Control circuit and method for energy storage system, and energy storage system

Abstract

Disclosed in the present application are a control circuit and method for an energy storage system. The control circuit for an energy storage system comprises a battery cell module, a control module and a reversing module, wherein the battery cell module, the control module and the reversing module are sequentially connected; the battery cell module comprises n modular battery cell control units, each modular battery cell control unit comprising a battery cell, a first switch and a second switch; the battery cell and the first switch are connected in series and are then connected in parallel to the second switch; n is a positive integer; the first one of the first switches and the first one of the second switches are connected to serve as a first end of the battery cell module, and an n-th one of the battery cells and an n-th one of the second switches are connected to serve as a second end of the battery cell module; and the control module is in communication connection with the modular battery cell control units and the reversing module, and the control module is used for controlling the switching on or off of a first reversing switch, a second reversing switch, a third reversing switch and a fourth reversing switch.

Description

Energy storage system control circuit, method and energy storage system

[0001] This application claims priority to Chinese patent applications filed with the China Patent Office on June 30, 2023, with application numbers 202310802285.X, 202321712965.4, 202310795655.1 and 202321701876.X. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of power supply circuit technology, and in particular to a control circuit, method, and energy storage system for an energy storage system. Background Art

[0003] In related technologies, lithium-ion battery energy storage systems primarily consist of a battery system and a power conversion system (PCS). The PCS primarily uses power electronics technology to convert the battery's DC voltage to the grid's AC voltage. The PCS controls the battery system's charging and discharging, performing AC-DC conversion and enabling direct power supply to AC loads in the absence of a power grid. The battery system is constructed by connecting 15s or 16s cells in series to form modules, which are then connected in series to form packs (assembly batteries). Multiple packs are then connected in series to form battery clusters. Once the required high voltage is achieved, energy is exchanged with the AC grid through the PCS. The battery modules or packs contain slave control units of the Battery Management System (BMS), while the battery clusters contain master control units of the BMS to manage the battery system.

[0004] However, as battery cell capacity and size continue to grow, individual cells become larger and heavier. If these cells are connected in series to form modules, the modules become very large and weigh several hundred kilograms, making assembly inconvenient. Furthermore, due to the high costs of BMS and PCS, PCS systems are bulky, resulting in high energy storage system costs and the inability to mix old and new battery cells. Technical issues

[0005] The present application provides a control circuit, method and energy storage system for an energy storage system, which can reduce the size of the energy storage inverter, reduce costs, improve the utilization rate of the energy storage system and increase profits. Technical Solutions

[0006] In a first aspect, an embodiment of the present application provides a control circuit of an energy storage system, the control circuit of the energy storage system comprising: a battery cell module, a control module, and a reversing module, wherein the battery cell module, the control module, and the reversing module are connected in sequence;

[0007] The battery module includes n modular battery control units, each of which includes a battery, a first switch, and a second switch; the battery and the first switch are connected in series and then connected in parallel with the second switch; wherein n is a positive integer;

[0008] The first first switch and the first second switch are connected to serve as the first end of the battery module, and the nth battery cell and the nth second switch are connected to serve as the second end of the battery module;

[0009] The reversing module includes a first reversing switch, a second reversing switch, a third reversing switch, a fourth reversing switch and a filter unit, the filter unit includes a first end, a second end and a third end, the first end of the battery cell module is respectively connected to the first end of the first reversing switch and the third reversing switch, the second end of the first reversing switch is connected to the first end of the filter unit, and the second end of the third reversing switch is connected to the third end of the filter unit; the second end of the battery cell module is respectively connected to the first end of the second reversing switch and the fourth reversing switch, the second reversing switch is connected to the first end of the filter unit, and the second end of the fourth reversing switch is connected to the third end of the filter unit, and the AC power grid is connected between the second end and the third end of the filter unit;

[0010] The control module is in communication with the modular battery cell control unit and the reversing module, and is used to control the opening or closing of the first reversing switch, the second reversing switch, the third reversing switch, and the fourth reversing switch.

[0011] In a second aspect, an embodiment of the present application provides a method for controlling an energy storage system, the method comprising:

[0012] Detect AC grid voltage;

[0013] Calculating the phase angle between the grid voltage and the loop voltage based on the AC grid voltage and the battery cell series loop voltage;

[0014] Determining an operating mode of the energy storage system, wherein the operating mode includes a discharge mode and a charge mode;

[0015] The energy storage system is in a charging mode and the grid voltage and the phase angle meet preset conditions, and the control module performs switching according to a first preset control strategy;

[0016] The energy storage system is in a discharge mode and the grid voltage and the phase angle meet preset conditions, and the control module performs switching according to a second preset control strategy. Beneficial effects

[0017] In a third aspect, an embodiment of the present application provides an energy storage system, comprising: n-stage modular battery cell control units connected in series, the modular battery cell control unit comprising an external connection terminal, a battery cell, a temperature detection circuit, a battery cell microcontroller module, a battery cell voltage detection circuit, a communication circuit, and a switch switching module; wherein n is a positive integer; BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The battery cell is electrically connected to the external connection terminal through the switch module; the switch module is used to control whether the battery cell is connected to the energy storage system;

[0019] The temperature detection circuit is electrically connected to the battery cell and the battery cell micro-control module respectively, and the temperature detection circuit is used to detect the temperature of the battery cell and send the temperature information of the battery cell to the battery cell micro-control module;

[0020] The battery cell voltage detection circuit is connected in series between the battery cell and the battery cell micro-control module, and the battery cell voltage detection circuit is used to detect the voltage of the battery cell and send the voltage information of the battery cell to the battery cell micro-control module;

[0021] The communication circuit is in communication connection with the cell microcontroller module, and the communication circuit is used for information exchange between the modular cell control unit and the upper control unit;

[0022] The cell micro-control module is also electrically connected to the switch switching module, and the cell micro-control module is used to control the switch switching module according to the temperature information and / or voltage information of the cell and / or the interactive information of the upper control unit.

[0023] The embodiment of the present application forms an energy storage system by integrating the control circuit and the battery cell into a single module. The product is modularized and standardized, making assembly and wiring convenient. The energy storage system can be formed without a separate BMS and PCS, which makes assembly more convenient. Since a separate BMS and PCS are not required, the volume is reduced, so the overall cost of the entire energy storage system will be very low. The bus capacitor in the traditional energy storage inverter is eliminated, and the volume can be very small; the filter device does not need to be as large as the traditional energy storage inverter, which can also reduce the cost and volume; the control circuit can bypass the faulty battery cell without affecting the normal operation of the energy storage system, which is beneficial to improve the utilization rate of the energy storage system and increase the profit. Since high-voltage battery cells are used first during discharge and low-voltage battery cells are used first during charging, there is no need for an additional BMS to control the battery cells, which reduces the cost of the BMS. The battery cells can be connected in series to the system circuit according to a certain algorithm, and new and old battery cells can be mixed, which improves the utilization rate of the energy storage system and increases the profit.

[0024] In addition, the technical solution of the embodiment of the present application sets up a modular battery cell control unit, and uses the temperature detection circuit and battery cell voltage detection circuit therein to detect the temperature and voltage information of the battery cell, and sends it to the battery cell micro-control module. The battery cell micro-control module uploads the information to the superior control unit through the communication circuit. The superior control unit sends instructions to the battery cell micro-control module based on the information of each module. The battery cell micro-control module controls the switch switching module according to the instruction signal to control the battery cell to be connected to or disconnected from the energy storage system. The technical solution provided by the embodiment of the present application can modularize the battery cell control unit, and the energy storage system can be formed without the need for a battery management system and an energy storage converter, which is convenient for assembly and operation and can reduce costs. In summary, the present application solves the problems in the prior art of large energy storage inverters, high cost of energy storage systems, and inability to mix new and old battery cells.

