Sensorless commutation of micro PMSMs for high-performance high-speed applications

This paper presents a preliminary analysis of a sensorless sinusoidal commutation of micro slotless PMSMs which can be used in high-performance, high-speed applications. Since the inductance of a micro slotless PMSM is extremely small, three-phase back electromotive forces (BEMFs) can be estimated with a first-order delay filter. The terminal phase voltages of the micro PMSM are generated based on the estimated BEMFs and a required current amplitude. The resulted terminal voltages are sinusoidal and almost synchronous to BEMFs in a high operating-speed range