Equalizing charge circuit and battery pack

Abstract

An equalizing charge circuit comprises a first input end, a second input end, a third input end, an output plus end, an output minus end, a detection circuit U1 and a flyback DC-DC converter 10. The junction of a drain of an N-MOS (N-channel metal oxide semiconductor) transistor Q and a primary winding NP of a transformer B is further connected with an anode of a diode D1, a cathode of the diode D1 is connected with the third input end, and a capacitor C is parallelly connected between the second input end and the third input end. The output plus end is connected on the anode of the batter pack, and the output minus end is connected on the cathode of the battery pack. When the detection circuit detects that voltage of a battery cell is larger than a set value, the converter 10 starts working, charge current to the battery cell is extracted and returned to charge the chatter pack, energy generated by leakage inductance of the flyback converter can be used for charging a previous battery cell, and accordingly equalizing charge of the battery pack is realized; when the detection circuit U1 composed of a single chip microcomputer is utilized, an infrared receiving head is added to synchronously adjust a set value, and equalizing discharge can be realized. The flyback circuit is high in reliability, simple in composition, low in cost, high in efficiency and easy to maintain.

Description

technical field [0001] The invention relates to a charging device for a battery pack or a supercapacitor pack, in particular to a balanced charging circuit for each monomer in the battery pack or the supercapacitor pack. Background technique [0002] At present, in systems where batteries are used as energy storage units, the capacity of individual batteries is relatively low, which cannot meet the requirements of large-capacity systems. Therefore, it is necessary to connect individual batteries in series to form a battery pack; parallel connection can increase capacity, but its terminal voltage is still very high. Low, it is still regarded as a "single" battery. In this case, it is used directly. Due to the considerable loss of the switching device and the voltage drop of the diode, in high-power applications, it is still necessary to connect the single cells in series to form a battery pack, such as figure 1 As shown, in order to improve the power supply voltage and storag...

AI Technical Summary

Problems solved by technology

Its disadvantages are: the control is complicated. If you want to temporarily change the number of series cells of the battery pack, you must use three cells as a group. The degaussing of the power supply is not mentioned

[0009] The Chinese application number 201010034137.0 of the Institute of Electrical Engineering, Chinese Academy of Sciences authorized the invention "A Balanced Equipment for Series Battery Packs", which shows: an improved version of 200810063915.1, which is also a working group of three single batteries. During charging or discharging, the extra The disadvantage of releasing energy to this working group is that the control is complicated. If you want to temporarily change the number of series cells of the battery pack, you must use three cells as a group. Only the basic topology is involved, and the demagnetization of the switching power supply is not mentioned

[0010] 3. The 201110043546.1 application of AVIC Lithium Battery (Luoyang) Co., Ltd. "A Charge and Discharge Equalization Circuit for Multi-cell Series Power Lithium Battery Pack" shows that: the voltage of this level of battery is high, and it is transmitted to another battery step by step, and the number of stages is more , large energy loss

At present, the efficiency of the switching efficiency is 90%, which is relatively high. After 6 stages of transmission, the efficiency is only 53%. The disadvantages are: when there are many stages, the energy loss is large; Overall, higher system requirements

Its disadvantages are: the bidirectional converter is a topology that has existed for a long time. In fact, there are not many successful applications, the control is complicated, and the single cells in each group are not well balanced.

[0013] (1) The resistive bypass circuit has a large power consumption and high heat consumption, and the operational amplifier type also has low efficiency and large power consumption, and the cost of low-voltage and high-current op-amps is not low;

[0014] (2) The control is complicated, and three monomers must be used as a group, and it is difficult to connect non-three times;

[0015] (3) When there are many stages, that is, when there are many batteries connected in series, the energy loss will be large; if there is a problem with any one of the converters, it will affect the overall situation and have higher requirements for the system; when reconnecting in series, it cannot be connected freely, and the MCU microprocessor must be reset. program;

[0016] (4) The control of the bidirectional converter is complicated, and the cells in each group are not well balanced

[0017] Generally speaking, the efficiency is low, or the control is complicated; it cannot be freely connected in series

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