Equalization fault-tolerant circuit structure and equalization fault-tolerant method for series lithium battery pack

Abstract

The invention provides an equalization fault-tolerant circuit structure and equalization fault-tolerant method for a series lithium battery pack. The equalization fault-tolerant circuit includes the reconstructed fault-tolerant loop, a battery selection network, and a flyback converter bridge network. Each lithium battery is connected in series with a group of bidirectional MOSFET shutdown switches, and is connected in parallel with a unidirectional MOSFET bypass switch and a diode to form the reconstructed fault-tolerant loop. The battery selection network consists of bidirectional MOSFET selection switches. Each lithium battery is connected to two groups of bidirectional MOSFET selection switches. Two adjacent lithium batteries share one group of bidirectional MOSFET selection switches.The flyback converter bridge network consists of a flyback converter, a MOSFET switch, and a diode. The equalization fault-tolerant method comprises estimating the state of charge and the state of health of each lithium battery; reconfiguring and isolating a certain lithium battery when the state of health of the certain lithium battery is lower than a failure threshold; calculating a capacity difference between the lithium battery having the most remaining capacity and the lithium battery having the least lithium battery; and starting equalization when the capacity difference is greater thana set threshold. The method improves the energy use efficiency, reliability and safety of the lithium battery pack.

Description

technical field [0001] The invention relates to the technical field of lithium battery energy balance and reconfigurability, in particular to a balance fault-tolerant circuit structure and a balance fault-tolerant method of a lithium battery pack connected in series. Background technique [0002] Facing the increasingly urgent problems of energy depletion and environmental pollution, the development of new energy vehicles has become a common choice for all countries. Due to the low nominal voltage of single lithium batteries, multiple lithium battery cells need to be used in series to meet the power supply requirements of new energy vehicles. There is inconsistency between the single lithium batteries in the lithium battery pack, the lithium battery pack is repeatedly charged and discharged over time during use, and each lithium battery cell shows different degradation characteristics, especially one or more performance indicators are poor Lithium-ion batteries complete cha...

AI Technical Summary

Problems solved by technology

[0003] At present, there are relatively few studies on the energy balance of lithium batteries considering fault tolerance by relevant research institutions at home and abroad. Most of the research focuses on only using the energy transfer balance method to solve the inconsistency of single lithium batteries, without considering the long-term operation of lithium batteries. Reliability and safety. When a lithium battery in a lithium battery pack is seriously degraded and fails, the entire lithium battery pack will fail in a short time or even a serious safety accident will occur.

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