A hybrid level shifted carrier‐based PWM technique for modular multilevel converters

Abstract

Abstract This paper presents a hybrid level shifted carrier‐based pulse width modulation (HLSC‐PWM) technique for modular multilevel converters (MMCs). The concept of the proposed HLSC‐PWM method is developed by combining the principles of phase disposition PWM (PD‐PWM), phase opposition disposition PWM (POD‐PWM), and alternate phase opposition disposition PWM (APOD‐PWM) methods. The main aim of the proposed HLSC‐PWM method is to generate an output voltage with half‐wave and quarter‐wave symmetries. The generated symmetrical PWM output voltage based on the proposed HLSC‐PWM method provides less total harmonic distortion (THD) and enhances the DC‐Link voltage utilization (DCLVU). A generalized mathematical model is formulated to develop a single HLSC for MMC with an N number of submodules (SMs) per arm. Theoretical analysis of DCLVU for the proposed method is described. The functionality and performance of the HLSC‐PWM method are carried out on a three‐phase five‐level MMC in MATLAB/Simulink. A hardware prototype of a single‐phase five‐level MMC is designed for experimental validation. The proposed HLSC‐PWM method is implemented on an Altera/Cyclone I series (EP1C12Q240C8N) field‐programmable gate array (FPGA), simulation and experimental results are presented.

Keywords

• Power electronics, supply and supervisory circuits
• Logic circuits
• Power convertors and power supplies to apparatus