Voltage-Sharing Control Method of Series- Connected Bi-Directional DC-DC Converters based on Battery SOC for Hybrid Electric Vehicle

摘要

This paper proposes voltage-sharing control method of series-connected bi-directional DC-DC converters based on battery SOC for hybrid electric vehicle. Series-connected DC-DC converters is capable to achieve high step-up DC link voltage for propulsion of electric motor. This circuit can contribute to step-down output voltage of DC-DC converters. However, this configuration causes state-of-charge(SOC) differences between battery modules which connected in each DC-DC converters and decrease of the available battery capacity to generate electric motor. To increase the available battery capacity and balance the SOC difference, voltage-sharing control method is proposed. A scaled down prototype carried out with three-phase series-connected DC-DC converter and simulation results are indicated to confirm the validity of proposed SOC balancing algorithm.