In the alternators presently available, a communication connection is very often provided between a voltage regulator included in the alternator and an electronic control unit of the vehicle.
This electronic control unit is frequently the so-called engine control unit, which is dedicated to the control and management of the thermal motorisation of the motor vehicle, but can also assure the control and monitoring of the alternator.
By means of this communication connection, the electronic control unit can communicate with the regulator of the alternator, and control a particular functioning mode of the latter. Thus, it is possible for the electronic control unit to provide the regulator with instructions such as a voltage command, and to receive in return information relating to the actual functioning of the alternator.
The information which is transmitted in return to the electronic control unit by the regulator is often information relating to an excitation current of the alternator. This information allows the electronic control unit to verify the state of functioning of the alternator in relation to the instructions provided, and optionally to adjust these instructions by creating an additional regulation loop which is added to the one created locally by the regulator itself.
According to the motor vehicle manufacturers, the signals which are representative of the information required in return, in relation to an excitation current of the alternator, are different. In fact, certain manufacturers require the part manufacturer to design a regulator which can provide the electronic control unit with a pulse width modulated (PWM) signal which is present at the output of a PWM modulator included in the regulator. Other manufacturers prefer to have a signal which is directly representative of the signal which is present on the gate of a power MOSFET transistor which is present in the regulator, and supplies the excitation coil of the alternator with switched current, and yet others prefer the electronic control unit to receive a signal which represents directly the excitation voltage at the terminals of the excitation coil of the alternator.
A situation of this type has the consequence of making the task of the part manufacturer more difficult, and of increasing the costs, since the latter must continually adapt and modify their circuits in order to fulfill the needs of different clients.