Enhancing Low-Speed Sensorless Control of PMSM . Using Phase Voltage Measurements and Online Multiple Parameter Identification

This article mainly concerns the performance improvement of active flux (AF)-based sensorless control for permanent magnet synchronous machines (PMSMs) in the low-speed range. An adaptive position observer based on the AF model is adopted to provide rotor position estimate. A convenient implementation of phase voltage measurement circuit mainly consists of a divider and a low-pass filter (LPF) is designed. Then, the AF-based observer uses the measured phase voltages directly instead of command voltages. Meanwhile, the phase shift and amplitude attenuation due to the hardware LPF are compensated. Moreover, a robust online resistance and inductance identification strategy is integrated to the position observer. The high-frequency sinusoidal voltages are imposed on the alpha beta-axis to identify the d- and q-axis inductances, and the dc voltage injected on the alpha-axis is used to identify the resistance. The experimental results carried out on a 150-W PMSM drive demonstrate the effectiveness of the proposed sensorless control strategy. With the use of phase voltage measurements, the low-speed operating range can he extended and speed reversal can also be implemented. And the online multiple parameter identification can improve the accuracy of the estimated position.