LC bipolar resonant-based Cells-to-Cells equalization circuit and control method thereof

Abstract

The invention discloses an LC bipolar resonant-based Cells-to-Cells equalization circuit and a control method thereof. During the equalization process, a microcontroller outputs four paths of rectangular wave driving signal of which frequencies are half of an LC resonant frequency, the phase difference is 90 degree and the duty ratio is 25% so that an equalization source unit and an equalization target unit are bipolarly and circularly connected to an LC resonant branch by a switch network, the LC resonant branch circularly works in states of positive polarity charging, positive polarity discharging, reverse polarity charging and reverse polarity discharging, and zero-current switch equalization of which energy is transmitted from the source unit to the equalization target unit is achieved. By the equalization circuit, equivalent release of a residual voltage of a resonant capacity C during the equalization process is achieved, the equalization source unit and the equalization target unit both can be adjacent arbitrary sections of Cells, the equalization circuit has the advantages of high power density, high equalization efficiency and control flexibility, and modular manufacturingis easy.

Description

technical field [0001] The invention relates to the technical field of battery pack equalization, in particular to a Cells-to-Cells equalization circuit based on LC bipolar resonance and a control method thereof. Background technique [0002] With the gradual depletion of traditional energy sources and the gradual enhancement of people's awareness of environmental protection, the development of "zero-emission" electric vehicles has been vigorously promoted by governments and major automobile manufacturing companies, and the scale of new energy power generation has also increased rapidly. Lithium-ion batteries are usually used to form battery packs in electric vehicles. This is because lithium-ion batteries have the advantages of high energy density, low self-discharge rate, no memory effect, and long cycle life, which can meet the requirements of high power and long battery life of electric vehicles. need. New energy power generation systems also require a large number of l...

AI Technical Summary

Problems solved by technology

However, due to the introduction of the release state, the LC conversion module is not connected to any battery unit in the release state, that is, it does not perform energy transmission for 1 / 3 of the time, which reduces the speed of equalization and also leads to equalization efficiency. a little drop

The Adjacent Cell-to-Cell structure of this invention also makes it impossible to realize the transmission of energy between non-adjacent battery cells. The energy is transmitted through all the battery cells in the battery pack, so that the battery cells that do not need to be balanced undergo redundant charging and discharging processes, which consumes the service life of the battery and also makes the balancing efficiency low

In addition, in this invention, once the parameters of the LC conversion module are determined, the microcontroller cannot control the size of the equalization current during the equalization process, making it difficult to switch between large current equalization and small current equalization according to actual needs in practical applications, and the control is not enough flexible

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