Sensorless Control of PMaSynRM with HFI Method using Modified PLL for Low Speeds

Nowadays, Permanent Magnet Assisted Synchronous Reluctance Motor, is a favorable alternative for variable speed drive systems. It has the advantages of comparable costs, low maintenance requirements, and superior efficiency and power density compared to the conventional counterparts like Induction Motors and Permanent Magnet Synchronous Motors. Despite the advantages of the sensorless control of these motors at low and zero speed, they still need some improvements. The extended electromotive force sensorless control method is usually regarded as insufficient in literature; thus, the high frequency injection method is often recommended. In this study, improvements are introduced to the selected high frequency injection method. It is based on injecting high frequency sinusoidal voltages with constant amplitude in the αβ0 axis. That provides a more robust and efficient sensorless control. The improvements which are basic but effective include an adaptive bandpass filter, modified phase-locked loop, and angle compensation. First, the proposed high frequency injection method is simulated and then implemented experimentally. This improved high frequency injection method is suitable for the sensorless control of PMaSynRM.