TSB backs converter development for hybrid cars

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Electrical power systems on future hybrid vehicles could be less expensive, lighter and more compact with a new flexible DC-to-DC converter capable of handling multiple voltages simultaneously.

The technology is the intended result of work being conducted by a consortium led by research and development firm Prodrive.

Manchester University, Raytheon Systems, Scisys, International Transformers and Tata Motors European Technical centre are taking part in the three-year programme, which is being supported by investment from the government-backed Technology Strategy Board (TSB).

A DC-to-DC converter is an electronic circuit that converts a source of direct current (DC) from one voltage level to another. This is particularly important in hybrid and electric vehicles because the battery cell voltage varies with state of charge. The battery state of charge can vary a vehicle’s performance so a DC-to-DC converter is necessary to maintain the voltage level.

Currently, hybrid vehicles use multiple DC-to-DC converters because various devices − including traction motors, cabin electrical systems, fuel-cell stacks or supercapacitors − have different voltage needs.

Pete James, Prodrive’s technical specialist, said existing hybrids, such as the Toyota Prius, need one DC-to-DC converter for the traction motor and another for the vehicle’s 12V system.

If these two converters were replaced with one flexible DC-to-DC converter it would save 39 per cent on cost, he claimed, and 37 per cent on weight.

The flexible converter will have to be capable of handling multiple voltages simultaneously through different ports, while achieving conversion efficiencies equal to the best single-range converters currently available.

Prodrive expects to present a driveable demonstration car in three years time, with market introduction expected to be five to seven years away.