Energy storage system and under-voltage starting method thereof

Abstract

The invention relates to an under-voltage starting method for an energy storage system, and the method comprises the steps: providing low-voltage power for a BMS module through an external low-voltage auxiliary power supply after a battery pack enters an under-voltage state, the BMS module controls a high-voltage loop to be disconnected, and the BMS module is powered off, so as to enable the BMS module to be powered on; and the BMS module controls the high-voltage loop to be closed, so that the inverter charges the battery pack through the high-voltage loop. And when the battery pack enters the under-voltage protection state, low-voltage electricity is provided for the BMS module through an external low-voltage auxiliary power supply, so that the BMS module enters a black box starting mode, and in the black box starting mode, the BMS module controls the high-voltage loop to be closed, so that the inverter charges the battery pack through the high-voltage loop, and the battery pack is in the under-voltage protection state. Therefore, the battery pack is charged in the under-voltage protection state of the battery pack, and charging of the battery pack in the under-voltage protection state is more efficient and low in cost.

Description

Technical Field

[0001] The present disclosure relates to the technical field of energy storage system charging, and in particular to an energy storage system and an undervoltage starting method thereof. Background Art

[0002] The home energy storage system mainly stores the excess electricity generated by solar panels in battery packs, making it convenient for families to use at any time.

[0003] The home energy storage system consists of modules such as a battery pack (PACK), a battery management system (BMS), an inverter (PCS, Power Conversion System), and photovoltaic panels. When the battery pack is discharged and left stationary for a long time, the battery pack voltage will be too low due to the standby power consumption of electronic components and the self-discharge of the battery cells. The power supply of the BMS is generally provided by converting the high voltage of the battery pack into a low voltage through a DCDC (direct current-to-direct current converter). After the energy storage system is started, the BMS module detects that the battery pack voltage is too low and disconnects the high-voltage circuit. After the high-voltage circuit is disconnected, the DCDC has no low-voltage output and stops supplying power to the BMS. The BMS cannot work due to lack of power and cannot control the closure of the relay in the high-voltage circuit, resulting in the PCS being unable to charge the battery pack. Summary of the invention

[0004] The present disclosure provides an energy storage system and an undervoltage starting method thereof, so as to solve the problem that a battery pack cannot be charged when the battery pack is undervoltage protected.

[0005] In a first aspect, the present disclosure provides an undervoltage startup method for an energy storage system, which is applied to an energy storage system, characterized in that the energy storage system comprises: a battery pack, a high-voltage circuit, a DC-DC converter, a low-voltage switching module and a BMS module;

[0006] The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter;

[0007] The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit;

[0008] The energy storage system undervoltage starting method comprises the steps of:

[0009] When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, after the BMS module is powered off, the external low-voltage auxiliary power supply provides low-voltage power to the BMS module, so that the BMS module is powered on;

[0010] The BMS module controls the high-voltage circuit to be closed so that the inverter charges the battery pack through the high-voltage circuit.

[0011] In one embodiment, the high voltage circuit includes a high voltage circuit breaker and a high voltage relay.

[0012] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0013] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0014] The step of controlling the high-voltage circuit to be closed by the BMS module so that the inverter charges the battery pack through the high-voltage circuit includes:

[0015] The BMS module first controls the high-voltage circuit breaker to close, and then controls the high-voltage relay to close, so that the inverter charges the battery pack through the high-voltage circuit.

[0016] In one embodiment, the high voltage circuit includes a high voltage circuit breaker and a high voltage relay.

[0017] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0018] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0019] When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include:

[0020] The BMS module collects the voltage of the battery pack. When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module determines that the battery pack enters an undervoltage state, and the BMS module controls the high-voltage relay to disconnect.

[0021] When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to open, and the BMS module is powered off.

[0022] In one embodiment, when the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the step of the BMS module controlling the high-voltage relay to disconnect includes:

[0023] When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected;

[0024] The BMS module detects whether the voltage of each battery cell in the battery pack is less than a first preset voltage value and the duration reaches a first preset time;

[0025] When the BMS module detects that the voltage of at least one battery cell in the battery pack is less than the first preset voltage value and the duration reaches the first preset time, the BMS module enters the sleep standby mode.

[0026] In one embodiment, when the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include:

[0027] When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected;

[0028] The BMS module collects the voltage of the battery pack once at a second preset time interval, and detects whether the voltage of the battery pack is lower than a second under-voltage protection voltage value;

[0029] When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to disconnect, and the BMS module is powered off;

[0030] Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the second preset time is greater than the fourth preset time.

[0031] In one embodiment, the step of the BMS module controlling the high-voltage circuit to close so that the inverter charges the battery pack through the high-voltage circuit includes:

[0032] The BMS module collects the voltage of the battery pack once at a third preset time interval, and detects whether the voltage of the battery pack is lower than the first under-voltage protection voltage value;

[0033] Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the third preset time is greater than the fourth preset time.

