Torque Coupling Mode: When the traction motor is energized, its torque can be added to the torque output of the ring gear to form the torque coupling mode. There are six possible sub-modes of operation and they are shown in Figures 5a to g.

Regenerative Braking: When the vehicle experiences braking, the traction motor, EM or both can produce braking torque and recapture part of the braking energy to charge the electrical energy storage device (also known as peaking power source). In this mode of operation the engine is switched off and the energy flow path is shown in Figure 6 .