An active equalization control system and method for an energy storage battery

Abstract

The present invention discloses an active balancing control system and method for energy storage batteries, which includes: a battery cell, a BMS battery management module, a fully isolated DC converter, and the BMS monitors each battery BATT 1 to BATT N The cell voltages are V1~V N , the voltage value of the reference cell is V max , the voltage value of the lowest voltage cell V min , and set the rated pressure difference value V E , when V max ‑V min >V E , BMS battery management module controls the fully isolated DC converter to BATT V min The cells are balanced charged until the voltage is consistent, BATT V min For one or more of the cells, the cell is charged by a fully isolated DC converter connected one-to-one with each cell, which has high flexibility. Since the charging start is controlled by an optocoupler and combined with a zero-loss standby circuit, it is not only safe, but also has zero loss during unbalanced standby, which greatly reduces energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical fields of battery active balancing and charging, and particularly relates to an energy storage battery active balancing control system and method. Background Art

[0002] Currently used battery balancing systems are all passive, and the balancing is achieved by the way of energy loss through resistor heating. The active balancing system also discharges the battery cells with higher voltage to the battery cells with lower voltage. Because the structure of each battery cell is in series, there is a phenomenon that the positive and negative electrodes of the two battery cells are not isolated when discharging the battery cells with higher voltage to the battery cells with lower voltage, which greatly increases the potential safety hazard. Summary of the Invention

[0003] The purpose of the present invention is to provide an energy storage battery active balancing control system with good safety, high flexibility and low energy consumption.

[0004] To solve the above technical problems, the present invention adopts the following technical scheme: an energy storage battery active balancing control system, which includes: a lithium battery pack, which includes a plurality of cell monomers; a BMS battery management module;

[0005] The control system further includes a plurality of fully isolated DC converters, and each of the fully isolated DC converters is connected to each of the cell monomers in a one-to-one correspondence for charging the cell monomers.

[0006] The BMS battery management module is used to detect the voltage of each cell monomer. When the BMS battery management module detects that the voltage of a certain cell monomer drops faster than that of other cell monomers, it actively activates the fully isolated DC converter to charge the cell monomer with a lower voltage.

[0007] Optimally, the BMS battery management module includes a battery sampling chip and an MCU control chip. The battery sampling chip is used to collect the voltage of the cell monomers and transmit the state information of the lithium battery pack to the MCU control chip.

[0008] Furthermore, each of the fully isolated DC converters includes a standby zero-loss circuit, a PWM chip, and an isolation transformer.

[0009] When the battery sampling chip collects that the voltage of a cell monomer drops faster than that of other cell monomers, the MCU control chip outputs a charging signal to the standby zero-loss circuit. The standby zero-loss circuit outputs a charging signal to supply power to the PWM chip, and then the PWM chip outputs a driving signal to start the isolation transformer to charge the cell monomer.

[0010] Further, each of the fully isolated DC converters further includes a primary-secondary isolated feedback optocoupler, a rectifier diode, an absorption circuit, and an output voltage stabilizing feedback diode. The primary-secondary isolated feedback optocoupler is connected to the power supply of the PWM chip. There are two rectifier diodes, and they and the absorption circuit are respectively electrically connected to the isolation transformer.

[0011] The standby zero-loss circuit further includes an optocoupler, a triode electrically connected to the optocoupler, a front-end resistor, and a rear-end resistor. The front-end resistor is connected between the output end of the optocoupler and the base of the triode. The rear-end resistor is connected between the base and the emitter of the triode. The collector of the triode is connected to the power supply terminal of the PWM chip.

[0012] The present invention also provides a control method based on the energy storage battery active balancing control system described in any one of the above. The method is characterized in that: the BMS battery management module monitors the cell voltages of each battery BATT 1 to BATT N in the battery pack, and the real-time voltages of each cell are V1 to V N , select the cell with a higher voltage as the reference cell, and the voltage value of the reference cell is V max , and the voltages of the cells with lower voltages are all V min , and set the rated voltage difference V E , when V max - V min > V E , the BMS battery management module controls the fully isolated DC converter to perform balanced charging on the cells with low BATT voltages until the voltages are the same, and BATT V min is one or more of the cells.

