FPGA based variable frequency AC to AC power conversion

Abstract

AC/AC variable frequency power conversion system is proposed which makes use of a cycloconverter in newer form, ac–ac matrix converter. An attempt has been made to operate this matrix converter both in conventional low frequency ac–ac converter, cycloconverter and new high frequency ac–ac converter, cycloinverter. The ability to directly affect the frequency conversion of power without any intermediate stage involving DC power is a huge advantage of the system. The undesirable harmonic components in the output of the matrix converter have been minimized using an advanced modulation technique called as trapezoidal modulation technique. The technique offers several advantages compared to other modulation techniques in terms of easy and fast real-time waveform generation with higher fundamental output voltage. The converter is simulated using well known software package MATLAB. Simulations results are presented for both cycloconverter as well as for cycloinverter. It has been found that for cycloinverter operation the total harmonic distortion (THD) is more as compared to cycloconverter mode of operation. The simulated results are also validated with experimental results by implementing the trigger controller circuit to generate trapezoidal modulated trigger signal for matrix converter on field programmable gate array (FPGA). Peripheral input–output and FPGA interfacing has been developed through Xilinx 9.2i using very high speed integrated circuit hardware description language (VHDL). The circuit has been tested qualitatively by observing various waveforms on digital storage oscilloscope (DSO). The operation of proposed system has been found satisfactory.