[0025] FIG1 is a circuit schematic diagram of a control circuit of an energy storage system provided according to an embodiment of the present application;

[0026] FIG2 is a circuit schematic diagram of a control circuit of another energy storage system provided according to an embodiment of the present application;

[0027] FIG3 is a schematic diagram of an AC-DC conversion method according to an embodiment of the present application;

[0028] FIG4 is a flow chart of a cell switching algorithm logic provided according to an embodiment of the present application;

[0029] FIG5 is a schematic diagram of a voltage waveform change provided according to an embodiment of the present application;

[0030] FIG6 is a waveform diagram of inductive reactive power and capacitive reactive power according to an embodiment of the present application;

[0031] FIG7 is a waveform diagram of another inductive reactive power and capacitive reactive power provided according to an embodiment of the present application; Modes for Carrying Out the Invention

[0032] FIG8 is a waveform diagram of another inductive reactive power and capacitive reactive power provided according to an embodiment of the present application;

[0033] FIG9 is a waveform diagram of another inductive reactive power and capacitive reactive power provided according to an embodiment of the present application;

[0034] FIG10 is a topological diagram of a three-phase energy storage system provided according to an embodiment of the present application;

[0035] FIG11 is a schematic diagram of voltage waveform changes of a three-phase energy storage system provided according to an embodiment of the present application;

[0036] FIG12 is a schematic structural diagram of a modular battery cell control unit provided according to an embodiment of the present application;

[0037] FIG13 is a schematic circuit diagram of a modular battery cell control unit according to an embodiment of the present application;

[0038] FIG14 is a flow chart of a method for controlling an energy storage system according to an embodiment of the present application;

[0039] FIG15 is a schematic structural diagram of an energy storage system provided in an embodiment of the present application;

[0040] FIG16 is a schematic structural diagram of another energy storage system provided in an embodiment of the present application.

[0041] Figure 1 is a circuit schematic diagram of a control circuit of an energy storage system provided according to an embodiment of the present application. Referring to Figure 1, an embodiment of the present application provides a control circuit of an energy storage system, wherein the control circuit of the energy storage system includes: a battery module 10, a control module 20 and a reversing module 30, wherein the battery module 10, the control module 20 and the reversing module 30 are connected in sequence; the battery module 10 includes n modular battery control units 11, and the modular battery control unit 11 includes a battery cell, a first switch and a second switch; the battery cell and the first switch are connected in series and then connected in parallel with the second switch; wherein n is a positive integer; the first first switch and the first second switch are connected as the first end of the battery module 10, and the nth battery cell and the nth second switch are connected as the second end of the battery module 10; the reversing module 30 includes a first reversing switch Kb, a second reversing switch Kc, a third reversing switch Kd, a fourth reversing switch Ke and a filter unit 31, and the filter unit 31 includes a first end 311, a first switch 322 and a second switch 333. The second end 312 and the third end 313, the first end of the battery cell module 10 are respectively connected to the first ends of the first reversing switch Kb and the third reversing switch Kd, the second end of the first reversing switch Kb is connected to the first end 311 of the filter unit 31, and the second end of the third reversing switch Kd is connected to the third end 313 of the filter unit 31; the second end of the battery cell module 10 is respectively connected to the first ends of the second reversing switch Kc and the fourth reversing switch Ke, the second reversing switch Kc is connected to the first end 311 of the filter unit 31, and the second end of the fourth reversing switch Ke is connected to the third end 313 of the filter unit 31, and the AC power grid is connected between the second end 312 and the third end 313 of the filter unit 31; the control module 20 is communicatively connected to the modular battery cell control unit 11 and the reversing module 30, and the control module 20 is used to control the opening or closing of the first reversing switch Kb, the second reversing switch Kc, the third reversing switch Kd and the fourth reversing switch Ke.

[0042] Specifically, the battery module 10 is composed of n modular battery control units 11, the energy storage inverter can be a filter unit 31, and the battery cell can be replaced by a module with any battery cell combination. The B- of the modular battery control unit 11 is connected to the B+ of the lower unit, the B+ is connected to the B- of the upper unit, the B+ of the top unit is connected to the reversing unit, and the B- of the bottom unit is connected to the reversing module 30. If the energy storage system is connected to the grid, the number of modular battery cells is limited by the grid voltage. Taking the 230V grid as an example, the number of modular battery cells in series = 230V × 1.1 × 1.414 / 2.5V = 144, so the 230V grid system requires at least 144 modular battery control units 11 connected in series.

[0043] The control module 20 exchanges information with the modular cell control unit 11 via optical fiber communication. The control module 20 activates and deactivates the first, second, third, and fourth reversing switches Kb, Kc, Kd, ​​and Ke via optical fiber. Control modules 20 can also communicate with each other via optical fiber. Optionally, the control module 20 can exchange information with external mobile devices such as mobile phones and computers via Bluetooth, 5G, or Wi-Fi.

[0044] The commutation module 30 is composed of a commutation control unit and a filter unit 31. The commutation control unit is used to commutate the half-wave sinusoidal voltage, and the filter unit 31 is used to smooth the step wave of the battery cell. The commutation control unit can be composed of 4 power switch tubes, and the filter unit 31 can be composed of LC filter devices. The filter unit 31 can select any combination of LC, LCL and other filter circuits according to actual conditions. Figure 1 shows an example of the filter unit 31 consisting of an inductor L and a capacitor C. The inductor L and the capacitor C form an AC output filter circuit to make the AC output voltage smoother. The first commutation switch Kb, the second commutation switch Kc, the third commutation switch Kd, the fourth commutation switch Ke, the n first switches and the n second switches are all high-power switching devices of the same model. The high-power switching devices can withstand higher voltages and are turned off and on by isolation drive. For example, the high-power switching device can be any one of MOSFET, IGBT, SCR, SiC, and GaN.

[0045] The basic principle of the system is as follows: the modular cell control unit 11 collects the temperature and voltage of the cell and uploads the data to the external control board via optical fiber communication. The external control board sends instructions to the modular cell control unit 11 via optical fiber communication according to a certain algorithm based on the collected information of each cell and the power grid status. By controlling the on and off of the corresponding first switch K1 and second switch K1a, the external control board determines whether the cell is connected in series in the entire energy storage system.

[0046] The cell fault bypass principle is as follows: When a cell fails, the modular cell control unit 11 simply opens the first switch K1 connected in series with that cell and closes the second switch K1a connected in parallel with it, bypassing the cell without affecting normal system operation. At this point, the modular cell control unit 11 quickly flashes an LED to notify staff of the cell failure, facilitating prompt replacement of the faulty cell.

[0047] The embodiments of the present application integrate the control circuit and battery cells into a single module to form an energy storage system. This modularized and standardized product facilitates assembly and wiring. The energy storage system can be assembled without the need for a separate BMS and PCS, making assembly more convenient. The reduced size and overall cost of the entire energy storage system are significantly lower due to the elimination of the busbar capacitors found in traditional energy storage inverters. The filter components do not need to be as large as in traditional energy storage inverters, further reducing cost and size. The control circuit can bypass faulty battery cells without affecting the normal operation of the energy storage system, thereby improving energy storage system utilization and increasing profitability. Because high-voltage batteries are prioritized during discharge and low-voltage batteries during charging, there is no need for an additional BMS to control the batteries, reducing BMS costs. The batteries can be connected in series to the system circuit according to a specific algorithm, and new and old batteries can be mixed, improving energy storage system utilization and increasing profitability. In summary, the present application addresses the existing issues of large energy storage inverters, high energy storage system costs, and the inability to mix new and old batteries.

[0048] Figure 2 is a circuit schematic diagram of a control circuit of another energy storage system provided according to an embodiment of the present application. Referring to Figure 2, optionally, the modular battery cell control unit 11 also includes a battery cell sampling chip 111, and the control module 20 also includes a main controller 21; the battery cell sampling chip 111 is respectively communicated with n battery cells and the main controller 21, and the battery cell sampling chip 111 is used to collect the voltage and temperature of the n battery cells and send them to the main controller 21; the main controller 21 is communicated with the first reversing switch Kb, the second reversing switch Kc, the third reversing switch Kd and the fourth reversing switch Ke, and the main controller 21 is used to analyze and calculate the received voltage and temperature, and control the opening or closing of the n first switches, the n second switches, the first reversing switch Kb, the second reversing switch Kc, the third reversing switch Kd and the fourth reversing switch Ke.