[0034] In one embodiment, the step of the BMS module controlling the high-voltage circuit to close so that the inverter charges the battery pack through the high-voltage circuit includes:

[0035] The BMS module controls the high-voltage circuit to close and sends a charging request to the inverter, so that the inverter charges the battery pack through the high-voltage circuit.

[0036] In a second aspect, the present disclosure provides an energy storage system, including: a battery pack, a high voltage circuit, a DC-DC converter, a low voltage switching module and a BMS module;

[0037] The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter;

[0038] The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit;

[0039] The BMS module is used to control the high-voltage circuit to be disconnected when the battery pack enters an undervoltage state;

[0040] The low-voltage switching module is used to supply the low-voltage electricity of the external low-voltage auxiliary power supply to the BMS module when the high-voltage circuit is disconnected and the external low-voltage auxiliary power supply is connected;

[0041] The BMS module is also used to operate when powered by the low-voltage power from the external low-voltage auxiliary power supply, and control the high-voltage circuit to close, so that the inverter charges the battery pack through the high-voltage circuit.

[0042] In one embodiment, the high voltage circuit includes a high voltage circuit breaker and a high voltage relay.

[0043] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0044] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0045] The BMS module is used to first control the high-voltage circuit breaker to close and then control the high-voltage relay to close under the low-voltage power supply of the external low-voltage auxiliary power supply, so that the inverter charges the battery pack through the high-voltage circuit.

[0046] In one embodiment, the high voltage circuit includes a high voltage circuit breaker and a high voltage relay.

[0047] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0048] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0049] The BMS module is used to collect the voltage of the battery pack. When the voltage of the battery pack is lower than a first undervoltage protection voltage value, it is determined that the battery pack enters an undervoltage state and controls the high-voltage relay to disconnect; when the voltage of the battery pack is lower than a second undervoltage protection voltage value, it controls the high-voltage circuit breaker to disconnect.

[0050] The above-mentioned energy storage system and undervoltage starting method thereof, when the battery pack enters the undervoltage protection state, provides low voltage electricity to the BMS module through an external low-voltage auxiliary power supply, so that the BMS module enters the black box starting mode. In the black box starting mode, the BMS module controls the high-voltage circuit to be closed, so that the inverter charges the battery pack through the high-voltage circuit, thereby realizing charging of the battery pack in the undervoltage protection state of the battery pack, making the charging of the battery pack in the undervoltage protection state more efficient and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0052] Figure 1 A schematic diagram of a flow chart of an undervoltage starting method for an energy storage system provided in one embodiment of the present disclosure;

[0053] Figure 2 A system logic structure block diagram of an energy storage system provided in one embodiment of the present disclosure;

[0054] Figure 3 A schematic flow chart of an undervoltage startup method for an energy storage system provided in accordance with another embodiment of the present disclosure.

[0055] In the drawings, the same reference numerals are used for the same components, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, and to fully understand and implement how the present disclosure applies technical means to solve technical problems and achieve the corresponding technical effects, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only embodiments of a part of the present disclosure, not all of the embodiments. The embodiments of the present disclosure and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the scope of protection of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present disclosure.

[0057] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0058] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0059] Embodiment 1

[0060] Figure 1 A schematic diagram of a flow chart of an undervoltage startup method for an energy storage system provided by an embodiment of the present disclosure. The intelligent device control method is applied to an energy storage system, such as Figure 2 As shown, the energy storage system includes: a battery pack, a high-voltage circuit, a DC-DC converter, a low-voltage switching module and a BMS module;

[0061] The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter;

[0062] The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit;

[0063] like Figure 1 As shown, the undervoltage starting method of the energy storage system includes:

[0064] Step 110, when the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, after the BMS module is powered off, the external low-voltage auxiliary power supply provides low-voltage power to the BMS module, so that the BMS module is powered on;

[0065] Step 120: The BMS module controls the high-voltage circuit to be closed so that the inverter charges the battery pack through the high-voltage circuit.

[0066] In this embodiment, in a non-undervoltage state, the voltage of the battery pack is relatively high, and the battery pack supplies power to the BMS module through a high-voltage circuit, so that the BMS module works normally. Specifically, the high-voltage output end of the battery pack outputs high-voltage direct current to the input end of the DC-DC converter through the high-voltage circuit, and the DC-DC converter converts the high-voltage direct current into low-voltage direct current and transmits it to the first input end of the low-voltage switching module. The low-voltage switching module transmits the low-voltage direct current to the BMS module through the low-voltage output end, so that the BMS module works.

[0067] At this time, since the high-voltage circuit remains in the on state, the electric energy from the external power source such as the photovoltaic panel can be transmitted to the high-voltage circuit through the inverter, and the battery pack is charged through the high-voltage circuit.

