An all-new Electric Vehicle powertrain is being developed by Zytek Automotive, a UK technology specialist with more production EV experience than any other company worldwide. Building on the knowledge gained from more than 15 years of niche EV design, manufacture and operation, this new third generation unit is a clean-sheet-of-paper design that will significantly simplify the introduction of next-generation electric vehicles, from niche models to high-volume global programmes.
“The steps required to move from today’s low-volume trials to tomorrow’s fully-homologated production vehicles are very substantial and must not be under estimated,” says Zytek Automotive managing director Neil Heslington. “Everything has to be re-evaluated, from development processes to dealer training. This new powertrain, combined with our substantial experience of EV and hybrid vehicle production programmes, will take time and cost out of this activity while helping to deliver the quality, refinement and driving experience that discerning customers demand.”
The turn-key package is extremely compact and in air-cooled configuration is up to 45 percent lighter than today’s production EV powertrains. Even the water cooled version, suitable for demanding drive cycles, is up to 30 percent lighter. Available in sizes from 25kW, the highly integrated modular system can be configured for a wide range of vehicle sizes, applications and architectures.
At the heart of the powertrain is Zytek’s new, high efficiency permanent magnet synchronous motor. The high maximum machine speed of 14,000 rpm has enabled generated torque and hence machine size to be reduced considerably, bringing further reductions in cost and weight. When used in conjunction with the Zytek Electric Vehicle Control Module, torque delivery is scheduled in a way that further improves overall efficiency, whilst also eliminating the harshness that can occur during changes in torque demand.
Parallel design and integration of the major subsystems has allowed a high level of optimisation. An example is the integration of the charger within the inverter, reducing the number of separate enclosures and connectors required in the vehicle, reducing cost and increasing reliability.
A new transmission, designed specifically for use with the new electric machine, is being developed by transmission specialist Vocis. “We are working closely with Zytek to ensure that the motor and gearbox are optimised as a single system, delivering maximum efficiency and installation flexibility with minimum cost, weight and packaging requirement,” explains Vocis managing director Mike Everitt. “The width across the gearbox is just 138mm and transmission weight is only 10kg, which we have achieved without any compromise in performance. Testing has already shown that this is a very robust unit that delivers excellent durability and refinement.”
The compact dimensions of the new drivetrain make mechanical integration with the vehicle much simpler. The main connections required are High Voltage (to the traction battery) and Low Voltage (for electrical interface with the vehicle). The air cooling option brings a further substantial contribution to reducing weight and complexity by potentially eliminating the entire water cooling system.
The Zytek electric vehicle control module interfaces with all standard vehicle systems such as ABS (Antilock Braking System) and ESP (Electronic Stability Programme). It also provides the complete range of expected diagnostic information as well as its own range of diagnostic codes.
The homologation challenge
One of the issues receiving a lot of thought is homologation. “Zytek was the first company to design a powertrain for a fully homologated electric vehicle, so we have spent a long time working with the type approval authorities to understand how to demonstrate compliance with standards written essentially for very different technologies. It’s been challenging, but we have learnt a lot,” says managing director Neil Heslington.
Engineering programme manager Neil Cheeseman is looking even further ahead. “As the homologation environment for electric vehicles is not yet mature, Zytek is experienced in analysing the many SAE and international standards that provide overlapping information on many aspects of electric vehicle safety, in order to provide a vehicle that is suitable for volume sales in all major world markets,” he explains..“All of our new powertrains are being designed to accommodate the most likely type-approval scenarios.”
Zytek has designed and integrated electric drive systems for a wide range of European and US vehicle manufacturers and is currently building high performance electric drivetrains up to 70kW and 300Nm for cars, buses and light commercial vehicles. Their UK facility can accommodate up to 6,000 E-Drive integrations a year in batches as low as 100, providing vehicle manufacturers and large fleets with a highly flexible specialist production resource for their low carbon programmes. Zytek can also manufacture up to around 18,000 high efficiency electric traction motors each year, with the option of integrated control systems to further improve overall system weight and packaging.
The design and build of 100 first generation smart ed electric vehicles was managed by Zytek, including support for fleet trials, and the company is now working with smart to manufacture the second generation electric vehicle at ‘smartville’ in Hambach, France. As a supplier of engine management systems for internal combustion engines, Zytek is also well-placed to deliver hybrid vehicle programmes. The company was amongst the first to design and validate a diesel hybrid and engineered the control systems for the GM Silverado, the first production hybrid to be engineered outside Japan.