Study Of Optimal Strategy Of SVPWM In AC Speed-Adjustable System Based On DSP

Aimed at improving the efficiency of inverters in the speed-adjustable system, under the application of AC speed regulation of inverter—induction motor system, the research of this thesis uses inverters switching loss optimized SVPWM control method, which can both improve the efficiency of the system and ensure its steady operation in a long time.This thesis combines theory analysis, simulation verification and experiment operation. A simulation model of the induction motor in two-phase-axis system is established first using SIMULINK tool of MATLAB 6.5. Besides, simulation models both in voltage source inverter—induction motor speed-adjustable system of one group of PWM—SPWM (sinusoidal PWM)and SVPWM( Space vector PWM)is also established. According to the contrast of simulation result, SVPWM and SPWM represent their respective advantages and disadvantages.Then, this thesis analyses two optimized methods of SVPWM ("normal optimized SVPWM" and "switching loss optimized SVPWM") . Two optimized methods of SVPWM are analysed based on the characteristic of harmonic current, harmonic loss, harmonic torque ripple and switching loss. The performance comparisons of the two optimized SVPWM methods are made and the simulation results are shown. The "switching loss optimized SVPWM" method is the better one while applying SVPWM control into the voltage source inverter—induction motor speed-adjustable system. It is characterized by not only low switching losses, but also low harmonic current at high modulation index which leads to low harmonic losses and reduced torque ripple.Based upon the thoroughly study of switching loss optimized SVPWM control method, this thesis puts forward an overall plan of system hardware and software design centering on DSP chip TMS320F2812, establishing a set of experiment system on inverter—induction motor speed-adjustable system, designing main modules, including main circuits, control circuits and detector circuits; the software design use switching loss optimized SVPWM control method instead of traditional SPWM and normal optimized SVPWM adjusting method and achieve the arithmetic based on DSP chip. Furthermore, the experiments have proved the system operation stability and feasibility of switching loss optimized SVPWM method.