Mitsubishi Electric claims to have developed the world’s highest-capacity IGBT (insulated gate bipolar transistor) power module by combining silicon carbide (SiC) diodes with silicon transistors. It says that the 1.2kA/1.7kV module is more efficient than earlier designs and could lead to smaller, lighter inverters.

Mitsubishi has already demonstrated the modules in a 300kW three-phase inverter for railway applications, which exhibits losses up to 29% lower than inverters based on standard silicon designs. In practice, the losses are expected to be an average of 18% lower than existing technologies.

Silicon carbide devices can operate at higher temperatures and with lower switching losses than traditional silicon components. Semiconductor and inverter developers around the world have been working on SiC technologies for many years, but the devices are still relatively expensive.

In Mitsubishi’s 1.2kA modules, eight 75A/1.7kV SiC-Schottky barrier diodes are connected in parallel with 150A/1.7kV silicon transistors. The company says that the design reduces transistor losses by about 55% and diode recovery losses by more than 95%.

Mitsubishi has applied for 83 Japanese and 17 foreign patents to protect its technology which it plans to develop further and commercialise, especially for applications, such as trains, where the high efficiencies and low weights of the inverters would be a particular advantage.