Battery energy storage system and control device and method thereof

Abstract

The invention discloses a control device of a battery energy storage system, the battery energy storage system and a control method thereof, and the device comprises an energy storage module which supplies power to a voltage conversion circuit and a first switching power supply; the voltage conversion circuit performs voltage conversion with at least one of an external photovoltaic end, a mains supply end and a load end under the control of the control circuit; the first switching power supply supplies power to the control circuit; the first normally-closed switch is arranged between the energy storage module and the first switching power supply; and the second normally-closed switch and the standby power taking device are arranged between the commercial power end and the first switching power supply in a matched manner. According to the scheme, the power is taken from the mains supply end when the energy storage battery is in the complete discharge state, so that the control circuit works normally to charge the energy storage battery, and the energy storage battery is switched to supply power to the control circuit when the energy storage battery is charged to the set value, so that the normal work of the battery energy storage system can be ensured, and the service life of the energy storage battery can be prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery energy storage systems, and specifically relates to a control device of a battery energy storage system, a battery energy storage system and a control method thereof, and more particularly to a charge and discharge control circuit of a low-voltage energy storage battery in a low-voltage energy storage system, a battery energy storage system and a control method thereof. Background Art

[0002] In the field of battery energy storage systems, especially low-voltage energy storage batteries, they have become a hot topic in energy management research in recent years due to their wide applications in distributed power generation, electric vehicles, home energy storage systems, etc. Low-voltage energy storage batteries, such as lithium-ion batteries, lead-acid batteries, sodium-ion batteries, etc., not only provide solutions for the integration and balance of renewable energy, but also serve as a beneficial supplement to traditional power grids, improving the stability and reliability of the power grid.

[0003] In the low-voltage energy storage system, the battery outputs low-voltage DC power on the battery side in the discharge mode, which is boosted by a bidirectional DCDC (i.e. DC-DC) converter to convert the low-voltage DC power into high-voltage DC power, which can be used to power DC loads, and then converted from the high-voltage DC power into high-voltage AC power through an inverter circuit, which can be used to power AC loads; in the charging mode, the photovoltaic DC voltage can be boosted by a BOOST boost circuit (i.e. a switching DC boost circuit, whose output voltage can be higher than the input voltage) and then input to the high-voltage side of the bidirectional DCDC converter, and the battery is charged after the voltage is reduced by the bidirectional DCDC converter, or it can be converted into high-voltage DC power through a rectifier circuit through the AC power supply, and then stepped down by the bidirectional DCDC converter to charge the battery.

[0004] For the low-voltage energy storage system, during the entire process of charging and discharging the low-voltage battery, whether in charging mode or discharging mode, the power supply of the control circuit chip of the entire system (such as the main chip, switch tube driver chip, switch power supply chip, voltage and current sampling chip, etc.) and the power supply of each relay are all derived from the supply of the low-voltage side battery. When the battery is completely exhausted, it is impossible to supply power to the control circuit chip of the entire system. At this time, photovoltaic or AC power is needed to charge the battery, but because the control circuit chip has no power supply, the entire system cannot charge the battery.

[0005] It can be seen that for the control circuit of the low-voltage battery energy storage system, if the energy storage battery is in a fully discharged state, the low-voltage battery energy storage system cannot continue to use the energy storage battery to power the control circuit, causing the low-voltage battery energy storage system to fail to work.

[0006] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0007] The object of the present invention is to provide a control device of a battery energy storage system, a battery energy storage system and a control method thereof, so as to solve the problem that for a control circuit of a low-voltage battery energy storage system, if the energy storage battery is in a fully discharged state, the low-voltage battery energy storage system cannot continue to use the energy storage battery to power the control circuit, resulting in the low-voltage battery energy storage system being unable to work. When the energy storage battery is in a fully discharged state, power is taken from the mains terminal to enable the control circuit to work normally so as to charge the energy storage battery. When the energy storage battery is charged to a set value, the control circuit is switched to be powered by the energy storage battery, so as to ensure the normal operation of the battery energy storage system and help to extend the service life of the energy storage battery.

[0008] The present invention provides a control device for a battery energy storage system, comprising: a main circuit, a first switching power supply and a control circuit; the main circuit has an energy storage module and a voltage conversion circuit; the energy storage module is used to supply power to the voltage conversion circuit and the first switching power supply respectively; the voltage conversion circuit is used to perform voltage conversion with at least one of an external photovoltaic terminal, a mains terminal, and a load terminal under the control of the control circuit; the first switching power supply is used to supply power to the control circuit; and further comprises: a first normally closed switch, a second normally closed switch, and a backup power supply; the first normally closed switch is arranged between the energy storage module and the first switching power supply; the second normally closed switch and the backup power supply are cooperatively arranged between the mains terminal and the first switching power supply; wherein, when the remaining power of the energy storage module is above a preset remaining power threshold, the control circuit controls the operation of the battery energy storage system: the control circuit does not control the The first normally closed switch, i.e., the first normally closed switch, is closed, and the control circuit controls the second normally closed switch to be opened; during the operation of the battery energy storage system, if the control circuit determines that the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop operating: the control circuit does not control the second normally closed switch, i.e., the second normally closed switch, to be closed, so that the backup power supply device supplies power to the control circuit through the first switching power supply after taking power from the mains end; the control circuit controls the first normally closed switch to be opened, and the control circuit controls the mains end to charge the energy storage module through the voltage conversion circuit; until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the control circuit controls the second normally closed switch to be opened, and the control circuit does not control the first normally closed switch, i.e., the first normally closed switch to be closed, so that the power supply from the mains end to the first switching power supply is switched to the power supply from the energy storage battery to the first switching power supply.

[0009] In some embodiments, the backup power supply device includes: a rectifier module and a second switching power supply; wherein the AC power end is connected to the first switching power supply after passing through the rectifier module, the second normally closed switch, and the second switching power supply.

[0010] In some implementations, the invention further includes: a power rail; and the first switching power supply is arranged in the power rail.

[0011] In some embodiments, the main circuit further has a first switch, a second switch, and a third switch; the voltage conversion circuit includes: a DCDC module, and a DCAC module (such as a DC / AC circuit); wherein the energy storage module, after passing through the first switch, the DCDC module, and the DCAC module: is connected to the load end through the second switch, and is connected to the mains end through the third switch; a common end of the DCDC module and the DCAC module is connected to the photovoltaic end; a control end of the first switch, a control end of the second switch, a control end of the third switch, a control end of the DCDC module, and a control end of the DCAC module are all connected to the control circuit to perform corresponding actions under the control of the control circuit.

[0012] In some embodiments, the main circuit further has a BMS; the BMS is connected to the energy storage battery.

