Resonance converter with a toroidal transformer for a tram-train vehicle

In order to build a tram-train transport system, it is necessary to have a rail vehicle capable of running off both 3300Vdc railway electric overhead lines and 600Vdc tramway overhead lines. One of the solutions would be to build a high voltage reducing converter. This article presents a design of a resonance converter with a toroidal transformer and discusses results of laboratory tests carried out on this device. Given the input voltage level of 3300Vdc, the authors have decided to use a configuration comprising a half-bridge with a series resonant circuit on the transformer primary side. As operation in the resonant mode makes it possible to increase operating frequency of the system, the size and weight of the transformer can be reduced. The primary function of the converter is to provide power to the (inverter-based) drive system in a dual system tram-train vehicle capable of running at both 3000Vdc and 600Vdc. For this purpose a special transformer has been designed and built, incorporating a nanocrystal toroidal core, with active power of 120kW. The article also presents results of efficiency measurements on the resonance converter.