German carmakers eye multi-speed transmission

System allows the motor to be smaller and more efficient by running a more power-efficient regime of the electric motor

A British engineering company is hoping to attract German carmakers to invest in a multi-speed transmission system (MSYS) that could extend the range of battery electric and hybrid vehicles.

The MSYS transmission was developed by Evolute Drives in Leamington Spa, under an Innovate UK-funded project. The technology is now ready for low-volume production, and managing director Alex Tylee-Birdsall is looking for commercial investment. “The German carmakers are expressing a keen interest in our high-efficiency transmission for hybrid and electric vehicles,” he said. With global patents now secured, Evolute is demonstrating the technology to vehicle manufacturers and their tier-one suppliers.

The MSYS transmission allows the motor to be smaller and more efficient by running a more power-efficient regime of the electric motor. For single-speed drives, motors must have a high-speed range to allow low-speed manoeuvring and high-speed motorway cruising. To make a motor run at high speed, the resistance of the magnetic field needs to be overcome so it is weakened. This field weakening requires additional power and larger, inefficient power electronics. However, a multi-speed transmission allows the motor to run at lower speed, eliminating the field-weakening power loss – worth 10-15% reduction in power consumption – but allowing the power electronics and motor to be smaller and lower-cost.

With a multi-speed system, it can be a problem changing gear automatically without affecting passenger comfort or using power to hold in gear. The MSYS shift technology provides a seamless shift but without requiring power to hold in gear, as the system latches once the shift is completed, said Tylee-Birdsall.

As well as the premium hybrid and electric vehicle applications, Evolute is seeing interest in more efficient automated manual transmissions for conventional powertrains, particularly in developing markets such as India.

“There is a commercial opportunity for an efficient four- or five-speed automated manual transmission,” said Tylee-Birdsall. “We’re receiving interest in these markets for our patented, high-efficiency gearbox designs.”