[0049] Specifically, the cell sampling chip 111 can be a microcontroller unit (MCU), which is primarily used to collect information such as the cell voltage and temperature. The main controller 21 collects the total voltage of the cell module 10, enabling dynamic monitoring of the total voltage. Based on the total voltage data, the main controller 21 generates a control sequence to convert AC to DC and DC to AC by controlling the on / off of switching devices. The main controller 21 is used to control the on / off of n first switches and n second switches, as well as perform data analysis and algorithm calculations. The main controller 21 can consist of a single MCU, which simplifies the circuit structure and reduces costs, or it can consist of multiple MCUs, which can increase data processing speed and improve efficiency.

[0050] Continuing to refer to Figure 2, optionally, the commutation module 30 also includes a voltage sampling unit 32 and a current detection unit 33; the first end and the second end of the voltage sampling unit 32 are respectively connected to the eleventh end and the tenth end of the main controller 21, and the third end and the fourth end of the voltage sampling unit 32 are respectively connected to the second end 312 of the filtering unit 31 and the third end 313 of the filtering unit 31; the first end of the current detection unit 33 is connected to the twelfth end 12 of the main controller 21, and the second end of the current detection unit 33 is connected to the second end 312 of the filtering unit 31.

[0051] FIG3 is a schematic diagram of an AC-DC conversion according to an embodiment of the present application. Referring to FIG3 , the detailed working principle of the control circuit of the energy storage system is as follows:

[0052] 1) Accept user power demand instructions, which can be active power P & reactive power Q or active power P & power factor.

[0053] 2) The modular cell control unit detects the voltage and temperature of the cell and uploads them to the control module.

[0054] 3) Detect the grid voltage Vs and calculate its amplitude and phase.

[0055] 4) Calculate the amplitude and phase angle δ of the cell series circuit voltage Vi using P = 3Vs × Vi × sinδ / jWL; Q = 3Vs × (Vs-Vi × conδ / jWL). The phase angle δ is the angle between the grid voltage Vs and the cell series circuit voltage Vi.

[0056] 5) Divide the Vi sine half wave into 288 equal parts. The voltage peak at time nT is Vi×sin(180×nT / 288).

[0057] 6) When the grid voltage Vs and phase angle δ meet the preset conditions, start switching the modular cell control units. The sum of the voltages of the switched modular voltage units must be close to Vi×sin(180×nT / 288).

[0058] It should be noted that there are many possible logic algorithms for modular cell switching. Let's take the example of prioritizing cells with lower voltages during charging and discharging cells with higher voltages. For example, in charging mode, at 144T, the voltage peak is Vi × sin90 = Vi. The cell voltages are summed from low to high until they are approximately equal to Vi. The control unit then sends a command to the modular cell units to close K1 and disconnect K1a, connecting these cells in series to the system circuit. The remaining cells close K1a and disconnect K1. At this point, the voltage of the entire system circuit is approximately equal to Vi. This creates a stepped half-sine wave between 1T and 288T. Commutating the second half-sine wave creates a stepped sine wave, which then passes through LC filtering to a smooth sine wave.

[0059] FIG4 is a flow chart of a cell switching algorithm logic provided according to an embodiment of the present application. Referring to FIG4 , the cell switching idea is: when charging, charge the cell with low voltage first; when discharging, discharge the cell with high voltage first.

[0060] When the energy storage system is in charging mode, the control module 20 sorts the voltage values ​​of the cells in the modular cell control unit from low to high. When the grid voltage Vs and phase angle δ meet preset conditions, the modular cell units are switched in and out, adding the cells in ascending order until the value is approximately equal to Vi × sin (180 × nT / 288). These modular cells are then switched into the circuit.

[0061] When the energy storage system is in discharge mode, the control module 20 sorts the voltage values ​​of the cells in the modular cell control unit from high to low. When the grid voltage Vs and phase angle δ meet preset conditions, the modular cell units are switched in and out, adding the cells in descending order until the value is approximately equal to Vi × sin (180 × nT / 288). These modular cells are then switched into the circuit.

[0062] FIG5 is a schematic diagram of a voltage waveform change provided according to an embodiment of the present application. Referring to FIG5 , FIG5 exemplarily shows a voltage waveform change during cell switching control of a single-phase energy storage system.

[0063] Figure 6 is a waveform diagram of inductive reactive power and capacitive reactive power provided according to an embodiment of the present application, Figure 7 is another waveform diagram of inductive reactive power and capacitive reactive power provided according to an embodiment of the present application, Figure 8 is another waveform diagram of inductive reactive power and capacitive reactive power provided according to an embodiment of the present application, and Figure 9 is another waveform diagram of inductive reactive power and capacitive reactive power provided according to an embodiment of the present application. Referring to Figures 6, 7, 8 and 9, whether the energy storage system operates in rectification mode or inverter mode, and whether it is inductive reactive power or capacitive reactive power is determined according to the user's demand instructions. Finally, the control module 20 calculates Vi and δ values ​​according to the instructions. The waveform diagrams of rectification mode and inverter mode, inductive reactive power and capacitive reactive power are shown in Figures 6, 7, 8 and 9. FIG10 is a topological diagram of a three-phase energy storage system according to an embodiment of the present application, and FIG11 is a schematic diagram of a voltage waveform change of a three-phase energy storage system according to an embodiment of the present application. Referring to FIG10 and FIG11 , the working principle of the three-phase energy storage system is as follows: it is composed of three units: an A-phase unit, a B-phase unit, and a C-phase unit. The N line of each phase unit is connected, and the live line of each phase unit corresponds to the three-phase live lines R, S, and T of the three-phase power grid. The A-phase unit serves as the main control unit, and its control module 20 communicates with the other two phases via optical fiber communication. The main control unit controls the B-phase and C-phases to have a phase angle of 120 degrees apart in sequence. Each phase can be connected in series with the corresponding battery cells into the circuit according to the principle of a single-phase energy storage system.

[0064] Figure 12 is a structural diagram of a modular battery cell control unit provided according to an embodiment of the present application. Referring to Figure 12, optionally, the modular battery cell control unit further includes: a temperature detection circuit 112, a power supply circuit 113, a battery cell voltage detection circuit 114, an indication circuit 115 and a communication circuit 116; a first end of the temperature detection circuit 112 is connected to the power supply circuit 113, a second end of the temperature detection circuit 112 is connected to a first end 1 of the battery cell sampling chip 111, a third end of the temperature detection circuit 112 is connected to a second end 2 of the battery cell sampling chip 111, a fourth end of the temperature detection circuit 112 is connected to a third end 3 of the battery cell sampling chip 111, and a fifth end of the temperature detection circuit 112 is grounded GND; The first end of the source circuit 113 is connected to the positive electrode of the battery cell, and the second end of the power circuit 113 is connected to the battery cell voltage detection circuit 114; the first end of the battery cell voltage detection circuit 114 is connected to the ninth end 9 of the battery cell sampling chip 111, the second end of the battery cell voltage detection circuit 114 is connected to the positive electrode of the battery cell, and the third end of the battery cell voltage detection circuit 114 is connected to the negative electrode of the battery cell; the first end of the indication circuit 115 is connected to the eighth end 8 of the battery cell sampling chip 111, and the second end of the indication circuit 115 is connected to the fourth end 4 of the battery cell sampling chip 111; the first end of the communication circuit 116 is connected to the sixth end 6 and the seventh end 7 of the battery cell sampling chip 111, and the second end of the communication circuit 116 is connected to the external control unit for communication.

