Energy storage system

Abstract

The utility model discloses an energy storage system, and belongs to the technical field of power electronics. The energy storage system comprises a power conversion device and a battery system, the power conversion device comprises a control circuit, a direct current bus and a bus capacitor unit, and the battery system is electrically connected with the direct current bus; the power supply circuit is electrically connected with the power supply end of the control circuit and the bus capacitor unit and is configured to form a main power supply loop and a bus capacitor power supply loop, and when the output voltage of the main power supply loop is larger than or equal to a voltage threshold value, the main power supply circuit is used for supplying power to the control circuit, or the bus capacitor power supply loop is used for supplying power to the bus capacitor unit. And when the output voltage of the main power supply loop is smaller than the voltage threshold value, the bus capacitor unit is used for supplying power to the control circuit. According to the energy storage system, when the power conversion equipment breaks down or stops working, the power supply circuit supplies power to the control circuit through the bus capacitor unit, the control circuit consumes electric energy to discharge the bus capacitor unit, the hardware cost is reduced, and the damage risk of the power supply circuit is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to an energy storage system. BACKGROUND

[0002] A plurality of bus capacitors are usually arranged in the energy storage converter. When working normally, a large amount of electric energy exists in the bus capacitors. When the equipment needs to be repaired due to a fault, the electric energy on the bus capacitors needs to be rapidly discharged to below a safe voltage, and then the equipment is maintained. If the bus capacitors cannot be normally discharged, the bus capacitors or other circuit parts connected with the bus capacitors may bear a large voltage stress, and long-term existence in this state may cause damage to the energy storage converter. CONTENT OF THE UTILITY MODEL

[0003] The application aims to at least solve one of the technical problems existing in the prior art. To this end, the application provides an energy storage system, which consumes electric energy by using a control circuit to discharge a bus capacitor unit, does not need an additional discharge circuit, reduces hardware cost, and reduces the risk of damage to a power supply circuit.

[0004] The application provides an energy storage system, which comprises a power conversion device and a battery system, and the power conversion device comprises:

[0005] a control circuit, a direct-current bus, and a bus capacitor unit connected between a positive electrode and a negative electrode of the direct-current bus, and the battery system is electrically connected with the direct-current bus;

[0006] a power supply circuit, which is electrically connected with a power supply end of the control circuit and the bus capacitor unit respectively, and is configured to form a main power supply circuit and a bus capacitor power supply circuit, and in a case where an output voltage of the main power supply circuit is greater than or equal to a voltage threshold, the control circuit is supplied with power by using the main power supply circuit, or in a case where the output voltage of the main power supply circuit is less than the voltage threshold, the control circuit is supplied with power by using the bus capacitor unit.

[0007] According to the energy storage system of the application, when the power conversion device works normally, the main power supply circuit provides electric energy for the control circuit, when the power conversion device fails or stops working, the power supply circuit supplies the control circuit with power by using the bus capacitor unit, the electric energy is consumed by the control circuit to discharge the bus capacitor unit, an additional discharge circuit is not needed, hardware cost is reduced, and the risk of damage to the power supply circuit is reduced.

[0008] According to one embodiment of the application, the power supply circuit comprises:

[0009] a switching circuit, a first input end of the switching circuit being electrically connected with the direct-current bus, and a second input end of the switching circuit being electrically connected with the bus capacitor unit;

[0010] The first auxiliary power supply circuit has an input end electrically connected with the output end of the switching circuit, and has an output end electrically connected with the power supply end of the control circuit, and is configured to reduce the output voltage of the switching circuit to the working voltage of the control circuit.

[0011] According to one embodiment of the present application, the switching circuit comprises:

[0012] The loss-of-mains relay has a normally open contact electrically connected with the DC bus, and has a normally closed contact electrically connected with the bus capacitor unit.

[0013] According to one embodiment of the present application, the first normally open contact of the loss-of-mains relay is electrically connected with the positive pole of the DC bus, and the first normally closed contact of the loss-of-mains relay is electrically connected with the positive pole of the bus capacitor unit; and / or

[0014] The second normally open contact of the loss-of-mains relay is electrically connected with the negative pole of the DC bus, and the second normally closed contact of the loss-of-mains relay is electrically connected with the negative pole of the bus capacitor unit.

