Deactivation Of Hybrid Drive System, Function - GF08.30-P-1004RFH
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
Function requirements for deactivating a hybrid drive system, general points
- Hybrid drive system "READY"
Deactivating a hybrid drive system - general points
To deactivate the hybrid drive system, the CDI control unit (N3/9) (for a diesel engine) or ME-SFI [ME] control unit (N3/10) (for a gasoline engine) sends a request to the battery management system control unit (N82/2) to switch off the contactor (A100s1). The CDI control unit or ME-SFI [ME] control unit assesses its status and controls discharging of the high voltage intermediate circuit over the power electronics control unit (N129/1) and retracts release of system readiness.
To do this, the CDI control unit or ME-SFI [ME] control unit reads in the following sensors and signals via the CAN network:
- Power electronics control unit
- Status of the electrical machine (A79/1)
- Voltage status of the intermediate circuit discharge
- Battery management system control unit
- Voltage of high-voltage battery (A100g1)
- Contactor status
- Temperature of high-voltage battery
Function sequence for deactivation of the hybrid drive system
If the conditions described further below are met, the CDI control unit or ME-SFI [ME] control unit requests switching off the contactor via the CAN network from the battery management system control unit.
Switching off path
The switching off path is used for very serious system failures (e.g. a CAN network failure) to power down the high voltage on-board electrical system and the hybrid drive. The status "READY" of the hybrid drive system is retracted after powering down, the internal combustion engine is switched off and the vehicle is no longer ready to drive.
If a severe error in the hybrid drive system is detected, the CDI control unit or the ME-SFI [ME] control unit uses the switch-off path to send a signal to shut down the hybrid drive system to the power electronics control unit.
After successful switching off of the contactor, the battery management system control unit alters the status of the contactor and sets it on 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.
If information is provided about the contactor being switched off in the event of a crash, the CDI control unit or ME-SFI [ME] control unit requests active discharge of the condensers (high voltage intermediate circuit) via the CAN network from the power electronics control unit. In order to secure discharging of the high voltage intermediate circuit, the power electronics control units checks the voltages after opening of the contactor and reports this via the CAN network to the CDI control unit or the ME-SFI [ME] control unit. 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. If the minimum value of the voltages is not reached after the maximum discharge time, a fault memory entry takes place in the CDI control unit or ME-SFI [ME] control unit.
After successful switching off of the high voltage on-board electrical system, the CDI control unit or the ME-SFI [ME] control unit retracts system readiness of the hybrid drive system. The CDI control unit or the ME-SFI [ME] control unit transmits this status via the CAN network to the instrument cluster (A1), which switches off the "READY" display.
After successful retraction of the system readiness and discharging of the intermediate circuit, the CDI control unit or the ME-SFI [ME] control unit retracts the system readiness "READY" of the hybrid drive system and switches off the internal combustion engine if necessary.
The vehicle is no longer ready to move without the system readiness "READY".
| Electrical function schematic for deactivation of the hybrid drive system | PE08.30-P-2064-97FBH | ||
| Overview of system components, hybrid drive system | GF08.30-P-9999RFH |