EXPERIMENTAL IMPLEMENTATION OF CARRIER PHASE SHIFT PULSE WIDTH MODULATION TECHNIQUE IN MODULAR MULTILEVEL CONVERTER

Abstract

The modular multilevel converter (MMC) is an emerging and highly efficient voltage source converter (VSC) topology for medium and high voltage applications. The converter has multivariable that need to be controlled for proper oper-ation of the converter. All the MMC control loops are linked to the modulation voltage synthesis for providing appro-priate gate signals for the converter switches. Different modulation techniques have been proposed to obtain appro-priate switching pulses. The most common ones being stair case modulation and carrier phase shift pulse width mod-ulation (CPS-PWM) techniques. This paper presents an experimental implementation of CPS-PWM in MMC which is the most suitable and recommended modulation technique for small and medium scale MMC with reduced number of submodules (SMs). The concept is experimentally demonstrated on an MMC with three SMs per arm. The results show perfect harmonic performance with fundamental switching frequency.