[0013] In some embodiments, the control circuit includes: a main control module, a sampling module, and a comparison module; wherein the sampling module is used to sample the remaining power of the energy storage module before the battery energy storage system is operated; during the operation of the energy storage module, sample the discharge voltage of the energy storage module; and, during the process of charging the energy storage module from the mains end through the voltage conversion circuit, sample the voltage of the charged energy storage module to obtain the charging voltage of the energy storage module; the comparison module is used to compare the remaining power of the energy storage module obtained by sampling with a preset remaining power threshold to obtain a remaining power comparison result; compare the discharge voltage of the energy storage module obtained by sampling with a preset discharge voltage threshold to obtain a discharge voltage comparison result; and compare the charging voltage of the energy storage module obtained by sampling with a preset charging voltage threshold to obtain a charging voltage comparison result; the main control module is used to control the operation of the battery energy storage system according to the remaining power comparison result, if it is determined that the remaining power of the energy storage module is above the preset remaining power threshold: control the first normally closed switch to close, and control the second normally closed switch to open; the main control module , and is also used to determine that the energy storage module is in a fully discharged state and control the battery energy storage system to stop running if it is determined that the discharge voltage of the energy storage module is less than a preset discharge voltage threshold according to the discharge voltage comparison result: control the second normally closed switch to be closed so that the backup power supply device supplies power to the control circuit through the first switch power supply after taking power from the mains end; control the first normally closed switch to be opened, and control the mains end to charge the energy storage module through the voltage conversion circuit; the main control module is also used to control the second normally closed switch to be opened and control the first normally closed switch to be closed if it is determined that the charging voltage of the energy storage module is greater than a preset charging voltage threshold according to the charging voltage comparison result, so that the power supply from the mains end to the first switch power supply is switched to the power supply from the energy storage battery to the first switch power supply; wherein, the main control module controls the first normally closed switch to be closed, so that the first normally closed switch is automatically closed when the control of the preset effective level sent by the main control module is lost; the main control module controls the second normally closed switch to be closed, so that the second normally closed switch is automatically closed when the control of the preset effective level sent by the main control module is lost.

[0014] In some embodiments, the control circuit further includes: a switch driving module, a DCDC driving module, and a DCAC driving module; wherein, when the main circuit also has a first switch, a second switch, and a third switch, the switch driving module is used to drive the corresponding switches among the first switch, the second switch, and the third switch under the control of the main control module; when the voltage conversion circuit includes a DCDC module, the DCDC driving module is used to drive the DCDC module under the control of the main control module; when the voltage conversion circuit includes a DCAC module, the DCAC driving module is used to drive the DCAC module under the control of the main control module.

[0015] Matching the above device, the present invention further provides a battery energy storage system on the other hand, including: the control device of the battery energy storage system described above.

[0016] Matching the above-mentioned battery energy storage system, the present invention provides a control method for a battery energy storage system on another aspect, comprising: obtaining the remaining power of the energy storage module; if it is determined that the remaining power of the energy storage module is above a preset remaining power threshold, controlling the battery energy storage system to operate: controlling the first normally closed switch to close, and controlling the second normally closed switch to open; during the operation of the battery energy storage system, obtaining the discharge voltage of the energy storage module; determining whether the discharge voltage of the energy storage module is less than a preset discharge voltage threshold: if so, determining that the energy storage module is in a fully discharged state, otherwise continuing to put the energy storage battery in a discharge mode; in the When the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop running: the second normally closed switch is controlled to be closed, so that the backup power supply device draws power from the mains end and supplies power to the control circuit through the first switching power supply; the first normally closed switch is controlled to be disconnected, and the mains end is controlled to charge the energy storage module through the voltage conversion circuit; until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be disconnected, and the first normally closed switch is controlled to be closed, so as to switch the power supply from the mains end to the first switching power supply to the energy storage battery.

[0017] In some embodiments, until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed, including: in the process of the mains end charging the energy storage module through the voltage conversion circuit, obtaining the voltage of the energy storage module after charging, and obtaining the charging voltage of the energy storage module; determining whether the charging voltage of the energy storage module is greater than a preset charging voltage threshold; if it is determined that the charging voltage of the energy storage module is greater than the preset charging voltage threshold, controlling the second normally closed switch to be opened, and controlling the first normally closed switch to be closed, so as to switch the power supply from the mains end to the first switching power supply to the power supply from the energy storage battery; if it is determined that the charging voltage of the energy storage module is not greater than the preset charging voltage threshold, continuing to allow the mains end to charge the energy storage module through the voltage conversion circuit.

[0018] Therefore, the solution of the present invention is aimed at a battery energy storage system (such as a low-voltage battery energy storage system) having a main circuit, a power rail and a control circuit. An energy storage battery (such as a low-voltage energy storage battery) and a voltage conversion circuit (such as a DCDC circuit, a DC / AC circuit, etc.) are arranged in the main circuit, a first switching power supply (such as a switching power supply I) is arranged in the power rail, a main chip and a functional circuit (such as a sampling circuit, a communication circuit, a relay drive circuit, a DCDC drive circuit, a DCAC drive circuit, etc.) are arranged in the control circuit, and the energy storage battery supplies power to the control circuit after the first switching power supply; the voltage conversion circuit can be connected to an external photovoltaic power generation component, a mains access terminal, and a load; a first normally closed switch (such as a normally closed relay K1) is arranged between the energy storage battery and the first switching power supply, a rectifier bridge and a second switching power supply (such as a switching power supply II) are arranged at the mains access terminal, and a second normally closed switch (such as Normally closed relay K2), the second switch power supply is connected to the first switch power supply; when the power of the energy storage battery is sufficient and the battery energy storage system operates normally, the first normally closed switch is closed and the second normally closed switch is opened; when the energy storage battery is in a fully discharged state, the second normally closed switch is closed, and the second switch power supply uses the mains power to supply power to the first switch power supply, so that the control circuit can work and control the first normally closed switch to be opened, and the battery energy storage system charges the energy storage battery until the voltage of the energy storage battery is higher than the set value, the first normally closed switch is controlled to be closed, and the second normally closed switch is controlled to be opened, and the power supply from the mains power to the first switch power supply is switched to the power supply from the energy storage battery to the first switch power supply; thus, by taking power from the mains power end when the energy storage battery is in a fully discharged state to enable the control circuit to operate normally so as to charge the energy storage battery, and when the energy storage battery is charged to the set value, switching to the power supply from the energy storage battery to the control circuit can ensure the normal operation of the battery energy storage system and help to extend the service life of the energy storage battery.