[0015] According to one embodiment of the present application, the first normally open contact is electrically connected with the positive pole of the DC bus, and the first normally closed contact is electrically connected with the positive pole of the bus capacitor unit, and the switching circuit further comprises:

[0016] The first unidirectional conduction device has an input end electrically connected with the negative pole of the bus capacitor unit, and has an output end electrically connected with the negative pole of the DC bus.

[0017] According to one embodiment of the present application, the first unidirectional conduction device is a first diode, the anode of the first diode is electrically connected with the negative pole of the bus capacitor unit, and the cathode of the first diode is electrically connected with the negative pole of the DC bus.

[0018] According to one embodiment of the present application, the power supply circuit comprises:

[0019] The second auxiliary power supply circuit has an input end electrically connected with the bus capacitor unit;

[0020] The switching circuit has a first input end electrically connected with the external power supply node, has a second input end electrically connected with the output end of the second auxiliary power supply circuit, and has an output end electrically connected with the power supply end of the control circuit.

[0021] According to one embodiment of the present application, the switching circuit comprises:

[0022] The second unidirectional conduction device has an input end electrically connected with the bus capacitor unit, and has an output end electrically connected with the external power supply node and the power supply end of the control circuit, respectively.

[0023] According to one embodiment of the present application, the at least one second unidirectional conducting device comprises:

[0024] a second diode, an anode of the second diode being electrically connected to the positive pole of the bus capacitor unit, a cathode of the second diode being electrically connected to the positive pole of the external power supply node and the power supply end of the control circuit respectively; and / or

[0025] a third diode, an anode of the third diode being electrically connected to the negative pole of the bus capacitor unit, a cathode of the third diode being electrically connected to the negative pole of the external power supply node and the power supply end of the control circuit respectively.

[0026] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0028] Figure 1 is a structural block diagram of the energy storage system provided by the embodiments of the present application;

[0029] Figure 2 is one of the circuit diagrams of the energy storage system provided by the embodiments of the present application;

[0030] Figure 3 is the second of the circuit diagrams of the energy storage system provided by the embodiments of the present application;

[0031] Figure 4 is the third of the circuit diagrams of the energy storage system provided by the embodiments of the present application.

[0032] REFERENCE NUMERALS:

[0033] control circuit 10, battery system 20, power supply circuit 30, first switching circuit 31, first unidirectional conducting device 311, second switching circuit 32, second unidirectional conducting device 321, first auxiliary power supply circuit 33, second auxiliary power supply circuit 34, bus capacitor unit 40, first to third diodes D1-D3, power failure relay K, external power supply node Vcc. DETAILED DESCRIPTION

[0034] The embodiments of the present application are described in detail below with reference to the accompanying drawings. Examples of the embodiments described below are illustrative, and are provided for explanation only, and are not to be understood as a limitation of the present application.

[0035] In the following description, "circuit" refers to a circuit composed of at least one element or sub-circuit connected electrically or electromagnetically. When it is said that an element or circuit is "coupled to" or "connected to" another element or that the element / circuit is "coupled between" or "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between elements can be physical, logical, or a combination thereof. On the contrary, when it is said that an element is "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0036] In the description, the terms "first", "second", and the like are used to distinguish similar objects, and are not used to describe a particular order or sequence. It should be understood that the numerical descriptors used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of a kind and are not limited in number, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the objects before and after are in an "or" relationship.

[0037] In addition, the description of the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0038] Power conversion devices are widely used in various fields, including power systems, industrial automation, consumer electronics, renewable energy, communications, etc. Power conversion devices are used to change the form, nature or transmission mode of electrical energy. With the continuous development of technology, the types and functions of power conversion devices are also expanding, and power conversion devices can include inverters, DC-DC converters, or energy storage converters, etc.

[0039] The power conversion device includes a positive bus, a negative bus, a bus capacitor unit, and a control circuit. The bus capacitor unit is electrically connected between the positive bus and the negative bus. When the power conversion device is working, the bus capacitor unit can effectively filter out voltage fluctuations (such as high-frequency noise, fluctuations in switching frequency) caused by power conversion processes through its capacitance characteristics, so that the bus voltage remains constant, and the converter can be avoided. Misoperation or damage due to unstable voltage.

[0040] In normal operation, there is a large amount of electrical energy in the bus capacitor unit. When the power conversion device fails and needs to be repaired or the power conversion device is shut down, the electrical energy on the bus capacitor needs to be quickly discharged to a safe voltage, and then the device is maintained.

