Speed control of three phase induction motors using space vector PWM technique

ABSTRACT Master Thesis SPEED CONTROL OF THREE PHASE INDUCTION MOTORS USING SPACE VECTOR PWM TECHNIQUE Hakan ÇELİK Firat University Graduate School of Natural and Applied Scieces Department of Electric and Electronics Engineering 2004, Pages: 112 Recently, it has been obtained much development in DC- link inverter used in the speed control of electric motors with the improvements in both power electronics and microprocessor technologies. Depending upon the development the speed and torque control of the induction motors could have done in an easier way. The Pulse Width Modulation (PWM) techniques used in DC-link inverter affect directly the output performance of the inverter. The most well know of the PWM techniques used in industry is the sinusoidal PWM technique. The technique is based upon comparing the reference sinusoidal wave with a carrier wave. In microprocessors, the comparing process is not possible to realize in real time. In order to get rid of this problem, the reference sinusoidal wave is sampled in a regular way. In the sinusoidal PWM, the case in which the output voltage for linear modulation region is not bigger than the DC-link voltage reveals an alternative modulation technique to this modulation technique. This modulation technique is known as the space vector PWM (SVPWM). In SVPWM technique, the output voltage is able to ascent to the desired high values and it can be realized digitally. Hence it can be applied easily in industry. However computing for the required durations to provide PWM signals is made wing complex processes. The complex processes have been worked out easily thanks to the recent improvements in both power electronics and microprocessor technologies. In this thesis, the modulation techniques have been simulated in the Matlab/Simulink environment and compared with the other techniques in detiail. In addition, by making V/f speed control of three-phase induction motor supplied by the voltage source inverter it has been demonstrated that the SVM techniques have superior advantages to the others. Keywords: Three-phase induction motor, space vector PWM, V/f speed control, Simulink. XIII