The electromagnetic compatibility design considerations of the input filter of a 3-phase inverter in a railway traction system

In this paper, the design considerations of the input filter of the 3-phase inverters in a railway traction system are given. The input filter design should consider the system stability in case of dead-time power gap, the stability of the train performance of the train at low speed, the speed of response of the inverter system due to a load change or a supply voltage change, Electromagnetic Interference limits (EMI), and the correspondence with the impedance at the substation of the wayside. A generic approach and a detailed procedure for the sound design of the input filter are given. Simulation and experimental results are presented from a production train to prove the validity of the proposed approach. The converter is qualified against the EN 50121-3 standards for revenue service purposes. Analytical, simulation and experimental results of a 750Vdc/700Vac 400kW converter are presented to offer the proof of concept.