| Summary: | 碩士 === 國立成功大學 === 工程科學系碩博士班 === 97 === Electrical machines have already become the major source of motive power in the present age. The brushless dc motors possess some advantages such as higher power density, higher efficiency, and simpler controllability. Hence synchronous ac motors become rather popular for many applications, such as compressors, automotive, and household products etc.
For the speed drive of a BLDC motor, information on rotor position is indispensable. However, mounting a position sensor on the rotor causes several drawbacks from the viewpoints of reliability, cost, size, and cable wiring. In order to cope with these drawbacks, a number of sensorless control methods have been proposed so far. In the last two decades, several approaches on sensorless control for BLDC motor have been proposed and developed.
This thesis proposes a sensorless control method using a rotor flux state observer to estimate rotor position and speed estimator. In the proposed rotor flux state observer, the flux due to rotor magnet is chosen as the state variable, and the rotor position and speed could be estimated. The Lyapunov stability theorem is used to prove the rotor flux state observer system is stable. Finally, simulated and experimental results are presented and verify the proposed sensorless method is feasible.
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