ASSESSMENT AND PRELIMINARY DESIGN OF AN ENERGY BUFFER FOR REGENERATIVE BRAKING IN ELECTRIC VEHICLES

摘要

The original objectives of this program were to: provide an assessment of electric vehicle energy buffers with currently available state of the art, off-the-shelf components, and design, fabricate, and test an engineering model of a selected buffer. The selected buffer was not to include flywheel or electrochemical concepts. A hydropneumatic (liquid and gas) buffer concept was selected for design. The significant components in this buffer are the hydropneumatic accumulator and hydralic motor/pump. Vehicle energy to provide braking is stored compressing gas in the hydropneumatic accumulator with a hydralic pump. Energy is provided during acceleration by discharging the stored energy in the accumulator through the hydraulic motor into the drive train. Detailed analysis of this concept using actual manufacturer-supplied data for weights and efficiencies shows that, compared with a straight electric vehicle, this concept yields only a 5% improvement in range for the electric vehicle when using commercial, currently available motor/pumps and near-term-available lightweight, fiber-wrapped accumulators. Therefore, the design, fabrication, and test portion of the program was terminated. In its place, a hydraulic motor/pump and accumulator study and buffer design effort was conducted to define to what extent product development was necessary to improve the components sufficiently for a usable concept. Lighter-weight, improved-performance motor pumps to be available in 1980 and lighter stronger pressure vessels could result in a 19% improvement in range for electric vehicles. (ERA citation 05:035114)