Constant stator current control for three-phase induction motor drive with fixed exciting current

In this paper, a constant stator current control for three-phase induction motor drive with fixed exciting current is proposed. The motor drive consists of three power switches, three power diodes and two dc power sources. Due to the usage of three-switch inverter and the special three-phase current waveforms, the three windings of induction motor open alternately in the operation. And one of windings of induction motor is used to detect air gap flux, it corrects stator current to achieve fixed exciting current. Then the performance of the proposed drive will not be affected by variation of motor parameters and the system´s stability is also increased. Besides, DSP TMS320F2812 and VisSim development software are also adopted in order to realize fully digital-controlled circuit. Finally, some experimental results are presented to verify the feasibility of fixed exciting current in the proposed motor drive.