A new sensor-less position estimation method for a nine-phase Interior Permanent Magnet machine using a high frequency injection in a non-torque generating circuit

This paper presents a sensor-less method to estimate the rotor angle and speed of a nine-phase Interior Permanent Magnet (IPM) machine. The major contributions of this work include the injection of high frequency voltage signals into a non-torque producing circuit of the machine in which the rotor angle is estimated without generating any high frequency torque ripple. The inductances of the third sequence of the nine-phase machine are used to modulate the high frequency injected voltage signals from which the third sequence currents are extracted. Using a heterodyning method and the Luenberger observer, the rotor position is estimated. The requirement of only one low pass filter in the angle estimation algorithm is another novelty. This rotor estimation method can be used for a wide speed range including the zero speed. The proposed method has been tested using the coupled full order model of the nine-phase IPM machine including all the higher order MMF harmonics. Simulation and experimental results are presented.