Isolating two-way constant current maintenance system based on a power supply for shared equipment

Abstract

An isolating two-way constant current maintenance system based on a power supply for shared equipment, used for maintaining battery packs consisting of battery cells, characterized in that it comprises a power supply, an electronic switch K1, a current sensor, a main battery management system controller, and a plurality of secondary battery management system controllers, wherein the power supply is connected to the current sensor; the current sensor is connected to the electronic switch K1 and the main battery management system controller respectively; the electronic switch is connected to the main battery management system controller and the secondary battery management system controllers respectively; the main battery management system controller is in communication link with the plurality of secondary battery management system controllers;and the individual secondary battery management system controllers are connected to a battery pack; ; wherein the individual secondary battery management system controllers consist of a maintenance circuit, a battery cell detection circuit and a secondary MCU (microprogrammed control unit); and the secondary MCU is connected to the maintenance circuit and the battery cell detection circuit, respectively; wherein the main battery management system controller consists of a battery pack sensing circuit and a main MCU; wherein the main MCU is connected to the battery pack sensing circuit; and the battery pack sensing circuit is connected to two ends of the battery pack; wherein the maintenance circuit consists of a PWM (pulse width modulation) controller, a filter capacitor LL1, a field-effect tube Q1, a transformer T, a field-effect tube Q2, a filter capacitor LL2, a clocking switch K, a signal circuit, a control circuit, and a voltage-current sensing and feedback circuit; two terminals, a, b, of a main coil of transformer T are each connected to one end of filter capacitor LL1 and a drain electrode of field-effect tube Q1; a source electrode of field-effect tube Q1 is connected to the other end of filter capacitor LL1 and is grounded; two terminals, c, d, of a secondary coil of transformer T are each connected to one end of filter capacitor LL2 and a drain electrode of field-effect tube Q2;a source electrode of the field-effect tube Q2 is connected to the other end of the filter capacitor LL2 and the voltage-current sensing and feedback circuit; grid electrodes of the field-effect tubes Q1 and Q2 are each connected to the control circuit; terminal a of the main coil and terminal c of the secondary coil of the transformer T are each connected to the voltage-current sensing and feedback circuit; the two ends of the filter capacitor LL1 are each connected to an anode and a cathode of the power supply; the PWM control is connected to the voltage-current sensing and feedback circuit, the signal circuit, and the power supply; the signal circuit is connected to the control circuit; the voltage-current sensing and feedback circuit is connected to the clocking switch; and the clocking switch is connected to a tested battery pack; wherein the timing switch consists of a plurality of anode switches K4 and cathode switches K5, which correspond one-to-one to the battery cells; one end of each anode switch K4 is connected to the voltage-current sensing and feedback circuit and the other end is connected to the anode of the corresponding battery cell; and one end of each cathode switch K5 is connected to the voltage-current sensing and feedback circuit and the other end is connected to the cathode of the corresponding battery cell.

Description

Technical area

[0001] The present invention relates to an isolating two-way constant current maintenance system based on a shared equipment power supply, which belongs to the field of battery maintenance management. Description of the state of the art

[0002] US 2012 / 0 086 390 A1 describes a charge balancing device and a charge balancing method for a series-connected battery pack. Each individual battery in the battery pack shares a single voltage measurement module and a single charge balancing module. A two-stage switch block provides a current path for measuring the voltage of individual batteries in the battery pack and simultaneously provides a charge or discharge path for a weakly charged or overcharged battery within the battery pack. A low-voltage switch is used for this purpose.

[0003] CN 1 03 117 577 A describes an energy balancing circuit for a battery pack of an electric vehicle. The circuit comprises a balancing controller, several balancing subcircuits, and a bus for connecting these subcircuits. Each balancing subcircuit is arranged on an individual battery unit, connected to the balancing controller, and includes an isolated bidirectional flyback transformer and an electronic switch. The ends of the primary coil of the flyback transformer are connected to the anode and cathode of the bus, while the ends of the secondary coil are connected to the anode and cathode of an individual battery. An electronic switch is connected in series between the cathode of the battery and the secondary coil, and another switch is connected in series between the cathode of the bus and the primary coil.