[0019] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an embodiment of a control device for a battery energy storage system of the present invention;

[0022] Figure 2 It is a structural schematic diagram of an embodiment of a low-voltage energy storage system in a related scheme;

[0023] Figure 3 It is a structural schematic diagram of an embodiment of a low-voltage energy storage system of the present invention;

[0024] Figure 4 A schematic flow chart of an embodiment of a method for controlling a low-voltage energy storage system of the present invention;

[0025] Figure 5 A schematic diagram of a flow chart of an embodiment of a method for controlling a battery energy storage system of the present invention;

[0026] Figure 6 The present invention is a flow chart of an embodiment of controlling the second normally closed switch to open and the first normally closed switch to close in the charging mode of the energy storage battery in the method of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Considering that in the charging and discharging process of the low-voltage energy storage system, in all the circuits of the controller, the work of the control circuit modules such as DCDC, DCAC (i.e. direct current-alternating current), ACDC (i.e. alternating current-direct current), sampling circuit, protection circuit, etc. all need to be controlled to realize their functions, and the control chip used needs to be supplied with the required chip power to make the chip work. Therefore, the energy storage system not only needs input to work, but also needs other power supplies to control the work of each control circuit module to output the required results, otherwise the control circuit module will not work. Among them, in the low-voltage energy storage system, the battery terminal voltage is used to provide power to the control circuit module through the power conversion circuit, but when the battery is completely dead, the low-voltage energy storage system cannot supply power to the control circuit module, and then the low-voltage energy storage system cannot work.

[0029] Figure 2 FIG. 1 is a schematic diagram of a structure of an embodiment of a low-voltage energy storage system in a related solution. Figure 2 As shown, the main circuit includes: Battery Monitoring and Management System (BMS), low-voltage energy storage battery (such as 48V energy storage battery), bidirectional DCDC buck-boost circuit, DC / AC circuit, relay K3, relay K4, and relay K5. The power rail includes: switching power supply I. The control circuit includes: relay drive circuit, DCDC drive circuit, DCAC drive circuit, sampling circuit, and main chip.

[0030] Among them, the low-voltage energy storage battery is connected to the BMS and the switching power supply I respectively. The low-voltage energy storage battery can supply power to household appliances through relay K3, bidirectional DCDC buck-boost circuit, DC / AC circuit, and relay K4. The mains power can also supply power to household appliances through relay K5 and relay K4. The switching power supply I outputs 24V voltage to supply power to the relay drive circuit; the relay drive circuit drives relay K3, relay K4 and relay K5 respectively. The switching power supply I outputs 18V voltage to supply power to the DCDC drive circuit and the DCAC drive circuit. The DCDC drive circuit can output PWM wave (Pulse width modulation wave) to control the bidirectional DCDC buck-boost circuit under the control of the main chip, and the DCAC drive circuit can output PWM wave to control the DC / AC circuit under the control of the main chip. The switching power supply I outputs 3.3V voltage to supply power to the main chip. The switching power supply I also outputs 3.3V voltage to supply power to the sampling circuit.

[0031] The control method in the relevant scheme is to detect the battery power on the low-voltage side during the battery discharge process, and remind the user to charge when the power drops to a certain safety threshold to avoid entering a fully discharged state. This method can protect the battery from a zero-power state to maintain the battery life, and can continue to provide power to the control circuit during charging. However, when the battery power reaches the minimum threshold, if it cannot be charged for a long time, the battery power will actually be completely released. At this time, the battery will not be able to be charged by AC or photovoltaic power, and the battery can only be taken to a specific location to be charged separately. This will not only consume manpower, but also be very costly. Leaving the battery in a fully discharged state for a long time will also reduce the battery life. Therefore, the control method in the relevant scheme is not very effective in the field of energy storage system control.

[0032] That is to say, when the low-voltage energy storage system is performing normal charging and discharging, the power required by its control circuit is supplied by the power converted from the battery terminal voltage. That is to say, under normal circumstances, as long as the battery has power, the system can work normally; and when the battery is in a fully discharged state, that is, the battery is completely out of power (this will happen when the energy storage system battery is not used for a long time), the control circuit in the system cannot be powered, causing the system to be unable to work normally, and charging and discharging cannot be performed (at this time, it is necessary to find a battery manufacturer to use specific tooling for charging).

[0033] Therefore, the scheme of the present invention proposes a control device for a battery energy storage system, specifically a charge and discharge control circuit for a low-voltage energy storage battery in a low-voltage energy storage system. When the control circuit of the low-voltage battery energy storage system draws power from the battery side, if the battery is in a fully discharged state and cannot work, the control circuit is first powered by the mains and then switched to battery power supply. The control circuit can be powered by the mains for a short time, and then automatically switched to battery power supply when the battery has power. This can at least avoid the situation where the battery cannot be charged in a fully discharged state and can only be charged outsourced, so that the low-voltage energy storage system can work normally, and is beneficial to reducing costs and extending battery life.

[0034] According to an embodiment of the present invention, a control device for a battery energy storage system is provided. Figure 1The structure diagram of an embodiment of the device of the present invention is shown. The control device of the battery energy storage system may include: a main circuit, a first switching power supply (such as switching power supply I) and a control circuit; the main circuit has an energy storage module (such as a 48V low-voltage energy storage battery) and a voltage conversion circuit (such as a DCDC circuit and a DC / AC circuit, etc.); the energy storage module is used to supply power to the voltage conversion circuit and the first switching power supply respectively; the voltage conversion circuit is connected to the external photovoltaic end, the mains end, and the load end, and is used to perform voltage conversion between at least one of the external photovoltaic end, the mains end, and the load end under the control of the control circuit; the first switching power supply is connected to the control circuit and is used to supply power to the control circuit. The control device of the battery energy storage system also includes: a first normally closed switch (such as a normally closed relay K1), a second normally closed switch (such as a normally closed relay K2), and a backup power supply; the first normally closed switch is arranged between the energy storage module and the first switching power supply; the second normally closed switch and the backup power supply are arranged in cooperation between the mains end and the first switching power supply.

[0035] Wherein, when the remaining power of the energy storage module is above a preset remaining power threshold, the control circuit controls the battery energy storage system to operate: the control circuit does not control the first normally closed switch, that is, the first normally closed switch is closed, and the control circuit controls the second normally closed switch to be open, so that the energy storage module is in a discharge mode.

[0036] During the operation of the battery energy storage system, if the control circuit determines that the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop operating, that is, the energy storage module is exited from the discharge mode: the control circuit does not control the second normally closed switch, that is, the second normally closed switch is closed, so that the backup power supply device draws power from the mains end and supplies power to the control circuit through the first switching power supply; the control circuit controls the first normally closed switch to be disconnected, and the control circuit controls the mains end to charge the energy storage module through the voltage conversion circuit, so that the energy storage module is in the charging mode.