[0065] Specifically, the battery cell is a large-capacity battery cell, characterized by large size and heavy weight. The battery cell sampling chip 111 can be an MCU, and the first switch K1 is connected in series with the battery cell and is turned on and off by the control of the MCU. The battery cell and the first switch K1 are connected in series and then in parallel with the second switch K1a, and its opening and closing are controlled by the MCU. The MCU is used to receive the battery cell temperature collected by the temperature detection circuit 112 and the battery cell voltage detected by the battery cell voltage detection circuit 114, and upload their data to the battery cell level control board via optical fiber communication. The battery cell level control board can be connected to the control module 20 for communication, data upload and instruction reception, and control the on and off of the first switch K1 and the second switch K1a according to the instructions received by the battery cell level control board. The MCU controls the on and off of the indicator circuit 115 according to the temperature and voltage value of the battery cell voltage.

[0066] The temperature detection circuit 112 is used to collect the temperature of the battery cell and send it to the MCU. The power supply circuit 113 draws power directly from the battery cell and converts it into 5V or 3.3V required by the MCU and other circuits. The battery cell voltage detection circuit 114 collects the voltage of the battery cell and transmits it to the MCU. The indication circuit 115 is used to indicate the operating status of the modular battery cell control unit. When the indication circuit 115 is always on, the modular battery cell control unit is operating normally. When the indication circuit 115 flashes, the modular battery cell control unit fails. The communication circuit 116 is composed of an optical fiber terminal and an optical fiber communication chip, which is used to exchange information with the control module 20. The battery cell-level control board can be on the side of the battery cell or on the front of the electrode. Depending on the actual situation, it can be structurally integrated with the battery cell to achieve modularization.

[0067] Figure 13 is a schematic circuit diagram of a modular battery cell control unit provided according to an embodiment of the present application. Referring to Figure 13, optionally, the temperature detection circuit includes: an NTC thermistor, a first resistor R1, a second resistor R2, and a first capacitor C1; a first end of the NTC thermistor is connected to the first end of the first resistor R1 and the first end of the second resistor R2, a second end of the first resistor R1 is connected to the power supply circuit 113, a second end of the second resistor R2 is connected to the first end 1 of the battery cell sampling chip 111, the first capacitor C1 is connected between the second end 2 and the third end 3 of the battery cell sampling chip 111, and the second end of the NTC thermistor is connected to the second end of the first capacitor C1 and then connected to the ground GND.

[0068] Specifically, an NTC thermistor is attached to the battery cell. The NTC thermistor, the first resistor R1, the second resistor R2, the first capacitor C1 and the power supply form a temperature detection circuit to collect the temperature of the battery cell and send it to the MCU.

[0069] The resistance of an NTC (Negative Temperature Coefficient) thermistor decreases as the temperature increases.

[0070] Continuing to refer to Figure 13, optionally, the battery cell voltage detection circuit includes: an operational amplifier U4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; the first end of the operational amplifier U4 is connected to the first end of the seventh resistor R7, the second end of the seventh resistor R7 is connected to the ninth end 9 of the battery cell sampling chip 111, the second end of the operational amplifier U4 is connected to the first end of the fifth resistor R5, the second end of the fifth resistor R5 is connected to the positive electrode of the battery cell, the third end 3 of the operational amplifier U4 is connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is connected to the negative electrode of the battery cell.

[0071] Specifically, the operational amplifier U4 and the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 form a cell voltage detection circuit to collect the voltage of the cell and transmit it to the MCU.

[0072] Continuing to refer to Figure 13, optionally, the indication circuit includes: an eighth resistor R8 and a light-emitting diode D1, the first end of the eighth resistor R8 is connected to the eighth end 8 of the battery cell sampling chip 111, the second end of the eighth resistor R2 is connected to the anode of the light-emitting diode D1, and the cathode of the light-emitting diode D1 is connected to the fourth end 4 of the battery cell sampling chip 111.

[0073] Specifically, the light-emitting diode D1 is used to indicate the operating status of the modular battery cell control unit. When the light-emitting diode D1 is always on, it indicates that the modular battery cell control unit is operating normally. When the light-emitting diode D1 flashes, it indicates that the modular battery cell control unit has a fault.

[0074] Continuing with reference to Figure 13, optionally, the modular battery cell control unit further includes: an isolation driver, a third resistor R3, and a fourth resistor R4; the first end of the isolation driver is connected to the control end of the first switch K1, the second end of the isolation driver is connected to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is connected to the third end 3 of the battery cell sampling chip 111, the first end of the third resistor R3 is connected to the control end of the second switch K1a, and the second end of the third resistor R3 is connected to the second end 2 of the battery cell sampling chip 111.

[0075] Optionally, the isolation driver includes a transformer or an optocoupler.

[0076] Specifically, the high-voltage portion of the circuit includes the battery cells, while the low-voltage portion includes the battery sampling chip. Therefore, an isolation driver is required between the high-voltage and low-voltage portions. A transformer or optocoupler is used to isolate the control portion of the circuit from the main circuit, preventing strong current in the main circuit from interfering with weak current signals in the control circuit. Optocoupler isolation primarily prevents interference caused by electrical connections, particularly between low-voltage control circuits and external high-voltage circuits. Transformer isolation is primarily used to isolate hazardous voltages to ensure safe circuit operation.

[0077] FIG14 is a flow chart of a method for controlling an energy storage system according to an embodiment of the present application. Referring to FIG14 , an embodiment of the present application further provides a method for controlling an energy storage system, which includes the following steps:

[0078] S110: Detect the AC grid voltage.

[0079] S120. Calculate the phase angle between the AC grid voltage and the loop voltage according to the AC grid voltage and the battery cell series loop voltage.

[0080] S130: Determine an operating mode of the energy storage system, where the operating mode includes a discharge mode and a charge mode.

[0081] S140: The energy storage system is in charging mode and the grid voltage and phase angle meet preset conditions. The control module performs switching according to a first preset control strategy.

[0082] S150: The energy storage system is in a discharge mode and the grid voltage and phase angle meet preset conditions. The control module switches the energy storage system according to a second preset control strategy.

[0083] Specifically, the system receives user power demand instructions, which can be active power P & reactive power Q or active power P & power factor. The modular cell control unit detects the cell voltage and temperature and uploads them to the control module. It detects the grid voltage Vs and calculates its amplitude and phase. The amplitude and phase angle δ of the cell series circuit voltage Vi are calculated using the formula P = 3Vs × Vi × sinδ / jWL; Q = 3Vs × (Vs - Vi × conδ / jWL). The phase angle δ refers to the angle between the grid voltage Vs and the cell series circuit voltage Vi. The Vi sinusoidal half-wave is divided into 288 equal parts, and the peak voltage at time nT is Vi × sin(180 × nT / 288). When the grid voltage Vs and phase angle δ meet preset conditions, the modular cell control unit is switched on and off. The sum of the voltages of the switched modular voltage units must be close to Vi × sin(180 × nT / 288).

[0084] When the energy storage system is in charging mode, the control module sorts the voltage values ​​of the modular cell control units from low to high. When the grid voltage Vs and phase angle δ meet preset conditions, the modular cell units are switched in and out, adding the cells in ascending order until the value is approximately equal to Vi × sin (180 × nT / 288). These modular cells are then switched into the circuit.

[0085] When the energy storage system is in discharge mode, the control module sorts the voltage values ​​of the modular cell control units from high to low. When the grid voltage Vs and phase angle δ meet preset conditions, the modular cell units are switched in and out, adding the cells in descending order until the value is approximately equal to Vi × sin (180 × nT / 288). These modular cells are then switched into the circuit.

[0086] The control method of the energy storage system provided in the embodiment of the present application is applied to the control circuit of the energy storage system. Its technical principles and effects are similar and will not be repeated here.

[0087] FIG15 is a schematic diagram of the structure of an energy storage system provided in an embodiment of the present application. Referring to FIG15 , the energy storage system includes: n-stage modular battery cell control units 51 connected in series, each modular battery cell control unit 51 including an external connection terminal 511, a battery cell 512, a temperature detection circuit 112, a battery cell microcontroller module 514, a battery cell voltage detection circuit 114, a communication circuit 116, and a switch module 517, where n is a positive integer.

[0088] The battery cell 512 is electrically connected to the external connection terminal 511 via a switch module 517 ; the switch module 517 is used to control whether the battery cell 512 is connected to the energy storage system.

