Frequency-variable-amplitude AC low-temperature self-heating method for lithium-ion batteries

Abstract

The invention relates to a variable-frequency and variable-amplitude AC low-temperature self-heating method of a lithium ion battery. The variable-frequency and variable-amplitude AC low-temperature self-heating method comprises the steps of determining a polarization voltage amplitude range having no influence on lifetime of a lithium ion battery, selecting sine AC polarization voltage amplitudeaccording to the range, and determining sine AC current amplitude according to the sine AC polarization voltage amplitude and battery internal resistance under a current temperature; calculating to obtain a frequency at which heating power is maximum under the current temperature according to a relation between the heating power and the frequency and a relation between battery impedance and the frequency under the selected sine AC polarization voltage amplitude; performing low-temperature self-heating on the battery by a sine AC current signal according to the determined amplitude and the frequency; compensating the sine AC current amplitude per certain temperature in real time under the condition that constant polarization voltage amplitude is ensured, finding out optimal heating frequency under the current temperature, and changing the amplitude and the frequency of the applied sine AC current signal. The variable-frequency and variable-amplitude AC low-temperature self-heating method has the advantages of good self-heating rate, no influence on service lifetime of the battery and good heating temperature uniformity.

Description

technical field [0001] The invention relates to the technical field of battery self-heating, in particular to a low-temperature self-heating method for a lithium-ion battery under variable-frequency and variable-amplitude AC working conditions. In particular, it refers to the low-temperature self-heating method of lithium-ion batteries under the condition of variable-frequency and variable-amplitude AC, which has no effect on the life of lithium-ion batteries. Background technique [0002] The dual pressure of energy crisis and environmental protection has boosted the rapid development of electric vehicles. Lithium-ion batteries have become the first choice for electric vehicle power batteries due to their advantages such as high energy density, long service life, energy saving and environmental protection. However, due to the variation of parameters with conditions, there are still some challenges in the practical application of Li-ion batteries. In a low temperature envi...

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Problems solved by technology

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a low-temperature self-heating method for lithium-ion batteries with frequency-variable-amplitude alternating current, which improves the low efficiency of externally heating lithium-ion batteries in the prior art and has a great impact on battery life. , low heat generation rate and uneven battery temperature distribution

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