Design and Testing of Filters to Reduce EMC Interference in a Power-Flow Controller Based on Power electronics

(EV) chargers, modern power grids face challenges such as voltage range violations, uneven load distribution, line overload, insufficient fault currents, and reverse power flow. In short, the distribution grid turns weak. Under the umbrella of soft open points (SOP) and series voltage regulators, full ac-ac converters and unified power flow controllers (UPFC) can mitigate these issues but rely on bulky and costly transformers. To solve this limitation, this work presents a fully power-electronics-based power-flow controller that does not require a low-frequency transformer capable of regulating current flow within grid lines to enhance power management and optimize voltage regulation. As switched-mode electronics, its electromagnetic interference

(EMI) becomes important to not disturb nearby equipment and violate electromagnetic compatibility (EMC) standards. This paper introduces a systematic procedure to design, model and validate filters that effectively reduce EMI. It develops compact internal EMI mitigation techniques for converters operating at high switching frequencies. Filtering solutions are designed for the active front end (AFE) converter, dual-active-bridge (DAB) converter, and the series stage to minimize both conducted and radiated emissions. Furthermore, the DAB converter circuit is redesigned to provide a low-impedance path for common-mode (CM) noise to reduce EMI without bulky passive filters. Strategically placed Y-capacitors further suppress

CM noise. Simulation and experimental results demonstrate up to 40 dB(μV) attenuation at switching harmonic frequencies while maintaining high efficiency and compactness.