Control of the electric auxiliary heater

On vehicles with diesel engines and without independent heating, the heat exchanger for the heating system is heated additionally with an electric auxiliary heater based on the PTC principle. The electric auxiliary heater is one of the consumer units that need a relatively high amount of power (up to 1300 W) and it is thus regulated by power management. These high electrical loads are regulated as follows:

• The IHKA control unit controls the electric auxiliary heater (via local interconnect network bus).
• The power management in the DDE regulates the maximum electrical power output of the electric auxiliary heater (signal in a CAN signal).

  The maximum power of the electric auxiliary heater depends on the alternator load and the vehicle condition (high necessary steering power for the electromechanical power steering, lowering of alternator torque to relieve the combustion engine, high necessary power consumption by the electric fan).

• The electric auxiliary heater regulates the heater output of the heating register depending on the specifications of the power management.