CESG power supply in the hydrogen vehicle

Power supply

There are three batteries in the BMW Hydrogen 7 vehicle - one AGM technology vehicle battery and two batteries to ensure the power supply of the hydrogen system and of all the components and functions involved (so-called ”CE batteries”)

The vehicle battery supplies the vehicle network and starts the combustion engine. The two CE batteries supply only the Clean Energy control unit (CESG). Power diodes switched in the locking direction at the positive terminals of the CE batteries prevent that other consumer units in the vehicle network are able to draw energy from the CE batteries.

All batteries are charged via the on-board alternator.

The status of the two CE batteries is determined by an allocated intelligent battery sensor (IBS). Each IBS is connected to the CESG via the BSD bus.

Energy management monitoring

The necessity for energy management with permanently correct function means there is a complex monitoring strategy for the energy household of the Hydrogen 7 vehicle. The monitoring of the energy management consists essentially of:

• Determining the charge statuses of the CE batteries
  
• Evaluation of measured values and calculated values
  
• Energy management system diagnoses
  

Diagnoses

The test module for component power supply is used when the communication is faulty or cannot be established. Furthermore, this test module covers all CAN message errors:

• all message errors for Fuel CAN, flap statuses, H2 CAN, PT CAN communication faults, etc.
  In the event of such faults, it makes sense to start the system analysis diagnosis author in order to be able to treat message errors in the diagnosis is the best way possible.
  
• 64D6 dehumidification unsuccessful
  
• 64C3 fuel tank insulation vacuum
  
• 64BE CE-SG, channel 2 failure of power supply
  
• 64Bd CE-SG, channel 1 failure of power supply
  
• 64BC on-board supply voltage
  
• 648E control units internal fault
  
• 6496 communication with DME disrupted