Power Control Unit (PCU)

The Power Control Unit (PCU) is chiefly installed to avoid or reduce the energy load on the system battery in the case of automatic engine start-stop function stop. The reduction in cyclisation (= number of cycles of the automatic engine start-stop function) of the system battery extends the service life.

The preconditions for adjusting the energy management are derived from the usage of the vehicle. When the engine is running, the auxiliary battery is loaded from the vehicle electrical system basic version. During the phases with automatic engine start-stop function stop, the energy from the auxiliary battery is fed back into the vehicle electrical system basic version.

The Power Control Unit has a nominal power of 500 watt (maximum permanently 656 W). The Power Control Unit contains the control unit and a DC/DC converter.

The DC/DC converter in the Power Control Unit transfers electrical energy from the vehicle electrical system basic version to the additional vehicle electrical system and vice versa.

The Power Control Unit is connected to the vehicle via 2 plug connections. The PCU control unit is connected at the powertrain CAN and the wake-up line.

Fig 1: Identifying Power Control Unit

Courtesy of BMW OF NORTH AMERICA, INC.