Control optimization of automatic multistage transmission in city electric bus

Abstract

The threatening ecological situation in modern cities overloaded with traffic makes it expedient to replace buses with diesel
engines with electric buses. In order to increase the energy efficiency of a drive of electric bus and, thanks to this, to expand its
power reserve, the paper investigates the feasibility of using a multistage automatic transmission (AT). For research, the Electron
E19101 electric bus was taken and two of its variants were considered – a studied one with a six-speed AT and a basic one with a
single-speed transmission. For each of the options, the traction characteristics of the electric drive for different positions of the
accelerator pedal were formed. Comparative studies of the operation of both variants of the electric bus were carried out by means of
computer simulation. For this, computer models of all subsystems of electric buses, as well as external influences that resist
movement and determine the load on the electric drive system, were built using the Energetic Macroscopic Representation method in
the Matlab/Simulink environment. The application of the specified method makes it possible to simulate the movement of electric
bus during a long-term of the adapted FTP-75 standard urban transport cycle. For the studied variant, the AT control system was
developed with the aim of current selection of the optimal value of the gearbox transmission ratio, for which the maximum value of
the efficiency of the electric drive system is obtained in specific driving conditions. The research results showed a 3.35 % advantage
in energy costs for movement in the applied transport cycle of the electric bus with the multistage transmission over the single-stage
one. However, as also shown, this advantage increases to 5.3 % during the buses move in the similar transport cycle at low speeds,
which occurs in today's traffic-congested cities. In addition, the use of the AT makes it possible to reduce the rated power of the
electric bus motor, increase its maximum traction force, which will ensure the possibility of moving with a full load on a large slope,
as well as significantly increase the maximum speed of movement, which is important for suburban transportation.