[0013] The present invention also provides a control method based on the energy storage battery active balancing control system described in any one of the above. The method is characterized in that: the BMS battery management module monitors the cell voltages of each battery BATT1 to BATT N , and at every interval of time δT, collect the cell voltages V1 to V N , and calculate the voltage drops of each cell within the time δT as δV1 to δV N , calculate the difference between δV max and δV min , and set the rated voltage drop as δV e When δV max - δV min > δV e , then the BMS battery management module controls the fully isolated DC converter to perform balanced charging on the cells of BATT V min until the voltage is the same as that of other cells.

[0014] The beneficial effects of the present invention are as follows: The present invention charges each battery cell monomer through a fully isolated DC converter connected to each battery cell monomer one by one, with high flexibility. Since optocoupler control is used to initiate charging and a standby zero-loss circuit is incorporated, not only is the safety good, but also there is no imbalance, and there is zero loss during standby, greatly reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a block diagram of an active balancing control system for an energy storage battery

[0016] Figure 2 It is an active balancing module (DC-DC fully isolated converter)

[0017] Figure 3 It is a schematic diagram of the BMS circuit. SPECIFIC EMBODIMENTS

[0018] The present invention will be described in detail below with reference to the embodiments shown in the drawings:

[0019] As Figures 1-3 shown, an active balancing control system for an energy storage battery includes: a lithium battery pack, which includes a number of battery cell monomers BATT1 to BATT N , a BMS battery management module, and a number of fully isolated DC converters DC-DC1 to DC-DC N , each of the fully isolated DC converters is connected to each of the battery cell monomers one by one for charging the battery cell monomers.

[0020] The BMS battery management module is used to detect the voltage of each battery cell monomer. When the BMS battery management module detects that the voltage of a battery cell monomer drops faster than that of other battery cells, it actively activates the fully isolated DC converter to charge the battery cell with a lower voltage. The BMS battery management module includes a battery sampling chip IC1 and an MCU control chip IC2. The battery sampling chip IC1 is used to collect the voltage of the battery cell monomer and transmit the state information of the lithium battery pack to the MCU control chip IC2. Each of the fully isolated DC converters includes a standby zero-loss circuit, a PWM chip, and an isolation transformer. When the battery sampling chip detects that the voltage of a battery cell monomer drops faster than that of other battery cells, the MCU control chip outputs a charging signal to the standby zero-loss circuit. Subsequently, the standby zero-loss circuit outputs a charging signal to supply power to the PWM chip, and then the PWM chip outputs a driving signal to start the isolation transformer to charge the battery cell monomer.

[0021] Each of the fully isolated DC converters further includes a primary-secondary isolated feedback optocoupler, a rectifier diode, an absorption circuit, and an output voltage stabilizing feedback diode. The primary-secondary isolated feedback optocoupler is connected to the PWM chip. There are two rectifier diodes, which are connected to the absorption circuit and the isolation transformer respectively. Taking the first fully isolated DC converter as an example, it further includes a primary-secondary isolated feedback optocoupler U3, rectifier diodes D1, an absorption circuit D2, C2, R2, and an output voltage stabilizing feedback diode D4. The primary-secondary isolated feedback optocoupler U3 is connected to the PWM U2 chip. There are two rectifier diodes D1, D3, which are connected to the absorption circuit D2, C2, R2 and the isolation transformer T1 respectively.

[0022] The standby zero-loss circuit includes an optocoupler, a triode electrically connected to the optocoupler, a front-end resistor, and a rear-end resistor. The front-end resistor is connected between the output terminal of the optocoupler and the base of the triode. The rear-end resistor is connected between the base and the emitter of the triode. The collector of the triode is connected to the PWM chip.

[0023] Taking one of the standby zero-loss circuits, the first standby zero-loss circuit as an example, the first standby zero-loss circuit includes a first optocoupler U1, a first triode Q1 electrically connected to the first optocoupler, and a third resistor R3 (i.e., the front-end resistor) and a fifth resistor R5 (i.e., the rear-end resistor). The third resistor is connected between the output terminal of the first optocoupler and the base of the first triode. The fifth resistor is connected between the base and the emitter of the first triode. The collector of the first triode is connected to the first PWM chip. Taking one of the absorption circuits, the first absorption circuit as an example, it includes a second resistor R2, a second diode D2, and a second capacitor C2.

