High performance low speed sensorless control of interior permanent magnet synchronous motor

The work presented in this paper deals with the issues in practical implementation of the high-frequency injection methods for control of IPM machines without shaft position sensors. Implementing a high-frequency injection technique for rotor position estimation requires intense signal processing of the measured currents as well as the filtering of the signals to extract the rotor position information. These tasks turn in complicate control algorithm, but more importantly degrade the overall system performance by introducing delays, increasing response times and decreasing the bandwidth of the controller. Moreover some specific filtering techniques limit the operation of the machines to the very narrow operating range. These issues and their specific effects are discussed in this paper and mitigation procedures are proposed, implemented and verified through the experimental setups. Experimental results of a new high-performance controller without rotor position sensors are presented as well. The major contribution of this work is a new controller based on the high-frequency injection method that eliminates the need for low-pass filtering and improves the performance of the machine.