| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系 === 103 === The thesis mainly discusses the dynamic starting protection method for the single-phase brushless DC fan motor. The concept of implementation is to first determine whether the motor rotates and the direction of rotation before the start of the motor. For the reverse-rotation case, it is needed to brake the motor first and then start the motor to reduce the starting current to achieve the protection of the driving system of the fan motor.
This paper proposes a new method which uses the back-EMF phase sensing by a circuit composed of a diode and resistors and Hall signal to determine the direction of rotation of the motor by Micro-control unit. With respect to the traditional use of the optical sensor and encoder to determine the direction of rotation, the proposed method has the advantages of low cost and relatively easy arrangement in space. About the part of the motor brake, it uses a new regenerative braking method. With the controllable braking current, the new method uses the motor speed as a feedback control parameter to control the braking current below the allowable rating of motor to achieve the protection. In this paper, software of the finite-element FLUX2D and MATLAB is used to simulate and analyze the fan motor system with the proposed method. Implementation of a single-phase four-pole brushless DC fan motor driver with the new intelligent starting method is accomplished with the application of digital signal processor TMS320F28335. The simulation and experimental results verify the feasibility and accuracy of the proposed circuit and method.
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