MATHEMATICAL MODEL OF TRACTION BATTERY CAPACITY

The article describes the methodology for determining energy capacity of a traction battery for wheeled vehicles intended for urban passenger transportation. Then, the factors affecting energy capacity of a traction battery are analyzed. The mathematical model of traction battery capacity is developed. The object of research is a traction storage battery as an electric energy storage device for autonomous driving trolleybus movement on route sections where there is no catenary. The purpose of the study is to develop a method for determining the energy characteristics of a traction battery as an energy storage device depending on traffic conditions on a bus route to substantiate the possibility of replacing a bus with an autonomous trolleybus. Research methods are analytical and mathematical. Analysis of the transport infrastructure of Ukrainian cities, where bus and trolleybus transport operate simultaneously, showed that in many cases there are bus routes, on some sections of which a trolleybus contact network is installed. In this case, the question arises about the advisability of replacing the bus with a trolleybus with an autonomous running, which does not require additional capital investments for the installation of catenary on sections of the bus route where it is absent, thanks to trolleybuses with autonomous driving are used. At the same time, the solution of using such trolleybuses instead of buses sets the primary task of method developing for substantiating the energy characteristics of a traction battery as an electric energy accumulator, depending on the driving conditions in the bus route. The states (charge and discharge) in which the traction battery is located when the trolleybus moves along the bus route are considered and analyzed. While moving along the section where there is no catenary, the TAB loses part of its capacity with a value of Cp, and when moving in an area where there is catenary, it will receive a part of the lost capacity Cs. The case is considered when Cp > Cs, which is the most likely situation in practice. The formulas are given for determining the minimum energy consumption of the TAB, which should be installed on the TAS, taking into account the difference between the energy received from the TAB and the energy received from the charger when the trolleybus moves along the route that has sections without catenary and sections with catenary for one return trip. The obtained mathematical model of the traction battery energy intensity allows vehicle manufacturers to substantiate the energy intensity of the traction battery of an autonomous trolleybus for route characteristics specified by the consumer, and for consumers (customers of transport services and transport enterprises) to determine the list of bus routes on which an autonomous trolleybus can be used. It can be equipped with a traction battery with the energy intensity specified in its operational documentation, and a consumer is able to make a decision to use the trolleybus on other routes in case of a decrease in traction battery energy intensity in operation. Further research in the direction of substantiating the traction battery capacity must be carried out in order to take into account the probabilistic characteristics of unit costs for an energy carrier, as well as average speed and vehicle mass. KEYWORDS: BUS, TROLLEYBUS, ROUTE, CATENARY, AUTONOMOUS DRIVING, SPECIFIC INDICATOR, TRACTION BATTERY.