Lithium battery pack charging and discharging device with balanced charging and discharging

Abstract

A lithium battery pack charging and discharging device with balanced charging and discharging belongs to the technical field of charging and discharging. The objective of the utility model is to solve the problems of low charging efficiency and time consumption of the existing battery active equalization scheme. The voltage of each lithium battery in the lithium battery pack is reported to the microprocessor in real time through the voltage sampling circuit, the maximum value selection circuit selects the maximum voltage from the voltages of all the lithium battery monomers, the minimum value selection circuit selects the minimum voltage from the voltages of all the lithium battery monomers, the difference between the maximum voltage and the minimum voltage is calculated through the difference circuit, and the difference between the maximum voltage and the minimum voltage is calculated. And if the difference value is less than or equal to the threshold voltage, closing the equalization circuit, and if the difference value is greater than the threshold voltage, opening the equalization circuit, discharging the lithium battery monomer with the maximum voltage, and charging the lithium battery monomer with the minimum voltage. The device is used for balanced charging and discharging of the lithium battery pack.

Description

Technical Field

[0001] The utility model relates to a balanced charging and discharging device, belonging to the technical field of charging and discharging. Background Art

[0002] With the development of society and economic progress, industrial and commercial electricity consumption is increasing, but energy supply is facing severe challenges. In order to solve this problem, energy storage technology has gradually been widely used in the industrial and commercial fields, and has achieved remarkable results.

[0003] The lithium battery management system or voltage sampling circuit is a battery management system used to monitor and control the lithium battery pack, including monitoring of battery status such as voltage, temperature, etc.

[0004] Battery balancing technology can achieve balanced charging of single cells in a battery pack to avoid the problem of unbalanced charging and discharging of certain batteries and extend the service life of the entire battery pack.

[0005] However, the current active battery balancing solutions used in lithium battery packs mostly use unidirectional solutions such as inductive and capacitive solutions. This solution first transfers the energy of one battery to the inductor or capacitor, and then transfers it to another battery. During this process, the inductor or capacitor will generate heat, so there will be energy loss. In addition, this solution charges the single batteries in turn, and cannot specify any one battery to charge. The charging efficiency is low and time-consuming. Utility Model Content

[0006] The utility model aims to solve the problems of low charging efficiency and time-consuming in the existing active battery equalization scheme, and proposes a lithium battery pack charging and discharging device for balanced charging and discharging.

[0007] A lithium battery pack charging and discharging device for balanced charging and discharging, the device comprising a voltage sampling circuit, a microprocessor, a maximum value selection circuit, a minimum value selection circuit, a differential circuit, a comparison circuit and a balancing circuit;

[0008] The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the voltage sampling circuit, the voltage signal output end of the voltage sampling circuit is connected to the voltage signal input end of the microprocessor, the maximum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the minimum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the maximum voltage signal output end of the maximum value selection circuit and the minimum voltage signal output end of the minimum value selection circuit are each connected to a differential signal input end of the differential circuit, the differential signal output end of the differential circuit is connected to the differential signal input end of the comparison circuit, and the comparison result output end of the comparison circuit is connected to the comparison result input end of the microprocessor;

[0009] The balancing circuit includes n primary drive circuits, 1 secondary drive circuit, n primary current sensors, 1 secondary current sensor, a transformer T1, n primary MOS tubes and 1 secondary MOS tube;

[0010] The drive signal output end of the microprocessor is connected to the drive signal input end of n primary drive circuits, the drive signal output end of each primary drive circuit is connected to the gate of a primary MOS tube, the drain of each MOS tube is connected to one end of a primary coil of the transformer T1, the other end of each primary coil of the transformer T1 is connected to the positive electrode of a lithium battery cell, the source of each MOS tube is connected to the current signal input end of a primary current sensor, the current signal output end of each primary current sensor is connected to the negative electrode of a lithium battery cell, and the current sampling signal output end of each primary current sensor is connected to the microprocessor. The current sampling signal input end of the processor and the drive signal output end of the microprocessor are connected to the drive signal input end of the secondary drive circuit, the drive signal output end of the secondary drive circuit is connected to the gate of the secondary MOS tube, the drain of the secondary MOS tube is connected to one end of the secondary coil of the transformer T1, the other end of the secondary coil of the transformer T1 is connected to the positive electrode of the lithium battery pack, the source of the secondary MOS tube is connected to the current signal input end of the secondary current sensor, the current signal output end of the secondary current sensor is connected to the negative electrode of the lithium battery pack, and the sampling current signal output end of the secondary current sensor is connected to the sampling current signal input end of the microprocessor.