[0037] During the charging process of the energy storage module, until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the control circuit controls the second normally closed switch to be disconnected, and the control circuit does not control the first normally closed switch, that is, the first normally closed switch to be closed, so as to switch the power supply from the mains end to the first switching power supply to the energy storage battery. The preset charging voltage threshold is, for example, voltage Vref2.

[0038] The scheme of the present invention is based on the control method adopted in the circuit topology of the low-voltage battery energy storage system in the related scheme. In order to solve the problem that the system cannot continue to use the energy storage battery to power the control circuit when the battery is fully discharged, a switching power supply circuit is added at the mains end, and a normally closed relay is added at the rear end of the rectifier bridge and the battery end of the circuit. When the battery is fully discharged, the DC power converted by the added switching power supply is supplied to the original switching power supply conversion circuit, so that the system can complete the battery charging action and the battery obtains power; and by detecting the power, the two normally closed relays are controlled to switch on and off, and the mains disconnection is completed to switch to battery power supply, so that the system can work normally again. In this way, it can avoid that the battery cannot be charged when it is fully discharged, reduce costs and extend the battery life.

[0039] In some embodiments, the backup power supply device includes: a rectifier module (such as a rectifier bridge) and a second switching power supply (such as switching power supply II); wherein the AC power end is connected to the first switching power supply after passing through the rectifier module, the second normally closed switch, and the second switching power supply.

[0040] Figure 3 FIG. 1 is a schematic diagram of the structure of an embodiment of a low-voltage energy storage system of the present invention. Figure 3 As shown, Figure 2 The example shown differs in that Figure 3 In the example shown, on the low-voltage energy storage battery side, a normally closed relay K1 is provided between the 48V low-voltage energy storage battery and the switching power supply I. On the mains side, a rectifier bridge and a switching power supply II are provided, and a normally closed relay K2 is provided between the rectifier bridge and the switching power supply II. The mains is connected to the switching power supply II via the rectifier bridge, the normally closed relay K2. The main chip is connected to the control end of the normally closed relay K2, and the switching power supply II is connected to the switching power supply I. The control end of the normally closed relay K2 is used to receive the control signal sent by the main chip; the control signal sent by the main chip is used to control the closing and opening of the normally closed relay K2.

[0041] The circuit topology of the energy storage system involved in the control method in the related scheme is as follows: Figure 2 As shown, the control method used in the solution of the present invention is improved on this basis. Figure 3 As shown, a switching power supply II is added to the mains side. The output of the switching power supply II is only used to power the switching power supply I. The power required by the subsequent control circuit of the energy storage system is still provided by the switching power supply I, which can avoid adding too many additional switching power supply circuits. At the same time, in the switching power supply circuit, a normally closed relay (such as Figure 3The normally closed relay K1 and the normally closed relay K2 in the example shown detect the battery terminal voltage through the sampling circuit to determine whether the battery has power and at the same time the power reaches the set value that can be used by the control circuit to control the on and off of the two normally closed relays, so that when the battery is fully discharged, the control circuit can be powered by the mains for a short time, and when the battery has power, it will automatically switch to battery power supply. Among them, since the power supply of the switching power supply is powered by the energy storage battery, the voltage of the energy storage battery is sampled. Thereby, it can be avoided that the battery cannot be charged in the fully discharged state and can only be charged by outsourcing, which reduces costs and prolongs the battery life. At the same time, the voltage detection control relay is used to switch the power supply between the mains and the battery, which can also avoid excessive use of additional mains power.

[0042] In some embodiments, the control device of the battery energy storage system described in the solution of the present invention further includes: a power rail; the first switching power supply is arranged in the power rail. A power rail refers to a power supply line that provides a stable DC voltage for an electronic circuit. In an electronic device, different circuit modules may require power supplies of different voltage levels, so there may be multiple power rails in a system. Each power rail is usually generated and maintained by a power management chip (such as a voltage regulator, a DC-DC converter, etc.). The power rail is used to provide the small voltages required by each module of the entire system, such as 24V, 12V, 18V, 3.3V and other small voltages. That is to say, the control device of the battery energy storage system includes: a main circuit, a power rail and a control circuit; the main circuit has an energy storage module (such as a 48V low-voltage energy storage battery) and a voltage conversion circuit (such as a DCDC circuit and a DC / AC circuit, etc.); the power rail has a first switching power supply (such as a switching power supply I); the energy storage module is used to supply power to the voltage conversion circuit and the first switching power supply respectively; the voltage conversion circuit is connected to an external photovoltaic end, a mains end, and a load end, and is used to perform voltage conversion with at least one of the external photovoltaic end, the mains end, and the load end under the control of the control circuit; the first switching power supply is connected to the control circuit and is used to supply power to the control circuit.

[0043] In the solution of the present invention, a first switching power supply (such as switching power supply I) is arranged in the power rail, and power is supplied to the control circuit through the power rail, which can meet the power supply needs of multiple power-consuming modules in the control circuit, making the power supply convenient and safe; and a switching power supply II is added at the mains end, and the output of the switching power supply II is only used to power the switching power supply I. The power required for the subsequent control circuit of the energy storage system is still provided by the switching power supply I, which can avoid adding too many additional switching power supply circuits.

[0044] In some embodiments, the main circuit also has a first switch (such as relay K1), a second switch (such as relay K2), and a third switch (such as relay K3); the voltage conversion circuit includes: a DCDC module (such as a bidirectional DCDC buck-boost circuit), and a DCAC module (such as a DC / AC circuit).

[0045] Wherein, the energy storage module, after passing through the first switch, the DCDC module and the DCAC module: is connected to the load end through the second switch, and is connected to the mains end through the third switch; the common end of the DCDC module and the DCAC module is connected to the photovoltaic end. The control end of the first switch, the control end of the second switch, the control end of the third switch, the control end of the DCDC module, and the control end of the DCAC module are all connected to the control circuit to perform corresponding actions under the control of the control circuit.

[0046] The energy storage system circuit topology adopted by the solution of the present invention is as follows Figure 3 As shown, when the energy storage system is in the discharge mode, the low-voltage battery end converts the low-voltage DC into high-voltage DC through a bidirectional DCDC boost converter (such as a bidirectional DCDC buck-boost circuit), and then converts it into AC that can be used for household appliance loads through a DC-AC inverter circuit converter (such as a DC / AC circuit). When the system is in the mains charging mode, the high-voltage AC input from the mains end is converted into high-voltage DC through an AC-DC rectifier circuit converter (such as a rectifier bridge), and then the high-voltage DC is converted into low-voltage DC for battery charging through a bidirectional DCDC buck converter; when the battery is in the charge and discharge mode, its relay drive, the switch tube drive circuit of the DCDC / DCAC circuit, the sampling circuit, and the main chip power supply are powered by the battery side, which can realize the low-voltage energy storage power supply between the photovoltaic end, the load end, the energy storage battery end and the mains end, and meet the normal operation requirements of the low-voltage energy storage system. When the low-voltage energy storage system is in normal charging and discharging operation, the power supply required by its control circuit is the power supply converted from the battery end voltage, that is, under normal circumstances, as long as the battery is still charged, the system can work normally.

