Modeling and research on high-frequency AC heating system for lithium-ion battery based on bidirectional buck-boost topology

Abstract

Lithium-ion battery (LIB) performance decreases in cold climates, preheating is necessary to improve the output power and life decay of low-temperature LIB. At present, a variety of internal alternative current (AC) heating methods are used to achieve fast and temperature-consistent heating. However, existing AC heating devices are constrained by the problems of changing the battery structure, and also need for an additional power supply to power the battery, which have effect on the battery life. Meanwhile, the conventional model is not suitable for AC preheating simulation, especially at high frequencies. Under above scenarios, a high-frequency AC heating method using a bidirectional boost converter is designed and a high-frequency thermoelectric model based on lithium-ion transmission is developed. In the paper, the proposed high-frequency AC heating structure and thermal-electrical coupling model are verified by experimental results to test the validity of different AC heating frequencies, which solves the lack of comprehensive theoretical and experimental verification in the field of high-frequency AC heating. The experimental results show that increasing the AC heating frequency at the same current multiplicity can significantly increase the heating rate. An optimal frequency is acquired, the optimal heating rate can reach 4.65 K/min at 800 Hz without affecting the service life of the battery. The high-frequency AC heating method provides a new solution framework for the LIB performance enhancement in cold climates.