A novel generalized speed-varying ellipse voltage injection method for sensorless drive of salient-pole PMSMs

Abstract

This paper proposes a new generalized speed-varying ellipse voltage injection method for sensorless drive of PMSMs. The injected high-frequency voltage has unique spatially-rotating ellipse-shape, whose both amplitudes of the major and minor axes vary dependently of the motor speed. Although the voltage shape can be designed through selecting a design parameter, the associated high-frequency current can hold the speed-independence property, which allows stable rotor phase estimation even in wide speed range. Through selection of the design parameter, property of the high-frequency current can be adjusted so that the correlation between phases of the rotor and the major axis, and the norm ratio of negative/positive phase components can match appropriately a motor drive system. The current property is directly related to the phase estimation robustness.