[0041] In the related art, a group of resistors are usually connected in series with the capacitor through a switch, and the bus capacitor voltage is quickly reduced by discharging through the resistors after the device is shut down. However, this scheme needs an additional special discharge circuit for discharging, which is high in cost and has a risk of overheating damage of the resistors in long-term use.

[0042] Reference Figure 1 , Figure 1 The structure of the power supply circuit provided by the embodiment of the application is shown. One embodiment of the application provides an energy storage system, which includes a power conversion device and a battery system 20. The power conversion device includes a control circuit 10, a direct current bus, and a bus capacitor unit 40 connected between the positive and negative poles of the direct current bus. The battery system 20 is electrically connected to the direct current bus. A power supply circuit 30 is electrically connected to the power supply end of the control circuit 10 and the bus capacitor unit 40 respectively, and is configured to form a main power supply circuit and a bus capacitor power supply circuit. When the output voltage of the main power supply circuit is greater than or equal to a voltage threshold, the control circuit 10 is powered by the main power supply circuit, or when the output voltage of the main power supply circuit is less than the voltage threshold, the control circuit 10 is powered by the bus capacitor unit 40.

[0043] In order to better illustrate the working principle of the power supply circuit, the power conversion device is taken as an example of an energy storage converter in the following description.

[0044] The battery system 20 is electrically connected to the direct current bus in the power conversion device, and is mainly used for storing excess electrical energy and releasing it during peak demand to balance the load of the power system.

[0045] The control circuit 10 usually refers to a module in the energy storage converter that applies a driving signal to a controlled electrical element according to demand. The controlled electrical element usually includes sensors, relays, and power switching devices, etc. The power switching device can be an IGBT (Insulate-Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), etc.

[0046] It should be noted that the specific structure of the control circuit 10 can be determined according to the actual application scenario, which is not limited here. In general, the control circuit 10 includes modules for implementing energy regulation, battery management, fault diagnosis, temperature control and other functions in the energy storage converter. For example, the control circuit 10 can also include a signal acquisition circuit, such as a voltage acquisition circuit and a current acquisition circuit.

[0047] The control circuit 10 needs a stable power supply to drive its internal logic, current and voltage sensing, protection circuit, communication module and other functions. The power supply end is mainly used to transmit electrical energy to the control circuit 10, so that each component inside it can work as expected.

[0048] The power supply circuit 30 is mainly used to provide a transmission path for electrical energy according to the needs of the energy storage converter. The power supply circuit 30 is formed with a main power supply loop and a bus capacitor power supply loop. The main power supply loop refers to the loop that provides electrical energy to the control circuit 10 when the energy storage converter is in a normal operating state. The source of electrical energy of the main power supply loop can be determined according to the actual application scenario, which is not limited here. For example, the electrical energy of the main power supply loop can come from the battery system 20 in the energy storage system, or from a direct current source or other power supply module outside the energy storage converter. The bus capacitor power supply loop refers to the electrical energy transmission path between the bus capacitor unit 40 and the power supply end of the control circuit 10.

[0049] When the output voltage of the main power supply loop is greater than or equal to the voltage threshold, it indicates that the energy storage converter is in a normal operating state, and at this time the power supply circuit 30 supplies power to the control circuit using the main power supply loop.

[0050] When the output voltage of the main power supply loop is less than the voltage threshold, it indicates that the main power supply loop cannot normally supply power to the control circuit, at which time the energy storage converter may be malfunctioning or in a shutdown state, at which time the power supply circuit 30 uses the bus capacitor unit to supply power to the control circuit 10, transfers the energy stored in the bus capacitor unit 40 to the power supply end of the control circuit 10, and provides the required electrical energy to the control circuit 10. The control circuit 10 consumes electrical energy to discharge the bus capacitor unit 40, without the need for an external load to discharge.

[0051] The specific value of the voltage threshold can be determined according to the actual application scenario, which is not limited here. For example, the threshold voltage can be 5V or 10V, etc.

[0052] The specific structure of the power supply circuit 30 can be selected according to the actual application scenario, which is not limited here. For example, the power supply circuit 30 can include a single-pole double-throw switch, the common terminal of the single-pole double-throw switch is electrically connected to the power supply terminal of the control circuit 10, the normally open terminal of the single-pole double-throw switch is arranged on the main power supply loop, and the normally open terminal of the single-pole double-throw switch is arranged on the bus capacitor power supply loop. When the energy storage converter is normally running, the common terminal of the single-pole double-throw switch is connected to the normally open terminal, and the main power supply loop supplies power to the control circuit 10; when the energy storage converter is stopped, the common terminal of the single-pole double-throw switch is connected to the normally closed terminal, and the bus capacitor power supply loop supplies power to the control circuit 10, thereby achieving discharging of the bus capacitor unit 40.

