Injection-Free Rotor Position Estimation Error Compensation for Simplified Salient High-Speed Permanent Magnet Synchronous Machine Sensorless Drive

High power density is the distinguished advantage of high-speed permanent magnet synchronous machines (HSPMSMs), which will even be improved by the saliency introduced due to the artificially asymmetric magnetic circuit, namely, different d- and q-axis inductances ( <tex-math notation="LaTeX">Ld </tex-math>/ <tex-math notation="LaTeX">Lq </tex-math>). Furthermore, for the salient PMSM sensorless drive, the low switching-to-fundamental frequency ratio (SFFR) makes the accurate rotor position estimation more complicated. Present algorithms require extensive nonlinear matrix computations, which are not convenient for large-scale applications. Although silicon carbide (SiC) devices are employed to address the low SFFR issue, the improved cost usually limits its applications. As a compromise, a salient PMSM can be assumed as a nonsalient one, and consequently, the phase winding inductance <tex-math notation="LaTeX">Lₛ </tex-math> is approximately calculated by <tex-math notation="LaTeX">Lₛ=(Ld+Lq) </tex-math>/2. Such assumptions will inevitably cause rotor position estimation errors, and hence, in this article, a current ripple sampling (CRS)-based method is proposed to identify the error. It should be noted that such a method is injection-free, dead-time effect (DTE)-immune, and detection-free. Furthermore, the identified position errors can be smoothly compensated by noise suppression filters [e.g., recursive autoregressive least-squares method (LSM)] and closed-loop regulations (e.g., PI controllers). Finally, experimental validations are conducted on a prototype with 45 kr/min used for hydrogen pumps.