The A class application provides ‘plug-and-play’ functionality, with the motor, inverter and control electronics integrated into a single unit. The complete assembly fits neatly onto the existing engine mounting points with just three additional connections (water, high voltage electrics and low voltage electrics) and will interface with all existing vehicle systems including ABS (Antilock Braking System), ESP (Electronic Stability Programme) and OBD (onboard diagnostics).
Current production applications for E-Drive, which is available in high power density 55kW and 70kW versions, range from the highly-regarded smart fourtwo electric city car, through a number of C segment family saloons and light duty vans, to several categories of heavier commercial vehicle. Low volume vehicle build, typically for fleet trials, is conducted at Zytek, while for higher volumes the company supports assembly at the customer’s vehicle manufacturing facility, with the highly integrated design of E-Drive making it ideal for integration alongside standard models.
For the A-Class demonstrator, a new version of the proven 55kW E-Drive was developed, using a higher current switching system to increase the maximum torque from 120Nm to 160Nm. Zytek also increased the maximum motor speed from 12,000rpm to 13,000rpm to provide a top speed of 70mph whilst providing sufficient torque to ensure good low speed performance and the ability to comfortably climb steep gradients.
Power is provided by two air-cooled sodium nickel chloride battery packs, neatly integrated under the floor of the vehicle so they don’t compromise luggage space or vehicle stability. Range is expected to exceed 120miles in a typical mixed drive cycle and the level of regenerative braking can be easily calibrated to match customer requirements for driveability and refinement.
Performance of the Zytek electric A-Class is brisk, even though the power output is electronically limited to 40kW to increase battery life. “The rated power doesn’t sound much, but comparisons with conventional engines are irrelevant because of the completely different torque characteristics,” highlights programme manager Neil Cheeseman.
Zytek Automotive sales and marketing director Steve Tremble agrees. “One of the reasons for building the demonstrator was to show the flexibility of the high torque 55kW E-Drive in vehicles up to1700kg,” he says. “This is a very nice car to drive, with performance and refinement that comfortably meets users expectations.”
Taking a vehicle like this into manufacture would be relatively simple, says Tremble. “The E-Drive has been designed with homologation in mind, and the modular nature of the unit, with the small number of fixings, means that it can be simply installed on the production line alongside conventional power units. We are already managing this process for one premium manufacturer.”
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, busses 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 with a highly flexible specialist production resource for their low carbon programmes.
Although the design and build of the A-Class demonstrator is an entirely Zytek activity, the company has worked with Mercedes on a range of projects over more than a decade. Most recently, Zytek managed the design and build of 100 first generation smart ed electric vehicles and is now working with smart on a production version of the second generation vehicle. As a supplier of engine management systems for internal combustion engines, Zytek is also well-placed to deliver hybrid vehicle programmes and has already worked on a number of vehicles, including two ground-breaking diesel applications.