[0089] The temperature detection circuit 112 is electrically connected to the battery cell micro-control module 514 . The temperature detection circuit 112 is used to detect the temperature of the battery cell 512 and send the temperature to the battery cell micro-control module 514 .

[0090] The cell voltage detection circuit 114 is connected in series between the cell 512 and the cell micro-control module 514 . The cell voltage detection circuit 114 is used to detect the voltage of the cell 512 and send the voltage to the cell micro-control module 514 .

[0091] The communication circuit 116 is in communication with the cell microcontroller module 514 and is used for information exchange between the modular cell control unit 51 and the upper control unit. The cell microcontroller module 514 is also electrically connected to the switch module 517 and is used to control the switch module 517 based on the temperature and voltage information of the cell 512 and / or the interaction information of the upper control unit.

[0092] Among them, the communication circuit 116 may include an optical fiber terminal and an optical fiber communication chip. Specifically, the working principle of the modular battery cell control unit 51 is as follows: the temperature detection circuit 112 detects the temperature information of the battery cell 512 and sends it to the battery cell micro-control module 514. The battery cell voltage detection circuit 114 detects the voltage information of the battery cell 512 and sends it to the battery cell micro-control module 514. The battery cell micro-control module 514 uploads the received temperature and voltage information of the battery cell 512 to the upper control unit through the communication circuit 116. The upper control unit sends instructions to the battery cell micro-control module 514 through the communication circuit 116 according to the information of each module and the power grid status, and according to the preset control strategy. After receiving the instruction signal, the battery cell micro-control module 514 controls the switch switching module 517 to perform the corresponding action according to the instruction, and controls the battery cell 512 to be connected in series in the energy storage system or disconnected from the energy storage system.

[0093] The technical solution of this embodiment is to set up a modular battery cell control unit 51, and use the temperature detection circuit 112 and the battery cell voltage detection circuit 114 therein to detect the temperature and voltage information of the battery cell 512, and send it to the battery cell micro-control module 514. The battery cell micro-control module 514 uploads the information to the superior control unit through the communication circuit 116. The superior control unit sends instructions to the battery cell micro-control module 514 based on the information of each module. The battery cell micro-control module 514 controls the switch switching module 517 according to the instruction signal to control the battery cell 512 to connect to the energy storage system or disconnect from the energy storage system. The technical solution provided in this embodiment can modularize the battery cell 512 control unit, and can form an energy storage system without a battery management system and an energy storage converter, which is convenient for assembly and operation and can reduce costs.

[0094] 13 , based on the above embodiments, optionally, the external connection terminal 511 includes a positive connection terminal B+ and a negative connection terminal B−, and the negative connection terminal B− is electrically connected to the negative electrode of the battery cell 512 .

[0095] The switch switching module 517 includes a first switch K1 and a second switch K1a. The first switch K1 is connected in series between the positive electrode of the battery cell 512 and the positive electrode connection terminal B+, and the second switch K1a is connected in series between the positive electrode connection terminal B+ and the negative electrode connection terminal B−.

[0096] Continuing to refer to FIG. 13 , based on the above embodiments, optionally, the first switch K1 and / or the second switch K1 a includes a MOS transistor.

[0097] Specifically, the cell microcontroller module 514 issues a drive signal based on instructions from the superior control unit to drive the MOS transistors in the first switch K1 and the second switch K1a to close or open, thereby controlling whether the cell 512 is connected to the energy storage system. For example, if the MOS transistor in the first switch K1 is closed, the positive electrode connection terminal B+ is connected to the positive electrode of the cell 512; if the MOS transistor in the second switch K1a is opened, the negative electrode connection terminal B- is connected to the negative electrode of the cell 512, and the cell 512 is connected to the energy storage system. For another example, if the MOS transistor in the first switch K1 is opened, the positive electrode connection terminal B+ is disconnected from the positive electrode of the cell 512; if the MOS transistor in the second switch K1a is closed, the negative electrode connection terminal B- is connected to the positive electrode connection terminal B+, and the cell 512 is disconnected from the energy storage system.

[0098] In this embodiment, by providing a first switch K1 and a second switch K1a in the switch switching module 517, the external connection terminal 511 can be connected to or disconnected from the positive and negative electrodes of the battery cell 512 by closing or opening the MOS tubes therein, thereby controlling whether the battery cell 512 is connected to the energy storage system, making the energy storage system more convenient to operate.

[0099] Referring to Figure 13 , power supply voltage source 17 provides voltage to NTC resistor NTC1 through first resistor R1. NTC resistor NTC1 detects the cell temperature and transmits the temperature information to the cell microcontroller through second resistor R2. First capacitor C1 is used to filter out high-frequency interference signals from the power supply or circuit board induction.

[0100] In this embodiment, an NTC resistor NTC1, a first resistor R1, and a second resistor R2 are provided in the temperature detection circuit 112 to detect the temperature of the battery cell and transmit the temperature information to the battery cell microcontroller. This arrangement facilitates the battery cell microcontroller and the upper control unit to control the battery cell based on the temperature information. The first resistor R1 and the second resistor R2 prevent excessive current in the circuit, thereby improving the safety of the energy storage system.

[0101] Continuing to refer to FIG13 , based on the above embodiments, optionally, the energy storage system further includes:

[0102] The power circuit 113 is electrically connected to the battery cell; the power circuit 113 is used to provide a power supply voltage source for the modular battery cell control unit.

[0103] Specifically, the power circuit 113 directly draws power from the battery cell and converts it into the voltage required by the modular battery cell control unit. For example, the voltage may be 5V or 3.3V.

[0104] In this embodiment, the modular battery cell control unit is powered by a power circuit 113. This configuration makes it easier to assemble and operate the modular battery cell control unit due to the simple structure and flexible design of the power circuit 113.

[0105] 13 , based on the above embodiments, the cell micro-control module optionally includes a micro-control chip U2 , an isolation drive circuit U3 , a third resistor R3 , and a fourth resistor R4 . In one embodiment of the present application, the micro-control chip U2 is the same as the cell sampling chip 111 described above.

[0106] The microcontroller chip U2 includes a first drive signal pin and a second drive signal pin, a third resistor R3 connected in series between the first drive signal pin and the control end of the second switch K1a, and an isolation drive circuit U3 and a fourth resistor R4 connected in series between the second drive signal pin and the control end of the first switch K1.

[0107] Specifically, the microcontroller U2 outputs a first drive signal through its first drive signal pin, driving the second switch K1a to close or open. It also outputs a second drive signal through its second drive signal pin, driving the first switch K1 to close or open. Because the MOS transistors in the first and second switches K1a operate at high frequencies and have high input impedances, making them susceptible to interference, an isolation drive circuit U3 is provided to isolate the main circuit from the control circuit, providing strong anti-interference capabilities and preventing interference from the power stage circuitry on the control signal. The third and fourth resistors R3 and R4 are used to prevent excessive current from damaging the circuit.

[0108] In this embodiment, the microcontroller chip U2, the isolation drive circuit U3, the third resistor R3, and the fourth resistor R4 are provided in the cell microcontroller module to control the first switch K1 and the second switch K1a. This arrangement allows for safe and effective control of whether the chip is connected to the energy storage system, facilitating assembly and operation.

[0109] Referring to Figure 13, the cell voltage detection circuit includes an operational amplifier U4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The voltage signal from the positive electrode of the cell is input to the operational amplifier U4 through the fifth resistor R5, while the voltage signal from the negative electrode of the cell is input to the operational amplifier U4 through the sixth resistor R6. This generates a voltage difference, which is the voltage across the cell. This voltage is amplified by the operational amplifier U4 and then input to the cell microcontroller through the seventh resistor R7.

[0110] In this embodiment, an operational amplifier U4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7 are provided in the cell voltage detection circuit 114 to detect the cell voltage information and transmit it to the cell microcontroller. This arrangement facilitates the cell microcontroller and the upper control unit to control the cell based on the voltage information. The fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 prevent excessive current in the circuit from damaging the operational amplifier U4, thereby improving the safety of the energy storage system.

