Antonov study of multi-speed transmission for EVs finds improved efficiency over different drive cycles
|Antonov’s study found that its multi-speed electric vehicle transmission can deliver 10% better efficiency compared with a single speed gearbox. Click to enlarge.|
Automatic transmission specialist Antonov reports that its comparative studies of an electric vehicle equipped with its multi-speed transmission over eight different drive cycles suggest that the transmission delivers typically 10% better cycle efficiency than a single-speed solution. (Earlier post.)
Antonov has been invited by the Technology Strategy Board (TSB) to present its findings at the LCV2011 event being hosted by Cenex this week at the Rockingham Motor Speedway in Corby, Northamptonshire. The TSB has helped fund several transmission research and development projects with the company’s involvement.
The majority of electric vehicles are currently equipped with a single speed, so there are clear implications for the next generation of electric vehicles. Our analysis shows that with a single speed gearbox there is significant variation in drive cycle efficiency, whereas a multi-speed transmission tends to be more consistent with better overall cycle efficiency.
The results are consistent with the multi-speed transmission keeping an electric motor operating in its peak efficiency range. Inevitably, there is a compromise with a single speed gearbox particularly in terms of low speed acceleration, hill climbing and high speed cruising. The 10 per cent step change improvement in efficiency can be achieved with just two ratios, but technical compromises remain in other areas. Three or more ratios are better, delivering additional improvements in performance and refinement as well as efficiency, with each additional ratio providing small incremental gains in cycle efficiency.— Antonov’s business development manager David Paul
Antonov has developed its latest modeling tools to help demonstrate the performance and efficiency benefits of its powershift multi-speed transmission to electric vehicle manufacturers. The company can determine the ideal motor and transmission combination, as well as optimizing the gear ratios and final drive ratio for any given electric vehicle application. The analysis supports real world vehicle trials.
Antonov is supplying Smith Electric Vehicles with a prototype of its multi-speed transmission for a TSB funded research and development project. The ‘E-Van’ electric vehicle demonstrator is based on Smith’s Edison 3.5 tonne delivery van, with Antonov’s 3-speed transmission currently being installed for test and evaluation.
Antonov’s multi-speed transmission was first evaluated in a Jaguar Limo-Green research vehicle as part of a consortium project with Jaguar Land Rover and MIRA. This research and development project was also part funded by the TSB.
Now looking at a wide range of vehicle applications, particularly commercial vehicles, Antonov says the technology with its seamless shift quality has strong potential for further development as a 4 or 5-speed transmission, with virtually the same packaging. The design of Antonov’s powershift electric vehicle transmission is such that additional ratios can be easily added. It is also scalable to different classes of vehicle ranging from family cars to light commercial vehicles, taxis, delivery trucks and public transport buses.