This paper presents an experimental investigation of four switch inverter performance fed
three phase induction motor drives. The speed estimation based on fundamental wave
models using model reference adaptive system as speed estimator technique. The motor is
fed from four switch three phase inverter. A comparative study for sensorless speed
estimation using four switch three phase inverter and six switch inverter is experimentally
investigated. Also a comparison of system performance based on four switch inverter and
conventional six switch inverter in terms of speed response and total harmonic distortion of
stator currents is presented. Experimental results at different point of operations are
presented verifying robustness of sensorless speed estimation at different load levels.
Sensorless speed estimation based on four switch three phase inverter is quite acceptable
considering its speed response.