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

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 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 CDI control unit (N3/9) (for a diesel engine) or the ME-SFI [ME] control unit (N3/10) (for a gasoline engine) gathers and prioritizes torque requests and coordinates, how the requested torque is 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 CDI control unit or 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 reduction/dynamics
  • Request for regenerative braking torque
• Radar sensors control unit (N62/1), (with code 23P (Driving assistance package)) via CAN network:
  • Request for a change of torque
• Fully integrated transmission control unit (Y3/8n4) via the CAN network:
  • Drive position
  • 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 systems regenerative braking system (RBS), Electronic Stability Program (ESP®), electronic traction system (ETS), cruise control (Cc [TPM]), DISTRONIC PLUS (DTR) (with code 23P (Driver assistance package) as well as the driver request torques and transmit these requests via the CAN network to the CDI control unit or ME-SFI [ME] control unit. The CDI control unit or 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, control unit
• engine load request from the driver and regenerative braking system (RBS)
• DISTRONIC (with CODE 23P (Driving assistance package)) or cruise control

Function sequence for coordination of torque generation 

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

To do this the CDI or 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 CDI control unit or 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 so generated via the CAN network to the CDI control unit or 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).