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A multispeed transmission for electric vehicles that promises to reduce their energy consumption by up to 15% will be installed in a demonstrator by the end of the year.
The MSYS transmission has been developed by Warwickshire-based consultancy Drive System Design using funding by the Technology Strategy Board and is suitable for use in both electric vehicles (EVs) and hybrids.
Alex Tylee-Birdsall, technical director of Drive System Design, said: “The prototype’s built and will be tested at Mira soon. By the end of the year we will have it installed and running in a demonstration vehicle.
“The TSB project funding ends in February and we are currently looking for investors to take it to market. The potential impact of this transmission on the EV market is massive. After its established there, the main IP, our powershift technology, could cross back over into the mainstream.”
All current production EVs, with the exception of the Tesla Roadster, use single speed transmissions. The torque is varied by adjusting the amount of power supplied. However, single speed transmissions are not optimised for automotive applications and a multispeed transmission places less demand on the battery at lower speeds, meaning you don’t use as much power, said Tylee-Birdsall.
“Compared to a single speed EV or HEV transmission, MSYS provides a 40% weight saving and 10 to 15% lower energy consumption, because it permits the downsizing of the motor and extends the time the motor spends operating at high efficiency, thanks to being in the optimum gear ratio more often. It also allows motors to run at lower speeds that don’t require high levels of field weakening that would increase energy consumption from the batteries.”
Most other multispeed solutions for EVs in development use dual clutch shift systems that hold clutches open or closed and require continuous power. The main advantages of MSYS over these solutions, said Tylee-Birdsall, is that it only draws power during a shift and that its powershift system enables smoother shifts to ensure passenger comfort.
According to Drive System Design, the weight of the MSYS-3 powertrain including motor and fluids is 45kg. The system can produce an output torque of 2000 Nm with a continuous power rating of 55 kW and a peak of 100 kW for 60 seconds. Overall system efficiency, including the power electronics, is 91%.