A bi-directional power flow IPM-BLDC motor drive for electrical scooters

This paper presents a bi-directional power flow interior permanent magnet brushless DC (IPM-BLDC) motor drive for electrical scooters. A new control scheme is proposed for the motoring operation. It has high energy conversion efficiency in the low speed and high torque region as well as high speed region. The basic control idea follows the maximum torque per ampere (MTPA) control of an interior permanent magnet synchronous motor (IPMSM). For the regenerative braking operation, a new switching pattern of the one switch active scheme is presented. It can provide a quite symmetry line current waveform for smooth regenerative braking. A low cost digital signal processor is used to implement the control core to reduce the development cost. Experimental results show that the proposed scheme can provide a smooth output torque and can improve the drive efficiency for the motoring operation as well as that the performance of the regenerative braking is quite satisfactory.