[0011] Preferably, the transformer is a flyback transformer.

[0012] Preferably, the comparison circuit comprises resistors R1-R4, a comparator AR1 and a diode D1;

[0013] The differential signal output end of the differential circuit is simultaneously connected to the positive input end of the comparator AR1 and one end of the resistor R2, the other end of the resistor R2 is connected to the power ground, the negative input end of the comparator AR1 is simultaneously connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the threshold current, the output end of the comparator AR1 is connected to one end of the resistor R4, the other end of the resistor R4 is simultaneously connected to the other end of the resistor R3 and the positive electrode of the diode D1, and the negative electrode of the diode D1 is connected to the comparison result input end of the microprocessor.

[0014] Preferably, the voltage sampling circuit includes a lithium battery cell voltage sampling circuit and a data transmission circuit;

[0015] The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the lithium battery cell voltage sampling circuit, and the parallel signal output end of the lithium battery cell voltage sampling circuit is connected to the parallel signal input end of the data transmission circuit.

[0016] Preferably, the threshold voltage is 30 mV.

[0017] Preferably, the microprocessor is implemented using a RISC-V single-chip microcomputer.

[0018] The beneficial effects of the present invention are:

[0019] 1. The utility model adopts the domestic RISC-V single-chip microcomputer as the main control chip. Compared with the use of STM series single-chip microcomputers, it reduces the cost and improves the localization rate of devices.

[0020] 2. The utility model adopts active balancing technology to reduce the energy loss of the lithium battery pack during balancing and improve the balancing efficiency. The active balancing solution of the utility model does not use active balancing chips, which further reduces the cost and can maximize the performance of the RISC-V microcontroller.

[0021] 3. The utility model adopts a bidirectional flyback active balancing solution, which can designate any battery in the lithium battery pack for charge and discharge control, so as to further improve the balancing efficiency.

[0022] 4. The utility model adds a current sensor to the active balancing module to monitor the working status of the power device, transformer and drive circuit in real time, and ensure the balance of the power of the entire lithium battery pack in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the principle of a lithium battery pack charging and discharging device for balanced charging and discharging;

[0024] Figure 2 is a circuit diagram of a comparison circuit. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0028] Specific implementation method 1: Combination Figure 1The present embodiment is described. The lithium battery pack charging and discharging device for balanced charging and discharging described in the present embodiment includes a voltage sampling circuit, a microprocessor, a maximum value selection circuit, a minimum value selection circuit, a differential circuit, a comparison circuit and a balancing circuit.

[0029] The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the voltage sampling circuit, the voltage signal output end of the voltage sampling circuit is connected to the voltage signal input end of the microprocessor, the maximum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the minimum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the maximum voltage signal output end of the maximum value selection circuit and the minimum voltage signal output end of the minimum value selection circuit are each connected to a differential signal input end of the differential circuit, the differential signal output end of the differential circuit is connected to the differential signal input end of the comparison circuit, and the comparison result output end of the comparison circuit is connected to the comparison result input end of the microprocessor;

[0030] The balancing circuit includes n primary drive circuits, 1 secondary drive circuit, n primary current sensors, 1 secondary current sensor, a transformer T1, n primary MOS tubes and 1 secondary MOS tube;

[0031] The drive signal output end of the microprocessor is connected to the drive signal input end of n primary drive circuits, the drive signal output end of each primary drive circuit is connected to the gate of a primary MOS tube, the drain of each MOS tube is connected to one end of a primary coil of the transformer T1, the other end of each primary coil of the transformer T1 is connected to the positive electrode of a lithium battery cell, the source of each MOS tube is connected to the current signal input end of a primary current sensor, the current signal output end of each primary current sensor is connected to the negative electrode of a lithium battery cell, and the current sampling signal output end of each primary current sensor is connected to the microprocessor. The current sampling signal input end of the processor and the drive signal output end of the microprocessor are connected to the drive signal input end of the secondary drive circuit, the drive signal output end of the secondary drive circuit is connected to the gate of the secondary MOS tube, the drain of the secondary MOS tube is connected to one end of the secondary coil of the transformer T1, the other end of the secondary coil of the transformer T1 is connected to the positive electrode of the lithium battery pack, the source of the secondary MOS tube is connected to the current signal input end of the secondary current sensor, the current signal output end of the secondary current sensor is connected to the negative electrode of the lithium battery pack, and the sampling current signal output end of the secondary current sensor is connected to the sampling current signal input end of the microprocessor.

