Cascaded H-bridge Multilevel Topology Research Articles

Study of Cascaded H-Bridge Converter Control Strategies and their Impact on Switching Harmonics

The Cascaded H-Bridge (CHB) multilevel static synchronous compensator (STATCOM) has been widely accepted in the industry [1]-[8]. An outstanding advantage of the CHB multilevel topology is their modular structure. This enables higher-level STATCOM to be easily implemented through series connection of more cells. since the pulse-width modulation (PWM) signals of each cell are generated all by the central controller instead of their own controller, the cell does not look like an “independent module”. To achieve “true” modular implementation, a distributed control system (DCS) for the CHB multilevel STATCOM should be developed.

Evaluating the capacity of power and energy balance for cascaded H‐bridge multilevel inverter using different PWM techniques

Among the different multilevel topologies for inverters, cascaded H-bridge multilevel topology has been a good solution for high-power medium-voltage applications because of its modularity structure, voltage balancing, separated DC sources, harmonics reduction, reliability and lower stresses on switching devices. The most widely used pulse width modulation (PWM) techniques for cascaded H-bridge multilevel inverter are known as phase shifted and level shifted. This study presents a comparison of power and energy distribution (inter-phase and inter-bridge power and energy) of three-phase cascaded H-bridge multilevel inverter for the phase-shifted and the level-shifted carrier PWM (phase disposition). A detailed comparison of different PWM techniques with reference to total harmonic distortion in the output voltages, both cases using a filter and without filter are presented also in this study. Simulation for 11-level cascaded H-bridge inverter is carried out in MATLAB/SIMULINK and simulation results are presented.