[0068] When the battery pack is discharged or has been in standby mode for a long time, causing the voltage of the battery pack to drop, and the battery pack enters an undervoltage state, the BMS module controls the high-voltage circuit to be disconnected. Specifically, the undervoltage state is also called the undervoltage protection state. In the undervoltage state, the high-voltage circuit of the battery pack is disconnected. Since the high-voltage circuit is disconnected, the BMS module cannot obtain power from the battery pack, the BMS module stops working, and cannot control the high-voltage circuit to be turned on. In this way, the inverter cannot charge the battery pack through the high-voltage circuit.

[0069] Therefore, in order to charge the battery pack in an undervoltage state, in this embodiment, when the battery pack enters an undervoltage state, the BMS module is provided with low voltage electricity through an external low-voltage auxiliary power supply, so that the BMS module is powered on again and enters a black box startup mode. In the black box startup mode, it is allowed to close the high-voltage circuit breaker and the high-voltage relay. Therefore, when the external low-voltage auxiliary power supply supplies power to the BMS module, the BMS module controls the high-voltage circuit to close, so that the inverter can charge the battery pack through the high-voltage circuit. When the battery pack is charged to a normal state (non-undervoltage state), the battery pack resumes power supply to the BMS module, so that the BMS module works normally and keeps the high-voltage circuit on.

[0070] In the above embodiment, when the battery pack enters the undervoltage protection state, low voltage power is provided to the BMS module through an external low-voltage auxiliary power supply, so that the BMS module enters the black box startup mode. In the black box startup mode, the BMS module controls the high-voltage circuit to be closed, so that the inverter charges the battery pack through the high-voltage circuit, thereby realizing charging of the battery pack in the undervoltage protection state of the battery pack, making the charging of the battery pack in the undervoltage protection state more efficient and low-cost.

[0071] In order to prevent the instantaneous current of the high-voltage circuit from impacting the battery pack, in one embodiment, the high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay.

[0072] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0073] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0074] The step of controlling the high-voltage circuit to be closed by the BMS module so that the inverter charges the battery pack through the high-voltage circuit includes:

[0075] The BMS module first controls the high-voltage circuit breaker to close, and then controls the high-voltage relay to close, so that the inverter charges the battery pack through the high-voltage circuit.

[0076] In this embodiment, the battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, and the power input / output terminal of the high-voltage circuit breaker can input power to the battery pack and also supply power to the BMS module with the power received from the battery. In some embodiments, the power input / output terminal of the high-voltage circuit breaker includes a power input terminal and a power output terminal, which are respectively used to input the power transmitted by the high-voltage relay into the battery pack and receive the power of the battery pack to supply power to the BMS module. The input terminal of the high-voltage circuit breaker is used to receive power from the inverter from the power output terminal of the high-voltage relay.

[0077] In the non-undervoltage state, the voltage of the battery pack is relatively high, the high-voltage circuit breaker and the high-voltage relay are in a closed state, and the battery pack supplies power to the BMS module through the high-voltage circuit breaker. Specifically, the battery pack outputs high-voltage direct current to the input end of the DC-DC converter through the high-voltage output end of the high-voltage circuit breaker, and the DC-DC converter converts the high-voltage direct current into low-voltage direct current, and transmits it to the first input end of the low-voltage switching module. The low-voltage switching module transmits the low-voltage direct current to the BMS module through the low-voltage output end, so that the BMS module works. At this time, since the high-voltage circuit breaker and the high-voltage relay are both in a closed state, the electric energy of an external power source such as a photovoltaic panel can be transmitted to the power input end of the high-voltage relay through the inverter, and then transmitted to the high-voltage circuit breaker by the high-voltage relay, and then transmitted to the battery pack by the high-voltage circuit breaker, thereby charging the battery pack.

[0078] In this embodiment, the high-voltage circuit breaker is closed first and then the high-voltage relay is closed, which can reduce the impact on the battery pack at the moment when the current is turned on. The reason is that the closing point of the high-voltage circuit is at the high-voltage relay, and the high-voltage relay is not directly connected to the battery pack. If the high-voltage relay is closed first and then the high-voltage circuit breaker, since the closing point of the high-voltage circuit is at the high-voltage circuit breaker, and the high-voltage circuit breaker is directly connected to the battery pack, in this way, at the moment when the high-voltage circuit breaker is closed, the strong current will have a momentary impact on the battery pack, which may cause damage to the battery pack. Therefore, in this embodiment, the high-voltage circuit breaker is closed first and then the high-voltage relay is closed, which can reduce the impact on the battery pack at the moment when the current is turned on.

[0079] In one embodiment, the high voltage circuit includes a high voltage circuit breaker and a high voltage relay.

[0080] The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter;

[0081] The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0082] When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include:

[0083] The BMS module collects the voltage of the battery pack. When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module determines that the battery pack enters an undervoltage state, and the BMS module controls the high-voltage relay to disconnect.

[0084] When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to open, and the BMS module is powered off.

