GF42.22-P-1000LEH Regenerative Brake Mode, Function

GF42.22-P-1000LEH Regenerative brake mode, function

Component Identification:

Function requirements for regenerative brake mode, general
^ Hybrid drive system "READY"
^ Selector lever position "D"
^ Vehicle speed > 20 km/h

Regenerative brake mode, general
The driver's brake command is monitored by the pedal angle sensor and transmitted by the regenerative braking system control unit.

The regenerative braking system control unit communicates permanently over the chassis CAN (CAN E) with the ME-SFI [ME] control unit (N3/10).

The ME-SFI [ME] control unit requests the current status of the available regenerative braking torque from the power electronics control unit over the drive train sensor CAN (CAN I).

Regenerative brake mode function sequence
The ME-SFI [ME] control unit forecasts the current status of the maximum available regenerative braking torque, which can be generated by the integrated starter alternator.

This then sends it over the chassis CAN to the regenerative braking system control unit.

On the regenerative braking system control unit the brake pedal connection to the push rod of the BAS brake booster has free travel (3) integrated into it.

This is used to display the regenerative braking system control unit's functionality. When in normal operation the driver's brake command (pedal travel) is monitored by the pedal angle sensor and read-in and processed by the regenerative braking system control unit.

At the same time the brake pressure simulator generates a simulated pedal resistance each time the brakes are actuated. If regenerative braking is used, it increasingly reduces the free travel (3) between the brake pedal and push rod as the regenerative braking torque increases.

The regenerative braking system must be activated during the first brake actuation. While doing so, the brake pressure simulator is deactivated resulting in a somewhat longer pedal travel than in normal operation during the first brake actuation. Once the brake pedal has been completely released again, the regenerative braking system is activated again.

As a matter of principle, the brake pedal feeling on a regenerative braking system is perceived differently from that on a conventional brake system.

Regenerative braking is switched off for the ignition sequence, when:

- The requested regenerative braking torque is not provided correctly or
- There is a fault in the hybrid drive system.

The actual realized braking torque, set by the power electronics control unit, is sent by the ME-SFI [ME] control unit over the chassis CAN back to the regenerative braking system control unit. This checks the realization of the requested overall braking torque and hydraulically regulates as required, or it sends a new request to the ME-SFI [ME] control unit.

The three-phase AC voltage generated during regenerative braking by the integrated starter alternator, is converted by the power electronics control unit into a high-voltage DC voltage and supplied to the high-voltage battery (A100g1).