A Quasi Edge Aligned Pulse-Width Modulation to Enhance Low-Speed Sensorless Control of PMSMs With a Single DC-Bus Current Sensor

The low-speed sensorless control of permanent magnet synchronous machines (PMSMs) with a single DC-bus current sensor has not been solved thoroughly from the prior literatures. This article proposes a novel quasi edge aligned pulse-width modulation (QEAPWM) to realize this purpose. Compared with the conventional phase-shifting PWM, the QEAPWM has several advantages of the accurate reconstructed phase-current and the fixed current sampling time interval, which are beneficial to obtain the current ripple evoked by the high-frequency (HF) injected voltage to estimate rotor position. The effectiveness of the proposed method is verified on a 500-W PMSM drive and compared with three state-of-the-art methods. The experimental results verify that the QEAPWM-based sensorless control achieves satisfactory performance both in the transient and steady-state processes with the maximum 15° position estimation error without a magnetic cross-coupling saturation compensation, and nearly zero error with this compensation.