Lithium ion battery energy balance system and implementation method thereof

Abstract

The invention discloses a lithium ion battery energy balance system and an implementation method thereof, the system comprises a lithium ion battery pack, n voltage detection circuits, n DCDC converters, n main control chips, a data processing chip, a CAN communication module and a current detection circuit, the lithium ion battery pack consists of n single lithium ion batteries which are connected in series, the input end of the Kth voltage detection circuit is connected with the positive electrode and negative electrode of the kth single lithium ion battery, sampling is started when voltage detection requires conducting, the sampling value is isolated and then transmitted to the kth set of main control chips, each DCDC converter directly carries out charging and discharging to each single lithium ion battery in the lithium ion battery pack respectively through controlling the switch of an MOS pipe, simultaneously, the balanced current is adjusted through switching frequency, the lithium ion battery energy balance system and the implementation method thereof use a second-order RC model to simulate a lithium ion battery chemistry model, and uses the SOC generated by linear regression as the judging basis of lithium ion battery equalization, thereby achieving the equalization purpose.

Description

technical field [0001] The invention relates to a lithium-ion battery energy balance system and its implementation method, in particular to a battery SoC-based lithium-ion battery energy balance system and its implementation method. Background technique [0002] The key to the development of pure electric vehicles is the battery. In recent years, lithium battery technology has made great progress. Lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide and other batteries have significantly improved the performance of lithium batteries; but the inconsistency between single cells in lithium battery packs is naturally widespread. The parameters of lithium batteries inevitably produce some slight differences in the mass production process, mainly manifested in inconsistencies in the internal resistance, capacity, and open circuit voltage of lithium batteries. With the increasing use of lithium batteries, long-term self-discharge and the influence of large tempera...

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Problems solved by technology

How to control the equalization circuit is also a relatively complicated problem. Due to the highly nonlinear characteristics of lithium-ion batteries, there is no more accurate mathematical model

Therefore, the control strategy is also difficult to determine, such as input and output factors, how to effectively control, etc.

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