[0053] According to the power supply circuit of the present application, when the energy storage converter is normally running, the main power supply loop provides power to the control circuit 10; when the energy storage converter fails or stops running, the power supply circuit 30 uses the bus capacitor unit to supply power to the control circuit, and the control circuit 10 consumes power to discharge the bus capacitor unit 40, without the need for an additional discharging loop, thereby reducing hardware costs and reducing the risk of power supply circuit damage.

[0054] Referring to Figure 2 , Figure 2 A storage system provided by an embodiment of the present application is shown. In some embodiments, the power supply circuit 30 includes a first switching circuit 31 and a first auxiliary power supply circuit 33. The first input terminal of the first switching circuit 31 is electrically connected to the DC bus, and the second input terminal of the first switching circuit 31 is electrically connected to the bus capacitor unit 40; the input terminal of the first auxiliary power supply circuit 33 is electrically connected to the output terminal of the first switching circuit 31, and the output terminal of the first auxiliary power supply circuit 33 is electrically connected to the power supply terminal of the control circuit 10, and the first auxiliary power supply circuit 33 is configured to reduce the output voltage of the first switching circuit 31 to the working voltage of the control circuit 10.

[0055] The battery system 20 is electrically connected to the DC bus, and the first input terminal of the first switching circuit 31 is electrically connected to the DC bus, that is, the power source of the main power supply loop is derived from the battery system 20. When the voltage of the DC bus is greater than or equal to the voltage threshold, the first switching circuit 31 can conduct the first input terminal and the output terminal of the first switching circuit 31, at this time the voltage output by the battery system 20 is transmitted to the power supply terminal of the control circuit 10 after being processed by the first auxiliary power supply circuit 33, thereby providing power to the control circuit 10. When the voltage of the DC bus is less than the voltage threshold, the first switching circuit 31 can conduct the second input terminal and the output terminal of the first switching circuit 31, at this time the voltage across the bus capacitor unit 40 is transmitted to the power supply terminal of the control circuit 10 after being processed by the first auxiliary power supply circuit 33, thereby providing power to the control circuit 10.

[0056] The first auxiliary power supply circuit 33 is mainly used for voltage step-down processing of the DC bus voltage and the voltage of the bus capacitor unit 40, so that the processed voltage is within the normal working voltage range of the control circuit 10.

[0057] The specific structure of the first auxiliary power supply circuit 33 can be selected according to the actual application scenario, which is not limited here. For example, the first auxiliary power supply circuit 33 can be a buck circuit and the like.

[0058] In some embodiments, the first switching circuit 31 includes a dropout relay K. The normally open contact of the dropout relay K is electrically connected to the DC bus, and the normally closed contact of the dropout relay K is electrically connected to the bus capacitor unit 40.

[0059] It should be noted that when the output voltage of the battery system 20 is greater than or equal to the voltage threshold, the dropout relay K is powered, the normally open contact of the dropout relay K is closed, and the normally closed contact is opened; when the output voltage of the battery system 20 is less than the voltage threshold, the dropout relay K is de-energized, the normally open contact of the dropout relay K is opened, and the normally closed contact is closed.

[0060] The normally open contact of the dropout relay K is arranged between the DC bus and the input end of the first auxiliary power supply circuit 33, and the normally closed contact is arranged between the bus capacitor unit 40 and the input end of the first auxiliary power supply circuit 33. When the energy storage converter is normally working, the output voltage of the battery system 20 is greater than or equal to the voltage threshold, the normally open contact of the dropout relay K is closed, the normally closed contact is opened, the electric energy is transmitted from the DC bus to the input end of the first auxiliary power supply circuit 33, and then transmitted to the power supply end of the control circuit 10 after being processed by the first auxiliary power supply circuit 33, thereby maintaining the normal working of the control circuit 10. When the energy storage converter fails or stops working, the output voltage of the battery system 20 is less than the voltage threshold, the normally open contact of the dropout relay K is opened, and the normally closed contact is attracted, thereby cutting off the electric energy transmission path between the battery system 20 and the first auxiliary power supply circuit 33. The electric energy is transmitted from the bus capacitor unit 40 to the input end of the first auxiliary power supply circuit 33, and then transmitted to the power supply end of the control circuit 10 after being processed by the first auxiliary power supply circuit 33, so that the control circuit 10 continues to run in a short time, reduces the risk of data loss or operation interruption of the system due to instantaneous power failure, and the control circuit 10 consumes the electric energy stored in the bus capacitor unit 40, thereby reducing the bus capacitor voltage.