[0085] In this embodiment, the first undervoltage protection voltage value is a preset third-level undervoltage protection threshold, and the second undervoltage protection voltage value is a preset fourth-level undervoltage protection threshold. In this embodiment, in order to determine whether the battery pack has entered an undervoltage state, the BMS module collects the voltage of the battery pack in real time, and detects whether the voltage of the battery pack is less than the first undervoltage protection voltage value. When the voltage of the battery pack is less than the first undervoltage protection voltage value, the BMS module determines that the battery pack has entered an undervoltage state. At this time, the high-voltage relay is first controlled to disconnect and the inverter stops charging the battery pack. At this time, since the high-voltage circuit breaker remains closed, the battery pack will continue to supply power to the BMS module, the BMS module continues to work, and continues to collect and detect the voltage of the battery pack. When the voltage of the battery pack is less than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to disconnect, the connection between the battery pack and the BMS module is disconnected, and the BMS module is powered off and stops working.

[0086] In one embodiment, when the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the step of the BMS module controlling the high-voltage relay to disconnect includes:

[0087] When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected;

[0088] The BMS module detects whether the voltage of each battery cell in the battery pack is less than a first preset voltage value and the duration reaches a first preset time;

[0089] When the BMS module detects that the voltage of at least one battery cell in the battery pack is less than the first preset voltage value and the duration reaches the first preset time, the BMS module enters the sleep standby mode.

[0090] In this embodiment, when the voltage of the battery pack is lower than the first undervoltage protection voltage value, the high-voltage relay is first disconnected to stop the inverter from charging the battery pack. At the same time, it is detected whether the voltage of each battery cell of the battery pack is less than the first preset voltage value, and whether the duration of the state that the voltage of the battery cell is less than the first preset voltage value reaches the first preset time. When the duration of the state that the voltage of the battery cell is less than the first preset voltage value reaches the first preset time, in order to further save the energy consumption of the energy storage system, the BMS module enters the sleep standby mode, thereby reducing the standby energy consumption of the BMS module. In one embodiment, the first preset voltage value is 2.3V, and the first preset time is 30 minutes.

[0091] In one embodiment, when the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include:

[0092] When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected;

[0093] The BMS module collects the voltage of the battery pack once at a second preset time interval, and detects whether the voltage of the battery pack is lower than a second under-voltage protection voltage value;

[0094] When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to disconnect, and the BMS module is powered off;

[0095] Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the second preset time is greater than the fourth preset time.

[0096] It should be understood that when the voltage of the battery pack is not undervoltage, that is, when the voltage of the battery pack is greater than the first undervoltage protection voltage value, the time interval for the BMS module to collect the voltage of the battery pack is the fourth preset time. In this embodiment, when the voltage of the battery pack is lower than the first undervoltage protection voltage value, the time interval for the BMS module to collect and detect the voltage of the battery pack is extended to the second preset time. In one embodiment, the second preset time is 60S (seconds). By extending the time interval for collecting and detecting the voltage of the battery pack, the standby energy consumption can be further reduced.

[0097] In one embodiment, when the BMS module detects that the voltage of the battery pack is lower than a first under-voltage protection voltage value, the BMS module controls the high-voltage relay to disconnect, and the BMS module detects whether the voltage of each battery cell in the battery pack is lower than a first preset voltage value and the duration reaches a first preset time; when the BMS module detects that the voltage of at least one battery cell in the battery pack is lower than the first preset voltage value and the duration reaches the first preset time, the BMS module enters a sleep standby mode, and the BMS module collects the voltage of the battery pack once at a second preset time interval, and detects whether the voltage of the battery pack is lower than the second under-voltage protection voltage value.

[0098] In this embodiment, when the voltage of the battery pack is lower than the first under-voltage protection voltage value, and the voltage of at least one battery cell in the battery pack is lower than the first preset voltage value, and the duration reaches the first preset time, the BMS module enters the sleep standby mode, and the time interval for the BMS module to collect and detect the voltage of the battery pack is extended to the second preset time. In this way, the standby energy consumption in the sleep standby mode can be further reduced.

[0099] In one embodiment, the BMS module controls the high-voltage circuit to be closed so that the inverter charges the battery pack through the high-voltage circuit, and then includes:

[0100] The BMS module collects the voltage of the battery pack once at a third preset time interval, and detects whether the voltage of the battery pack is lower than the first under-voltage protection voltage value;

[0101] Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the third preset time is greater than the fourth preset time.

