alternátors

An alternator is an electrical generator that converts mechanical energy into electrical energy in the form of alternating current. In common usage, the term often refers to the devices in vehicles that charge the battery and supply electrical power, though it also describes large generators in power plants that produce AC for the grid.

Principle and construction: An alternator consists of a rotor that provides a rotating magnetic field and a stator with stationary winding coils. As the rotor turns, the changing magnetic field induces three-phase alternating current in the stator windings. The output can be used as AC or rectified to DC in applications requiring DC power. In many systems the generated AC is rectified by diodes and smoothed by capacitors. Automotive alternators typically use a rotating field fed by a DC excitation circuit and a voltage regulator that maintains a charging voltage around 13.8 to 14.4 volts.

Automotive applications: In vehicles, the alternator is driven by the engine via a belt and charges the battery while the engine runs, while also powering electrical systems. Modern automotive alternators are largely brushless and integrate the rectifier and voltage regulator within the unit. They produce three-phase AC that is rectified to DC for the vehicle’s electrical bus.

Industrial and power generation: In power plants, alternators are large synchronous generators that produce three-phase AC at the grid frequency (50 or 60 Hz). They are normally driven by steam or gas turbines, with a rotor excited by DC through brushes and slip rings, and a stator that delivers the output to the transmission network. An automatic voltage regulator helps maintain stable voltage under varying load.