[0047] In some embodiments, the main circuit further has a BMS; the BMS is connected to the energy storage battery.

[0048] In the solution of the present invention, the energy storage module, such as a 48V low-voltage energy storage battery, is controlled by a BMS to ensure the safety of the low-voltage energy storage battery. BMS is an electronic system for managing and monitoring battery packs (especially lithium-ion battery packs), mainly used to ensure the safe, efficient and reliable operation of battery packs.

[0049] In some embodiments, the control circuit includes: a main control module (such as a main chip), a sampling module (such as Figure 3 The sampling circuit in the example shown), and the comparison module (such as Figure 3 The comparison circuit in the example shown).

[0050] The sampling module is used to sample the remaining power of the energy storage module before the battery energy storage system is operated; to sample the discharge voltage of the energy storage module during the operation of the energy storage module; and to sample the voltage of the energy storage module after charging in the process of the mains end through the voltage conversion circuit to obtain the charging voltage of the energy storage module. The sampling module can directly detect the voltage at both ends of the battery at the battery output end, and after processing the detected signal, judge and make corresponding control through the main chip.

[0051] The comparison module is used to compare the remaining power of the energy storage module obtained by sampling with a preset remaining power threshold to obtain a remaining power comparison result; compare the discharge voltage of the energy storage module obtained by sampling with a preset discharge voltage threshold to obtain a discharge voltage comparison result; and compare the charging voltage of the energy storage module obtained by sampling with a preset charging voltage threshold to obtain a charging voltage comparison result. The preset discharge voltage threshold is such as voltage Vref1, and the preset charging voltage threshold is such as voltage Vref2.

[0052] The main control module is used to control the operation of the battery energy storage system by controlling the first normally closed switch to close and the second normally closed switch to open if it is determined that the remaining power of the energy storage module is above a preset remaining power threshold based on the remaining power comparison result.

[0053] The main control module is further used to determine that the energy storage module is in a fully discharged state if it is determined that the discharge voltage of the energy storage module is less than a preset discharge voltage threshold value based on the discharge voltage comparison result, and control the battery energy storage system to stop running, that is, to make the energy storage module exit the discharge mode: control the second normally closed switch to be closed, so that the backup power supply device draws power from the mains end and supplies power to the control circuit through the first switching power supply; control the first normally closed switch to be disconnected, and control the mains end to charge the energy storage module through the voltage conversion circuit, so that the energy storage module is in a charging mode.

[0054] The main control module is further used to control the second normally closed switch to open and the first normally closed switch to close if it is determined that the charging voltage of the energy storage module is greater than a preset charging voltage threshold based on the charging voltage comparison result, so as to switch the power supply from the AC power end to the first switching power supply to the energy storage battery.

[0055] The main control module controls the first normally closed switch to close, which means that the first normally closed switch automatically closes when it loses the control of the preset effective level sent by the main control module; the main control module controls the second normally closed switch to close, which means that the second normally closed switch automatically closes when it loses the control of the preset effective level sent by the main control module. The preset effective level is such as a high level, and the situation of losing the control of the preset effective level sent by the main control module is such as receiving a preset invalid level such as a low level.

[0056] Figure 4 The figure is a flow chart of an embodiment of the control method of the low-voltage energy storage system of the present invention. The control method of the related scheme is to detect the battery power on the low-voltage side during the battery discharge process, and remind the user to charge when the power drops to a certain safety threshold to avoid entering a fully discharged state; however, when the battery reaches the threshold, if it cannot be charged for a long time due to the lack of AC power or photovoltaic power, the battery power will actually be completely released, and the battery will not be able to be charged by AC power or photovoltaic power. The control process of the scheme of the present invention is as follows Figure 4 As shown in the figure, based on the control method of the related scheme, a switching power supply II is added to the input side of the mains, and a normally closed relay is added to the rear end of the rectifier bridge at the switching power supply II and between the battery end and the switching power supply I. Figure 4 As shown, the control method of the low-voltage energy storage system includes:

[0057] Step 11, when the low-voltage energy storage battery has power and the low-voltage energy storage system operates normally, that is, the battery is not in a fully discharged state, the control circuit power supply of the system is taken from the battery end, and the control circuit is powered by the switch power supply I. At this time, the normally closed relay K1 is turned on, and the normally closed relay K2 is controlled to be turned off. It is only powered by the battery, and then step 12 is executed.

[0058] Step 12: The system discharge mode operates normally, and then step 13 is executed.

[0059] Step 13, the sampling and comparison circuit detects the voltage Vbat at both ends of the battery, and determines whether the voltage Vbat at both ends of the battery is less than the threshold Vref1: if so, execute step 14, otherwise return to step 12.

[0060] Step 14: When the battery detects that the power level is lower than the threshold value Vref1 during the discharge process, the system stops discharging the battery and reminds the user to charge, and then executes step 21.

[0061] Step 21, after the battery detects that the power level is lower than the threshold value Vref1 during the discharge process, the system stops discharging the battery. When the battery is not charged for a long time and the remaining power of the battery is completely released in the air, when the battery is charged again at this time, the circuit control circuit power supply cannot be powered by the battery side, and can only be powered by the AC power. Since the normally closed relay K1 and the normally closed relay K2 keep the relay closed and conducting when no control signal is received, the AC power switch is turned on at this time, and the AC power passes through a switching power supply II and is rectified into DC power by a rectifier bridge. After passing through the normally closed relay K2, power conversion is performed. The converted DC power is only used for the switching power supply I to work, so that the system can charge the battery and notify the control normally closed relay K1 to turn off, cut off the battery power supply, that is, replace the energy storage battery to power the switching power supply I for a short time, and the battery starts to charge, and then execute step 22.

[0062] Step 22: When the battery starts to charge, the sampling circuit samples the battery terminal voltage Vbat and detects it, and then executes step 23.

[0063] Step 23, compare with the set value Vref2 through a comparator to determine whether the battery terminal voltage Vbat is greater than the set value Vref2: if so, execute step 24, otherwise return to step 21.

