Stability of a PWM current-source rectifier/inverter fed induction motor drive

The stability of pulse width modulated current-source rectifier/inverter fed induction motor drives is considered in the paper. Rectifier/inverter operations are considerably complicated because of the high frequency pulse width modulated switching of power devices. To investigate the system stability successfully, an analysis without a complete simulation is performed by introducing synchronously rotating reference frames at the input and output terminals. The linearised equations are easily obtained so the intrinsic open-loop instability and the effects of circuit parameters under closed-loop operation can be made clear by determination of their dominant roots. The relevance of the results is verified by the transient characteristics of the nonlinear model, with and without a PI controller for constant V/f control