Resonating Power Decoupling Using Multifunctional Bidirectional DC/DC Converter in Hybrid Railway Traction Application

For the single-phase high-power railway traction system, the inevitable second-order resonating power has become a critical issue to the traction system. In this article, a power-decoupling solution is proposed to replace the conventional passive LC resonance filter by utilizing the buck-type bidirectional dc/dc converter (BBDC) of hybrid electric multiple units, which is designed to power the train in nonelectrified routes using the on-board battery. By considering both the current ripples in the battery mode and the power decoupling in the catenary mode, the corresponding parameter design process of the BBDC is presented. Based on the power coupling phenomenon and the spectrum characteristic of the BBDC, a direct resonance control method is proposed to decouple the low-order resonating power. Simulations and experiments are carried out to validate the effectiveness of the new proposal. The results demonstrate that the proposal is almost the same as using the conventional passive LC resonance filter for power decoupling in both steady and dynamic operation scenarios.