A novel position estimation technique for interior permanent magnet synchronous motor control

A new sensorless position estimation technique for interior permanent magnet synchronous motor (IPM) is presented. Permanent magnet synchronous motors generally require a rotor position sensor to achieve the vector control, however, this sensor increases product cost and maintenance. From these backgrounds, position sensorless schemes have received wide interest for industrial applications. The phase impedance of IPM motors varies appreciably as function of rotor position. This fact is used for the estimation of the rotor position. The scheme is based on injection of a high frequency current explorer signal by means of a current delta modulation controlled inverter. A signal processing technique is used to estimate the phase impedance. A previous knowledge of impedance angular position relation permits the estimation of rotor position. The technique was tested by simulation of a 5 HP 460 V IPM motor. The test results have been found satisfactory in both steady and transient states.