Power electronics for environmental car

By Svein Tønseth
Photo: Volvo

The Volvo Environmental Concept Car is based on a Volvo 850 chassis.

Swedish industry wants to get into the coming market for environmentally friendly vehicles. The demonstration car that is the starting point of its push has convertors from EFI in the SINTEF Group under its aluminium bodywork.

On the basis of their many years of research collaboration, ABB, Volvo Flygmotor and Vattenfall set up a separate company in late autumn 1993. HSG Development will manufacture power generators for hybrid electric vehicles (cars that combine two sources of power).

In collaboration with Volvo Personvagnar, the three industrial partners have turned the results of their research into the Volvo ECC (Environmental Concept Car) prototype, which is based on a Volvo 850 chassis. The car is driven by an electric motor, which obtains its current in several ways, depending on how much power it needs. The major news item under the bonnet is the combination of gas turbine and high-speed generator (HSG), which turns the car into a mobile power station.

"Our company will develop and manufacture generators. However, the development work that EFI has done for the ECC has also given us one of the most advanced drive systems in the world. We will also offer this system to our future customers, and perhaps also develop it further", says Anders Malmquist, electric drive systems project manager in HSG Development.

The Volvo ECC can be driven on electric power alone (on power that comes from the car´s 350 kg of nickel-cadmium batteries), on electricity from the gas-turbine/HSG generator, or from both batteries and generator.

"The positive reception that the Volvo ECC has been given has led us to go even further and industrialize the gas-turbine/generator technology. HSG Development will develop the hybrid system further, but we will also supply prototypes to customers in the vehicle industry and utilities," says Anders Malmquist.

The power regulator (invertor) that drives the Volvo ECC´s electric motor was developed by EFI, which also developed the power regulator (convertor) that transmits power to and from the battery.

"The systems developed by EFI mean that we are a world leader in power electronics for electric-power vehicles. The two convertors from EFI look just the same, but they perform quite different functions. The convertor that transmits power to and from the battery regulates the whole drive system, and is a very important component in the Volvo ECC. The drive system is based on hitherto unproven technology, and it functions perfectly," says Malmquist.