implementing igbt-based dc/dc converters for advanced control of dc traction motors in train refurbishment

The first-generation trains of tehran metro are designed with a dc propulsion system and the dc traction motor current control with multiple resistors and contactors. the disadvantage of this structure is the diversity of mechanical elements, high failure rate, torque shocks during operation, and the failure to regenerate braking power to the dc network. by studying the structure of the existing train system and reviewing the principles of dc motor controlling, the modernization of this propulsion system is proposed to solve the existing problems. this new converter consists of a half-bridge dc/dc converter used for field current control a bidirectional dc/dc used for four quadrant operation of the train and a chopper converter for over-voltage protection and dynamic braking. the electrical performance of this new converter was analyzed and approved by simulations in matlab software and the experimental results.