[0111] Continuing to refer to FIG13 , based on the above embodiments, optionally, the energy storage system further includes: an eighth resistor R8 and an indicator light module D1, the eighth resistor R8 and the indicator light module D1 are connected in series between the battery cell micro-control module and the ground terminal; the indicator light module D1 is used to indicate the status of the modular battery cell control unit.

[0112] The indicator light module D1 may include a light emitting diode or an incandescent lamp.

[0113] Specifically, the cell microcontroller controls the indicator light module D1 based on the cell temperature and voltage information, indicating the operating status of the modular cell control unit. For example, if the indicator light is permanently on, the modular cell control unit is operating normally; if the indicator light flashes, the modular cell control unit is malfunctioning. The eighth resistor R8 is used to prevent excessive current.

[0114] In this embodiment, the eighth resistor R8 and the indicator light module D1 are provided to indicate the operating status of the modular cell control unit. This has a simple structure and facilitates the user to understand the operating status of each modular cell control unit. When a fault occurs, the user can promptly identify the fault point, facilitating troubleshooting.

[0115] On the basis of the above embodiments, the temperature detection circuit 112 , the cell micro-control module 514 , the cell voltage detection circuit 114 , the communication circuit 116 and the switch switching module 517 are all arranged on the cell-level control board 10 .

[0116] Specifically, the temperature detection circuit 112, the cell microcontroller module 514, the cell voltage detection circuit 114, the communication circuit 116, and the switch module 517 are integrated on the cell-level control board 10, which can simplify circuit design, reduce circuit volume, and lower costs. Depending on the actual situation, the cell-level control board 10 can be installed on the side or front of the cell, forming an integrated structure with the cell, thereby realizing the modularization of the cell control unit.

[0117] In this embodiment, by providing a cell-level control board 10, the temperature detection circuit 112, cell microcontroller module 514, cell voltage detection circuit 114, communication circuit 116, and switch module 517 are integrated onto the cell-level control board 10, thereby reducing circuit volume and effectively lowering costs. Furthermore, the cell-level control board 10 and the battery cells form an integrated structure, further facilitating assembly and operation of the energy storage system.

[0118] FIG16 is a schematic diagram of the structure of another energy storage system provided in an embodiment of the present application. Referring to FIG16 , based on the above embodiments, the energy storage system may optionally further include:

[0119] Superior control unit 2;

[0120] The reversing module 3 includes a first reversing switch Kb, a second reversing switch Kc, a third reversing switch Kd, a fourth reversing switch Ke, and a filter unit 30; wherein the filter unit 30 includes a filter input terminal, a filter output terminal, and a common terminal; the first reversing switch Kb is connected in series between the positive electrode of the first-level modular battery cell control unit 1 and the filter input terminal; the second reversing switch Kc is connected in series between the negative electrode of the n-th-level modular battery cell control unit 1 and the filter input terminal; the third reversing switch Kd is connected in series between the positive electrode and the common terminal of the first-level modular battery cell control unit 1; the fourth reversing switch Ke is connected in series between the negative electrode and the common terminal of the n-th-level modular battery cell control unit 1; the filter output terminal and the common terminal serve as the output terminal of the reversing module 3;

[0121] The upper control unit 2 is used to control the states of the first reversing switch Kb, the second reversing switch Kc, the third reversing switch Kd and the fourth reversing switch Ke to convert the direct current of the modular battery cell control unit 1 into alternating current.

[0122] In one embodiment, the superior control unit 2 is the same as the aforementioned control module 20 .

[0123] Continuing to refer to FIG. 16 , optionally, the filtering unit 30 includes a first filtering inductor L and a first filtering capacitor C.

[0124] Continuing with FIG16 , optionally, n levels of modular cell control units are connected in series to form a modular cell unit. The positive electrode connection terminal B+ of the first-level modular cell control unit is electrically connected to the reversing module 3 , the negative electrode connection terminal B- of the first-level modular cell control unit is electrically connected to the positive electrode connection terminal B+ of the second-level modular cell control unit, and the remaining modular cell control units sequentially connect their positive electrode connection terminals B+ to the negative electrode connection terminals B- of the previous-level modular cell control unit, and the negative electrode connection terminal B- of the n-th-level modular cell control unit is electrically connected to the reversing module 3 .

[0125] Continuing to refer to FIG. 16 , optionally, the upper-level control unit 2 includes a main control chip 20 , a first communication unit 21 and a second communication unit 22 .

[0126] Specifically, the upper control unit 2 interacts with the modular cell control unit 1 via the first communication unit 21 and drives the switch in the commutation module 3 to turn on or off via the second communication unit 22. The commutation module 3 is used to commutate the half-wave sinusoidal voltage. The filtering unit 30 is used to smooth the step wave of the cell. The upper control unit 2 can also exchange information with a mobile device via Bluetooth, 5G, or Wi-Fi. For example, the mobile device can be a mobile phone or computer.

[0127] When the energy storage grid is connected, the number of modular cell control units is limited by the grid voltage. Taking a 230V grid as an example, the number of modular cell control units is n = 230 × 1.1 × 1.414 / 2.5 = 144. Therefore, a 230V grid system requires at least 144 modular cell control units 1 connected in series.

[0128] Continuing to refer to FIG16 , based on the above embodiments, optionally, the energy storage system further includes:

[0129] The current detection unit 4 is electrically connected to the upper control unit 2 and is used to detect the current at the filter output end and send it to the upper control unit 2;

[0130] The voltage sampling unit 5 is electrically connected to the upper-level control unit 2 . The voltage sampling unit 5 is used to detect the voltage at the output end of the commutation module 3 and send it to the upper-level control unit 2 .

[0131] Specifically, the voltage sampling unit 5 is used to phase-lock the grid voltage. The current detection unit 4 is used to detect the system current and disconnect the switch in the reversing module 3 when the current exceeds a preset threshold.

[0132] The working principle of the energy storage system in this embodiment of the application is:

[0133] S110: Power on the system.

[0134] S120: Receive a user power demand instruction, wherein the user power demand instruction includes an active power instruction and a reactive power instruction or an active power instruction and a power factor instruction.

[0135] S130 , the modular cell control unit 1 detects the voltage and temperature of the cell and uploads the detected voltage and temperature to the upper-level control unit 2 .

[0136] S140 , detecting the grid voltage Vs, and calculating its amplitude and phase.

[0137] S150, calculate the amplitude and phase angle δ of the series circuit voltage Vi of the n-level modular battery cell control unit 1. The calculation formula is:

[0138] P=3Vs×Vi×sinδ / jωL

[0139] Q=3Vs×(Vs-Vi×cosδ) / jωL

[0140] Among them, P represents active power, Q represents reactive power, and L represents filter inductance.

[0141] S160 , dividing the sinusoidal half-wave voltage Vi of the series circuit of the n-level modular battery cell control unit 1 into 288 equal parts, and the voltage peak at time nT is Vi×sin(180×nT / 288).

[0142] S170: Start switching the modular cell control units 1 at the grid voltage phase angle δ. The sum of the voltages of the switched modular cell control units 1 must be close to the voltage peak.

[0143] In this embodiment, by setting up a current detection unit 4 and a voltage sampling unit 5, the grid voltage and the output current of the filter end are detected, which is beneficial to the voltage calculation when switching the modular battery control unit 1 and improving the safety of the system circuit.

[0144] The technical solution of this embodiment converts the DC power of the modular cell control unit into AC power by providing a superior control unit 2 and a commutation module 3. The technical solution of this embodiment does not require the installation of an energy storage inverter, which can reduce the cost and size of the system.

[0145] It should be noted that there are multiple logic algorithms for switching the modular battery cell control unit. The following is a specific explanation of the switching logic algorithm that charges the battery cells with low voltage first when charging and discharges the battery cells with high voltage first when discharging, but it is not a limitation of this application.

[0146] On the basis of the above embodiments, referring to FIG. 5 , the voltage waveform is commutated into a complete sine wave.