[0102] In this embodiment, after the external low-voltage auxiliary power supply is connected, the BMS module enters the black box startup mode. In the black box startup mode, the collection and detection of the voltage of the battery pack is extended to the third preset time. The purpose of collecting and detecting the voltage of the battery pack is to judge the undervoltage state of the battery pack. The reason is that after the BMS module controls the high-voltage circuit to be turned on, the inverter can charge the battery pack through the high-voltage circuit. The battery pack cannot quickly recover to a normal state (non-undervoltage state) in a short time. Therefore, by extending the judgment time of the undervoltage state of the battery pack to the third preset time, sufficient time is reserved for charging the battery pack, and the high-voltage circuit is avoided from being disconnected due to the undervoltage of the battery pack being detected again in a short time. In order to reserve enough charging time for the battery pack, in one embodiment, the third preset time is greater than the second preset time. For example, the third preset time is 10 minutes. In this way, the BMS module will not detect the voltage of the battery pack for a long time after entering the black box startup mode, thereby reserving enough time for charging the battery pack, so that the energy storage system can fully get out of the undervoltage state.

[0103] In one embodiment, the step of the BMS module controlling the high-voltage circuit to close so that the inverter charges the battery pack through the high-voltage circuit includes:

[0104] The BMS module controls the high-voltage circuit to close and sends a charging request to the inverter, so that the inverter charges the battery pack through the high-voltage circuit.

[0105] In this embodiment, when the BMS module enters the black box startup mode, in the black box startup mode, the BMS module sends a charging request to the inverter, so that an external power source, such as a photovoltaic panel, can charge the battery pack through a high-voltage relay and a high-voltage circuit breaker.

[0106] Embodiment 2

[0107] In this embodiment, Figure 2 As shown, an energy storage system is provided, including: a battery pack, a high voltage circuit, a DC-DC converter, a low voltage switching module and a BMS module;

[0108] The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter;

[0109] The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit;

[0110] The BMS module is used to control the high-voltage circuit to be disconnected when the battery pack enters an undervoltage state;

[0111] The low-voltage switching module is used to supply the low-voltage electricity of the external low-voltage auxiliary power supply to the BMS module when the high-voltage circuit is disconnected and the external low-voltage auxiliary power supply is connected;

[0112] The BMS module is also used to operate when powered by the low-voltage power from the external low-voltage auxiliary power supply, and control the high-voltage circuit to close, so that the inverter charges the battery pack through the high-voltage circuit.

[0113] In this embodiment, the BMS module is also used to enter the black box start-up mode under the low voltage power supply of the external low voltage auxiliary power supply. In the black box start-up mode, the high voltage circuit is controlled to be closed so that the inverter charges the battery pack through the high voltage circuit.

[0114] In this embodiment, in a non-undervoltage state, the voltage of the battery pack is relatively high, and the battery pack supplies power to the BMS module through a high-voltage circuit, so that the BMS module works normally. Specifically, the high-voltage output end of the battery pack outputs high-voltage direct current to the input end of the DC-DC converter through the high-voltage circuit, and the DC-DC converter converts the high-voltage direct current into low-voltage direct current and transmits it to the first input end of the low-voltage switching module. The low-voltage switching module transmits the low-voltage direct current to the BMS module through the low-voltage output end, so that the BMS module works.

[0115] At this time, since the high-voltage circuit remains in the on state, the electric energy from the external power source such as the photovoltaic panel can be transmitted to the high-voltage circuit through the inverter, and the battery pack is charged through the high-voltage circuit.

[0116] When the battery pack is discharged or has been in standby mode for a long time, causing the voltage of the battery pack to drop, and the battery pack enters an undervoltage state, the BMS module controls the high-voltage circuit to be disconnected. Specifically, the undervoltage state is also called the undervoltage protection state. In the undervoltage state, the high-voltage circuit of the battery pack is disconnected. Since the high-voltage circuit is disconnected, the BMS module cannot obtain power from the battery pack, the BMS module stops working, and cannot control the high-voltage circuit to be turned on. In this way, the inverter cannot charge the battery pack through the high-voltage circuit.

[0117] Therefore, in order to charge the battery pack under the undervoltage state, in this embodiment, when the battery pack enters the undervoltage state, the second input end of the low-voltage switching module is connected to the external low-voltage auxiliary power supply. At this time, the first input end of the low-voltage switching module cannot obtain electric energy from the battery pack. Therefore, the input of electric energy is switched to the second input end of the low-voltage switching module, and the second input end of the low-voltage switching module obtains low voltage from the external low-voltage auxiliary power supply to supply the BMS module. The BMS module is provided with low voltage electricity through the external low-voltage auxiliary power supply, so that the BMS module is powered on again and enters the black box startup mode. In the black box startup mode, the high-voltage circuit breaker is allowed to be closed and the high-voltage relay is closed. Therefore, when the external low-voltage auxiliary power supply supplies power to the BMS module, the BMS module controls the high-voltage circuit to be closed, so that the inverter can charge the battery pack through the high-voltage circuit. When the battery pack is charged to a normal state (non-undervoltage state), the battery pack resumes powering the BMS module, so that the BMS module works normally and keeps the high-voltage circuit on.

