Selection of the capacity of the onboard energy storage device for a high-mobility wheeled vehicle wear-resistant brake system with an electric machine

Abstract

With the growth of the average speed of wheeled vehicles, the wear-resistant brake system which would increase their mobility by improving their braking performance and lower the heat loads on the service brake system is gaining interest of the manufacturers. At the same time, a good option for increasing power efficiency of the high-mobility wheeled vehicles is to use an electric machine in the wear-resistant brake system. The electric machine can operate in the generator cycle and provide energy recuperation during braking. Recuperation at braking requires accumulation of high values of electric energy in a storage device (usually a molecular storage device), which brings to the forefront the problem of its efficient capacity selection. The article deals with the selection of the required capacity of an onboard energy storage device providing better power efficiency of the vehicle due to the use of an electric machine in the wear-resistant brake system. The method for the selection of the required capacity of the onboard energy storage device is based on the calculation of the energy spent by the vehicle for maintaining the given speed. The following strategy of the electric machine control was used in the research: the energy accumulated in the storage device after braking will be spent at the next acceleration. Therefore, the power efficiency can be increased only due to such compensation of the high frequency oscillations of the spent/accumulated electric energy in the potential storage device that would prevent reaching its maximum charge level in a typical driving cycle. Based on the results of the research the capacity of the storage device is assessed by the peak-to-peak amplitude of the time history of the accumulated/stored energy when driving along a given route. A method that allows formulation of the specifications for the onboard energy storage device used as an element of the wear-resistant brake system, the method uses statistical data on the road conditions of vehicles operation. The method provides selection of the optimal parameters (required capacity) of the electric energy storage device which would guarantee effective operation of high-mobility wheeled vehicles in typical driving cycles.