Electric supercharger showcased at LCV 2015

MAHLE’s 1.2-litre, three-cylinder gasoline engine generates 313Nm of torque and 161kW/litre power output, enabling reduced emissions and increased fuel economy.

“The eSupercharger delivers significant gains in the driveability, power and emissions reduction of downsized internal combustion engines and we are delighted to demonstrate the potential of our system in conjunction with MAHLE Powertrain UK,” says Bryn Richards, CEO, Aeristech. “Our 48V architecture is a cost effective solution for next-gen downsized internal combustion engines and could prove to be a vital tool in meeting stringent fleet CO₂ reduction targets, raising economy and improving driver enjoyment.”

The first version of MAHLE Powertrain UK’s engine utilised advanced twin-charging to give encouraging results. Further improvement has been gained by replacing the smaller, primary mechanical turbocharger with Aeristech’s eSupercharger, which has in turn enabled the fitting of a larger, more optimised secondary unit.

“The use of our technology has helped allay the fears over driveability that are often associated with using larger turbochargers; unlike alternative technologies, our eSupercharger is capable of providing continuous high levels of boost, which not only improves peak power but gives a wider spread of useable torque throughout the engine’s operating range,” explains Richards. “The engine in MAHLE’s C-segment demonstrator vehicle at LCV 2015 generates a maximum power output of 193kW and 33Bar BMEP output, the latter is in excess of any gasoline engine currently available in series production.”

Using an eSupercharger also has advantages for emissions control. Because it is fitted to the inlet side of the engine thermal mass in the exhaust stream is reduced, which helps to maintain catalyst temperature, especially at lower speeds and loads.

Aeristech’s motor control strategy separates commutation and power control which means the electrical switching frequency need be no higher than running speed. This fundamentally new approach dramatically reduces the cost of many key switching components while ensuring exceptionally accurate high-transient speed control.

The company’s expertise in permanent magnet e-machine design means the electric motor has class-leading power density and low inertia. The eSupercharger operates at up to 150,000rpm with a transient response of idle-to-target speed in under 0.4 seconds.

“We are the first company to make high performance permanent magnet motors sufficiently cost-effective for eSupercharger application,” says Richards. “It means we completely avoid the thermal issues that arise with switched reluctance motors, providing continuous levels of boost pressure. Together with the imminent arrival of 48V architectures throughout the industry, this will enable more downsizing and higher engine efficiencies, leading in turn to vehicles with both lower CO₂ emissions and better driveability.”