[0004] Currently, energy-saving stations, electric vehicles, and other devices require battery packs formed by connecting battery cells in series. Battery cells vary in battery capacity and performance due to manufacturing processes, etc. These variations are inevitably amplified during battery pack charging and discharging, increasing the risk of overcharging or overdischarging and reducing the utilization of battery pack capacity. If this situation continues, it leads to a vicious cycle that accelerates battery damage. To further improve the uniformity of battery packs, increase the utilization of battery pack capacity, and extend the service life of battery packs, battery pack maintenance is necessary.Batteries in a battery pack with low remaining capacity are charged, while those batteries in a battery pack with high remaining capacity are discharged.

[0005] Current maintenance methods are divided into energy consumption methods and energy-free methods. The energy-consumption method refers to discharging battery cells with high residual capacity using resistors to consume excess capacity so that the capacity of the battery cells in a battery pack is uniform. Such a method is simple and inexpensive, but it relies on discharging all battery cells using resistors to achieve consistency with the battery cell with the lowest power, which is why the work efficiency is extremely low and a lot of electricity is wasted. Various energy-free methods are available, mainly three types. The first type refers to gradual energy transfer in battery cells, in which the energy in high-capacity battery cells is transferred to those with low capacity.However, if there is a relatively large number of battery cells between two battery cells between which capacity is transferred, maintenance efficiency will be severely affected. The second method refers to charging or discharging battery cells using an isolating one-way maintenance power supply. In this method, all battery cells must be charged or discharged to achieve the same capacity, so the equalization efficiency is mediocre; simultaneous charging and discharging is also not possible. The third method refers to maintaining a battery pack using a two-way maintenance power supply.According to such a method, low-capacity battery cells are charged while high-capacity battery cells are discharged, which is equivalent to transferring power from high-capacity battery cells to low-capacity battery cells through two conversions, thus achieving high efficiency and fast maintenance. However, such a method is difficult to implement and costly, and additionally, a transfer power supply is usually required to achieve energy balance.

[0006] To overcome the technical disadvantages of the third type of maintenance method without energy consumption, the present invention provides an isolating two-way constant current maintenance system based on a shared equipment power supply. SUMMARY OF THE INVENTION

[0007] The present invention aims to provide an isolating two-way constant current maintenance system based on a shared equipment power supply. The system can maintain battery cells that need to be charged and battery cells that need to be discharged by selecting them from the battery pack during battery pack operation, and performs charging maintenance and discharging maintenance simultaneously, thereby effectively ensuring the uniformity of the battery pack, increasing the energy utilization of the battery pack, and extending the life expectancy of the battery pack.Compared with the prior art, the system solution of the present invention effectively reduces costs and overcomes the disadvantage of a general solution requiring an independent device power supply and a balanced power supply; also, the system does not require the device power supply for a long time, and after the formal commissioning of the device, the system can operate independently and does not require a power supply.

[0008] To achieve the objects of the present invention, the present invention provides an isolating two-way constant current maintenance system based on a shared equipment power supply for servicing battery packs composed of battery cells.The system includes a power supply, an electronic switch K1, a current sensor, a main battery management system controller, and a plurality of secondary battery management system controllers; wherein the power supply is connected to the current sensor; the current sensor is connected to each of the electronic switch K1 and the main battery management system controller; the electronic switch is connected to each of the main battery management system controller and the secondary battery management system controllers; the main battery management system controller is in communication with each of the plurality of secondary battery management system controllers; and the individual secondary battery management system controllers are connected to a battery pack.

[0009] Each secondary battery management system controller consists of a maintenance circuit, a battery cell detection circuit, and a secondary MCU (microprogrammed control unit); the secondary MCU is connected to the maintenance circuit and the battery cell detection circuit, respectively.

[0010] The main battery management system controller consists of a battery pack detection circuit and a main MCU; the main MCU is connected to the battery pack detection circuit; and the battery pack detection circuit is connected to two ends of the battery pack.

