Alternator

The alternator exchanges data with the engine control unit using a serial data interface. The alternator provides the engine control unit with information, e.g type and manufacturer. This enables alternator-specific information to be processed inside the engine control unit and adapts the control of the alternator to the installed alternator type.

With Intelligent Generator Control IGR, the alternator voltage is correspondingly more frequently in the low voltage range in order to achieve a better battery charge.

Functional Description

The alternator maintains the desired level of vehicle voltage. The alternator also supplies all electrical consumer units during driving. The controller regulates the output voltage of the electrically excited alternator with uncontrolled rectifier by applying the excitation current.

For the alternator with serial data interface, the following functions are implemented in the engine control unit :

• Switching the alternator on and off on the basis of defined parameters
• Temperature-dependent maximum permitted power consumption of the alternator
• Calculation of the alternator input torque and the alternator current based on the parameters transmitted by the alternator regulator.
• Control of the reaction of the alternator with addition of high power consumers (load-response functions)
• Alternator diagnosis and diagnosis of the data line between alternator and engine control unit.
• Storage of any faults that occurs on the alternator in the fault memory of the engine control unit.

Failure of the component

The main function of the alternator is also ensured in the event of interruption of the communication between the alternator and engine control unit. The following fault causes are distinguish by the fault memory entries :

• Overheating function : The alternator is overloaded. For safety reasons, the alternator voltage is reduced until the alternator has cooled down again. That is a normal operating condition for the alternator.
• Mechanical fault  : There is mechanical block in the alternator or the belt drive is defective.
• Electrical fault  : Defect in the excitation power circuit (transistor, diode), open circuit in the excitation coil, faulty controller.
• Communication failure : Faulty cable between engine control unit and alternator.
• Incorrect type of alternator : Incorrect or non-approved alternator installed.

An interrupt or short circuit in the coils of the alternator can not be detected.