Power recovery and cost reduction oriented optimization of regenerative cells embedded in cascaded multilevel converter

The novel hybrid cascaded multilevel converter, with partial regenerative cells supplied by bidirectional rectifiers, is cost effective to recover the regenerative energy. To apply it in industrial fields containing various motors with loads, a systematic scheme designing the power cells is indispensable. This paper reveals that the maximum power factor angle of the motor is determined by the deceleration velocity, and that the controllable domain of the converter is determined by the sum of the DC voltage of the regenerative cells. From these analyses derives a step-by-step designing scheme. Furthermore, the scheme is optimized to reduce the regenerative cells, so as to be more cost effective. The results of simulation and experiment demonstrate that the optimized scheme can enable the converter to cost effectively recover the regenerative energy.