Abstract
This paper presents a simulation model of an alternator in order to get its performance characteristic I(n). A car alternator has an important role: to produce electric energy necessary to supply the electric and electronic systems of the car and to charge the battery. One of the most important characteristic of an alternator is the performance curve that distinguishes it from the DC generator called dynamo. This curve has a special shape that gives an advantageous behaviour to the alternator and this is the main reason why the alternator has totally substituted the dynamo in the electric power generating process for cars. The special shape of an alternator can be understood better using advanced engineering methods. Studying the construction and operation of the alternator we can develop a mathematical model for it and simulations can be performed. We expect to obtain through simulation similar characteristics with those obtained experimentally. First, it can be observed that the alternator is a synchronous generator. The induced alternating voltage changes its amplitude and frequency as the speed of the shaft changes. This depends on the rpm of the main shaft of the internal combustion engine. The saturation of the magnetic flux and frequency dependence of impedance have great influence on the performance characteristic of the alternator. The supplied alternating current has to be rectified by applying diodes in order to be able to charge the battery. Setting the parameters of the simulation model we can immediately obtain the performance curve. In this way it is easier to study the influence of different parameters in the design process.
Keywords: automotive electric and electronic systems, alternator, simulation, performance curve.