All-SiC Traction Converter for Light Rail Transportation Systems: Design Methodology and Development of 165 kVA Prototype

The design and development of a high-performance 165 kVA, 750 V DC all-silicon carbide (SiC) traction converter for new generation light rail transportation systems (LRTSs) are described. In the design of the traction motor drive, the efficiency of the overall system is maximized and the line current harmonic content of the traction motor is minimized. A complete mathematical model of the physical system is derived to carry out real-time simulations and proper control of the LRTS on a real rail track. The electrical and thermal performances of traction-type SiC power MOSFET modules are compared with those of alternative hybrid and Si-IGBT modules for various switching frequencies. The implementation of the developed system is also described. The performance of the resulting system is verified experimentally on a full-scale physical simulator as well as for various track conditions. Very promising results for the next generation railway traction motor drives have been obtained in terms of performance criteria, such as very high efficiency, low harmonic distortion of the motor line current, low cooling requirement, relatively high switching frequency, and hence, superior controller performance. The effects of the SiC power MOSFET operation on the insulation of the available traction motors are also examined experimentally. This paper is accompanied by a video demonstrating the experimental work.