Optimal current slew rate control for a three-phase MOSFET inverter driving a PMSM

The active control of the current slew rate of hard switched voltage source inverters is a common method to reduce the electromagnetic emissions, overshoot and ringing. In a previous work, the authors derived a model-based optimal slew rate control strategy which combines iterative learning control (ILC) with an adaptive feedforward control for a single half-bridge inverter. This control strategy minimizes the switching losses while the current slew rate stays within desired limits. This paper presents the required extensions of the current slew rate control strategy for a three-phase voltage source inverter driving a permanent magnet synchronous machine (PMSM). The extended control strategy is implemented on a rapid prototype test bench to verify the performance by a number of measurement results. The results show that the current slew rate of each phase is controlled separately within the defined limits while the switching losses are minimized, independent of the load current, the supply voltage and the temperature.