Switching Strategy to Reduce Inductor Current Ripple and Common Mode Voltage in Quasi Z-Source Ultra Sparse Matrix Converter

Abstract

This paper aims to reduce the ripple current in the inductor used in a Quasi Z-source Ultra Sparse Matrix Converter (QZSUSMC). The main limitations of the conventional Ultra Sparse Matrix Converter (USMC) are limited voltage gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(\leq 0.866)$</tex-math></inline-formula> and high common mode voltage (CMV). By integrating a quasi Z-source network in the DC link of USMC and providing a shoot-through (ST) state in a switching cycle, a voltage gain greater than unity can be achieved. Inductors are magnetised during the ST state and demagnetized during the nonshoot-through (NST) state. Hence with a proper arrangement of the ST and NST states, ripple in the inductor current can be minimised. In the proposed modulation, the total ST time is divided into six unequal parts and arranging them to minimize the inductor ripple current. in addition to it, proposed method also offers proper switching arrangements by using active vectors to attenuate peak-peak common mode voltage (CMV). As compared to the earlier reported methods, the proposed method produces a better inductor current ripple and a reduced peak of the CMV. Simulation and developed testing circuit results show the effectiveness of the proposed method.