Traction Torque Control Approach

The traction torque on the driven wheels is the sum of the torques transmitted from the ring gear of the planetary gear units and the traction motor. The traction torque on the driven wheels can be expressed as

(6)

In equation 6

The total traction torque request on the driven wheels, which is commanded by the driver through the accelerator pedal can be met by the torque outputs from the ring gear and the traction motor. In Figure 8 an example of drive train with full ICE throttle opening and full traction motor load is shown. The control strategy that is used to obtain Figure 8 is:

• At low speeds the ICE operates at constant speed and the EM operates with positive speeds
• At medium speeds the EM is locked to the vehicle frame and the engine speed linearly increases with vehicle speed.

At high vehicle speeds the ICE again operates with a constant speed and the EM operates with a negative
speed (rotating in opposite direction of the ICE).