[0064] Step 24, compare with the set value Vref2 through the comparator. If the battery terminal voltage exceeds the set value at this time, it means that the battery power is sufficient to supply power to the control circuit. At this time, the main chip controls the normally closed relay K1 to close and the normally closed relay K2 to open. The switch power supply I switches from AC power to battery power, and the system returns to normal operation.

[0065] In the solution of the present invention, based on Figure 2 The control circuit of the low-voltage energy storage system shown in the figure adds a switch power supply II at the mains end. The output of the switch power supply II is only used to power the switch power supply I. The power required for the subsequent control circuit of the energy storage system is still provided by the switch power supply I. A normally closed relay (such as ) is added to the rear end of the rectifier bridge on the mains side and the battery end (i.e., the 48V low-voltage energy storage battery side) Figure 3The normally closed relay K1 and the normally closed relay K2 in the example shown control the on and off of the two normally closed relays by judging whether the battery has power and that the power reaches a set value that can be used by the control circuit, so that when the battery is fully discharged, the control circuit can be powered by the AC power for a short time, and when the battery has power, it automatically switches to battery power supply, which at least avoids the inability to charge the battery when it is fully discharged, reduces costs and extends battery life. At the same time, the voltage detection control relay is used to switch between the AC power and the battery, which can also avoid excessive use of additional AC power.

[0066] In some implementations, the control circuit further includes: a switch driving module (such as a relay driving circuit), a DCDC driving module (such as a DCDC driving circuit), and a DCAC driving module (such as a DCAC driving circuit).

[0067] Wherein, in the case that the main circuit further comprises a first switch, a second switch and a third switch, the switch driving module is used to drive corresponding switches among the first switch, the second switch and the third switch under the control of the main control module.

[0068] In the case where the voltage conversion circuit includes a DCDC module, the DCDC driving module is used to drive the DCDC module under the control of the main control module.

[0069] In the case where the voltage conversion circuit includes a DCAC module, the DCAC driving module is used to drive the DCAC module under the control of the main control module.

[0070] In the solution of the present invention, based on Figure 2 In the energy storage system circuit topology shown in the figure, a switching power supply II is added to the mains side. The output of the switching power supply II is only used to power the switching power supply I. The power required for the subsequent control circuit of the energy storage system is still provided by the switching power supply I. At the same time, in the switching power supply circuit, a normally closed relay (such as Figure 3 The normally closed relay K1 and the normally closed relay K2 in the example shown detect the battery terminal voltage through a sampling circuit to determine whether the battery has power and at the same time the power reaches a set value that can be used by the control circuit to control the on and off of the two normally closed relays, so that when the battery is fully discharged, the control circuit can be powered by the AC power for a short time, and when the battery has power, it will automatically switch to battery power supply, which can avoid the situation where the battery cannot be charged in a fully discharged state and can only be charged by outsourcing, thereby reducing costs and extending battery life. At the same time, the voltage detection control relay is used to switch the power supply between the AC power and the battery, which can also avoid excessive use of additional AC power.

[0071] The technical solution of the present invention is adopted, by targeting a battery energy storage system (such as a low-voltage battery energy storage system) having a main circuit, a power rail and a control circuit, an energy storage battery (such as a low-voltage energy storage battery) and a voltage conversion circuit (such as a DCDC circuit, a DC / AC circuit, etc.) are arranged in the main circuit, a first switching power supply (such as a switching power supply I) is arranged in the power rail, a main chip and a functional circuit (such as a sampling circuit, a communication circuit, a relay drive circuit, a DCDC drive circuit, a DCAC drive circuit, etc.) are arranged in the control circuit, and the energy storage battery supplies power to the control circuit after the first switching power supply; the voltage conversion circuit can be connected to an external photovoltaic power generation component, a mains access terminal, and a load; a first normally closed switch (such as a normally closed relay K1) is arranged between the energy storage battery and the first switching power supply, a rectifier bridge and a second switching power supply (such as a switching power supply II) are arranged at the mains access terminal, and a second normally closed switch (such as Normally closed relay K2), the second switch power supply is connected to the first switch power supply; when the power of the energy storage battery is sufficient and the battery energy storage system operates normally, the first normally closed switch is closed and the second normally closed switch is opened; when the energy storage battery is in a fully discharged state, the second normally closed switch is closed, and the second switch power supply uses the mains power to supply power to the first switch power supply, so that the control circuit can work and control the first normally closed switch to be opened, and the battery energy storage system charges the energy storage battery until the voltage of the energy storage battery is higher than the set value, the first normally closed switch is controlled to be closed, and the second normally closed switch is controlled to be opened, and the power supply from the mains power to the first switch power supply is switched to the power supply from the energy storage battery to the first switch power supply; thus, by taking power from the mains power end when the energy storage battery is in a fully discharged state to enable the control circuit to operate normally so as to charge the energy storage battery, and when the energy storage battery is charged to the set value, switching to the power supply from the energy storage battery to the control circuit can ensure the normal operation of the battery energy storage system and help to extend the service life of the energy storage battery.

[0072] According to an embodiment of the present invention, a battery energy storage system corresponding to the control device of the battery energy storage system is also provided. The battery energy storage system may include: the control device of the battery energy storage system described above.

[0073] Since the processing and functions implemented by the battery energy storage system of this embodiment basically correspond to the embodiments, principles and examples of the device, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0074] According to an embodiment of the present invention, a control method for a battery energy storage system corresponding to the battery energy storage system is also provided, such as Figure 5 The flowchart of an embodiment of the method of the present invention is shown in FIG. The control method of the battery energy storage system may include: steps S110 to S160.

[0075] In step S110, before the battery energy storage system is operated, the remaining power of the energy storage module is obtained.

[0076] At step S120, if it is determined that the remaining power of the energy storage module is above the preset remaining power threshold, the battery energy storage system is controlled to operate: the first normally closed switch is controlled to be closed, and the second normally closed switch is controlled to be opened, so that the energy storage module is in a discharge mode.

[0077] At step S130, during the operation of the battery energy storage system, that is, when the energy storage battery is in a discharge mode, the discharge voltage of the energy storage module is obtained.

[0078] In step S140, it is determined whether the discharge voltage of the energy storage module is less than a preset discharge voltage threshold: if so, it is determined that the energy storage module is in a fully discharged state; otherwise, the energy storage battery continues to be in a discharge mode.

[0079] At step S150, when the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop running: the second normally closed switch is controlled to be closed, so that the backup power supply device draws power from the mains end and supplies power to the control circuit through the first switching power supply; the first normally closed switch is controlled to be disconnected, and the mains end is controlled to charge the energy storage module through the voltage conversion circuit, so that the energy storage battery is in a charging mode.

[0080] At step S160, during the charging process of the energy storage module, until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed, so as to switch the power supply from the AC power end to the first switching power supply to the energy storage battery.

