Module 12 : Design of Hybrid Electric vehicles

Lecture 43 : Design of Series-Parallel HEV Drivetrain

 

 

The ICE and the EM are connected to the yoke and sun gear respectively. Hence, the torque produced by the EM, applied to the sun gear of the planetary unit, has the direction opposite to its speed. Thus, in this case, the EM absorbs part of the ICE power to charge the batteries. The power on the EM shaft (ignoring the losses) is

(11)

 

(12)

In equation 12 the first term on the right hand side is the power that the engine produces and the second term is the power that is delivered to the driven wheels.

When the vehicle speed is higher than Vvehicle_low but lower than the maximum speed Vvehicle_high, that is

, the following actions are taken by the controller:

  1. the EM is de-energised and the sun gear (the shaft of the EM) is locked to the stationary frame of the vehicle.
  2. The drivetrain operates in the torque-coupling mode and the ICE speed is proportional to the vehicle speed.