BSD Interface to Alternator

BSD Interface To Alternator

The alternator with its BSD interface supports active communications with the engine-management control unit. The alternator is not directly connected to the charge-indicator lamp, but rather to the engine-management control unit. The alternator can detect various defects and malfunctions.

Function
For the alternator with BSD interface, the following functions are implemented in the engine-management control unit:
- Alternator activation and deactivation based on parameters defined in the application
- Definition of the maximum approved load factor for the alternator
- Control of the alternator's response to demand spikes (Load Response)
- Calculates alternator torque based on the proportion of total capacity being used
- Diagnosis of the data wire between the alternator and the engine-management control unit
- Stores alternator faults in the fault memory
- Activates the charge indicator lamp in the instrument cluster via CAN
Use of an alternator equipped with a BSD interface does not change the charge indicator lamp's display concept relative to that employed with earlier alternators.
The system ensures that the alternator continues to discharge its primary function even if communications between the alternator and the engine-management control unit are interrupted.

Potential malfunctions
The following possible defects and malfunctions can be identified based on DTC entries:
- Controlled load reduction at high temperatures: The alternator is overloaded and the alternator voltage is reduced as a precautionary measure; it remains at a reduced level until the alternator has cooled. The charge indicator lamp does not light up
- Mechanical fault: The alternator is physically seized or the belt drive is no longer operational.
- Electrical fault: Defective field diodes, interruption in generation of field current, overvoltage.
- Communications failure: Defect in wiring between engine-management control unit and alternator.
The following cannot be detected: Open winding or short circuit

Charge indicator light
The signal activating the charge indicator lamp is transferred to the instrument cluster on the CAN. The charge indicator lamp comes on in response to mechanical and electrical faults (see above).

Identification
The above-cited calculation of an alternator's torque and of the proportion of this alternator's capacity being used display substantial variations according to the type (output) and manufacturer.
This is why the engine-management control unit receives these data from the alternator. The engine-management control unit adapts its calculations and operational specifications to the precise type.

Objective
Precise calculation of alternator torque draw and control of the load-response function support a good engine idle Controlling alternator voltage based on setpoint data from the engine-management control unit allows the system to maintain a satisfactory charge balance for the battery.