Torque coordination, function

D08.10-A015-79

Function requirements for torque coordination, general points

 Circuit 15 ON

 Drive system "READY"

Torque coordination, general

The torque interface in the powertrain control unit (N127) coordinates and prioritizes (according to drivability and established priority) the requests of all systems that request engine torque. It also determines how dynamically each request is to be implemented.

The following systems and functions can request an engine torque from the powertrain control unit:

 Maximum torque limitation

 Rpm limitation

 Electronic Stability Program (ESP®)

 Driver, via accelerator pedal module and via drive program button (S2/2s2)

Function sequence for torque coordination

The traction and energy management takes place via the powertrain control unit. This directly reads in the signal of the accelerator pedal module (A68) and the signal of the drive program button. Further relevant data (e. g. the engaged drive range) for the vehicle control are also read in. From these data, the powertrain control unit determines the power requirement of the electric drive and requests this from the power electronics control unit (A79/3).

The power electronics control unit actuates the electric machine 1 (A79/1) with a 3­phase alternating voltage via the integrated power inverter and monitors it with regard to the temperature, motor speed and generated drive torque. The electric machine 1 transmits the drive torque via the fixed step-down ratio transmission to the drive shafts and front wheels.

Depending on the dynamics of the request, the power electronics control unit changes the torque via the following actions:

 Lifting or lowering the alternating voltage via the integrated power inverter

 Recuperative actuation of electric machine 1 via the integrated power inverter and generation of a braking torque