[0032] In this implementation, the voltage sampling circuit, the maximum value selection circuit, the minimum value selection circuit, the differential circuit and the comparison circuit are all existing circuits.

[0033] Specific implementation method 2: This implementation method further limits the balanced charging and discharging lithium battery pack charging and discharging device described in specific implementation method 1. In this implementation method, the transformer is a flyback transformer.

[0034] Specific implementation method three: Combination Figure 2 This embodiment is described. This embodiment further defines the balanced charging and discharging lithium battery pack charging and discharging device described in the specific embodiment 1. In this embodiment, the comparison circuit includes resistors R1-R4, a comparator AR1 and a diode D1;

[0035] The differential signal output end of the differential circuit is simultaneously connected to the positive input end of the comparator AR1 and one end of the resistor R2, the other end of the resistor R2 is connected to the power ground, the negative input end of the comparator AR1 is simultaneously connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the threshold current, the output end of the comparator AR1 is connected to one end of the resistor R4, the other end of the resistor R4 is simultaneously connected to the other end of the resistor R3 and the positive electrode of the diode D1, and the negative electrode of the diode D1 is connected to the comparison result input end of the microprocessor.

[0036] Specific implementation method 4: This implementation method further defines the balanced charging and discharging lithium battery pack charging and discharging device described in specific implementation method 1. In this implementation method, the voltage sampling circuit includes a lithium battery cell voltage sampling circuit and a data transmission circuit;

[0037] The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the lithium battery cell voltage sampling circuit, and the parallel signal output end of the lithium battery cell voltage sampling circuit is connected to the parallel signal input end of the data transmission circuit.

[0038] In this implementation, if the difference is less than or equal to the threshold voltage, the balancing circuit is turned off, and if the difference is greater than the threshold voltage, the balancing circuit is turned on.

[0039] Specific implementation mode 5: This implementation mode further limits the balanced charging and discharging lithium battery pack charging and discharging device described in specific implementation mode 1. In this implementation mode, the threshold voltage is 30mV.

[0040] Specific implementation method six: This implementation method further limits the balanced charging and discharging lithium battery pack charging and discharging device described in specific implementation method one. In this implementation method, the microprocessor is implemented using a single-chip microcomputer of the RISC-V model.

[0041] The working principle is:

[0042] First, the voltage sampling circuit reports the voltage of each lithium battery in the lithium battery pack to the microprocessor in real time. The maximum value selection circuit selects the maximum voltage from the voltages of all lithium battery cells, and the minimum value selection circuit selects the minimum voltage from the voltages of all lithium battery cells. The difference circuit makes a difference between the maximum voltage and the minimum voltage. If the difference is less than or equal to the threshold voltage, the balancing circuit is turned off, that is, the microprocessor does not send a driving signal.

[0043] If the difference is greater than the threshold voltage, the balancing circuit is turned on, including discharging the lithium battery cell with the maximum voltage and charging the lithium battery cell with the minimum voltage;

[0044] Among them, the discharge of the lithium battery cell with the maximum voltage is specifically as follows:

[0045] The microprocessor sends a drive signal which is amplified by a primary drive circuit to turn on the MOS tube, and the current ramps up on the primary side of the flyback transformer T1. When the current detected by the primary current sensor reaches the peak current preset by the microprocessor, the microprocessor sends a drive signal which is amplified by the primary drive circuit to turn off the primary MOS tube. The microprocessor drives the secondary drive circuit to turn on the secondary MOS tube, and the energy stored in the flyback transformer T1 is transferred to the secondary winding. The secondary MOS tube is turned on to minimize power loss during energy transfer. When the current detected by the secondary current sensor is zero, the secondary MOS tube is turned off, so that the power of the lithium battery cell with the maximum voltage is transferred to the entire lithium battery pack, thereby realizing the discharge of the lithium battery cell with the maximum voltage.

