Study On SVPWM Technique In Speed Regulation Of AC Motor

The flux sinusoidal PWM(SVPWM) technology can realize digitization more easily than normal SPWM .So it is used widely, and extends to high-voltage and large-capacity fields gradually. In such fields, switching losses are requested to decrease strongly. And lower the capacity standard of the switching devices.Firstly, the thesis analyzes the working principles of traditional flux sinusoidal PWM control technique in detail. And the modulation wave functions are deduced. To simplify the calculation, an optimized simpler method is used to realize the digital algorithm. At the same time, the method of realization in over-modulation range. And the digital simulation is done by computer to verify.To decrease switching dissipation and raise efficiency of the controller, switching times can usually be decreased to four during every sampling period by the means of selecting zero vectors properly. Switching frequency is decreased by 33 percents accordingly and switching losses is decreased largely at the same carrier wave frequency. This thesis analyses the peculiarity of several optimized methods of SVPWM roundly, simulation experiment is done. The harmonic peculiarity of carrier waves of each optimized method qualitatively, and expresses elementary ideas in methods of decreasing switching dissipation above-mentioned essentially by using harmonic injection method. Then, on the base of theoretic analysis, the thesis proves optimized SVPWM method is an ideal control strategy, of which the none-switching sectors in each half period, distributes on both sides of the current peak value symmetrically. To realize the arithmetic of the ideal optimized method, the thesis presents a simple digital arithmetic, and the simulation experiments proves the feasibility. The deficiencies in voltage utilities of the several optional methods are analyzed.Finally, the thesis describes the way and process of the realization of SVPWM and the optimized in DSP.