Sensorless induction motor drive with voltage inverter and sine-wave filter

This paper presents a speed sensorless control system of an induction motor with an output LC filter. It is known that the parameters design of the filter gives sine wave motor supply voltage but complicates control and estimation process. The reason is that the voltage drop and phase shift between filter input and output signals are imposed, and hence the motor voltages and currents differ from the inverter output waveforms. To overcome this problem proper control and estimation algorithms have to be modified. The control strategy proposed in this paper is based on motor feedback linearization control and multiloop control for LC filter whereas the estimator is a modified Luenberger observer with electromotive force calculation. The performance of the system is verified by simulations and experiments.