부산대학교 도서관

In this paper a regenerative braking scheme for a permanent magnet synchronous machine (PMSM) based electric vehicle (EV) is proposed. A vector control scheme is used to operate the machine in both motoring and generating mode. During braking operation, the PMSM is operated in generating mode to obtain the required braking torque. The power developed by PMSM during braking action is absorbed by a supercapacitor through a bidirectional synchronous buck converter. The power stored in the supercapacitor during braking is used to drive the motor or to charges the battery as per the operating condition of the EV. In case the supercapacitor is fully charged during braking operation, the battery is directly charged with the maximum allowable charging current while dissipating the rest of the power in a braking resistance. Since the fluctuating component of power generated during braking or rapid acceleration is mostly absorbed or delivered by the super-capacitor, the battery supplies a steady power which increases the life expectancy of the batteries. The performance of the proposed scheme is validated through a simulation study in Matlab/ Simulink.