System and method for modularizing battery pack balancer based on multi-winding transformers

Abstract

The invention discloses a system and a method for modularizing a battery pack balancer based on multi-winding transformers. Through anti-parallel connection of secondary sides of an odd number and an even number of the multi-winding transformers, balancing in modules and between the odd / even number of modules is realized based on forward conversion; the balancing between the odd number and the even number of the modules and the automatic demagnetization of the multi-winding transformers are realized based on flyback conversion; during control, direct, automatic and synchronous balancing from any battery monomer to any battery monomer in a battery pack can be realized just by a pair of control signals which are complementary in states, so that the balancing efficiency and the balancing speed are greatly increased, and the inconsistency between battery monomers can be effectively improved. The system and the method, disclosed by the invention, have the advantages that the balancing efficiency is high, the balancing speed is fast, the volume is small, the cost is low, the reliability is high, modularization is easy, the control is simple, a voltage detection circuit and a demagnetization circuit are not required, and the like.

Description

technical field [0001] The invention relates to a battery pack equalizer modular system and method based on a multi-winding transformer. Background technique [0002] Lithium-ion batteries are widely used in electric vehicles due to their advantages of no memory effect, high energy density, high cell voltage and good safety. In order to meet the voltage and power levels of electric vehicles, a large number of lithium-ion battery cells need to be combined in series and parallel. However, due to differences in manufacturing processes and working environments, the internal resistance and capacity of battery cells are not completely consistent. During the use of the battery pack, these inconsistencies will gradually accumulate, and cause the voltage imbalance of different battery cells in series, which may lead to overcharging or over-discharging of a certain battery cell, reducing the available capacity and cycle of the battery pack. life, and even cause damage to the battery...

AI Technical Summary

Problems solved by technology

However, this method requires an additional degaussing circuit (a capacitor and magnetizing inductance forming an LC resonant circuit) to absorb and discharge the energy stored in the transformer when the switch is turned off

This leads to the disadvantages of inconsistent transformer windings, high circuit cost, large size and complex design.

And in order to obtain soft switching, the equalization circuit can only work at a specific switching frequency and duty cycle, making its design and control complicated, especially, the equalization circuit is difficult to modularize

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