[0011] The maintenance circuit consists of a PWM (pulse width modulation) controller, a filter capacitor LL1, a field-effect tube Q1, a transformer T, a field-effect tube Q2, a filter capacitor LL2, a timing switch K, a signaling circuit, a control circuit, and a voltage-current detection and feedback circuit; two terminals, a, b, of a main coil of the transformer T are each connected to one end of the filter capacitor LL1 and a drain electrode of the field-effect tube Q1; a source electrode of the field-effect tube Q1 is connected to the other end of the filter capacitor LL1 and is grounded; two terminals, c, d, of a secondary coil of the transformer T are each connected to one end of the filter capacitor LL2 and a drain electrode of the field-effect tube Q2.a source electrode of the field-effect tube Q2 is connected to the other end of the filter capacitor LL2 and the voltage-current detection and feedback circuit; grid electrodes of the field-effect tube Q1 and the field-effect tube Q2 are respectively connected to the control circuit; the terminal a of the main coil and the terminal c of the secondary coil of the transformer T are respectively connected to the voltage-current detection and feedback circuit; the two ends of the filter capacitor LL1 are respectively connected to an anode and a cathode of the power supply; the PWM controller is respectively connected to the voltage-current detection and feedback circuit, the signal circuit, and the power supply; the signal circuit is connected to the control circuit; the voltage-current detection and feedback circuit is connected to the timing switch; and the timing switch is connected to a tested battery pack.

[0012] The timing switch consists of a plurality of anode switches K4 and cathode switches K5, which correspond one-to-one to the battery cells; one end of each anode switch K4 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the anode of the corresponding battery cell; and one end of each cathode switch K5 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the cathode of the corresponding battery cell.

[0013] Preferably, the PWM controller of each maintenance circuit is in communication with the main battery management system controller.

[0014] The communication mode of the present invention can be CAN communication, RS485 communication, GPRS, WLAN, 2.4G, Bluetooth, etc.

[0015] Preferably, the power supply is a switching power supply or a battery energy saving device.

[0016] Preferably, the signal circuit consists of two single-pole double-throw switches K2, K3; wherein one end of each single-pole double-throw switch K2, K3 is connected to a PWMA terminal and a PWMB terminal of the PWM controller, respectively, and the other end is connected to the control circuit.

[0017] The present invention has the following advantages: The system as a whole does not require a continuous or long-term power supply; once the system is operating normally, the power supply can be controlled to be off. At the same time, the control of a maintenance channel achieves bus power supply balancing through charge and discharge maintenance performed using the current sensor and the maintenance circuit, thus avoiding the disadvantage of other system solutions that require an independent and stable long-term power supply and an independent balanced power supply. The entire system can perform charge and discharge maintenance on multiple batteries requiring maintenance simultaneously.The PWM signals generated by the PWM controller are sent through the signal circuit to the field-effect tube control circuit; the field-effect tube control circuit controls the field-effect tubes; the timing switch clocks one of the battery cells in a battery module and causes the battery cell to charge or discharge. The PWM controller generates two PWM signals, PWMA and PWMB, where PWMA is a main excitation signal and PWMB is a synchronous rectification signal. During charging, the PWMA signal controls field-effect tube Q1, and the PWMB signal controls field-effect tube Q2. During discharging, the PWMA signal controls field-effect tube Q2, and the PWMB signal controls field-effect tube Q1. The voltage-current sensing and feedback circuit enables constant-current charging or discharging while also feeding back voltage to achieve overvoltage protection.The isolation two-way constant current maintenance system based on a shared equipment power supply has the advantages of small size, low cost, high power conversion efficiency, two-way and constant maintenance, and low stress on the power supply. The system can rapidly increase battery utilization and effectively extend the service life of the battery pack. BRIEF DESCRIPTION OF THE MULTIPLE VIEWS OF THE DRAWINGS Fig. 1 is a structural view of an isolating two-way constant current maintenance system based on a shared equipment power supply of the present invention; Fig. 2 is a circuit diagram of a maintenance circuit of the present invention; Fig. 3 is a circuit diagram of the connection of several maintenance circuits of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The invention will be further described in conjunction with the accompanying drawings and embodiments.

[0019] As in Fig. 1, an isolating two-way constant current maintenance system based on a shared equipment power supply is for servicing battery packs consisting of battery cells, and includes a power supply, an electronic switch K1, a current sensor, a main battery management system controller, and a plurality of secondary battery management system controllers, wherein the power supply is connected to the current sensor; the current sensor is connected to each of the electronic switch K1 and the main battery management system controller; the electronic switch is connected to each of the main battery management system controller and the secondary battery management system controllers; the main battery management system controller is in communication with each of the plurality of secondary battery management system controllers;and the individual secondary battery management system controllers are connected to a battery pack;

[0020] Each secondary battery management system controller consists of a maintenance circuit, a battery cell detection circuit, and a secondary MCU (microprogrammed control unit); and the main battery management system controller consists of a battery pack detection circuit and a main MCU. The individual secondary MCUs are respectively connected to the maintenance circuit and the battery cell detection circuit; the battery cell detection circuit is connected to two ends of a battery cell to detect data such as voltage, current, and temperature of the battery cell. The main MCU is connected to the battery pack detection circuit, and the battery pack detection circuit is connected to the two ends of a battery pack to detect data such as voltage, current, and temperature of the battery pack as a whole.

