Novel Speed Observer-Based Sensorless Control Strategy Without Signal Injection for PMSMs Over Low-Speed Range

This article proposes a novel speed observer-based sensorless control strategy for permanent magnet synchronous motors (PMSMs) operating in the low-speed range. First, a stable sliding mode observer (SMO) is used to identify the motor's real-time speed and the rotor position is calculated through integration. Second, an innovative pre-positioning method is developed to obtain the initial rotor position at standstill. Unlike traditional high-frequency signal injection-based sensorless control, the proposed method is suitable for both interior and surface-mounted PMSMs, and it avoids the negative impacts of high-frequency signals on control accuracy and electromagnetic noise. Finally, experiment is conducted on a surface-mounted PMSM prototypes to validate the proposed techniques.