High Torque Density Switched Reluctance Drive System for Low Carbon Vehicles

The HDSRDS project will develop a highly innovative electrical machine and drive system for low carbon vehicles, capable of providing tractive power or acting as a generator and which is both cost competitive and suitable for high volume manufacture. This project will go beyond the current state of the art in low carbon vehicle drivetrains by replacing electric motors which use rare earth magnets with one that does not and electronic control systems based on IGBT inverters with a high temperature alternative.
Demand for Rare Earths is forecasted to grow at 8-11% per year between 2011 and 2014 driven by increasing demand in hybrid and electric vehicles and wind turbines. Demand growth will occur in the context of increasingly restricted supply, exacerbated by China's draft ban on the export of Rare Earths from 2015, which is expected to lead to further large increases in the cost of rare earth magnets. HDSRDS will use the latest Switched Reluctance Machine designs to emerge from Newcastle University’s fundamental research. As these machines contain no rare earth magnets they meet the demands of automotive market for a low cost product with stable price and supply chain. These machines have simple structures for the windings and iron laminations making them suitable for low cost high volume manufacture.
In addition, the use of rare earth magnet materials limits the maximum operating temperature of the motor to below 150C. A review, conducted by Ricardo for the Government, highlighted hybridisation as a means of offering significant CO2 savings, but high integration cost, in particular in relation to the differing cooling needs of the electric and conventional drive elements of the system, has been seen as a major barrier. The proposed HDSRDS will use high temperature insulating materials allowing motor operation at 240C and explore the use of high temperature semiconductor devices rated for operation at 200C. This will allow the integrated package to operate at the higher temperature of an IC engine coolant loop, significantly reducing the cost and complexity of vehicle hybridisation.