Gear Shift Validation of Multi Speed EV transmission on Test Bench using Vehicle Control Unit

Electric vehicle (EV) transmissions play a vital role in powering EVs by channelling energy from the electric motor to the wheels. Recently, the focus has shifted to multi-speed transmissions in the EV sector due to their potential to improve efficiency and performance. By utilizing various gear ratios, these transmissions enable the motor to function within its most efficient range across different speeds. Most of these transmissions need electronic control unit (ECU) with software for optimal functionality and smoother gear shifting. These controllers incorporate controller area network (CAN) communication protocol to operate along with other ECUs. Thus validation of these transmissions is a challenge as they are clutch less, motor has to be controlled for speed matching and have electro mechanical systems replacing conventional systems for operation. This paper proposes a methodology to validate multispeed EV transmissions on a test bench. The validation setup consists of electric motor at the input of a two speed EV transmission and inertia at the output of the transmission to simulate vehicle along with control unit flashed with vehicle level software. Scripts based on C-language and panels are developed which use CAN database (dbc) file of the vehicle to communicate between electric motor, transmission and vehicle control unit. Using the panels the user either controls the gear shift actuation manually or automate the gear shifting process as per vehicle operating conditions for evaluating the gear shift process. Using the mentioned methodology various vehicle scenarios can be simulated and validated on test bench at early stages, thus providing important feedback in development stage for software refinement for optimal operation of the motor and transmission actuator during gear shift process. The developed scripts can be modified to match for other vehicle configurations.