Coupe
This example shows a full throttle acceleration maneuver for the Coupe electric vehicle with the Polynomial chassis and SingleMotorRWD powertrain using the open loop longitudinal driver.To enable the use of traction control, the controller in the powertrain has been redeclared to PropulsionControl torque controller. The parameter trc_routing={6} for the TorqueArbitration block inside the controller allows the torque limitation to be performed on the rear axle if either or both the wheels reach the lower slip limit defined by the slip_min parameter in the TRC3 block in the controller.
The plot below shows the following quantities:
- Vehicle longitudinal velocity: chassis.summary_v_x
- Actual motor torque: vehicle.powertrain.motor.summary.tau_rotor
- Motor torque requested: vehicle.powertrain.controller.controlBus.machine[1].tau_ref
- Maximum power limit from the motor: vehicle.powertrain.motor.core.limits.P_max_mot
- Power drawn by the motor: vehicle.powertrain.motor.summary.p_out_rotor
It can be seen that when full throttle is applied at 2 sec, the traction control system is limiting the maximum torque (360Nm) from being applied. Between 2.16 to 7 seconds the motor is producing the maximum torque as the motor power output is still below the limit of 250 kW. Once this limit is reached at 7 sec, the motor is operating in the constant power region seen as a reduction in torque as the motor rotational velocity increases.
Effect of traction control
The plot below shows the vehicle velocity, motor torque and the power drawn from the battery for two simulations run with and without traction control (Traction control can be turned off by setting on=false in the TRC3 block inside vehicle.powertrain.controller). It can be seen that without traction control, the peak torque is applied as soon as full throttle is applied resulting into wheel spin and the power limit being reached at 3.54 sec. This reduces the maximum torque available from the motor and shows the importance of including a traction control system in case of acceleration performance simulations for electric vehicles.
The traction control system implemented in this example is a simplified system with fixed slip limit targets. Implementing a more detailed system is made possible by the use of Interfaces and Templates for the ControlUnits for electric powertrains where custom torque modulation, addition and arbitration blocks can be used.