[0061] The lines between the main power supply circuit and the input terminal of the first auxiliary power supply circuit 33, and the lines between the bus capacitor unit 40 and the input terminal of the first auxiliary power supply circuit 33, share a set of power shortage relays K. By configuring the normally open and normally closed contacts of the power shortage relays K, the object that the energy storage system supplies to the control circuit 10 under different operating states can be automatically switched between the battery system 20 and the bus capacitor unit 40. No external control signal is required, which simplifies the circuit design, reduces the system complexity, and can ensure the continuous operation of the control circuit 10. It can also consume the power of the bus capacitor unit 40 when the energy storage system fails or stops, reduce the voltage of the bus capacitor unit 40, and protect the bus capacitor unit 40.

[0062] In some embodiments, the first normally open contact of the power failure relay K is electrically connected to the positive terminal of the DC bus, and the first normally closed contact of the power failure relay K is electrically connected to the positive terminal of the bus capacitor unit 40; and / or the second normally open contact of the power failure relay K is electrically connected to the negative terminal of the DC bus, and the second normally closed contact of the power failure relay K is electrically connected to the negative terminal of the bus capacitor unit 40.

[0063] It is understandable that a power failure relay K can be installed on either the positive or negative line, or on both lines. Installing power failure relays K on both lines allows the power supply path to be cut off even if the contacts of one relay K become stuck together, thus improving the safety of the energy storage converter.

[0064] Reference Figure 3 , Figure 3 An energy storage system provided in an embodiment of this application is illustrated. In some embodiments, the first normally open contact of the power failure relay K is electrically connected to the positive terminal of the DC bus, and the first normally closed contact of the power failure relay K is electrically connected to the positive terminal of the bus capacitor unit. The first switching circuit 31 further includes a first unidirectional conducting device 311, the input terminal of the first unidirectional conducting device 311 is electrically connected to the negative terminal of the bus capacitor unit 40, and the output terminal of the first unidirectional conducting device 311 is electrically connected to the negative terminal of the DC bus.

[0065] The first unidirectional conducting device 311 conducts when the input voltage is greater than the output voltage. When the voltage output by the battery system 20 is greater than the voltage threshold, the negative voltage of the DC bus is greater than the negative voltage of the bus capacitor unit 40, meaning the output voltage of the first unidirectional conducting device 311 is greater than the input voltage, and the first unidirectional conducting device 311 is reverse-biased and cut off. The first unidirectional conducting device 311 can disconnect the power transmission path between the bus capacitor unit 40 and the control circuit 10 when the main power supply circuit supplies power to the control circuit 10 and the normally closed contacts are stuck, thus protecting the energy storage converter.

[0066] In some embodiments, the first unidirectional conducting device 311 is a first diode D1, the anode of the first diode D1 is electrically connected to the negative terminal of the bus capacitor unit 40, and the cathode of the first diode D1 is electrically connected to the negative terminal of the DC bus.

[0067] The first diode D1 conducts when the anode voltage is greater than the cathode voltage. When the voltage output by the battery system 20 is greater than the threshold, the main power supply circuit supplies power to the control circuit 10. Since the cathode voltage of the first diode D1 is greater than the anode voltage, the first diode D1 is reverse-biased and cut off. This allows the power transmission path between the bus capacitor unit 40 and the control circuit 10 to be disconnected when the main power supply circuit supplies power to the control circuit 10 and the normally closed contacts are stuck, thus protecting the energy storage converter.

[0068] Reference Figure 4 , Figure 4 An energy storage system provided in an embodiment of this application is illustrated. In some embodiments, the power supply circuit 30 includes a second auxiliary power supply circuit 34 and a second switching circuit 32. The input terminal of the second auxiliary power supply circuit 34 is electrically connected to the bus capacitor unit; the first input terminal of the second switching circuit 32 is electrically connected to the external power supply node Vcc, the second input terminal of the second switching circuit 32 is connected to the output terminal of the second auxiliary power supply circuit 34, and the output terminal of the second switching circuit 32 is electrically connected to the power supply terminal of the control circuit 10.

