A High-Frequency and Large-Current Equalizer for Large-Scale Battery Packs

Due to the superior performance of the equalizer, it is widely used in the field of electric vehicles. The traditional equalizer based on flyback conversion has the advantages of great isolation performance and high efficiency. However, it has a large size and complex control strategy. By sharing the MOSFET array and optimized control strategy, a high-frequency and large-current equalizer is proposed. The series-connected battery units in the equalizer are divided into odd and even groups. Each group is paired with a flyback converter and a 12V onboard lead-acid battery. Adjacent batteries in two groups share a set of MOSFETs to reduce size. At the same time, the equalizer is set to work in an intermittent state and dynamically adjusts the duty cycle of the PWM to reduce the voltage stress on the switches. Through simulation, the proposed equalizer can work stably in the state of 100kHz switching frequency and 2A balance current. Finally, the voltage difference between series-connected cells is less than 5mV, which meets the requirements of consistency, and the equalization effect is satisfying.