This example shows the basic architecture of a dual-mode hybrid transmission. It consists of three planetary gear sets, plus four clutches which, when correctly operated, give four fixed gear ratios plus two power-split modes. The power split modes are used to transition between fixed gear ratios and for heavy acceleration/deceleration. The fixed ratios help with efficiency when cruising. For the first power split (input-split regime), only Clutch 1 is engaged. For the second power split (compound-split regime), only Clutch 2 is enagaged. Engaging two clutches simultaneously removes one degree of freedom and hence results in a fixed ratio.
In this example, the Strategy subsystem sets up a set of rules that determine when to change between transmission modes during a steady acceleration profile. A full vehicle control strategy would also need to include control of electrical power as a function of speed, driver demand and battery state.