Encoderless position estimation for symmetric cage induction machines 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 harmonies 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 shown, demonstrating sensorless position estimation at full flux and high loads. Initial experimental results are presented for encoderless position control under full flux.