[0081] The scheme of the present invention is based on the control method adopted in the circuit topology of the low-voltage battery energy storage system in the related scheme. In order to solve the problem that the system cannot continue to use the energy storage battery to power the control circuit when the battery is fully discharged, a switching power supply circuit is added at the mains end, and a normally closed relay is added at the rear end of the rectifier bridge and the battery end of the circuit. When the battery is fully discharged, the DC power converted by the added switching power supply is supplied to the original switching power supply conversion circuit, so that the system can complete the battery charging action and the battery obtains power; and by detecting the power, the two normally closed relays are controlled to switch on and off, and the mains disconnection is completed to switch to battery power supply, so that the system can work normally again. In this way, it can avoid that the battery cannot be charged when it is fully discharged, reduce costs and extend the battery life.

[0082] In some embodiments, in step S1260, when the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed. For the specific process, see the following exemplary description.

[0083] Combine the following Figure 6 The method of the present invention is shown as a flow chart of an embodiment of controlling the second normally closed switch to open and the first normally closed switch to close in the charging mode of the energy storage battery, further illustrating the specific process of controlling the second normally closed switch to open and the first normally closed switch to close in the charging mode of the energy storage battery in step S160, including: steps S210 to S240.

[0084] Step S210, when the mains end is charging the energy storage module via the voltage conversion circuit, that is, when the energy storage battery is in a charging mode, the voltage of the energy storage module after charging is obtained to obtain the charging voltage of the energy storage module.

[0085] Step S220, determining whether the charging voltage of the energy storage module is greater than a preset charging voltage threshold.

[0086] Step S230: If it is determined that the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed, so as to switch the power supply from the AC power end to the first switching power supply to the energy storage battery.

[0087] Step S240: If it is determined that the charging voltage of the energy storage module is not greater than the preset charging voltage threshold, the mains terminal continues to charge the energy storage module via the voltage conversion circuit, that is, the energy storage battery continues to be in the charging mode.

[0088] The control process of the scheme of the present invention is as follows Figure 4 As shown in the figure, based on the control method of the related scheme, a switching power supply II is added to the input side of the mains, and a normally closed relay is added to the rear end of the rectifier bridge at the switching power supply II and between the battery end and the switching power supply I. Figure 4 As shown, the control method of the low-voltage energy storage system includes:

[0089] Step 11, when the low-voltage energy storage battery has power and the low-voltage energy storage system operates normally, that is, the battery is not in a fully discharged state, the control circuit power supply of the system is taken from the battery end, and the control circuit is powered by the switch power supply I. At this time, the normally closed relay K1 is turned on, and the normally closed relay K2 is controlled to be turned off. It is only powered by the battery, and then step 12 is executed.

[0090] Step 12: The system discharge mode operates normally, and then step 13 is executed.

[0091] Step 13, the sampling and comparison circuit detects the voltage Vbat at both ends of the battery, and determines whether the voltage Vbat at both ends of the battery is less than the threshold Vref1: if so, execute step 14, otherwise return to step 12.

[0092] Step 14: When the battery detects that the power level is lower than the threshold value Vref1 during the discharge process, the system stops discharging the battery and reminds the user to charge, and then executes step 21.

[0093] Step 21, after the battery detects that the power level is lower than the threshold value Vref1 during the discharge process, the system stops discharging the battery. When the battery is not charged for a long time and the remaining power of the battery is completely released in the air, when the battery is charged again at this time, the circuit control circuit power supply cannot be powered by the battery side, and can only be powered by the AC power. Since the normally closed relay K1 and the normally closed relay K2 keep the relay closed and conducting when no control signal is received, the AC power switch is turned on at this time, and the AC power passes through a switching power supply II and is rectified into DC power by a rectifier bridge. After passing through the normally closed relay K2, power conversion is performed. The converted DC power is only used for the switching power supply I to work, so that the system can charge the battery and notify the control normally closed relay K1 to turn off, cut off the battery power supply, that is, replace the energy storage battery to power the switching power supply I for a short time, and the battery starts to charge, and then execute step 22.

[0094] Step 22: When the battery starts to charge, the sampling circuit samples the battery terminal voltage Vbat and detects it, and then executes step 23.

[0095] Step 23, compare with the set value Vref2 through a comparator to determine whether the battery terminal voltage Vbat is greater than the set value Vref2: if so, execute step 24, otherwise return to step 21.

[0096] Step 24, compare with the set value Vref2 through the comparator. If the battery terminal voltage exceeds the set value at this time, it means that the battery power is sufficient to supply power to the control circuit. At this time, the main chip controls the normally closed relay K1 to close and the normally closed relay K2 to open. The switch power supply I switches from AC power to battery power, and the system returns to normal operation.

[0097] In the solution of the present invention, based on Figure 2 The control circuit of the low-voltage energy storage system shown in the figure adds a switch power supply II at the mains end. The output of the switch power supply II is only used to power the switch power supply I. The power required for the subsequent control circuit of the energy storage system is still provided by the switch power supply I. A normally closed relay (such as ) is added to the rear end of the rectifier bridge on the mains side and the battery end (i.e., the 48V low-voltage energy storage battery side) Figure 3The normally closed relay K1 and the normally closed relay K2 in the example shown control the on and off of the two normally closed relays by judging whether the battery has power and that the power reaches a set value that can be used by the control circuit, so that when the battery is fully discharged, the control circuit can be powered by the AC power for a short time, and when the battery has power, it automatically switches to battery power supply, which at least avoids the inability to charge the battery when it is fully discharged, reduces costs and extends battery life. At the same time, the voltage detection control relay is used to switch between the AC power and the battery, which can also avoid excessive use of additional AC power.

[0098] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned battery energy storage system, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further description will be given here.

[0099] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0100] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A control device for a battery energy storage system, characterized in that: include: A main circuit, a first switching power supply and a control circuit; the main circuit has an energy storage module and a voltage conversion circuit; The energy storage module is used to supply power to the voltage conversion circuit and the first switching power supply respectively; the voltage conversion circuit is used to perform voltage conversion between at least one of an external photovoltaic terminal, a mains terminal, and a load terminal under the control of the control circuit; The first switching power supply is used to supply power to the control circuit; It also includes: a first normally closed switch, a second normally closed switch, and a backup power supply; the first normally closed switch is arranged between the energy storage module and the first switch power supply; the second normally closed switch and the backup power supply are cooperatively arranged between the mains terminal and the first switch power supply; in, When the remaining power of the energy storage module is above a preset remaining power threshold, the control circuit controls the battery energy storage system to operate: the control circuit does not control the first normally closed switch, that is, the first normally closed switch is closed, and the control circuit controls the second normally closed switch to be open; During the operation of the battery energy storage system, if the control circuit determines that the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop operating: the control circuit does not control the second normally closed switch, that is, the second normally closed switch is closed, so that the backup power supply device takes power from the mains end and supplies power to the control circuit through the first switch power supply; the control circuit controls the first normally closed switch to be disconnected, and the control circuit controls the mains end to charge the energy storage module through the voltage conversion circuit; Until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the control circuit controls the second normally closed switch to be disconnected, and the control circuit does not control the first normally closed switch, that is, the first normally closed switch to be closed, so as to switch the power supply from the AC power end to the first switching power supply to the energy storage battery.

