Centralized Active Power Decoupling Method for the CHB Converter With Reduced Components and Simplified Control

Abstract

Cascaded H-bridge converters (CHBCs) are widely utilized in medium- and high-voltage systems. However, they present challenges such as large submodule (SM) capacitance and complex capacitor voltage balancing strategy. To improve converter power density and reduce hardware consumption, this letter proposes a new topology for CHBC, which features centralized active power decoupling (APD) capability. The periodic parallel connection and energy interaction between the SMs allows for double-line frequency power fluctuation suppression of all SMs through only one APD branch, leading to reduced components and simplified control. This letter provides a detailed analysis on the operating, modulation, and control strategies of the proposed topology. Experimental results are also presented to demonstrate the feasibility of this new circuit.