Phase Shifted Carrier Pulse Width Modulation for Flying Capacitor MMC without Sensors

The capacitor voltage balancing in modular multilevel converter (MMC) is a phenomenon requires expensive voltage and current sensors. The 3L-Flying capacitor sub-module(3L-FCSM) has less capacitor voltage ripple and needs less foot print requirement as compared to 2L-half-bridge sub-module based MMC. This paper presents a phase shifted carrier pulse width modulation (PSC-PWM) technique-based voltage balancing method for 3L-FCSM MMC. The suggested method eliminates voltage and current sensors as well as removes the several stages like sorting, selection of capacitors for the capacitor voltage balancing. The proposed method increases the number of voltage levels at load side to 4N+1 from 2N+1 (where N is the number of SMs per arm) which substantially improves the harmonic performance. For the verification, simulation results are presented.