[0046] Among them, charging the lithium battery cell with the minimum voltage is specifically as follows:

[0047] The microprocessor sends a driving signal which is amplified by a secondary driving circuit to turn on the secondary MOS tube. The current flows from the entire battery pack through the flyback transformer T1. When the secondary current reaches the peak current preset by the microprocessor after being detected by the secondary current sensor, the secondary MOS tube is turned off, and the microprocessor drives the primary MOS tube of the primary driving circuit to turn on, so as to minimize the energy loss in the charging stage. Once the current sensor 1 detects zero, the primary MOS tube is turned off, so that the power of the entire lithium battery pack is transferred to the lithium battery cell with the minimum voltage, thereby realizing the charging of the lithium battery cell with the minimum voltage.

[0048] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A lithium battery pack charging and discharging device for balanced charging and discharging, characterized in that: The device includes a voltage sampling circuit, a microprocessor, a maximum value selection circuit, a minimum value selection circuit, a differential circuit, a comparison circuit and an equalization circuit; The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the voltage sampling circuit, the voltage signal output end of the voltage sampling circuit is connected to the voltage signal input end of the microprocessor, the maximum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the minimum voltage signal output end of the microprocessor is connected to the maximum voltage signal input end of the maximum value selection circuit, the maximum voltage signal output end of the maximum value selection circuit and the minimum voltage signal output end of the minimum value selection circuit are each connected to a differential signal input end of the differential circuit, the differential signal output end of the differential circuit is connected to the differential signal input end of the comparison circuit, and the comparison result output end of the comparison circuit is connected to the comparison result input end of the microprocessor; The balancing circuit includes n primary drive circuits, 1 secondary drive circuit, n primary current sensors, 1 secondary current sensor, a transformer T1, n primary MOS tubes and 1 secondary MOS tube; The drive signal output end of the microprocessor is connected to the drive signal input end of n primary drive circuits, the drive signal output end of each primary drive circuit is connected to the gate of a primary MOS tube, the drain of each MOS tube is connected to one end of a primary coil of the transformer T1, the other end of each primary coil of the transformer T1 is connected to the positive electrode of a lithium battery cell, the source of each MOS tube is connected to the current signal input end of a primary current sensor, the current signal output end of each primary current sensor is connected to the negative electrode of a lithium battery cell, and the current sampling signal output end of each primary current sensor is connected to the microprocessor. The current sampling signal input end of the processor and the drive signal output end of the microprocessor are connected to the drive signal input end of the secondary drive circuit, the drive signal output end of the secondary drive circuit is connected to the gate of the secondary MOS tube, the drain of the secondary MOS tube is connected to one end of the secondary coil of the transformer T1, the other end of the secondary coil of the transformer T1 is connected to the positive electrode of the lithium battery pack, the source of the secondary MOS tube is connected to the current signal input end of the secondary current sensor, the current signal output end of the secondary current sensor is connected to the negative electrode of the lithium battery pack, and the sampling current signal output end of the secondary current sensor is connected to the sampling current signal input end of the microprocessor.

2. The balanced charging and discharging lithium battery pack charging and discharging device according to claim 1, characterized in that: The transformer is a flyback transformer.

3. The balanced charging and discharging lithium battery pack charging and discharging device according to claim 1, characterized in that: The comparison circuit includes resistors R1-R4, a comparator AR1 and a diode D1; The differential signal output end of the differential circuit is simultaneously connected to the positive input end of the comparator AR1 and one end of the resistor R2, the other end of the resistor R2 is connected to the power ground, the negative input end of the comparator AR1 is simultaneously connected to one end of the resistor R1 and one end of the resistor R3, the other end of the resistor R1 is connected to the threshold current, the output end of the comparator AR1 is connected to one end of the resistor R4, the other end of the resistor R4 is simultaneously connected to the other end of the resistor R3 and the positive electrode of the diode D1, and the negative electrode of the diode D1 is connected to the comparison result input end of the microprocessor.

4. The balanced charging and discharging lithium battery pack charging and discharging device according to claim 1, characterized in that: The voltage sampling circuit includes a lithium battery cell voltage sampling circuit and a data transmission circuit; The voltage signal output end of each lithium battery cell is connected to a voltage signal input end of the lithium battery cell voltage sampling circuit, and the parallel signal output end of the lithium battery cell voltage sampling circuit is connected to the parallel signal input end of the data transmission circuit.

5. The balanced charging and discharging lithium battery pack charging and discharging device according to claim 1, characterized in that: The threshold voltage is 30mV.

6. The balanced charging and discharging lithium battery pack charging and discharging device according to claim 1, characterized in that: The microprocessor is implemented using a RISC-V microcontroller.

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