The Nikkei has reported that Sumitomo Electric Industries (SEI) hopes to have a prototype of a superconducting motor for electric buses ready for presentation to OEMs by spring 2013, and hopes to start volume production by 2020 for applications in forklift trucks and small on-road trucks besides buses.
SEI has not confirmed these targets but explores applications in ship propulsion and EVs of superconducting motors on its website. The company successfully demonstrated an electrified passenger car with a 30kW high temperature superconducting motor with 120Nm of torque in 2008.
Superconductivity allows electricity to be carried with almost zero electrical resistance, whereas a conventional EV motor uses copper wire coils which, heated by electrical resistance, convey only a limited value of current. A superconducting wire allows current to flow through without loss, thereby using battery energy with approx. 20-30% less than the usual +/- 10% energy conversion loss. SEI has developed a bismuth-based superconducting wire which it says offers the world’s highest level of critical current, and has participated in various projects related to superconducting technology, such as a high-temperature superconducting cable demonstration test in the US and a Japanese industry-academia project on the development of superconducting motors to propel ships.
