EV Transmissions Under Development

EV transmissions are under development and should be available soon, James Potter, controls manager for ZF Powertrain Technology, tells WardsAuto. “Two-speeds are coming out, and that will be the next generation,” he says. “For passenger cars, I would say we will probably eventually rise up to 3- or 4-speeds.”

The push to design transmissions for electric cars is part of the search for extended range. Potter believes adding a transmission will increase range by up to 20% while allowing auto makers to use smaller, lighter and less expensive batteries. He also expects transmissions to optimize the car for different tasks, whether highway travel or in town use. “If you get a Nissan LEAF and it’s the only car you have, now you need a car that is more customizable,” he says. “Maybe you need the ability to change battery size based on what you will use the car for, or maybe you need multiple transmission options based on what you’ll use the car for.”

Potter foresees the day when the electric motor and transmission will be combined into one hybrid unit. ZF already does something similar now for ActiveHybrid versions of BMW’s 3, 5 and 7 Series cars, in which the electric motor takes the place of the torque converter.

Even thought the video above shows a transmission system from KOM Advanced Powertrain Strategies, the transmissions under development by ZF will be similar in operation. For a car nut like me, the sweet sound of the drivetrain going up and down through the gears is music to my ears. I think I would really enjoy driving an electric car with a transmission.

Source: Gas2

Antonov Claims New EV Transmission Technology Scalable to Wide Range of Passenger and Commercial Vehicles

UK-based automatic transmission specialist Antonov, which is currently developing new gearboxes tailored specifically to electric vehicles to improve their performance and range and ancillary generators to improve low speed electrical power, says its high efficiency transmission systems are scalable for any torque applications and therefore beneficial to a wide range of passenger and commercial vehicles, which are increasingly employing electric drive systems.

Antonov will showcase its new and advanced 2-speed and 3-speed technology (earlier post) at the UK’s low carbon vehicle event LCV2010 being held at Millbrook Proving Ground on 15-16 September 2010. Detailed 3D stereolithographic models will be on display of both the 2-speed and 3-speed transmission technologies.

3-speed. The first application of Antonov’s 3-speed powershift transmission intended for traction motors is scheduled for evaluation early next year in the Jaguar Limo-Green electric vehicle research project. The development of this layshaft gearbox, which features two clutches for zero torque interrupt, is part funded by the UK TSB to design and develop a high efficiency transmission for electric vehicles.

Looking at additional vehicle applications, Antonov says the technology has strong potential for further development as a 4-speed transmission, with virtually the same packaging, for even greater efficiency.

Our new 3-speed transmission can to be tailored to suit different vehicle duty cycles. For increased passenger comfort we could for example programme the transmission to remain in second gear while the vehicle is stopping and then select first gear while the motor stationery.

Antonov has developed in-house control software which provides full control of the gear-change strategy, enabling accurate energy management of the vehicle’s battery. We are also particularly pleased with the seamless powershift system, which not only meets the high level of refinement required for passenger cars, but is also relevant for example to the comfort of passengers using public transport buses particularly if passengers are standing. Another ideal application would be an all-electric taxi.

—Simon Roberts, Antonov’s chief commercial officer

Another feature of Antonov’s all-new transmission system is a novel hydraulic circuit, which has the potential of being integrated with an oil-cooled traction motor. Electrical machines can generate a lot of heat, and this would provide an effective means of cooling the motor whenever the vehicle and motor are stationary.

The virtues of downsizing and de-speeding in pursuit of increased mechanical efficiency apply to electrical machines just as much as internal combustion engines. Size is everything and smaller electric motors are better for powertrain efficiency, overall vehicle performance and packaging. A powershift transmission with its choice of multiple gears allows an electric motor to operate within its most efficient speed range, effectively increasing the performance and range of the vehicle whether crawling through traffic or cruising along a motorway.

—Simon Roberts

2-speed. The same basic principle applies to its compact epicyclic gearbox intended for the development of more efficient ancillary motors and generators, including the 2-speed 24-volt alternator being developed under an engineering contract awarded by the UK Ministry of Defence (MoD). Smaller and lighter electrical machines use less material and are easier to package. They also require smaller batteries and can manage with less expensive power electronic devices.

In its low speed range, Antonov’s 2-speed alternator can match the output of a much larger and more expensive single-speed alternator. It has the potential therefore of replacing multiple alternators that are often required for heavy-duty military and commercial vehicle applications, the company says. Increased electrical power on demand at low engine speed ensures optimal battery charging and permits additional electrical equipment to be specified on the vehicle. Full electronic control of the speed change is implemented through an active clutch mechanism.

The development project has been undertaken in partnership with a major manufacturer of alternators and starter motors and with the design concept already signed off the work has moved rapidly into the area of detailed engineering design.

Source: Green Car Congress