[0021] As in Fig. 2 and Fig.As shown in Figure 3, the maintenance circuit includes a PWM (pulse width modulation) controller, a filter capacitor LL1, a field-effect tube Q1, a transformer T, a field-effect tube Q2, a filter capacitor LL2, a timing switch K, a signaling circuit 1, a control circuit 2, and a voltage-current detection and feedback circuit 3; wherein two terminals, a, b, of a main coil of the transformer T are respectively connected to one end of the filter capacitor LL1 and a drain electrode of the field-effect tube Q1; a source electrode of the field-effect tube Q1 is connected to the other end of the filter capacitor LL1 and is grounded; two terminals, c, d, of a secondary coil of the transformer T are respectively connected to one end of the filter capacitor LL2 and a drain electrode of the field-effect tube Q2;a source electrode of the field-effect tube Q2 is connected to the other end of the filter capacitor LL2 and the voltage-current detection and feedback circuit 3; grid electrodes of the field-effect tube Q1 and the field-effect tube Q2 are respectively connected to the control circuit 2; the terminal a of the main coil and the terminal c of the secondary coil of the transformer T are respectively connected to the voltage-current detection and feedback circuit 3; the two ends of the filter capacitor LL1 are respectively connected to an anode and a cathode of the power supply; the PWM controller is respectively connected to the voltage-current detection and feedback circuit 3, the signal circuit 1, and the power supply; the signal circuit 1 is connected to the control circuit 2; the voltage-current detection and feedback circuit 3 is connected to the timing switch; and the timing switch is connected to a tested battery pack.

[0022] The timing switch includes a plurality of anode switches K4 and cathode switches K5 that correspond one-to-one to the battery cells; one end of each anode switch K4 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the anode of the corresponding battery cell; and one end of each cathode switch K5 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the cathode of the corresponding battery cell.

[0023] The PWM controller of each maintenance circuit communicates with the main battery management system controller. The power supply is a switching power supply or a battery energy-saving device.

[0024] The signal circuit consists of two single-pole, double-throw switches K2 and K3. One end of each single-pole, double-throw switch K2 and K3 is connected to a PWMA terminal and a PWMB terminal of the PWM controller, respectively, and the other end is connected to the control circuit. The control circuit controls the activation of the field-effect tubes Q1 and Q2. The voltage-current sensing and feedback circuit is implemented using existing, mature techniques.

[0025] The operation of the present invention is as follows. The PWM controller generates two PWM signals, PWMA and PWMB, where PWMA is a main excitation signal and PWMB is a synchronous rectification signal. PWMA and PWMB are supplied to the field-effect tube Q1 and the field-effect tube Q2 through the signal circuit 1. During charging, the PWMA signal controls the field-effect tube Q1, and the PWMB signal controls the field-effect tube Q2. During discharging, the PWMA signal controls the field-effect tube Q2, and the PWMB signal controls the field-effect tube Q1. The timing switch K controls one of the battery cells in the battery pack under test for selection and can charge or discharge the selected battery cell.The voltage-current detection and feedback circuit 3 detects the strength of the charging or discharging current and feeds the detected data into the PWM controller to achieve constant current charging or discharging, and detects voltages on both sides simultaneously to achieve overvoltage protection. The on-off sequence of the field-effect tube Q1 and the field-effect tube Q2 during charging is as follows. I. The field-effect tube Q1 is turned on; the field-effect tube Q2 is turned off; and the energy in the power supply is transferred to the transformer T via the field-effect tube Q1; II. The field-effect tube Q1 is turned off; the field-effect tube Q2 is turned off; the energy in the transformer T is transferred to the filter capacitor LL2 and the battery cell via a body diode of the field-effect tube Q2; this process is short and dead zone time; III.The field-effect tube Q1 is turned off; the field-effect tube Q2 is turned on; the energy in the transformer T is transferred via the field-effect tube Q2 to the filter capacitor LL2 and the battery cell. The turn-on voltage drop of the field-effect tube Q2 is much lower than the turn-on voltage drop of its body diode, which is why the efficiency of power supply equalization is greatly increased by turning on the field-effect tube Q2 for synchronous rectification. IV. The field-effect tube Q1 is turned off; the field-effect tube Q2 is turned off; this process is short and dead zone time. This ends one cycle. The charging process is the continuous cycle of these four processes. During discharge, the time sequence of the field-effect tube Q1 and the field-effect tube Q2 is reversed to the charging process.

