But this is really a study in rightsizing, rightsizing an internal combustion engine for this extended range capability. This engine obviously has the capability of revving much higher and producing much more output.
The resulting Volt drive unit consists of two motors-a 111 kW main traction and 63 kW (at 4800 rpm) generator motor (55 kW generator output)-as well as three clutches and a planetary gear set tucked in the end of the traction motor that improve overall efficiency by reducing the combined rotational speed of the electric motors as needed. They thus decided to exploit the generator motor more thoroughly than it would otherwise have been if used exclusively as a generator in extended-range driving. Recognizing the benefits derived from their two-mode approach in their earlier hybrids, the engineering team also observed that they had a second motor-the generator motor-“ going along for the ride”, as Fletcher said during her presentation at the launch event in Detroit. Mechanical losses such as friction and windage dictate that the efficiency of an electric motor declines somewhat as motor speed increases. Pam Fletcher, Global Chief Engineer for Volt and Plug-In Hybrid Electric Powertrains That’s ultimately what the customer is looking for, is to maximize this notion of electric range, to maximize this notion of efficiency of the generator when we have to use it.
How do we take all this battery energy.and very efficiently and effectively drive the wheels. The story of the electric drive is really a story about efficiency. Put another way, the GM team wanted to extend the range of the vehicle as efficiently as possible, while maintaining quality driving dynamics and experience. Given that GM had committed to a combustion engine and a generator as a range extender for the battery, the engineering team set out to develop a drive system that could maximize the combined efficiency of all the components under the different driving modes (all battery electric, and extended range).
(The Volt could also be called a plug-in series hybrid, depending upon your taxonomic preference.) The Volt is an electric-drive vehicle, powered by a 16 kWh Li-ion battery, incorporating an internal combustion engine and generator to serve as a range extender an electrical plug is intended to be the primary source of stored energy used to deliver motive power.