Supercapacitor/battery hybrid energy storage unit for brushless DC motor operation

Abstract

In this study, a supercapacitor (SC)/battery hybrid energy storage unit (HESU) is designed with battery, SC and metal-oxide-semiconductor field-effect transistors. Combined with the operation of brushless DC motor (BLDCM) and the output mode of the proposed HESU, the vector combinations that are suitable for different operation states of the BLDCM are analysed. By using reasonable vector combinations, the HESU can utilise the SC to store the regenerative energy from BLDCM during the braking process and assist the battery to power the motor during the acceleration process. Also, the designed HESU can achieve high-voltage output by connecting the SC and battery in series, to suppress the commutation torque ripple of BLDCM in the motoring state. Finally, the correctness of the theoretical analysis and the feasibility of the proposed method are verified by the experiment results.