Sensorless position estimation for symmetric cage induction motor under loaded conditions

This paper presents sensorless position estimation using a conventional or "symmetric" cage-induction motor. The rotor position information is obtained by high frequency injection and using the modulating effect of the rotor slots. This makes true sensorless position control possible. The deteriorating effect of saturation harmonics for operation at full flux and higher loads is suppressed by using a harmonic compensation scheme based on parameters obtained from an automated commissioning process. Experimental results are presented showing sensorless position estimation at full flux and high loads. For a conventional machine, such high-load results have not been published before.