| Summary: | 碩士 === 國立宜蘭大學 === 機械與機電工程學系碩士班 === 101 === This research establishes a key technique for sensorless single-phase BLDC motor drive to improve the competitive advantage in reliability and cost-effectiveness of single-phase BLDC motors. For the design of a high reliability sensorless drive, we propose a positioning control technique to avoid the reversing rotation during starting. The technique can shorten the time to enter the open-loop starting, and reduce the problem of rotor oscillation caused by single-phase motor’s larger cogging torque. We also present a method to improve open-loop starting. Under the conditions of external load variation and unknown commutation sequence, the method can adjust armature voltage and commutation frequency automatically, and keep the torque angle in orthogonal lowering the energy loss during open-loop starting process. Instead of using the back EMF voltage zero crossing point detection in closed-loop commutation, a current zero crossing point detecting method is developed to extend the output power and speed of the sensorless single-phase BLDCM drive. Theoretical analysis and experimental results reveal that the proposed methods can effectively solve the problems such as reversing rotation phenomenon at starting, time-consuming trial and error tuning with the sensitivity to load variation during the open-loop starting interval. Moreover, the output power, speed, and efficiency can be improved significantly.
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