[0147] For example, in charging mode, the peak voltage Vp at time 144T is Vp = Vi × sin90° = Vi. The cell voltages of n modular cell control units 1 are summed sequentially from low to high until the sum of the m cell voltages approximately equals the peak voltage. The upper control unit 2 sends a command to the m modular cell control units 1 participating in the calculation, closing their first switch K1 and opening their second switch K1a. This connects the m cells in series to the energy storage system. Simultaneously, the upper control unit 2 sends a command to the remaining nm modular cell control units 1, opening their first switch K1 and their second switch K1a. These nm cells are then disconnected from the energy storage system. At this point, the entire system loop voltage is approximately equal to the peak voltage. Between 1T and 288T, the voltage forms a stepped half-sine wave. Commutating the second half-sine wave converts it into a stepped sine wave, which then passes through the filter unit 30 to form a smooth sine wave.

[0148] Referring to FIG6 above, when the grid voltage phase angle δ=0 and the voltage Vi of the series circuit of the n-level modular battery control unit 1 is greater than the grid voltage Vs, the system is in discharge mode, and the system output is pure active output. Referring to FIG7 above, when the grid voltage phase angle δ=0 and the voltage Vi of the series circuit of the n-level modular battery control unit 1 is less than the grid voltage Vs, the system is in charge mode, and the system output is pure active output. Referring to FIG8 above, when the grid voltage phase angle δ<0 and the voltage Vi of the series circuit of the n-level modular battery control unit 1 is greater than the grid voltage Vs, the system is in discharge mode, and the system output is active and inductive reactive output. Referring to FIG9 above, when the grid voltage phase angle δ>0 and the voltage Vi of the series circuit of the n-level modular battery control unit 1 is greater than the grid voltage Vs, the system is in discharge mode, and the system output is active and capacitive reactive output.

[0149] It should be noted that the energy storage system's operating mode and output reactive power type can be selected based on user needs. The energy storage system's operating modes include rectification mode and inverter mode. The reactive power output types include inductive reactive power and capacitive reactive power.

[0150] Cell Fault Bypass Principle: When a cell fails, the cell microcontroller 14 simply opens the first switch K1 of the modular cell control unit 1 and closes the second switch K1a to bypass the cell, without affecting normal system operation. At this time, the cell microcontroller 14 controls the indicator light module D1 to flash, indicating that the modular cell control unit 1 has failed.

[0151] The technical solution of this embodiment utilizes a switching logic algorithm that prioritizes charging cells with lower voltages during charging and discharging cells with higher voltages during discharging, eliminating the need for an additional battery management system to control the cells, thereby reducing the cost of the energy storage system. Furthermore, in the event of a single cell failure, the cell microcontroller module 14 controls the modular cell control unit 1 to open the first switch K1 and close the second switch K1a, thereby bypassing the cell. The indicator light module D1 is then controlled to alert the user, thereby preventing system operation from being affected and facilitating rapid troubleshooting.

[0152] Referring to Figure 10 above, the energy storage system outputs three-phase AC power;

[0153] The n-level modular battery cell control unit 1, the upper control unit 2 and the commutation module 3 connected in series form a single-phase AC output module of the energy storage system;

[0154] The three-phase AC output module outputs AC power with a phase angle difference of 120 degrees.

[0155] Continuing to refer to FIG. 10 , optionally, the superior control unit 2 further includes a third communication unit 23 .

[0156] Among them, the three-phase AC power output modules are respectively A-phase AC power output module, B-phase AC power output module and C-phase AC power output module.

[0157] Specifically, the neutral line N of each phase AC output module is connected, and the live line L of each phase AC output module is connected to the three-phase live lines (including the R line, S line, and T line) of the three-phase power grid. The upper control unit 2 in the A-phase AC output module serves as the master control unit, communicating with the other two-phase AC output modules via the third communication unit 23, controlling the AC outputs of the other two-phase AC output modules to have a phase angle of 120 degrees.

[0158] The technical solution of this embodiment utilizes a series connection of n-stage modular cell control units 1, a higher-level control unit 2, and a commutation module 3 to form a single-phase AC output module for the energy storage system. The energy storage system outputs three-phase AC power for connection to the power grid. This technical solution eliminates the need for a battery management system and energy storage converter to form a three-phase energy storage system, facilitating assembly and operation while reducing costs.

Claims

1. A control circuit of an energy storage system, comprising: A battery cell module, a control module and a commutation module, wherein the battery cell module, the control module and the commutation module are connected in sequence; The battery module includes n modular battery control units, and the modular battery control unit includes a battery, a first switch, and a second switch; the battery and the first switch are connected in series and then connected in parallel with the second switch; wherein n is a positive integer; The first first switch and the first second switch are connected to serve as the first end of the battery module, and the nth battery cell and the nth second switch are connected to serve as the second end of the battery module; The reversing module includes a first reversing switch, a second reversing switch, a third reversing switch, a fourth reversing switch and a filter unit, the filter unit includes a first end, a second end and a third end, the first end of the battery cell module is respectively connected to the first end of the first reversing switch and the third reversing switch, the second end of the first reversing switch is connected to the first end of the filter unit, and the second end of the third reversing switch is connected to the third end of the filter unit; the second end of the battery cell module is respectively connected to the first end of the second reversing switch and the fourth reversing switch, the second reversing switch is connected to the first end of the filter unit, the second end of the fourth reversing switch is connected to the third end of the filter unit, and the AC power grid is connected between the second end of the filter unit and the third end of the filter unit; The control module is in communication with the modular battery cell control unit and the reversing module, and is used to control the opening or closing of the first reversing switch, the second reversing switch, the third reversing switch, and the fourth reversing switch.

2. The control circuit according to claim 1, wherein: The modular battery cell control unit further includes a battery cell sampling chip, and the control module further includes a main controller; The battery cell sampling chip is respectively connected to the n battery cells and the main controller for communication, and the battery cell sampling chip is used to collect the voltage and temperature of the n battery cells and send them to the main controller; The main controller is communicatively connected with the first reversing switch, the second reversing switch, the third reversing switch and the fourth reversing switch, and is used to analyze and calculate the received voltage and temperature, and control the opening or closing of the n first switches, the n second switches, the first reversing switch, the second reversing switch, the third reversing switch and the fourth reversing switch.

3. The control circuit according to claim 2, wherein: The commutation module also includes a voltage sampling unit and a current detection unit; The first end and the second end of the voltage sampling unit are connected to the eleventh end and the tenth end of the main controller respectively, and the third end and the fourth end of the voltage sampling unit are connected to the second end and the third end of the filtering unit respectively; The first end of the current detection unit is connected to the twelfth end of the main controller, and the second end of the current detection unit is connected to the second end of the filter unit.

4. The control circuit according to claim 2, wherein: The modular battery cell control unit also includes: a temperature detection circuit, a power supply circuit, a battery cell voltage detection circuit, an indication circuit and a communication circuit; The first end of the temperature detection circuit is connected to the power supply circuit, the second end of the temperature detection circuit is connected to the first end of the battery cell sampling chip, the third end of the temperature detection circuit is connected to the second end of the battery cell sampling chip, the fourth end of the temperature detection circuit is connected to the third end of the battery cell sampling chip, and the fifth end of the temperature detection circuit is grounded; The first end of the power circuit is connected to the positive electrode of the battery cell, and the second end of the power circuit is connected to the battery cell voltage detection circuit; The first end of the battery cell voltage detection circuit is connected to the ninth end of the battery cell sampling chip, the second end of the battery cell voltage detection circuit is connected to the positive electrode of the battery cell, and the third end of the battery cell voltage detection circuit is connected to the negative electrode of the battery cell; The first end of the indication circuit is connected to the eighth end of the battery cell sampling chip, and the second end of the indication circuit is connected to the fourth end of the battery cell sampling chip; The first end of the communication circuit is connected to the sixth end and the seventh end of the cell sampling chip, and the second end of the communication circuit is communicatively connected to the external control unit.

