between the energy storage inverter test system and the power grid, saving electricity costs.

[0044] In one example, the energy storage converter test system also includes a third energy storage converter unit, a fourth energy storage converter unit, a second switching unit and a second energy storage unit. The structure of the second switching unit is the same as that of the first switching unit. The two input ends of the second switching unit are connected to the second energy storage unit, and the two output ends of the second switching unit are respectively connected to the third energy storage converter unit and the fourth energy storage converter unit; the first energy storage converter unit, the second energy storage converter unit, the third energy storage converter unit and the fourth energy storage converter unit are commonly connected to a power supply; an output end in the first switching unit is connected to an output end in the second switching unit through a fifth switch.

[0045] In this embodiment, the structure of the second switching unit is the same as that of the first switching unit, that is, it can be known that the second switching unit also has a first output end, a second output end, a first input end and a second input end, a first switch is connected between the first output end and the first input end, a second switch is connected between the second output end and the second input end, a third switch is connected between the first input end and the second input end, and a fourth switch is connected between the first output end and the second output end.

[0046] refer to Figure 5 As shown, the energy storage converter test system of this embodiment is Figure 4 The illustrated embodiment further includes an energy storage converter 3, an energy storage converter 4, a switching unit 2, an AC / DC power supply 3, an AC / DC power supply 4, and a switch K5. Switch K5 is connected between output terminal 1 or output terminal 2 of switching unit 1 and output terminal 1 or output terminal 2 of switching unit 2. This creates a system architecture in which four energy storage converter units are connected in parallel on the AC side and flexible output on the DC side. The DC side can be connected in parallel with four independent units, two units, or four units.

[0047] based on Figure 5In the energy storage converter test system shown, the control mode of the four independent switching units (including switching unit 1 and switching unit 2) is as follows: switch K5 is opened, switches K1 and K2 in switching unit 1 are closed, switches K3 and K4 are opened, switches K1 and K2 in switching unit 2 are closed, and switches K3 and K4 are opened. When two converters need to be connected in parallel, the control mode is as follows: switch K5 is opened, one of switches K3 or K4 in switching unit 1 is closed, and energy storage converter 1 and converter unit 2 operate simultaneously, switches K1 and K2 in switching unit 1 are closed, and one of switches K3 or K4 in switching unit 2 is closed. When energy storage converter unit 3 and converter unit 4 operate simultaneously, switches K1 and K2 in switching unit 2 are closed. When the DC sides of four converters need to be connected in parallel simultaneously, the control mode is as follows: switch K5 is closed, switches K1, K2, and K4 in switching unit 1 are closed, switch K3 is opened, switches K1, K2, and K4 in switching unit 2 are closed, and switch K3 is opened.

[0048] In one example, the energy storage converter test system may further include a fifth energy storage converter unit and a sixth energy storage converter unit, the first energy storage converter unit, the second energy storage converter unit, the fifth energy storage converter unit and the sixth energy storage converter unit are commonly connected to a power supply, and the output ends of the fifth energy storage converter unit and the sixth energy storage converter unit are also connected to the first energy storage unit.

[0049] refer to Figure 6 As shown, the energy storage converter test system of this embodiment includes an isolation transformer, energy storage converter unit 1, energy storage converter unit 2, a switching unit, AC / DC power supply 1, and AC / DC power supply 2. Based on this energy storage converter test system, test condition 1: a pairing test of energy storage converter unit 1 / energy storage converter unit 2 and energy storage converter unit 3 / energy storage converter unit 4. For example, energy storage converter unit 1 and energy storage converter unit 3 are paired with each other, with switch K1 in the switching unit closed and the other switches open. For example, the energy storage converter unit 2 and the energy storage converter unit 4 are tested in pairs. At this time, the switch K2 in the switching unit is turned on and the other switches are disconnected. Test condition two: the four energy storage converter units are tested in pairs. At this time, the energy storage converter unit 1 and the energy storage converter unit 2 are connected in parallel on the DC side, and the energy storage converter unit 3 and the energy storage converter unit 4 are connected in parallel on the DC side. The control method is: close the switches K1 and K2 in the switching unit, and close one of the switches K3 or K4 or both of them.

[0050] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosures are merely illustrative and do not constitute limitations on this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0051] It should be noted that, in order to simplify the presentation of this disclosure and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single embodiment disclosed above.

[0052] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. An energy storage converter test system, characterized in that: include: A first energy storage converter unit, a second energy storage converter unit, a first switching unit, and a first energy storage unit; wherein, The first switching unit has a first output terminal, a second output terminal, a first input terminal, and a second input terminal, a first switch is connected between the first output terminal and the first input terminal, a second switch is connected between the second output terminal and the second input terminal, a third switch is connected between the first input terminal and the second input terminal, and a fourth switch is connected between the first output terminal and the second output terminal; The first input end and the second input end are connected to the first energy storage unit, the first output end and the second output end are connected to the first energy storage converter unit and the second energy storage converter unit respectively, and the first energy storage converter unit and the second energy storage converter unit are commonly connected to a power supply.

2. The energy storage converter test system according to claim 1, wherein: It also includes a control unit, which is connected to the first switching unit and is used to control the closing and opening of each switch in the first switching unit.

3. The energy storage converter test system according to claim 2, wherein: The control unit includes a micro-control circuit and a digital output circuit connected to the micro-control circuit, and the signal output end of the digital output circuit is respectively connected to each switch in the first switching unit.

4. The energy storage converter test system according to claim 3, wherein: An auxiliary power supply is also included, and the auxiliary power supply is connected to the first switching unit, the digital output circuit and the micro-control circuit respectively.

5. The energy storage converter test system according to claim 3, wherein: Also included is a communication unit connected to the microcontroller circuit.

6. The energy storage converter test system according to claim 5, characterized in that: The communication unit includes an RS485 communication circuit and / or a CAN communication circuit.

7. The energy storage converter test system according to claim 5, characterized in that: It also includes a host computer connected to the communication unit.

8. The energy storage converter test system according to claim 1, wherein: The first energy storage unit includes a first battery compartment and a second battery compartment, wherein the first input end is connected to the first battery compartment, and the second input end is connected to the second battery compartment.

9. The energy storage converter test system according to claim 8, wherein: A DC / DC converter is connected between the first battery compartment and the second battery compartment.

10. The energy storage converter test system according to claim 1, wherein: The first energy storage unit includes a first AC / DC power supply and a second AC / DC power supply, wherein the first input end is connected to the first AC / DC power supply, and the second input end is connected to the second AC / DC power supply.

11. The energy storage converter test system according to claim 1, wherein: It also includes a third energy storage converter unit, a fourth energy storage converter unit, a second switching unit and a second energy storage unit. The structure of the second switching unit is the same as that of the first switching unit, the two input ends of the second switching unit are connected to the second energy storage unit, and the two output ends of the second switching unit are respectively connected to the third energy storage converter unit and the fourth energy storage converter unit; The first energy storage converter unit, the second energy storage converter unit, the third energy storage converter unit and the fourth energy storage converter unit are commonly connected to the power supply; An output terminal of the first switching unit and an output terminal of the second switching unit are connected through a fifth switch.

12. The energy storage converter test system according to claim 1, wherein: It also includes a fifth energy storage converter unit and a sixth energy storage converter unit. The first energy storage converter unit, the second energy storage converter unit, the fifth energy storage converter unit and the sixth energy storage converter unit are commonly connected to the power supply; the output ends of the fifth energy storage converter unit and the sixth energy storage converter unit are connected to the first energy storage unit.

Images