Realization method of energy balance of lithium-ion battery

Abstract

The invention discloses a lithium-ion battery energy balance system and its realization method. The system comprises: a lithium-ion battery pack, n voltage detection circuits, n DC / DC converters, n main control chips, data processing chips, A CAN communication module and a current detection circuit, the lithium-ion battery pack is composed of n lithium-ion battery cells connected in series, the input terminals of the kth voltage detection circuit are respectively connected to the positive pole and the negative pole of the k-th lithium-ion battery cell, and Sampling starts when voltage detection is required, and the sampled value is sent to the kth group of main control chips after isolation. Each DC / DC converter controls the switch of the MOS tube to control the switching of each lithium-ion battery in the lithium-ion battery pack. The battery is directly charged and discharged, and the balance current is adjusted through the switching frequency. The present invention uses the second-order RC model to simulate the chemical model of the lithium-ion battery, and uses the SOC generated by linear regression as the judgment basis for the balance of the lithium-ion battery to determine the balance current and Balance the time to achieve the purpose of balance.

Description

technical field [0001] The invention relates to a lithium-ion battery energy balance system and an implementation method thereof, in particular to a battery SoC-based lithium-ion battery energy balance system and an implementation method thereof. 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...

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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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