Electric vehicle motor system features built-in silicon carbide inverter

March 12, 2012 // By Julien Happich
Mitsubishi Electric has announced a prototype electric vehicle (EV) motor system with a built-in silicon carbide inverter. Measuring just half the dimensions of Mitsubishi Electric's existing motor system that uses an external inverter, the unit is claimed to be the smallest of its kind, with a loss below half that of silicon-based systems.

The motor system is expected to enable manufacturers to develop EVs offering more passenger space and greater energy efficiency. The company plans to commercialize the motor system after finalizing other technologies for motor/inverter cooling, downsizing and efficiency. The newly developed cylinder-shaped inverter matches the diameter of the motor, enabling them to be connected coaxially within a chassis, resulting in a substantial downsizing of the motor system. Silicon chips have been widely used in power devices for inverter switching.

Silicon carbide, however, is now recognized as a more suitable material for chips owing to its electrical characteristics, including a breakdown electric field that is 10 times greater compared to silicon chips. This greater breakdown electric field enables thinner chips, which reduces electrical resistance and lowers loss. All power chips in the inverter are silicon carbide-based, resulting in over 50% reduction of loss compared to the company’s silicon-based inverter system. The motor is a permanent magnet motor that uses a neodymium magnet. Mitsubishi Electric’s proprietary dense-winding structure enabled the company to use its poki-poki motor production technologies to reduce the size of the motor. The company claims an increased magnetic efficiency and a power output improved by 5% over previous motors.

Visit Mitsubishi Electric at www.MitsubishiElectric.com