A Simplified Voltage Balancing Control of a Modular Medium-Frequency Transformer-Based Current Source Converter

The modular medium-frequency transformer (MFT)-based current source converter is considered a promising topology for wind energy conversion systems. The use of modular MFT-based converter, however, introduces a potential issue, that is the capacitor voltage imbalance due to mismatches among the constituent modules of the modular converter. Model predictive control (MPC) with high dynamic performance is increasingly used in high power converters, but here, it suffers high computational burden and poor control performance due to high number of switching states. To solve this issue, a simplified MPC with better control performance is proposed to ensure capacitor voltage balancing without compromising the performance of traditional MPC. The operation principle and performance of the simplified MPC are illustrated and verified by experiments.