Digitally controlled sigma-delta modulated direct matrix converter for high frequency AC-AC Conversion

Abstract

In recent times, several digitally controlled modulation techniques (MTs) have envisioned for generating pulse width modulation (PWM) trigger pulses to improve the quality of the output (o/p) produced [in terms of reduced total harmonic distortion (THD)], from direct matrix converter (DMC). The development of a digital controller for single-phase DMC, producing o/p frequencies higher than the input frequency has been dealt with in this paper. Performance of the proposed DMC has been analysed by applying an advanced modulation technique, named as “Sigma-Delta modulation”. The complete system has been simulated on the MATLAB/SIMULINK platform as well as successfully implemented on the real-time digital simulator “OPAL-RT: OP4510”. Working of the proposed digital controller has been successfully verified for the DMC with o/p frequency, ranging from 100 Hz to 60 kHz. With the Sigma-Delta modulated trigger pulses, the lowest THD (associated with o/p voltage of the DMC) is found to be around 3.1 %. As the real-time results have been acquired in the close vicinity and conformity to the results achieved with simulations, this validates success of the proposed digital controller.