Accurate Rotor Position Detection for Low-Speed Operation of Switched Reluctance Drives

Switched reluctance machines (SRMs) exhibit the advantages of low-cost production and high reliability. Position sensorless control can contribute significantly to further improve these properties. Due to the salient structure of the SRM, the stator inductance can be used to determine the rotor position $\theta_{\mathrm{e}}$ from injected current peaks at standstill and low speeds. Exact torque and force control of SRMs requires highly accurate information about the machine's rotor position. Therefore, the purpose of this paper is to expose the advantages of position estimation algorithms implemented on field-programmable gate array (FPGA). The algorithm includes an inductance identification procedure and sophisticated signal filtering. Besides improvement measures based on modeling and signal conditioning, a method for reduction of the injection currents is demonstrated and evaluated. The developed algorithm considers the mutual coupling effect and is verified by simulation and experiment.