New Sensorless Permanent Magnet Synchronous Motor Drive
In permanent magnet synchronous motor (PMSM) drives, magnetic-saliency-based techniques have been widely used to detect rotor position and speed, especially during the starting and low-speed operations. Among these techniques, pulsating high-frequency signal injection (PHFSI) stands out as a commonly used technique in various industrial applications. However, a significant limitation arises when applying the PHFSI technique in surface PMSMs (SPMSMs) due to the absence of magnetic saliency. Additionally, implementing PHFSI is challenging due to the lack of clear guidelines for selecting the appropriate frequency (fh) and the amplitude (Vinj) of the injected high-frequency (HF) signal. This thesis addresses these challenges by making three novel contributions. The first two contributions propose techniques to create magnetic saliency in SPMSMs, while the third contribution proposes an optimisation model to determine optimal fh and Vinj used in PHFSI. As the first contribution, this thesis proposes a technique to change the d-axis inductance (Ld) of SPMSMs with respect to q-axis inductance (Lq) to introduce sufficient magnetic saliency for the implementation of PHFSI. This is achieved by changing the flux in the d-axis based on the knowledge of the load applied on the motor shaft. As the second contribution, the thesis proposes a novel asymmetric phase windings (APWs)-based PHFSI technique for rotor position detection in SPMSMs. By changing the number of turns in one phase, this technique introduces magnetic saliency into SPMSMs. The change in number of turns can be easily implemented during the design stage without compromising the overall performance of the motor. Experimental results are presented to validate the applicability of both proposed techniques. As for the third contribution, this thesis investigates the limitations of the PHFSI technique and identifies the factors that need considering when selecting fh and Vinj. A model based on a multi-objective and multi-constrained black box optimisation (BBO) algorithm is then proposed to determine the optimal fh and Vinj. The proposed optimisation model is used to obtain the optimal solutions of fh and Vinj for two motor types, a SPMSM and an interior PMSM (IPMSM). Finally, the effectiveness of the proposed optimisation model is validated through experimental results.
De Soysa, Warusahannadige Gayani Shashika
Permanent Magnet Synchronous Motors, High Frequency Signal Injection
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