5. The control circuit according to claim 4, wherein: The temperature detection circuit comprises: an NTC thermistor, a first resistor, a second resistor and a first capacitor; The first end of the NTC thermistor is connected to the first end of the first resistor and the first end of the second resistor, the second end of the first resistor is connected to the power supply circuit, the second end of the second resistor is connected to the first end of the battery cell sampling chip, the first capacitor is connected between the second end and the third end of the battery cell sampling chip, and the second end of the NTC thermistor is connected to the second end of the first capacitor and then grounded.

6. The control circuit according to claim 4, wherein: The cell voltage detection circuit comprises: an operational amplifier, a fifth resistor, a sixth resistor and a seventh resistor; The first end of the operational amplifier is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the ninth end of the battery cell sampling chip, the second end of the operational amplifier is connected to the first end of the fifth resistor, the second end of the fifth resistor is connected to the positive electrode of the battery cell, the third end of the operational amplifier is connected to the first end of the sixth resistor, and the second end of the sixth resistor is connected to the negative electrode of the battery cell.

7. The control circuit according to claim 4, wherein: The indication circuit includes: an eighth resistor and a light emitting diode, wherein the first end of the eighth resistor is connected to the eighth end of the battery cell sampling chip, the second end of the eighth resistor is connected to the anode of the light emitting diode, and the cathode of the light emitting diode is connected to the fourth end of the battery cell sampling chip.

8. The control circuit according to any one of claims 4 to 7, wherein: The modular battery cell control unit further includes: an isolation driver, a third resistor and a fourth resistor; The first end of the isolation driver is connected to the control end of the first switch, the second end of the isolation driver is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the third end of the battery cell sampling chip, the first end of the third resistor is connected to the control end of the second switch, and the second end of the third resistor is connected to the second end of the battery cell sampling chip.

9. The control circuit according to claim 8, wherein: The isolation driver includes a transformer or an optical coupler.

10. The control circuit according to any one of claims 1 to 7, wherein: The control module exchanges information with external mobile devices via Bluetooth, 5G or WIFI.

11. A control method for an energy storage system, comprising: Detect AC grid voltage; Calculating the phase angle between the grid voltage and the loop voltage according to the AC grid voltage and the battery cell series loop voltage; Determining an operating mode of the energy storage system, wherein the operating mode includes a discharge mode and a charge mode; The energy storage system is in charging mode and the grid voltage and the phase angle meet preset conditions, and the control module performs switching according to a first preset control strategy; The energy storage system is in a discharge mode and the grid voltage and the phase angle meet preset conditions, and the control module performs switching according to a second preset control strategy.

12. An energy storage system, comprising: An n-stage modular battery cell control unit connected in series, the modular battery cell control unit comprising an external connection terminal, a battery cell, a temperature detection circuit, a battery cell micro-control module, a battery cell voltage detection circuit, a communication circuit and a switch switching module; n is a positive integer; Wherein, the battery cell is electrically connected to the external connection terminal through the switch switching module; the switch switching module is used to control whether the battery cell is connected to the energy storage system; The temperature detection circuit is electrically connected to the battery cell and the battery cell micro-control module respectively, and the temperature detection circuit is used to detect the temperature of the battery cell and send the temperature information of the battery cell to the battery cell micro-control module; The battery cell voltage detection circuit is connected in series between the battery cell and the battery cell micro-control module, and the battery cell voltage detection circuit is used to detect the voltage of the battery cell and send the voltage information of the battery cell to the battery cell micro-control module; The communication circuit is in communication connection with the cell microcontroller module, and the communication circuit is used for information exchange between the modular cell control unit and the upper control unit; The battery cell micro-control module is also electrically connected to the switch switching module, and the battery cell micro-control module is used to control the switch switching module according to the temperature information and / or voltage information of the battery cell and / or the interaction information of the upper control unit.

13. The energy storage system according to claim 12, wherein: The external connection terminal includes a positive connection terminal and a negative connection terminal, and the negative connection terminal is electrically connected to the negative electrode of the battery cell; The switch switching module includes a first switch and a second switch, wherein the first switch is connected in series between the positive electrode of the battery cell and the positive electrode connection end, and the second switch is connected in series between the positive electrode connection end and the negative electrode connection end.

14. The energy storage system according to claim 13, characterized in that: The first switch and / or the second switch comprises a MOS tube.

15. The energy storage system according to claim 12, characterized in that: The temperature detection circuit includes an NTC resistor, a first resistor, a second resistor and a first capacitor; the first end of the NTC resistor is electrically connected to the first end of the first resistor, and the second end of the first resistor is electrically connected to a power supply voltage source; The first end of the second resistor is electrically connected to the first end of the first resistor, and the second end of the second resistor is electrically connected to the battery micro-control module; the first capacitor is electrically connected to the first end of the first resistor The first capacitor is electrically connected to the second end of the NTC resistor; the second end of the NTC resistor is grounded.

16. The energy storage system according to claim 15, characterized in that: The energy storage system further comprises: A power supply circuit, the power supply circuit is electrically connected to the battery cell; the power supply circuit is used to provide the power supply voltage source of the modular battery cell control unit.

17. The energy storage system according to claim 13, wherein: The battery cell micro-control module includes a micro-control chip, an isolation drive circuit, a third resistor and a fourth resistor; The microcontroller chip includes a first drive signal pin and a second drive signal pin, the third resistor is connected in series between the first drive signal pin and the control end of the second switch, and the isolation drive circuit and the fourth resistor are connected in series between the second drive signal pin and the control end of the first switch.

18. The energy storage system according to claim 13, characterized in that: The cell voltage detection circuit comprises an operational amplifier, a fifth resistor, a sixth resistor and a seventh resistor; The fifth resistor is connected in series between the positive electrode of the battery cell and the first input terminal of the operational amplifier, the sixth resistor is connected in series between the negative electrode of the battery cell and the second input terminal of the operational amplifier, and the seventh resistor is connected in series between the output terminal of the operational amplifier and the battery cell micro-control module.

19. The energy storage system according to claim 12, wherein: The energy storage system further includes: an eighth resistor and an indicator light module, wherein the eighth resistor and the indicator light module are connected in series between the battery cell micro-control module and a ground terminal; and the indicator light module is used to indicate the state of the modular battery cell control unit.

20. The energy storage system according to any one of claims 12 to 19, wherein: The energy storage system comprises: a cell-level control board; The temperature detection circuit, the battery cell micro-control module, the battery cell voltage detection circuit, the communication circuit and the switch switching module are all arranged on the battery cell level control board.

21. The energy storage system according to any one of claims 12 to 19, wherein: The energy storage system further comprises: The superior control unit; A reversing module, comprising a first reversing switch, a second reversing switch, a third reversing switch, a fourth reversing switch and a filter unit; wherein the filter unit comprises a filter input terminal, a filter output terminal and a common terminal; the first reversing switch is connected in series between the positive electrode of the first-stage modular battery cell control unit and the filter input terminal; the second reversing switch is connected in series between the negative electrode of the n-th-stage modular battery cell control unit and the filter input terminal; the third reversing switch is connected in series between the positive electrode of the first-stage modular battery cell control unit and the common terminal; the fourth reversing switch is connected in series between the negative electrode of the n-th-stage modular battery cell control unit and the common terminal; the filter output terminal and the common terminal serve as the output terminal of the reversing module; The superior control unit is used to control the states of the first reversing switch, the second reversing switch, the third reversing switch and the fourth reversing switch to convert the direct current of the modular battery cell control unit into alternating current.

22. The energy storage system according to claim 21, wherein: The energy storage system further comprises: A current detection unit, the current detection unit is electrically connected to the upper control unit, and the current detection unit is used to detect the current at the filter output end and send it to the upper control unit; A voltage sampling unit, the voltage sampling unit is electrically connected to the upper-level control unit, and the voltage sampling unit is used to detect the voltage at the output end of the commutation module and send it to the upper-level control unit.

23. The energy storage system according to claim 21, wherein: The energy storage system outputs three-phase alternating current; The n-stage modular battery cell control units, the upper control unit and the commutation module connected in series constitute a single-phase AC output module of the energy storage system; The alternating current output by the three-phase alternating current output module has a phase angle difference of 120 degrees.

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