Rotor Position Detection of IPMSM Based on Search Coil in Full-Speed Range

Using the search coil to provide the backup rotor position for the interior permanent magnet synchronous motor (IPMSM) can improve its operational reliability and prevent equipment damage. This article proposes a rotor position detection method for the IPMSM based on the search coil in the full-speed range. Make the search coil into the flexible printed circuit (FPC) and stick it on the top of the motor stator teeth to reduce the impact on the motor power density. By optimizing the connection method of the search coil, the electromagnetic coupling between the motor body and the search coil has been eliminated. Using the relationship between the inductance of the search coil and the rotor position, this article injects a 100 kHz ultrahigh-frequency voltage signal into the search coil. The backup rotor position is detected by extracting the effective value of the search coil voltage. The proposed method does not require switching the connection method of the search coil and can achieve rotor position detection within the full speed range. The search coil based on FPC and an experimental prototype were fabricated. The experimental results verified the correctness of the theoretical analysis and the effectiveness of the proposed method.