Power Regulation Method for (2k1)-Level Asymmetric Cascaded Η-Bridge Converters Based on Hybrid Modulation

Asymmetric Cascaded H-Bridge (ACHB) converters exhibit significant advantages in reducing the number of modules and improving power quality. However, traditional multi-level modulation poses challenges such as limited cascade numbers, power imbalance and power backflow risks for ACHB converters. To enhance modularity and achieve high performance and safe operation, a (2k1)-level ACHB converter topology along with its power regulation method is proposed. This structure comprises a single main module with dc-link voltage of kE and multiple auxiliary modules with a dc-link voltage of E. Initially, a power self-balancing modulation scheme is introduced, employing square-wave modulation for the main module operating at the fundamental frequency, while auxiliary modules adopt high-frequency phase disposition (PD) modulation improved by carrier permutation, ensuring balanced power distribution among modules. Building upon this, exploiting the flexibility of PD modulation, a carrier distribution modification scheme is proposed to mitigate power backflow risks and reduce computational burden, extendable to ACHB converters with multiple auxiliary modules. Simulation and experimental results verify the performance of the proposed power regulation method.