[0024] The working principle of the present invention is as follows: During charging, the BMS battery management system feeds back the detected voltage of each single cell to the single-chip microcomputer. If the voltage of the second cell is lower than the highest cell voltage, the BMS battery management system S2 outputs a high level to the S2 pin of DC-DC2 to start DC-DC2 to work and charge BATT2, so as to achieve the purpose of active charging balance control. The same applies to other cells when the charging voltage is low. During discharging, the BMS battery management system feeds back the detected voltage of each single cell to the single-chip microcomputer. If the voltage of the first cell is lower than the highest cell voltage, the BMS battery management system S1 outputs a high level to the S1 pin of DC-DC1 to start DC-DC1 to work and charge BATT1, so as to achieve the purpose of active discharging balance control. The same applies to other cells when the discharging voltage is low.

[0025] There are two control methods for the above energy storage battery active balance control system:

[0026] (1) BMS battery management module monitors each battery BATT1~BATT in the battery pack N The real-time voltage of each cell is V1~V N , select the cell with the highest voltage as the reference cell, the voltage value of the reference cell is V max , the battery cell voltage is low V min , and set the rated pressure difference value V E , when V max - V min >V E The BMS battery management module controls the fully isolated DC converter to balance the cells with low BATT voltage until the voltages are consistent. min For one or more cells. max The cells are compared with the cell with the highest voltage one by one. When the voltage difference between any one or more cells and the highest cell exceeds V E When the battery is charged, the one or more cells are charged.

[0027] (2) BMS battery management module monitors each battery BATT1~BATT in the battery pack N The cell voltage V1~V N , and calculate the voltage drop of each cell during δT time as δV1~δV N , calculate δV max and δV min The difference between the rated voltage drop and the rated voltage drop is set to δV e When δV max -δV min >δV e , the BMS battery management module controls the fully isolated DC converter to BATT V min Balance the cells until the voltage is consistent with that of other cells.

[0028] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. An energy storage battery active balancing control system, comprising: Lithium battery pack, It includes several battery cells and a BMS battery management module; its characteristics are: The control system further includes a plurality of fully isolated DC converters, each of which is connected to each of the battery cells in a one-to-one correspondence, and is used to charge the battery cells. The BMS battery management module is used to detect the voltage of each of the battery cells. When the BMS battery management module detects that the voltage of a battery cell drops faster than that of other batteries, it actively turns on the fully isolated DC converter to charge the battery cell with low voltage. The BMS battery management module includes a battery sampling chip and an MCU control chip. The battery sampling chip is used to collect the battery cell voltage and transmit the lithium battery pack status information to the MCU control chip. Each of the fully isolated DC converters includes a standby zero-loss circuit, a PWM chip, and an isolation transformer. When the battery sampling chip detects that the voltage of a single cell drops faster than that of other cells, the MCU control chip outputs a charging signal to the standby zero-loss circuit. The standby zero-loss circuit outputs a charging signal to start the PWM chip to supply power, and then the PWM chip outputs a driving signal to start the isolation transformer to charge the single cell. Each of the fully isolated DC converters also includes a primary-secondary isolation feedback optocoupler, a rectifier diode, an absorption circuit, and an output voltage stabilizing feedback diode. The primary-secondary isolation feedback optocoupler is electrically connected to the PWM chip. There are two rectifier diodes, which are connected to the absorption circuit and the isolation transformer respectively. The standby zero-loss circuit includes an optocoupler, a transistor connected to the optocoupler, and a front-end resistor and a rear-end resistor. The front-end resistor is connected between the output end of the optocoupler and the base of the transistor, the rear-end resistor is connected between the base and emitter of the transistor, and the collector of the transistor is connected to the PWM chip.

2. A control method based on the energy storage battery active balancing control system according to claim 1, characterized in that: The BMS battery management module monitors the cell voltage of each battery BATT 1 to BATT N in the battery pack. The real-time voltage of each cell is V1 to V N , select the cell with the highest voltage as the reference cell, the voltage value of the reference cell is V max , the battery cell voltage is low V min , and set the rated pressure difference value V E , when V max -V min >V E The BMS battery management module controls the fully isolated DC converter to balance the cells with low BATT voltage until the voltages are consistent. min For one or more of the battery cells.

3. A control method based on the energy storage battery active balancing control system according to claim 1, characterized in that: The BMS battery management module monitors the batteries BATT1 to BATT in the battery pack. N The cell voltage V1~V N , and calculate the voltage drop of each cell during δT time as δV1~δV N , calculate δV max and δV min The difference between the rated voltage drop and the rated voltage drop is set to δV e When δV max -δV min >δV e , the BMS battery management module controls the fully isolated DC converter to BATT V min Balance the cells until the voltage is consistent with that of other cells.

Images