Dual-Axis Alternating High-Frequency Square-Wave Voltage Injection-Based Sensorless Control for Dual Three-Phase PMSM Drives

Intensified magnetic saturation causes significant position estimation error as the load increases in sensorless dual three-phase permanent magnet synchronous motor (DTP-PMSM) drives using high-frequency (HF) voltage injection. To enhance the position estimation accuracy, a novel dual-axis alternating HF square-wave voltage injection-based sensorless control method is proposed. DTP-PMSMs exhibit inherent coupling inductance asymmetry (CIAS) due to magnetic circuit differences and manufacturing tolerances. Accordingly, an HF voltage model considering CIAS is established, and the bias disturbance introduced by CIAS into the position tracking error signal (PTES) is quantitatively analyzed, revealing its contribution to severe position estimation errors. By alternately injecting anti-phase HF voltages into the dual d-q axes, the half-wave antisymmetry of the bias disturbance in the PTES is achieved. Subsequently, by analyzing the HF current spectrum, the injection-frequency component with a relatively high signal-to-noise ratio (SNR) is extracted to reconstruct the PTES and achieve bias disturbance rejection. The proposed method is insensitive to motor parameters and is capable of rapidly suppressing position estimation errors caused by CIAS. Furthermore, the HF signal injection form is analyzed to further improve the control performance. Finally, the effectiveness of the proposed method is validated on a 3-kW DTP PMSM drive platform.