An integrated equalization method for series-parallel battery packs based on LC energy storage

Abstract

The invention discloses an integrated equalization method for series-parallel battery packs based on LC energy storage. The series-parallel battery packs have m groups of series-connected battery packs connected in parallel, and each series-connected battery pack contains n monomers; the balance topology of the series-parallel battery packs Including (2m*n+2m) MOS transistors, 2m*n diodes, an inductor, and a capacitor. The invention achieves the following beneficial effects: compared with the prior art, the invention establishes an integrated active equalization method for series-parallel battery packs based on LC energy storage. It can achieve series-parallel equalization at the same time, and the equalization energy can be directly transferred from high-battery monomers to low-battery monomers, and the equalization speed is fast; the MOS tube arrays on the left and right sides of the battery pack have strong symmetry, simple structure, small size, and control Simple; the balanced topology is easy to expand. Under the premise of meeting the limit value of the device, when the number of cells in the series battery pack or the number of parallel battery packs changes, only the corresponding MOS tubes need to be increased or decreased.

Description

technical field [0001] The invention belongs to the technical field of power battery equalization, and relates to an integrated equalization method of series-parallel battery packs based on LC energy storage, which is suitable for battery management systems of new energy vehicles. Background technique [0002] Due to the advantages of high energy density and long cycle life, lithium batteries have gradually become the main power source of new energy vehicles. Due to the low voltage and capacity of the single cells, it is necessary to connect the single cells in series and parallel to form a battery pack in the application. Affected by factors such as the production process, the monomer will appear inconsistent after a period of cycle charge and discharge, thereby reducing the energy utilization rate and cycle life of the battery pack, and easily leading to overcharge or overdischarge. Equalization technology is of great significance to improve the inconsistency of the batte...

AI Technical Summary

Problems solved by technology

The equalization topology based on switched capacitors has the advantages of small size and easy control, but its equalization efficiency is not high, and the capacitance equalization time is long. This problem is especially obvious when the voltage difference between the monomers is not large.

Inductor-based equalization topology has high equalization efficiency, but its circuit structure is complex, requiring a large number of MOS tubes and inductance, complex control and not conducive to the reduction of the volume of the equalization system

The balanced topology of series battery packs based on the LC resonant circuit, the LC resonant circuit is switched near the resonant frequency, so that the impedance in the balanced topology is minimized, which has the advantages of high equalization efficiency and fast equalization speed, but there are many switching devices and complicated control

The transformer-based balanced topology has the advantages of high balancing efficiency, simple control, and easy isolation, but the design of the transformer is more complicated and there is a problem of magnetic saturation, resulting in a larger balanced topology, which is not easy to modularize, high cost, and difficult to expand

The balanced topology based on converters such as Buck and Boost can realize bidirectional flow of energy, with high equalization efficiency and fast equalization speed, but still has the disadvantages of complex control and high cost.

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