DESIGN OF THREE PHASE AC CHOPPER WITH PULSE WIDTH MODULATION

SUMMARY DESIGN OF THREE PHASE AC CHOPPER WITH PULSE WIDTH MODULATION The popularity of power electronic is increasing day by day in parallel with the development of semiconductor switching elements. Thus, in all systems related to electricity and electronics, different applications belonging to the field of power electronics are used. The scope of this thesis is design three-phase PWM AC choppers system which is foremost power electronic circuits. AC chopper circuit is basically a power electronic circuit that can convert constant AC voltage (mainly supply) to another AC voltage with a desired amplitude without changing the frequency. It has a disadvantage of having high harmonics on the grid and load sides while having the advantageous feature of natural commutation formation. AC choppers are frequently used in industrial systems such as start-up and speed control of universal motors, electrical heating. However, as the use of such power electronic circuits in the specified areas has increased, various harmonic-based poor quality of the energy systems have emerged. With the developments in semiconductor technology has made considerable improvements in the chopper circuits. Pulse Width Modulation (PWM) method has begun to be used in the chopper circuits with the use of power electronic elements operating at high switching frequencies. PWM controlled AC chopper circuits have also reduced disadvantages of the choppers. In this thesis, load currents with less harmonics are obtained by using an efficient Hysteresis Band Current Controller (HBCC) for Three-Phase PWM AA Chopper simulations using IGBTs from semiconductor power switches. This approach, which is used in simulations using MATLAB software, has resulted in positive results. In the three-phase PWM AA chopper design, the waveforms of the load currents and voltages generated from the AA chopper circuit connected to the three-phase source voltage are obtained. The results of total harmonic distortion values are obtained from simulation and designed AC chopper circuit. These are compared to each other for analysing performance of algorithm. Keywords: Alternative Current (AC) Choppers, Hysteresis Band Current Controller (HBCC), Pulse Width Modulation (PWM).