Earlier this week we looked at the media launch of the Chevrolet Volt in our Green Piece Column (see article) and pointed out the conflicting reports surrounding the vehicle’s driving architecture – now General Motors (GM) has provided more details.
The complex system owes a lot to the two-mode hybrid that GM uses in a number of areas including the efficiency benefits of synchronous clutches; a multiple-motor approach; and the vehicle’s control software and architecture.
The Volt is powered by a 16kWh lithium-ion battery with an internal combustion engine and generator acting as a range extender. The electrical plug is meant to be the primary source of energy for motive power with the engineering team setting out to develop a drive system to maximise the efficiency of all the components in different driving modes.
Its drive unit consists of two motors – an 111kW main traction and 63kW generator motor – on top of three clutches and a planetary gear set that is tucked in the end of the traction motor and improves overall efficiency. The engine therefore has the capability of revving much higher and producing a greater output.
Its configuration means that the battery drains at steady state with cruising speeds ranging from 30mph-70mph. It delivers a pure electric range of between 25 and 50miles depending on the terrain and driving techniques employed.
The Volt has two primary driving modes – all battery electric; and extended range – with each supported by two drive unit operating modes: a low speed, 1-motor mode and a high-speed, two motor mode.
As for the drive unit itself, it is compact and includes power electronics as well as the engine, motor generator, traction motor and planetary gear-set.
