Torque Coordination For A Hybrid Drive System, Function - GF08.30-P-4001GRH

ENGINE 276.821 in MODEL 166 

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

We will not go into more detail here about internal signals and function sequences of the internal combustion engine.

Function requirements for torque coordination for a hybrid drive system - general points 

• Hybrid drive system "READY"

Torque coordination for a hybrid drive system - general points 

The ME-SFI [ME] control unit (N3/10) gathers and prioritizes torque requests and coordinates how the requested torque will be generated. To do so, it takes into account the conditions of the internal combustion engine and the electrical machine (A79/1) as well as the charge level of the high-voltage battery (A100g1) and the status of the automatic transmission.

Function sequence for torque coordination of a hybrid drive system 

The function sequence is described in the following steps:

• Function sequence for coordination of torque requests 
• Function sequence for coordination of torque generation 

Function sequence for coordination of torque requests 

The ME-SFI [ME] control unit reads in requests and signals from the following control units and sensors via the CAN network or a direct line to coordinate the torque requests:

• Accelerator pedal sensor (B37), driver engine load request
• Electronic Stability Program (N30/4), wheel speed via the CAN network:
  • Torque lowering/dynamic
  • Request for regenerative braking torque
• Radar sensors control unit (N62/1) (for code (23P) (Driving assistance package) via the CAN network:
  • Request for a change of torque
• Fully integrated transmission control unit (Y3/8n4) via the CAN network:
  • Gear range
  • Request for transmission protection
  • Wet clutch status
• Battery management system control unit (N82/2) via the CAN network:
  • High-voltage battery voltage
  • Temperature of high-voltage battery

The regenerative braking system (RBS), the Electronic Stability Program (ESP®), the electronic traction system (ETS), the cruise control (CC [TPM]), the DISTRONIC PLUS (DTR) (with CODE 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot)) and the driver request torques and transmit these requests via the CAN network to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit prioritizes these torque requests and uses them to calculate the necessary drive torque.

The prioritization of the system requirement occurs in the following sequence:

• Electronic Stability Program (ESP®)
• Fully integrated transmission control unit
• Engine load request from the driver and regenerative braking system (RBS)
• DISTRONIC (with CODE 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot)) or cruise control

Function sequence for coordination of torque generation 

The ME-SFI [ME] control unit coordinates the torque generation and torque interventions.

To do this, the ME-SFI [ME] control unit reads in the following signals:

• Power electronics control unit (N129/1) via the CAN network:
  • Status of power electronics
  • Available torque from electrical machine
  • Generative torque from electrical machine
  • Motor-generated torque from electrical machine
  • Rotational speed of electrical machine
  • Status of electrical machine
  • Tolerable discharge voltage/current, signal
  • Tolerable charging voltage/current, signal
  • Charging voltage/current, signal
• Battery management system control unit via the CAN network:
  • High-voltage battery voltage
  • Temperature of high-voltage battery
• Fully integrated transmission control unit via the CAN network:
  • Wet clutch status

Dynamic torque interventions are not exclusively implemented over the torque reserve of the internal combustion engine. The ME-SFI [ME] control unit initially implements torque interventions over the electrical machine in the current drive torque. To do this it requests actuation of the wet clutch via the CAN network from the fully integrated transmission control unit and requests engine produced torque from the electrical machine from the power electronics control unit via the CAN network, in order to increase the torque. Reducing torque interventions are realized through requests for a generated torque.

The power electronics control unit implements these requests and reports back the torque that is generated via the CAN network to the ME-SFI [ME] control unit.

If the torque interventions of the electrical machine are not sufficient then the torque from the internal combustion engine is additionally reduced or increased (torque reserve).