Higher Fundamental Output Voltage Research Articles

DSPACE Based Implementation of Multicarrier PWM Strategies for Three Phase Five Level Cascaded Inverter

This paper presents the comparison of unipolar multicarrier Pulse Width Modulation (PWM) techniques for the Cascaded Multi Level Inverter (CMLI). Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD) combination. The effectiveness of the PWM strategies developed using CFD are demonstrated by simulation and experimentation. The simulation results indicate that the chosen five level inverter triggered by the developed UISCPSPWM and UISCVFPWM strategy with sine and stepped wave references and UISCAPODPWM strategy with THI PWM and 60 degree reference exhibis reduced harmonics. UISCCOPWM provides higher fundamental RMS output voltage for all four chosen references. PWM strategies developed are implemented in real time using dSPACE/Real Time Interface (RTI). The simulation and experimental outputs closely match with each other validating the strategies presented

FPGA based variable frequency AC to AC power conversion

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.