Start Hybrid Drive System, Function - GF08.30-P-1003RFH

Engine 274.920 in model 205.047/147/247, 253.954 

Engine 274.920 in model 205.053/253 

Engine 274.920 in model 253.354 

Engine 651.921 in model 205.012/212 

Engine 654.920 in model 205.013/213 

The subfunction "hybrid drive system start, function" is considered and described from the point of view of the hybrid drive system.

Function requirements for starting the hybrid drive system - general points 

• Circuit 15 ON
• No crash signal in this ignition sequence
• Active and trouble-free CAN bus connections to all high-voltage components
• High voltage security checked and released (no crash in interlock circuit error, no insulation fault)

Starting a hybrid drive system - general points 

The activation function in the CDI control unit (N3/9) (for diesel engine) or ME-SFI control unit (N3/10) (for gasoline engine) actuates precharging of the high voltage intermediate circuit over the power electronics control unit (N129/1) and makes the request to battery management system control unit (N82/2) to switch on the contactor (A100s1), assesses its status and enables system readiness to operate.

Function sequence start for hybrid drive system 

When the hybrid drive system starts up, the CDI control unit or the ME-SFI [ME] control unit reads in the requests and signals from the following control units and sensors via the CAN network:

• Fully integrated transmission control unit (Y3/8n4) via the CAN network
  • Wet clutch status
• Battery management system control unit via CAN network:
  • Voltage of high-voltage battery (A100g1)
  • Temperature of high-voltage battery
• Power electronics control unit
  • Status of the electrical machine (A79/1)
  • Hybrid drive system, status

Upon switching on of circuit 15 the CDI control unit or the ME-SFI [ME] control unit makes the request from the power electronics control unit for precharging of the condensers (high voltage intermediate circuit) via the CAN network. After precharging and appropriate feedback, the CDI control unit or the ME-SFI [ME] control unit sends a request to the battery management system control unit to switch on the contactor via the CAN network.

After successfully switching on the contactor, the battery management system control unit sends the status of the contactor to the CAN network. In the case of failure of the status signal and CAN message failure, the CDI control unit or the ME-SFI [ME] control unit sets the status of the contactor to a substitute value.

After successful activation of the high voltage on-board electrical system the CDI control unit or the ME-SFI [ME] control unit sets the status of the hybrid drive system to "system readiness".

The CDI control unit or the ME-SFI [ME] control unit transmits this status via the CAN network to the IC (A1) which displays the message "READY" over the multifunction display (A1p13).

Further partial functions such as the automatic engine start or engine stop are dependent upon further release and system conditions.

	Electrical function schematic for starting the hybrid drive system		PE08.30-P-2056-97FBH
	Overview of system components, hybrid drive system		GF08.30-P-9999RFH