Mitsubishi Electric: Silicon Carbide gets traction at 3.3kV and 1500A

The JSAP (Japanese journal of applied physics) featured in its September 2015 issue an article from a team at Mitsubishi Electric. They successfully built a 3.3kV power module rated at 1500A using only Silicon Carbide devices (MOSFET and SBD). They tested the modules on the traction system of a train in real conditions.

A summary is presented here under. Follow this link for the full paper.

Next-generation power electronics capable of reducing energy consumption are in high demand, particularly in the transportation industries. A key way of saving energy in electronics is by reducing the losses inherent in switching processes and power conversion. Much attention is now being given to a compound form of silicon and carbon called silicon carbide (SiC) for electronic components, a material whose properties outperform conventional silicon in terms of thermal conductivity, loss reduction and the ability to withstand high voltages.

Satoshi Yamakawa and co-workers at Mitsubishi Electric Corporation have developed a new power module made from a SiC metal-oxide-semiconductor field-effect transistor (MOSFET) and a SiC Schottky barrier diode (SBD). The team successfully trialed the module in a train traction inverter – a device used to convert the direct current from the power source to three-phase alternating current suitable for driving the propulsion motors – with promising results.

For a power module in a traction inverter, low power loss, miniaturization, high voltage rating, and high temperature environmental resistance are required.

Yamakawa and his team prepared the SiC MOSFET for the power module by first n-type doping the junction field-effect transistor region: this reduced on-resistance of the device at high temperatures. By combining the SiC MOSFET with a SiC SBD – a diode which allows for fast and efficient switching – the team created a power module for a traction inverter rated at 3.3kV / 1500A.

A new traction inverter system equipped with their power module is stable, highly efficient and reduces switching losses by 55% compared with conventional silicon-based inverters.

Reference and Affiliation:

Kenji Hamada¹, Shiro Hino^1,2, Naruhisa Miura^1,2, Hiroshi Watanabe^1,2, Shuhei Nakata^1,2, Eisuke Suekawa³, Yuji Ebiike³, Masayuki Imaizumi³, Isao Umezaki³, and Satoshi Yamakawa^1,2. 3.3kV/1500A power modules for the world’s first all-SiC traction inverter. Japanese Journal of Applied Physics 54 04DP07 (2015)

http://dx.doi.org/10.7567/JJAP.54.04DP07

1. Advanced Technology R&D Center, Mitsubishi Electric Corporation, Amagasaki, Hyogo 661-8661, Japan

2. R&D Partnership for Future Power Electronics Technology (FUPET), Minato, Tokyo 105-0001, Japan

3. Power Device Works, Mitsubishi Electric Corporation, Fukuoka 819-0192, Japan

4. Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan