alternatore

An alternator, often referred to as alternatore in Italian, is an electrical machine that converts mechanical energy into electrical energy in the form of alternating current. In vehicles, it provides electrical power to the electrical system and charges the battery while the engine runs.

Principle of operation: An alternator contains a rotor (the rotating magnetic field) and a stationary stator with windings. The engine drives a belt that spins the rotor, creating a rotating magnetic field. This induces three-phase alternating current in the stator windings. The AC is converted to direct current by a diode rectifier and regulated by a voltage regulator to maintain a stable charging voltage, typically around 13.8 to 14.4 volts in a 12-volt system.

Construction and variants: Modern automotive alternators are brushless, with the rotor fed by a regulator through slip rings. They feature a cooling fan, a housing, bearings, and a pulley connected to the engine via a belt. The output is usually three-phase to improve efficiency and smoothness. Some larger or specialized systems use different rotor designs, including permanent magnet or separately excited configurations.

Applications and performance: The primary use is charging the car battery and supplying electrical loads when the engine is running. Automotive units typically deliver tens to over a hundred amperes, depending on engine size and electrical demand. Systems can operate at 12 or 24 volts, with regulation kept within a narrow voltage range to protect the battery and electrical components.

Maintenance and faults: Common issues include worn bearings, belt slippage, degraded voltage regulation, or failed diodes in the rectifier. Maintenance focuses on belt condition, noise, and charging voltage; replacement is common when performance declines or reliability is compromised.