Design and Operation Characteristics of Four-Two Pole High-Speed SRM for Torque Ripple Reduction

This paper presents the design and operation of a two-phase four-two pole switched reluctance motor (SRM) for a high-speed air blower. The air blower has unidirectional rotation and requires a wide positive torque region without torque dead zone. In order to achieve the requirements, a nonuniform air gap with asymmetric inductance profile is considered. For a flattop torque with a low torque ripple, the nonuniform air gap is also effective. Based on the output torque analysis at the rotor position for the given air gap, the air gap is modified to reduce the torque ripple. The optimized air gap at a given position cannot feel the effect of the air gap at a previous rotor position. Therefore, the output torque cannot fully satisfy the target torque in one optimization process. In order to satisfy the target torque and reduce the torque ripple, the second optimization process is implemented considering the output torque of the initial optimization process. The second target torque is determined by the torque error of the initial output torque and target torque of the first process. From this optimization sequence, the final air gap, as a function of the rotor position, can be determined to satisfy the torque ripple requirement. The proposed high-speed four-two pole SRM is tested to verify the high-efficiency and low-acoustic-noise characteristics.