부산대학교 도서관

In most of the applications involving three-phase machines, speed control of the machine plays an important role. For the speed control the most popular method used is the v/f method. The v/f method aims at maintaining the flux constant by varying voltage and frequency proportionately. But the v/f method has its own share of drawbacks. One of the major disadvantage of v/f method is the inferior dynamic performance. In order to overcome the disadvantages of the v/f method one of the best solution is preferring multiphase systems in spite of the conventional three-phase systems. In multiphase systems the effect of harmonics on the main flux is reduced in-turn reducing the pulsating torques. In this paper the v/f control of a threephase Induction motor is implemented and the results are analysed. A comparison is made between the three-phase and five-phase inverters with different PWM techniques. The inverters are modelled using MATLAB/SIMULINK, the results are compared and analysed. In this paper the %THD in phase voltages obtained from the three PWM technique applied for both three-phase and five-phase inverters is calculated and compared.