Zytek lightweight electric powertrain for Yamaha’s MOTIV.e city car concept
21 February 2014
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| Zytek’s lightweight 25kW powertrain drives the Yamaha MOTIV.e through a Vocis single ratio transmission. A further development of the electric machine will deliver more power and torque from the same compact package. Click to enlarge. |
Yamaha’s new MOTIV.e city car concept, shown at the Tokyo motorshow, is powered by an electric drive system from Zytek that employs a range of new design approaches to minimize the cost, weight and size of the powertrain while maximizing the performance and range. By supplying a number of core high-voltage components as an optimized system, Zytek is also minimizing the time required for vehicle development.
MOTIV.e comes from the partnership between Yamaha and Gordon Murray Design, using Murray’s iStream manufacturing technology; Murray has partnered in the past with Zytek on the T.27 City Car—the technology basis for the MOTIV.e. (Earlier post). Zytek Automotive, a specialist EV/HEV/fuel cell engineering consultancy, is a subsidiary of Continental, the global powertrain, chassis and interior products supplier.
Yamaha wanted the vehicle to reflect the company’s reputation for outstanding engines. 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 maximizing the range.
—Steve Tremble, Zytek sales and marketing director
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.
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To help achieve the light weight and high efficiency targets for the MOTIV.e, the 25kW motor revs to 15,000 rpm—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 13 kg [29 lbs], the gearbox just 11 kg [24 lbs]. These are components that you can pick up with one hand.
—Zytek’s engineering program manager, Neil Cheeseman
Cheeseman believes the power electronics also set new standards for weight and packaging. The inverter, for example, weighs just 7.5 kg [17 lbs].
By making everything in house, Continental has eliminated many of the compromises that stem from using bought-in components. 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.
—Neil Cheeseman
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, its 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. It optimizes the driver’s torque request based on a broad range of parameters including battery charge and temperature and the grip available at the tires. 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.
—Neil Cheeseman
Some interesting observations...
(1) This car was initially spec'd in 2010 as a 680kg vehicle with a 12kWh battery. With three years of industry advances to draw on (and not insignificant ones at that), it is now 50kg heavier with only about 70% as much energy available.
(2) Yet the >160km range has not budged, now bettering the Nissan Leaf by 3-4x. Must not be many accessories.
(3) Oddly Zytek believes that integrating sensor inputs from traction conditions, BMS parameters, temperature, etc into EVCS controls is new to the industry. This will be news to Tesla, Nissan, GM, and MHI.
I should add that I wish the Kei car type could find acceptance in America (both from a regulatory and marketplace perspective). I have no beef with the diminutive design. I just don't think much of GDM's expertise.
Posted by: Herman | 21 February 2014 at 10:53 AM