Dual-Axis Alternating High-Frequency Pulse Voltage Injection-Based Initial Position Detection Method for Dual Three-Phase PMSM Drives

Accurate initial rotor position information is crucial for the reliable startup of a sensorless dual three-phase permanent magnet synchronous motor (DTP-PMSM) drive system. To reduce the influence of the inherent coupling effect between multiple windings in the DTP-PMSM, a dual-axis alternating high-frequency (HF) pulse voltage injection-based initial position detection method is proposed. Based on the HF mathematical model of the DTP-PMSM, two sets of HF pulse signals are injected into the two windings alternatively. Then, the initial magnetic pole position and polarity can be detected simultaneously according to the induced dual-axis HF currents and their extreme values, respectively. Besides, based on the theoretical analysis of induced HF currents, the design process of injection amplitude, frequency, and interval time for these two sets of pulse signals are presented. Compared with the conventional method, this method fully uses the merits of two windings in DTP-PMSM, effectively mitigating the influence of coupling effect and improving the detection accuracy. The signal-to-noise ratio is higher and not affected by the digital delay. Experimental results on the developed DTP-PMSM drive platform verify the effectiveness of the proposed method.