| Summary: | 碩士 === 國立成功大學 === 系統及船舶機電工程學系碩博士班 === 96 === This thesis proposes a sensorless drive technique for brushless DC (BLDC) motors. There have been many sensorless techniques proposed for BLDC motors in recently years. However, the motor performance under rated load condition and the operating speed range have not been discussed. Common sensorless techniques cannot perform accurate commutation under a wide operating range, which results in low efficiency and limited speed range. Therefore, this thesis proposes a method that can overcome the problem of the inaccurate commutation. This technique allows the efficiency to be improved under rated torque, and a wide operation range can be accomplished.
The proposed technique is based on the comparison of motor terminal voltages and combines high- and low-pass filters. By regulating their cut-off frequencies according to the motor speed, not only the noises can be rejected but also the commutation can be more accurate for a wide speed range. The experimental studies show that the proposed technique has a superior performance to common approaches. Under rated load condition, the proposed method can drive the motors with close efficiencies to the case equipped with Hall effect sensors. Moreover, the speed range is wider compared to common senslorless methods.
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