Control Strategy Research For Induction Motor Speed Adjustment Feeding By Variable Frequency Converter

With the appearance of new integrated circuit chips and the power switch modules aswell as the development of modern control theory and the computer technologies, theinduction motor driving technologies are being improved quickly and new controlstrategies are developed and applied for different applications.The advanced ac motordriving systemes are of high performances and competable to the dc motor drivingsystemes.This thesis describes the implementations of Sine Pulse Width Modulation(SPWM)and Space Vector Pulse Width Modulation(SVPWM) using singlechip on a teachingplatform of electric power electron and electric drive, and achieves the purpose ofvariable-frequency adjusting-speed for induction motor.In this control system, the main high performance microprocessor chip is 80C196MCwhich is produced by Intel company and is specialized for motor control. Three phasemodulating wave is generated by wave form generator in CPU. The main circuit of thesystem adopts the AC-DC-AC topological structure. The power device usesIPM(Intelligent Power Module). This paper details the algorithm structure of SVPWM andSPWM based on 80C196MC single-chip computer, the relative parameters'calculation andthe setting method of some registers of the wave form generator. Both SPWM andSVPWM adopt three modulating methods: synchronous modulation, asynchronousmodulation and hybrid modulation. SPWM uses the regular sampling, and SVPWM usesthe combination of space vectors. The program is finished by assembly language.The design scheme is tested and debugged on an three-phase asynchronous motor inthe end, and the results show that the method of SVPWM has lower current harmonic,more efficient use of supply voltage, lower noise than the sine pulse widthmodulation(SPWM).