2. The control device of the battery energy storage system according to claim 1, characterized in that: The backup power supply device comprises: a rectifier module and a second switching power supply; wherein: The mains power end is connected to the first switch power supply after passing through the rectifier module, the second normally closed switch, and the second switch power supply.

3. The control device of the battery energy storage system according to claim 1 or 2, characterized in that: Also includes: Power rails; The first switching power supply is arranged in the power rail.

4. The control device of the battery energy storage system according to any one of claims 1 to 3, characterized in that: The main circuit further comprises a first switch, a second switch, and a third switch; The voltage conversion circuit includes: a DCDC module and a DCAC module; wherein, The energy storage module, after passing through the first switch, the DCDC module and the DCAC module: is connected to the load end through the second switch, and is connected to the mains end through the third switch; the common end of the DCDC module and the DCAC module is connected to the photovoltaic end; The control end of the first switch, the control end of the second switch, the control end of the third switch, the control end of the DCDC module, and the control end of the DCAC module are all connected to the control circuit to perform corresponding actions under the control of the control circuit.

5. The control device of the battery energy storage system according to claim 4, characterized in that: The main circuit also has a BMS; the BMS is connected to the energy storage battery.

6. The control device of the battery energy storage system according to any one of claims 1 to 5, characterized in that: The control circuit includes: a main control module, a sampling module, and a comparison module; wherein, The sampling module is used to sample the remaining power of the energy storage module before the battery energy storage system is operated; to sample the discharge voltage of the energy storage module during the operation of the energy storage module; and to sample the voltage of the energy storage module after charging during the charging of the energy storage module by the mains terminal through the voltage conversion circuit to obtain the charging voltage of the energy storage module; The comparison module is used to compare the remaining power of the energy storage module obtained by sampling with a preset remaining power threshold to obtain a remaining power comparison result; compare the discharge voltage of the energy storage module obtained by sampling with a preset discharge voltage threshold to obtain a discharge voltage comparison result; and compare the charging voltage of the energy storage module obtained by sampling with a preset charging voltage threshold to obtain a charging voltage comparison result; The main control module is configured to control the battery energy storage system to operate by controlling the first normally closed switch to close and the second normally closed switch to open if it is determined that the remaining power of the energy storage module is above a preset remaining power threshold according to the remaining power comparison result; The main control module is further used to determine that the energy storage module is in a fully discharged state and control the battery energy storage system to stop running if it is determined that the discharge voltage of the energy storage module is less than a preset discharge voltage threshold according to the discharge voltage comparison result: control the second normally closed switch to be closed so that the backup power supply device supplies power to the control circuit through the first switch power supply after taking power from the mains end; control the first normally closed switch to be disconnected, and control the mains end to charge the energy storage module through the voltage conversion circuit; The main control module is further configured to control the second normally closed switch to be opened and the first normally closed switch to be closed, so as to switch the supply of power from the mains end to the first switching power supply to the supply of power from the energy storage battery, if it is determined that the charging voltage of the energy storage module is greater than a preset charging voltage threshold value according to the charging voltage comparison result; Among them, the main control module controls the first normally closed switch to close, and the first normally closed switch automatically closes when the control of the preset effective level sent by the main control module is lost; the main control module controls the second normally closed switch to close, and the second normally closed switch automatically closes when the control of the preset effective level sent by the main control module is lost.

7. The control device of the battery energy storage system according to claim 6, characterized in that: The control circuit further includes: a switch driving module, a DCDC driving module, and a DCAC driving module; wherein, In the case where the main circuit further comprises a first switch, a second switch and a third switch, the switch driving module is used to drive a corresponding switch among the first switch, the second switch and the third switch under the control of the main control module; In the case where the voltage conversion circuit includes a DCDC module, the DCDC driving module is used to drive the DCDC module under the control of the main control module; In the case where the voltage conversion circuit includes a DCAC module, the DCAC driving module is used to drive the DCAC module under the control of the main control module.

8. A battery energy storage system, characterized in that: include: A control device for a battery energy storage system according to any one of claims 1 to 7.

9. A control method for a battery energy storage system as claimed in claim 8, characterized in that: include: Obtaining the remaining power of the energy storage module; If it is determined that the remaining power of the energy storage module is above a preset remaining power threshold, the battery energy storage system is controlled to operate: the first normally closed switch is controlled to be closed, and the second normally closed switch is controlled to be opened; During the operation of the battery energy storage system, obtaining the discharge voltage of the energy storage module; Determine whether the discharge voltage of the energy storage module is less than a preset discharge voltage threshold: if so, determine that the energy storage module is in a fully discharged state, otherwise continue to keep the energy storage battery in a discharge mode; When the energy storage module is in a fully discharged state, the battery energy storage system is controlled to stop running: the second normally closed switch is controlled to be closed, so that the backup power supply device takes power from the mains end and supplies power to the control circuit through the first switch power supply; the first normally closed switch is controlled to be opened, and the mains end is controlled to charge the energy storage module through the voltage conversion circuit; Until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed, so as to switch the power supply from the AC power end to the first switching power supply to the energy storage battery.

10. The control method of the battery energy storage system according to claim 9, characterized in that: until the charging voltage of the energy storage module is greater than a preset charging voltage threshold, controlling the second normally closed switch to be opened and controlling the first normally closed switch to be closed, comprising: In the process of charging the energy storage module from the mains terminal via the voltage conversion circuit, obtaining the voltage of the energy storage module after charging to obtain the charging voltage of the energy storage module; Determining whether the charging voltage of the energy storage module is greater than a preset charging voltage threshold; If it is determined that the charging voltage of the energy storage module is greater than a preset charging voltage threshold, the second normally closed switch is controlled to be opened, and the first normally closed switch is controlled to be closed, so as to switch the supply of power from the mains end to the first switching power supply to the energy storage battery; If it is determined that the charging voltage of the energy storage module is not greater than the preset charging voltage threshold, the mains terminal continues to charge the energy storage module via the voltage conversion circuit.

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