[0026] The specific embodiment described herein is merely illustrative of the spirit of the present invention. Those skilled in the art may make various modifications, additions, or substitutions based on the specific embodiments described. These modifications, additions, and substitutions are within the scope of the present invention.

Claims

[1] Isolating two-way constant current maintenance system based on a power supply of shared equipment, used to maintain battery packs consisting of battery cells, characterized bythat it comprises a power supply, an electronic switch K1, a current sensor, a main battery management system controller, and a plurality of secondary battery management system controllers, wherein the power supply is connected to the current sensor; the current sensor is connected to each of the electronic switch K1 and the main battery management system controller; the electronic switch is connected to each of the main battery management system controller and the secondary battery management system controllers; the main battery management system controller is in communication with each of the plurality of secondary battery management system controllers; and the individual secondary battery management system controllers are connected to a battery pack; wherein each secondary battery management system controller consists of a maintenance circuit, a battery cell detection circuit, and a secondary MCU (microprogrammed control unit); and the secondary MCU is connected to the maintenance circuit and the battery cell detection circuit, respectively; wherein the main battery management system controller consists of a battery pack detection circuit and a main MCU; wherein the main MCU is connected to the battery pack detection circuit; and the battery pack detection circuit is connected to two ends of the battery pack; wherein the maintenance circuit consists of a PWM (pulse width modulation) controller, a filter capacitor LL1, a field-effect tube Q1, a transformer T, a field-effect tube Q2, a filter capacitor LL2, a timing switch K, a signaling circuit, a control circuit, and a voltage-current detection and feedback circuit; two terminals, a, b, of a main coil of the transformer T are each connected to one end of the filter capacitor LL1 and a drain electrode of the field-effect tube Q1; a source electrode of the field-effect tube Q1 is connected to the other end of the filter capacitor LL1 and is grounded; two terminals, c, d, of a secondary coil of the transformer T are each connected to one end of the filter capacitor LL2 and a drain electrode of the field-effect tube Q2;a source electrode of the field-effect tube Q2 is connected to the other end of the filter capacitor LL2 and the voltage-current detection and feedback circuit; grid electrodes of the field-effect tube Q1 and the field-effect tube Q2 are each connected to the control circuit; the terminal a of the main coil and the terminal c of the secondary coil of the transformer T are each connected to the voltage-current detection and feedback circuit; the two ends of the filter capacitor LL1 are each connected to an anode and a cathode of the power supply; the PWM controller is each connected to the voltage-current detection and feedback circuit, the signal circuit, and the power supply; the signal circuit is connected to the control circuit; the voltage-current detection and feedback circuit is connected to the timing switch; and the timing switch is connected to a tested battery pack. wherein the timing switch consists of a plurality of anode switches K4 and cathode switches K5 that correspond one-to-one to the battery cells; one end of each anode switch K4 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the anode of the corresponding battery cell; and one end of each cathode switch K5 is connected to the voltage-current detection and feedback circuit, and the other end is connected to the cathode of the corresponding battery cell. [2] An isolating two-way constant current maintenance system based on a power supply of shared equipment according to claim 1, characterized by that the PWM control in each maintenance circuit is in communication with the main battery management system control. [3] An isolating two-way constant current maintenance system based on a power supply of shared equipment according to claim 1, characterized by that the power supply is a switching power supply or a battery energy saving device. [4] An isolating two-way constant current maintenance system based on a power supply of shared equipment according to claim 1, characterized by that the signal circuit consists of two single-pole double-throw switches K2, K3; wherein one end of each single-pole double-throw switch K2, K3 is connected to a PWMA terminal and a PWMB terminal of the PWM controller, and the other end is connected to the control circuit.

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