Energy consumption optimization of commercial electric bus in Indian city driving condition using two speed transmission

ABSTRACT Currently automobile industries are shifting towards electric powertrains from conventional internal combustion engines. With increase in use of electric vehicle, more focus is to increase the driving range of vehicle. As of now, most of the OEMs are using single speed transmission in their electric buses. Single speed transmission is effective in road having less traffic condition but during heavy traffic condition (like Mumbai city application), performance of motor gets deteriorated. In heavy traffic condition (city application), operating points of motor goes into less efficiency regions which results in high energy consumption. It will also affect the regeneration. In this study, focus is on commercial vehicle like electric buses. If there is a need to increase driving range, energy consumption must be optimized. Thus, higher energy consumption in heavy traffic condition can be managed by using multiple gear ratio. With use of optimum gear ratio, motor operating points can be shifted towards higher efficiency region which will leads to less power consumption and also help to improve motor regeneration percentage. In addition, this paper encapsulate the comparative study of motor torque requirement and battery current requirement with multiple optimised gear ratio vs single speed transmission considering Indian driving condition (for city application). On using different gear ratio, there is leverage of increasing the restart gradeability of vehicle and also vehicle top speed. So that same powertrain configuration can be used for highway and hilly area application. As a conclusion with optimized gear ratio and multiple gear speed, energy consumption can be reduced significantly.