2014-02-21 18:20:39 - Advances in ultra-high-speed motor design, thermal management and control integration cut cost, weight and size for new powertrain
Yamaha’s new MOTIV.e city car concept, shown at the Tokyo motorshow, is powered by an advanced electric drive from Zytek that employs a range of new design approaches to minimise the cost, weight and size of the powertrain while maximising the performance and range. By supplying a number of core high voltage components as an optimised system, Zytek is also minimising the time required for vehicle development.
MOTIV.e comes from the partnership between Yamaha and Gordon Murray Design, using Murray’s revolutionary iStream® manufacturing technology to deliver a highly efficient yet fun-to-drive electric vehicle at an affordable price. Zytek’s sales and marketing director, Steve Tremble says that taking a fresh approach to the powertrain is central to achieving these goals.
“Yamaha wanted the
vehicle to reflect the company’s reputation for outstanding engines,” he adds. “Interpreting this in an electric vehicle has driven excellence in performance and driveability, as well as in weight reduction and efficiency, building on the potential of iStream to deliver an agile drivers’ car as well as maximising the range.”
Zytek supplies the electric motor, paired with a single speed reduction gearbox from Vocis, and the electronic vehicle control module (EVCM) which provides the interface between the powertrain and the rest of the vehicle. The low cost power electronics is manufactured in high volumes by Zytek’s technical partner Continental. To help achieve the light weight and high efficiency targets for the MOTIV.e, the 25kW motor revs to 15,000rpm, much higher than comparable units. This substantial increase in motor speed allows the electric engine to be smaller, lighter and more cost-effective than previous-generation units.
“The motor weighs just 13kg, the gearbox just 11kg,” explains Zytek’s engineering program manager, Neil Cheeseman. “These are components that you can pick up with one hand.”
Cheeseman believes the power electronics also set new standards for weight and packaging. The inverter, for example, weighs just 7.5kg “By making everything in house, Continental has eliminated many of the compromises that stem from using bought-in components,” he said. “Their substantial investment in power electronics has delivered a scalable, power-dense and cost-effective product range that is already proven on everything from small city cars to hybrid commercial vehicles.”
The Zytek EVCM is unique, being built on an electronics platform that duals as a development tool and a cost-effective production unit complying with all relevant automotive standards. Zytek says that unlike other dual-purpose systems that are suitable for production, their unit is cost-competitive with bespoke production technologies. It is also thought to be the only EVCM that takes a big further step in powertrain control integration by including thermal management within the decision-making algorithms.
“This is a new generation of EVCM that integrates torque arbitration, temperature control and voltage management to allow better decision making,” Cheeseman explains. “It optimises the driver’s torque request based on a broad range of parameters including battery charge and temperature and the grip available at the tyres. By integrating these decisions, we can provide more with less to improve both the driving experience and the range while reducing the size, weight and cost of the power electronics and battery pack.”
Zytek says it is the world’s most experienced specialist EV/HEV design consultancy, having worked with many of the major vehicle manufacturers worldwide. Today the company is a leading supplier of all aspects of hybrid and electric vehicle powertrain technologies across all vehicle sectors, complemented by expertise in control systems, vehicle integration and manufacturing. There are now more than 4,000 vehicles on the road driven by Zytek powertrains. www.zytekgroup.co.uk
Richard Gotch, Market Engineering
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