Modeling and analysis of switching non-linearities of an inverter FED PMSM drive for low torque ripple application

Switching characteristics and associated nonli-nearities are quite critical for meeting the performance of an inverter fed permanent magnet synchronous motor (PMSM) drive used for safety critical high performance applications. The gate capacitance, turn-on, turn-off time etc play a vital role on the switching behavior of the power devices. Very often dead-time is provided which is a blank time between upper turn-off and lower turn-on time or vice versa of switching devices such as IGBT, FET etc of a power converter to avoid shoot through fault during commutation. This paper provides the modeling and analysis of the effect of dead-time, switching device parameters, and load current magnitude on the output torque of a PMSM drive used for an automotive applications. A simple dead-time compensation scheme that addresses the effect of dead-time, inherent parasitic parameters of the switching device and load current magnitude is proposed. Appropriate scheduling of the dead-time is also done to mitigate the risk of shoot through fault while maximizing the torque output with minimum torque ripple.