A Purely Mechanical Energy Storing Concept for Hybrid Vehicles
The paper contains the design and simulation of a purely mechanical system for storing energy during vehicle deceleration, which can be utilized during subsequent acceleration (regenerative braking). A continuously variable transmission (CVT) regulates the energy transfer, energy storage is accomplished by means of a spiral spring and additional use of a planetary transmission. The transmission ratio of the CVT is adapted by a combined feed-forward and feed-back control. A computer simulation for a vehicle with an overall mass of 1500kg, and an energy storage capacity of 30kJ was performed for different driving cycles. In a typical urban stop and go situation the proposed device will save up to 0.72kg fuel per 100km and the overall efficiency analysis together with simple design, easy recycling, and long life expectance, showed a clear advantage over other hybrid concepts for frequent stops and accelerations.
Rapid Recharge Capability of Valve Regulated Lead Acid Batteries For EV & HEV Applications
Range limitation is a significant drawback to the successful commercialization of Electric Vehicles (EV’s). An apt description of an EV is “a high performance vehicle with a one gallon fuel tank”. In the absence of a “super battery” there are at least two approaches to resolving this drawback. First rapid recharge; i.e. recharge the battery as close as possible to the same time period as it takes to fill the petrol tank of an internal combustion engine (ICE) powered vehicle. Whilst not extending the vehicle range as such, this approach does enable high usage of the vehicle without having unduly long recharge times. The ability of the battery to accept rapid recharge is paramount for this approach. Second, development of a Hybrid Electric Vehicle (HEV). The demand on the battery for this approach is the ability to provide, and also absorb from regenerative braking, high specific peak power levels over a wide range of battery state-ofcharge. This paper describes the ability and indeed limitations of the VRLA Genesis battery in meeting these requirements.
Modeling battery performance in electric vehicle applications
Abstract An interactive microcomputer software package, DIANE 2.1, has been developed for the analysis of battery performance in electric vehicle (EV) applications. The principal objective of this software package is to enable the prediction of EV performance on the basis of laboratory test data for batteries. The model provides a second-by-second simulation of battery voltage and current for any specified velocity/time or power/time profile. The capacity of the battery is modeled by an algorithm that relates the battery voltage to the withdrawn current, taking into account the effect of battery depth-of-discharge (DOD). Because of the lack of test data and other constraints, the current version deals only with vehicles using “fresh” batteries, with or without regenerative braking. Deterioration of battery capability due to aging can presently be simulated with user-input parameters accounting for an increase of effective internal resistance and/or a decrease of cell no-load voltage. DIANE 2.1 is written in the FORTRAN language for use on IBM-compatible microcomputers.