An AC motor drive with power factor control for low cost applications

In this work, a new concept of integrating motor and power factor controls, by using a single-phase to three-phase DSP based six-switch converter topology, is presented. Unlike other configurations which use extra switch(es) and/or extra boost inductor, in the proposed topology the boost action, for input current shaping, is done by the motor leakage inductances. The power factor control and inverter operation are performed by applying two modulating signals to the SPWM control logic of the converter. In this paper, the converter operation and its accompanying control strategy will be explained. Simulation and experimental results for a DSP based induction motor drive will be provided, as proof of concept. Furthermore, the practicability and potential of this configuration for ac motor drive applications will be established. The impact of this scheme on the machine operation will also be discussed.