[0069] The second auxiliary power supply circuit 34 is mainly used to step down the DC bus voltage so that the processed voltage is within the normal operating voltage range of the control circuit 10. The structure of the second auxiliary power supply circuit 34 can be referred to the first auxiliary power supply circuit 33 mentioned above, and will not be repeated here.

[0070] The first input terminal of the second switching circuit 32 is electrically connected to the external power supply node Vcc, indicating that when the energy storage converter is working normally, the external power supply node Vcc provides power to the main power supply circuit. The input terminal of the external power supply node Vcc can be a DC source outside the energy storage converter or a solar cell, etc.

[0071] When the voltage of the external power supply node Vcc is greater than or equal to the voltage threshold, the second switching circuit 32 can turn on the first input terminal and the output terminal of the second switching circuit 32. At this time, the voltage provided by the external power supply node Vcc is transmitted to the power supply terminal of the control circuit 10, providing power to the control circuit 10. When the voltage of the external power supply node Vcc is less than the voltage threshold, the second switching circuit 32 can turn on the second input terminal and the output terminal of the second switching circuit 32. At this time, the voltage across the bus capacitor unit is stepped down by the second auxiliary power supply circuit 34 and then transmitted to the power supply terminal of the control circuit 10, providing power to the control circuit 10.

[0072] In some embodiments, the second switching circuit 32 comprises at least one second unidirectional conducting device 321, an input end of the second unidirectional conducting device 321 being electrically connected with the bus capacitor unit, and an output end of the second unidirectional conducting device 321 being electrically connected with the external power supply node Vcc and the power supply end of the control circuit 10 respectively.

[0073] The second unidirectional conducting device 321 is turned on when the voltage at the input end is greater than the voltage at the output end, and is reverse blocked when the voltage at the input end is less than the voltage at the output end. When the external power supply node Vcc is greater than or equal to the voltage threshold, the voltage of the external power supply node Vcc is greater than the voltage output by the bus capacitor unit 40 after being stepped down by the second auxiliary power supply circuit 34, and at this time the second unidirectional conducting device 321 is reverse blocked, and the electric energy is transmitted from the external power supply node Vcc to the power supply end of the control circuit 10. When the external power supply node Vcc is less than the voltage threshold, the voltage of the external power supply node Vcc is less than the voltage output by the bus capacitor unit 40 after being stepped down by the second auxiliary power supply circuit 34, and at this time the second unidirectional conducting device 321 is turned on, and the voltage of the bus capacitor unit 40 after being stepped down by the second auxiliary power supply circuit 34 is transmitted to the power supply end of the control circuit 10.

[0074] The unidirectional conductivity of the second unidirectional conducting device 321 can realize automatic switching between the external power supply node Vcc and the bus capacitor power supply unit 40 for the object of supplying power to the control circuit 10 in different working states of the energy storage system, without the need for an external control signal, simplifying the circuit design, and achieving both the continuous operation of the control circuit 10 and the consumption of the electric energy of the bus capacitor unit 40 when the energy storage system fails or stops, thereby reducing the voltage of the bus capacitor unit 40 and protecting the bus capacitor unit 40.

[0075] In some embodiments, the at least one second unidirectional conducting device 321 comprises a second diode D2 and a third diode D3. An input end of the second diode D2 is electrically connected with the positive electrode of the bus capacitor unit 40, and an output end of the second diode D2 is electrically connected with the positive electrode of the external power supply node Vcc and the positive electrode input end of the control circuit 10 respectively; and / or an input end of the third diode D3 is electrically connected with the negative electrode of the bus capacitor unit 40, and an output end of the third diode D3 is electrically connected with the negative electrode of the external power supply node Vcc and the negative electrode input end of the control circuit 10 respectively.

[0076] The second diode D2 and the third diode D3 are turned on when the voltage at the input end is greater than the voltage at the output end, and are reverse blocked when the voltage at the input end is less than the voltage at the output end.

