A Damping Scheme With Coupled-Inductor Functional Extension for Common-Mode Leakage Current in Parallel Inverters Supplying AC Motors

This article presents a novel damping scheme designed to mitigate common-mode leakage currents in parallel inverters supplying ac motors, utilizing coupled inductors. High-speed switching can generate significant high-frequency common-mode voltage, leading to unwanted leakage currents. To investigate the mechanisms behind common-mode current generation, a circuit modeling analysis is included, providing valuable insights into their behavior. The proposed scheme integrates the filtering function into the coupled inductors, achieving both circulating current suppression and leakage current attenuation, with optimal damping selection further enhancing effectiveness. Simulation and experimental results demonstrate the effectiveness of the damping scheme in reducing common-mode leakage currents, suppressing common-mode voltage oscillations and improving both the winding-to-chassis voltage and common-mode electromagnetic interference in parallel inverter-fed ac motor systems.