[0118] In order to prevent current reverse flow, in one embodiment, the low-voltage switching module is provided with a diode protection circuit, which is used to prevent current reverse flow and protect the normal operation of the system, thereby improving safety. For example, when the second input terminal of the low-voltage switching module is connected to an external low-voltage auxiliary power supply, the BMS module is powered on, the BMS module controls the high-voltage circuit to close, and the external low-voltage auxiliary power supply supplies power to the BMS module through the low-voltage switching module, the diode protection circuit is used to prevent the current of the external low-voltage auxiliary power supply from flowing to the battery pack.

[0119] In one embodiment, the high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay, the battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to an inverter; the first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0120] The BMS module is used to first control the high-voltage circuit breaker to close and then control the high-voltage relay to close under the low-voltage power supply of the external low-voltage auxiliary power supply, so that the inverter charges the battery pack through the high-voltage circuit.

[0121] In this embodiment, the battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, and the power input / output terminal of the high-voltage circuit breaker can input power to the battery pack and also supply power to the BMS module with the power received from the battery. In some embodiments, the power input / output terminal of the high-voltage circuit breaker includes a power input terminal and a power output terminal, which are respectively used to input the power transmitted by the high-voltage relay into the battery pack and receive the power of the battery pack to supply power to the BMS module. The input terminal of the high-voltage circuit breaker is used to receive power from the inverter from the power output terminal of the high-voltage relay.

[0122] In the non-undervoltage state, the voltage of the battery pack is relatively high, the high-voltage circuit breaker and the high-voltage relay are in a closed state, and the battery pack supplies power to the BMS module through the high-voltage circuit breaker. Specifically, the battery pack outputs high-voltage direct current to the input end of the DC-DC converter through the high-voltage output end of the high-voltage circuit breaker, and the DC-DC converter converts the high-voltage direct current into low-voltage direct current, and transmits it to the first input end of the low-voltage switching module. The low-voltage switching module transmits the low-voltage direct current to the BMS module through the low-voltage output end, so that the BMS module works. At this time, since the high-voltage circuit breaker and the high-voltage relay are both in a closed state, the electric energy of an external power source such as a photovoltaic panel can be transmitted to the power input end of the high-voltage relay through the inverter, and then transmitted to the high-voltage circuit breaker by the high-voltage relay, and then transmitted to the battery pack by the high-voltage circuit breaker, thereby charging the battery pack.

[0123] In this embodiment, the high-voltage circuit breaker is closed first and then the high-voltage relay is closed, which can reduce the impact on the battery pack at the moment when the current is turned on. The reason is that the closing point of the high-voltage circuit is at the high-voltage relay, and the high-voltage relay is not directly connected to the battery pack. If the high-voltage relay is closed first and then the high-voltage circuit breaker, since the closing point of the high-voltage circuit is at the high-voltage circuit breaker, and the high-voltage circuit breaker is directly connected to the battery pack, in this way, at the moment when the high-voltage circuit breaker is closed, the strong current will have a momentary impact on the battery pack, which may cause damage to the battery pack. Therefore, in this embodiment, the high-voltage circuit breaker is closed first and then the high-voltage relay is closed, which can reduce the impact on the battery pack at the moment when the current is turned on.

[0124] In one embodiment, the high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay, the battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to an inverter; the first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay;

[0125] The BMS module is used to collect the voltage of the battery pack. When the voltage of the battery pack is lower than a first undervoltage protection voltage value, it is determined that the battery pack enters an undervoltage state and controls the high-voltage relay to disconnect; when the voltage of the battery pack is lower than a second undervoltage protection voltage value, it controls the high-voltage circuit breaker to disconnect.

[0126] In this embodiment, the first under-voltage protection voltage value is a preset third-level under-voltage protection threshold, and the second under-voltage protection voltage value is a preset fourth-level under-voltage protection threshold.

[0127] In order to determine whether the battery pack has entered an undervoltage state, the BMS module collects the voltage of the battery pack in real time, and detects whether the voltage of the battery pack is less than the first undervoltage protection voltage value. When the voltage of the battery pack is less than the first undervoltage protection voltage value, the BMS module determines that the battery pack has entered an undervoltage state. At this time, the high-voltage relay is first controlled to disconnect and the inverter stops charging the battery pack. At this time, since the high-voltage circuit breaker remains closed, the battery pack will continue to supply power to the BMS module, the BMS module continues to work, and continues to collect and detect the voltage of the battery pack. When the voltage of the battery pack is less than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to disconnect, the connection between the battery pack and the BMS module is disconnected, and the BMS module is powered off and stops working.

[0128] Embodiment 3

[0129] Based on the above embodiments, this embodiment provides an application example.

[0130] like Figure 2 As shown, during normal operation, the high-voltage current of the battery pack passes through the high-voltage circuit breaker to the DCDC module. The DCDC module provides low-voltage current output to the BMS module. The BMS module collects information such as the battery pack voltage, current, and temperature, and controls the high-voltage relay to output high voltage.