[0077] When the energy storage converter is in normal operation, the positive voltage of the external power supply node Vcc is greater than or equal to the positive voltage of the bus capacitor unit 40, that is, the second diode D2 is reverse blocked; when the energy storage converter is in fault or shutdown, the positive voltage of the external power supply node Vcc is less than the positive voltage of the bus capacitor unit 40, at this time the second diode D2 is turned on, and the control circuit 10 is powered by the bus capacitor unit 40, thereby realizing discharging of the bus capacitor unit 40.

[0078] The function of the third diode D3 in the circuit can refer to the second diode D2, which will not be described here.

[0079] When the second diode D2 sets the positive power transmission path and the third diode D3 sets the negative power transmission path, the switching of the power transmission path can still be realized when one of the diodes fails, thereby improving the safety of the system.

[0080] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. An energy storage system, characterized in that, Includes a power conversion device and a battery system, wherein the power conversion device includes: The system includes a control circuit, a DC bus, and a bus capacitor unit connected between the positive and negative terminals of the DC bus, wherein the battery system is electrically connected to the DC bus. The power supply circuit is electrically connected to the power supply terminal of the control circuit and the bus capacitor unit, respectively, and is configured to form a main power supply circuit and a bus capacitor power supply circuit. When the output voltage of the main power supply circuit is greater than or equal to a voltage threshold, the main power supply circuit is used to supply power to the control circuit; or when the output voltage of the main power supply circuit is less than a voltage threshold, the bus capacitor unit is used to supply power to the control circuit.

2. The energy storage system according to claim 1, characterized in that, The power supply circuit includes: A first switching circuit, wherein the first input terminal of the first switching circuit is electrically connected to the DC bus, and the second input terminal of the first switching circuit is electrically connected to the bus capacitor unit; A first auxiliary power supply circuit is configured to reduce the output voltage of the first switching circuit to the operating voltage of the control circuit. The input terminal of the first auxiliary power supply circuit is electrically connected to the output terminal of the first switching circuit, and the output terminal of the first auxiliary power supply circuit is electrically connected to the power supply terminal of the control circuit.

3. The energy storage system according to claim 2, characterized in that, The first switching circuit includes: A power-loss relay, wherein the normally open contact of the power-loss relay is electrically connected to the DC bus, and the normally closed contact of the power-loss relay is electrically connected to the bus capacitor unit.

4. The energy storage system according to claim 3, characterized in that, The first normally open contact of the power failure relay is electrically connected to the positive terminal of the DC bus, and the first normally closed contact of the power failure relay is electrically connected to the positive terminal of the bus capacitor unit; and / or The second normally open contact of the power failure relay is electrically connected to the negative terminal of the DC bus, and the second normally closed contact of the power failure relay is electrically connected to the negative terminal of the bus capacitor unit.

5. The energy storage system according to claim 4, characterized in that, The first normally open contact is electrically connected to the positive terminal of the DC bus, and the first normally closed contact is electrically connected to the positive terminal of the bus capacitor unit. The first switching circuit further includes: A first unidirectional conducting device, wherein the input terminal of the first unidirectional conducting device is electrically connected to the negative terminal of the bus capacitor unit, and the output terminal of the first unidirectional conducting device is electrically connected to the negative terminal of the DC bus.

6. The energy storage system according to claim 5, characterized in that, The first unidirectional conducting device is a first diode, the anode of the first diode is electrically connected to the negative terminal of the bus capacitor unit, and the cathode of the first diode is electrically connected to the negative terminal of the DC bus.

7. The energy storage system according to claim 1, characterized in that, The power supply circuit includes: The second auxiliary power supply circuit has its input terminal electrically connected to the bus capacitor unit. The second switching circuit has a first input terminal electrically connected to an external power supply node, a second input terminal connected to the output terminal of the second auxiliary power supply circuit, and an output terminal connected to the power supply terminal of the control circuit.

8. The energy storage system according to claim 7, characterized in that, The second switching circuit includes: At least one second unidirectional conducting device, the input terminal of which is electrically connected to the bus capacitor unit, and the output terminal of which is electrically connected to the external power supply node and the power supply terminal of the control circuit, respectively.

9. The energy storage system according to claim 8, characterized in that, The at least one second unidirectional conduction device includes: The second diode has its anode electrically connected to the positive terminal of the bus capacitor unit, and its cathode electrically connected to both the positive terminal of the external power supply node and the power supply terminal of the control circuit; and / or The third diode has its anode electrically connected to the negative terminal of the bus capacitor unit, and its cathode electrically connected to both the negative terminal of the external power supply node and the power supply terminal of the control circuit.

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