Sensorless Control for Six-Phase Permanent Magnet Synchronous Machines Based on Back-Electromotive Force Estimation

This paper presents a sensorless control algorithm based on back-electromotive force estimation for a six-phase permanent magnet synchronous machine drive. The proposed solution employs a hybrid state observer that uses two different flux estimators. To find the rotor flux position, the first observer uses the fundamental harmonic of the magnetic field, while the second observer uses the fifth harmonic. The control scheme fully exploits the degrees of freedom of multiphase machines and reduces the dependence on electrical parameters that may vary during motor operation. The experimental results confirm the robustness of the proposed solution and its independence from machine parameters. The experimental tests also demonstrate the satisfactory dynamic response and stable behavior of the drive at low speeds.