| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 104 === In this thesis, a novel modulation method which combining the concepts of six-step square wave and space vector modulation(SVM) is proposed. This novel modulation, unlike the old modulation methods which has to set dead time between every period of PWM, it’s no need to add dead time in the control signal, and has the advantages shown as below: a) This novel modulation method can avoid dead time and improve the energy efficiency by separating the enable time of two transistors in each phase. b) There are only three transistors operating in every section in a cycle of rotation, the others are unable in the same section. With this rule of modulation, it can reduce the switching loss of every transistors. c) The space vector modulation concept can reduce the ripple of output torque in brushless machine.
So far the researching progress has already derivate the specified section PWM duty ratio formula of each power transistors. And by using the electrical simulation software PSIM, the simulation model of this novel modulation method has been constructed and tested by three phase inductance-resistance load. Simulation results show that compared with sine-wave modulation(SPWM) and space vector modulation(SVPWM), this novel modulation method has higher output ability. But it’s denotes that there are voltage ripple occur in certain section which has to be avoid by simulation program. For future researching it will test in close loop current and speed control, and using DSP to realize the brushless motor driving.
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