A study of a coordinate optimal gear shifting control strategy for electric vehicles with two-speed transmission

Given that electric motors are speed controllable in a wide range of operating speeds, achieving integrated control of the powertrain system is a good idea for improving shift quality and efficiency. This study proposes a coordinate optimal gearshift control strategy for EVs with a two-speed transmission, where the motor torque control is introduced in a clutch slip process. Where the motor torque and clutch push force signal are selected as optimization controller inputs. The contradictive performance objectives (power performance, smooth performance, less losses) are regarded as the optimal goals; moreover, the variable horizon MPC is presented to ensure that clutch engagement is completed within a specified time. Considering swift shifting requirements, a fast solution based on the minimum principle and dichotomy method is applied. Finally, based on a developed simulation model of an electric vehicle, the offline simulation is used to evaluate the effectiveness and real-time performance of the proposed coordinate optimal controller.