Electronic Control of a Variable Speed Drive for Vehicle Applications

The use of continuously variable transmission drives in an automobile has been considered for long time as a means to achieve the optimum speed ratio between the engine and the vehicle axle at any operating condition. Several technological shortcomings, however, have prevented in the past a widespread use of these drives. The recent improvements in the technology and the availability of powerful electronic controllers make the continuously variable transmission drives a solution that can be cost effective, at least for cars of medium and large size. This paper outlines the engineering considerations which form the basis for the design of an electronically controlled continuously variable transmission drive.