[0131] When the battery pack is undervoltage, the BMS module disconnects the high-voltage relay and high-voltage circuit breaker for protection, and cannot be recharged. At this time, a low-voltage auxiliary power supply needs to be input from the outside to power the BMS module through the low-voltage switching module. The BMS module enters the black box startup mode, controls the high-voltage relay to close, and allows the PCS to recharge the battery pack.

[0132] For detailed process, see Figure 3 :

[0133] In 205, the BMS monitors the voltage, current, temperature and other information of the battery pack in real time;

[0134] In 210, the BMS determines whether the battery pack voltage or the battery cell voltage is lower than a preset third-level undervoltage protection threshold;

[0135] In 215, when the judgment result is lower than the preset third-level undervoltage protection threshold, the BMS disconnects the high-voltage relay. At the same time, the BMS judges that the cell voltage is less than or equal to 2.3V and lasts for 30 minutes, and enters the sleep standby mode. The BMS collects the voltage / temperature information of the slave control every 60 seconds to reduce the standby power consumption;

[0136] In 220, after a long period of static standby, the BMS determines whether the battery pack voltage or the battery cell voltage is lower than a preset four-level undervoltage protection threshold;

[0137] In 225, when it is determined that the voltage is lower than the preset level 4 undervoltage protection threshold, the BMS disconnects the high voltage circuit breaker and enters a power-off protection state;

[0138] In 230, the energy storage system is in an undervoltage state and cannot be powered on. It can be powered by an external low-voltage auxiliary power supply. A diode protection circuit is provided in the low-voltage switching module to prevent current reverse and protect the normal operation of the system;

[0139] In 235, the external low-voltage auxiliary source supplies power to the BMS through the low-voltage switching module, and the BMS enters the black box startup state. When the BMS is in the black box startup state, the judgment time for undervoltage faults is extended to 10 minutes to reserve time for the battery pack to recharge. In the black box startup state, it is allowed to close the high-voltage circuit breaker, close the high-voltage relay, and send a forced charging request to the external PCS;

[0140] At 240, the high voltage circuit breaker is closed;

[0141] In 245, the BMS controls the high-voltage relay to close and the high-voltage circuit to conduct. The process is to close the circuit breaker first and then the relay. In this way, the impact on the battery pack at the moment of current conduction can be reduced. The circuit closure point is at the relay, and the relay is not directly connected to the battery pack. If the relay is closed first and then the circuit breaker, the circuit closure point is at the circuit breaker, which will cause a momentary impact on the battery pack.

[0142] In 250, the external PCS can recharge the battery pack normally.

[0143] In this embodiment, the problem that the battery pack cannot supply power to the BMS module when it is undervoltage is solved, and the energy storage system can operate normally and replenish power normally by inputting an external low-voltage auxiliary power supply.

[0144] In each embodiment, the processor may include, but is not limited to, one or more processors or microprocessors, etc. Each processor may be an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components to execute the method in the above embodiments.

[0145] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, for example, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (such as hard disks, floppy disks, solid-state drives, removable disks, Blu-ray disks, etc.).

[0146] The computer-readable storage medium may also store at least one computer executable program, such as a computer-readable instruction. The computer-readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The computer-readable storage medium may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device runs the computer-readable instructions stored on the computer-readable storage medium, the various methods described above may be performed.

[0147] In addition, the computer device may also include (but not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (eg, keyboard, mouse, speaker, etc.), etc.

[0148] The processor may communicate with external devices via an I / O bus via a wired or wireless network.

[0149] In the embodiments provided in the present disclosure, it should be understood that the disclosed systems and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the above-mentioned module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0150] It should be noted that in the present disclosure, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element limited by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0151] Although the embodiments disclosed in the present disclosure are as above, the above contents are only embodiments adopted for facilitating the understanding of the present disclosure and are not intended to limit the present disclosure. Any technician in the technical field to which the present disclosure belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present disclosure, but the scope of patent protection of the present disclosure shall still be subject to the scope defined in the attached claims.

Claims

1. An undervoltage startup method for an energy storage system, applied to an energy storage system, characterized in that: The energy storage system includes: a battery pack, a high-voltage circuit, a DC-DC converter, a low-voltage switching module and a BMS module; The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter; The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit; The energy storage system undervoltage starting method comprises the steps of: When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, after the BMS module is powered off, the external low-voltage auxiliary power supply provides low-voltage power to the BMS module, so that the BMS module is powered on; The BMS module controls the high-voltage circuit to be closed so that the inverter charges the battery pack through the high-voltage circuit.

2. The method according to claim 1, characterized in that The high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay. The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter; The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay; The step of controlling the high-voltage circuit to be closed by the BMS module so that the inverter charges the battery pack through the high-voltage circuit includes: The BMS module first controls the high-voltage circuit breaker to close, and then controls the high-voltage relay to close, so that the inverter charges the battery pack through the high-voltage circuit.

