Step change

A UK engineering company has come up with a low-voltage control system that could open up lucrative opportunities in the automotive industry. Jon Excell reports.

A new type of electric power controller could make hybrid and electric vehicles both safer and more efficient, according to its inventor.

The developer of the device, Exeter-based 3DI Power of Exeter says that its controller was originally developed in response to a DTI competition to find new energy systems for an ultra-low carbon car.

Typically an automotive power controller takes power from the power source – a battery or fuel cell – and delivers it to the motor. The accelerator pedal hooks to a pair of potentiometers, which provide a signal that tells the controller how much power to deliver. A controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator), or any power level in between.

But 3Di Power’s chief executive, Neil Cooper, explained that while conventional power controllers simply carry out motor speed control, the new device also works as a DC-to-DC power converter. ‘There is no other available device that does both these,’ said Cooper. He joked that the absence of any competitive technology has made it difficult for him and his colleague, Tim Crocker, to come up with a name for the device.

The other crucial aspect of the technology is the fact that it functions at far lower voltages than power controllers used elsewhere in the automotive industry. ‘Our device operates at 12 – 42V DC. Anything else that we’re aware of on the market uses high 200V DC voltages which are basically unsafe,’ said Cooper.

He cited Toyota’s hybrid car the Prius, which has ‘danger, high voltage!’ written on the engine cover. This is because the Prius controller is IGBT based and to get it to work the low voltage from the battery must be stepped up.

An IGBT (insulated gate bipolar transistor) is a switching power device usually found in high-voltage circuits (above 300V) and widely used in motor control. By contrast 3DI’s device is based on ‘a completely new topology’ that uses low-voltage busbars – rigid conductors that serve as a common connection for two or more circuits. These busbars connect circuits based on MOSFET (metal oxide semiconductor field effect transistor) technology.

As well as being far safer, Cooper added that the device boasts an equivalent efficiency to high-voltage systems, and is smaller and considerably less expensive to make. These advantages are partly down to the scaleable nature of the technology. ‘If you have a base unit of 1.5kW you could get a 10kW unit by strapping eight of those together,’ he explained.

A 600W version of the controller will be officially launched later this month, but the idea has already aroused the interest of a number of automotive companies. Cooper said that Ricardo and MG Rover have expressed a ‘great deal’ of interest and, following meetings later this month, he said that he is confident they will agree to trial the controller on demonstration vehicles.

The controller also has a range of applications beyond the automotive industry, claimed Cooper, pointing to its potential use on electric vehicles such as bicycles and wheelchairs.

But the automotive market represents the most lucrative opportunity, he said. As well as being ideal for hybrid vehicles the device could also be used on non-hybrid vehicles within power steering systems.

‘The technology has the potential to be a multi- million pound business,’ he said.

The small company has received around £100,000 from private investors as well as two DTI Smart awards.