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 AFbased 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 αβ-axis to identify the d- and q-axis inductances, and the dc voltage injected on the α-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 be extended and speed reversal can also be implemented. And the online multiple parameter identification can improve the accuracy of the estimated position.