3. The method according to claim 1, characterized in that The high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay. The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter; The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay; When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include: The BMS module collects the voltage of the battery pack. When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module determines that the battery pack enters an undervoltage state, and the BMS module controls the high-voltage relay to disconnect. When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to open, and the BMS module is powered off.

4. The method according to claim 3, characterized in that When the BMS module detects that the voltage of the battery pack is lower than the first undervoltage protection voltage value, the step of the BMS module controlling the high-voltage relay to disconnect includes: When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected; The BMS module detects whether the voltage of each battery cell in the battery pack is less than a first preset voltage value and the duration reaches a first preset time; When the BMS module detects that the voltage of at least one battery cell in the battery pack is less than the first preset voltage value and the duration reaches the first preset time, the BMS module enters the sleep standby mode.

5. The method according to claim 3, characterized in that: When the battery pack enters an undervoltage state and the BMS module controls the high-voltage circuit to be disconnected, the steps after the BMS module is powered off include: When the BMS module detects that the voltage of the battery pack is lower than a first undervoltage protection voltage value, the BMS module controls the high-voltage relay to be disconnected; The BMS module collects the voltage of the battery pack once at a second preset time interval, and detects whether the voltage of the battery pack is lower than a second undervoltage protection voltage value; When the BMS module detects that the voltage of the battery pack is lower than the second undervoltage protection voltage value, the BMS module controls the high-voltage circuit breaker to disconnect, and the BMS module is powered off; Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the second preset time is greater than the fourth preset time.

6. The method according to claim 5, characterized in that The step of the BMS module controlling the high-voltage circuit to close so that the inverter charges the battery pack through the high-voltage circuit includes: The BMS module collects the voltage of the battery pack once at a third preset time interval, and detects whether the voltage of the battery pack is lower than the first under-voltage protection voltage value; Wherein, when the battery pack does not enter the undervoltage state, the time interval for the BMS module to collect the voltage of the battery pack is a fourth preset time, and the third preset time is greater than the fourth preset time.

7. The method according to any one of claims 1 to 6, characterized in that: The step of controlling the high-voltage circuit to be closed by the BMS module so that the inverter charges the battery pack through the high-voltage circuit includes: The BMS module controls the high-voltage circuit to close and sends a charging request to the inverter, so that the inverter charges the battery pack through the high-voltage circuit.

8. An energy storage system, characterized in that: include: Battery pack, high voltage circuit, DC-DC converter, low voltage switching module and BMS module; The battery pack is connected to one end of the high-voltage circuit, the high-voltage output end of the high-voltage circuit is connected to the input end of the DC-DC converter, and the power input end of the high-voltage circuit is used to connect to the inverter; The low-voltage output end of the DC-DC converter is connected to the first input end of the low-voltage switching module, the second input end of the low-voltage switching module is used to connect to an external low-voltage auxiliary power supply, the low-voltage output end of the low-voltage switching module is connected to the power input end of the BMS module, and the control output end of the BMS module is connected to the control input end of the high-voltage circuit; The BMS module is used to control the high-voltage circuit to be disconnected when the battery pack enters an undervoltage state; The low-voltage switching module is used to supply the low-voltage electricity of the external low-voltage auxiliary power supply to the BMS module when the high-voltage circuit is disconnected and the external low-voltage auxiliary power supply is connected; The BMS module is also used to operate when powered by the low-voltage power from the external low-voltage auxiliary power supply, and control the high-voltage circuit to close, so that the inverter charges the battery pack through the high-voltage circuit.

9. The system according to claim 8, characterized in that The high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay. The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter; The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay; The BMS module is used to first control the high-voltage circuit breaker to close and then control the high-voltage relay to close under the low-voltage power supply of the external low-voltage auxiliary power supply, so that the inverter charges the battery pack through the high-voltage circuit.

10. The system according to claim 8, characterized in that The high-voltage circuit includes a high-voltage circuit breaker and a high-voltage relay. The battery pack is connected to the power input / output terminal of the high-voltage circuit breaker, the high-voltage output terminal of the high-voltage circuit breaker is connected to the input terminal of the DC-DC converter, the input terminal of the high-voltage circuit breaker is connected to the power output terminal of the high-voltage relay, and the power input terminal of the high-voltage relay is used to connect to the inverter; The first control output terminal of the BMS module is connected to the control input terminal of the high-voltage circuit breaker, and the second control output terminal of the BMS module is connected to the control input terminal of the high-voltage relay; The BMS module is used to collect the voltage of the battery pack. When the voltage of the battery pack is lower than a first undervoltage protection voltage value, it is determined that the battery pack enters an undervoltage state and controls the high-voltage relay to disconnect; when the voltage of the battery pack is lower than a second undervoltage protection voltage value, it controls the high-voltage circuit breaker to disconnect.

Images