Load Point Shift

Load Point Shift

Each power unit operates most economically within a specific load range. If the combustion engine operates at partial load below this range or at full load above this range, the energy produced from the fuel is not utilized economically. The hybrid management system always attempts to operate the combustion engine within the most efficient range. At the same time, Porsche synchronises the operating points of the remaining assemblies, E-machine and high-voltage battery with the combustion engine so that the overall system operates with maximum efficiency. The aim of synchronization is not to drive as far as possible solely under electric power, but to ensure that the smallest amount of energy is consumed when the battery is charged.

Load point shift







If the current load point is below the optimum range, the hybrid management system switches the E-machine to generator mode while simultaneously opening the throttle. The "excess" mechanical energy is used to charge the traction battery. Absolute vehicle consumption increases when the load point is shifted upwards but from a relative perspective, the fuel is used more efficiently and the vehicle range under electric power without emissions is extended. The driver will not notice the shift in the load point because neither the engine nor the vehicle speed changes. The vehicle behaves as if it were driving at a constant speed along level terrain that merges into a gradient.

A diagram depicting the energy flows after the load increase appears on the multifunction display. The graph below illustrates a load point increase at approx. 2,400 rpm. The efficiency of the combustion engine can be increased by about 10 % (range 1 28 % -> range 2 38 %).







Load point reduction







If the load point exceeds the most economical range because of the driver setpoint torque and the charge state of the battery allows this, the E-machine assists the combustion engine (see Boosting) until the charge state (SOC) falls below the minimum level for this operating mode. As a result, fuel consumption and exhaust emissions are reduced considerably and a sporty driving style is possible.

The load decrease also appears on the multi-function display.