Microprocessor based Symmetrical Multipulse Modulation in a Three-Phase Improved Power Quality AC-DC Converter with Four-Quadrant Switch Realizations

摘要

A three-phase a.c. controller using power MOSFETs operating in high- frequency chopping mode has been developed fabricated and tested with resistive load. The microprocessor based firing scheme is used to test the four-quadrant switch realizations. The output voltage is smoothly varied using symmetrical multipulse modulation by varying the duty cycle, and the relevant experimental results are furnished. The harmonic analysis of the chopped wave is made in terms of the number of pulses per cycle and pulse width. For same values of power factor and per unit output voltage, it can be concluded from the test results that the proposed scheme has much lower values of lower order harmonics as compared to conventional thyristor phase control. The computed results have been experimentally validated.