Tokyo-based Mitsubishi Electric Corp has launched a railcar traction inverter system for 1500VDC catenaries that incorporates what is claimed to be the first all-silicon carbide (SiC) power modules made with SiC transistors and SiC diodes. The all-SiC inverter greatly reduces power loss, size and weight compared with conventional silicon-based insulated-gate bipolar transistor (IGBT) power modules and hybrid power modules made with silicon transistors and SiC diodes.
Graphic: Replacement of silicon-based IGBT with SiC MOSFET to create all-SiC power module.
Previously, in October 2011, Mitsubishi Electric produced a railcar traction inverter for 600VDC, 750V catenaries incorporating the first large-capacity hybrid SiC power modules. With help from Tokyo Metro Co Ltd, the system was field-tested in commercial railcars operating on its Ginza Line subway, demonstrating 38.6% energy reduction compared with conventional inverters in other railcars operating on the same line.
Mitsubishi Electric's new large-capacity, all-SiC power modules are expected to help save power as well as lower the size and weight of equipment used in high-power trains including Japan's Shinkansen.
Graphic: Application range of SiC power modules.
The new traction inverter system's switching loss is about 55% less than the firm's conventional inverter system incorporating IGBT power modules. The system also increases regenerated energy through the use of regenerative brakes in all speed ranges. Total energy consumption of railcar systems, including their motors, is hence cut by about 30% compared to conventional systems.
Size and weight are reduced by about 65% compared to conventional inverter systems with IGBT power modules and about 30% compared to existing hybrid inverter systems with SiC diodes.
The number of components is also reduced by integrating SiC transistors and diodes into one package per inverter circuit phase.
Energy saving in total railway systems is further enhanced by effectively transferring regenerated electric power from the railcar to stations to be equipped with station energy-saving inverters (S-EIV).
Development of the SiC power modules was supported partially by Japan's New Energy and Industrial Technology Development Organization (NEDO).
