Modern train traction systems use high-speed switching IGBTs in main circuits. High-speed switching reduces electromagnetic noise generated by the main motor and improves the efficiency of energy conversion. For the inverter control system, vector control is employed to control the torque current component and the exciting current component separately, which are output to the induction motor. Since vector control ensures high-speed torque control, it is also applied to slip-slide control to improve adhesion force. The maintenance work for contacts and pneumatic parts can be eliminated by replacing mechanical contacts in each unit with electronic contacts and by changing the pneumatic operation system to an electromagnetic one.
The numerous advantages of insulated gate bipolar transistor (IGBT) power modules and their ongoing development for higher voltage and current ratings make them interesting for traction applications. These applications imply high-reliability requirements. One important requirement is the ability to withstand power cycles. Power cycles cause temperature changes which lead to mechanical stress that can result in a failure. Lifting of bond wires is thereby the predominant failure mechanism. A fast power cycling test method activating the main failure mechanism has been developed which allows the reproduction of millions of temperature changes in a short time. The applicability of fast testing is supported by mechanical analysis.
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