Car Alternator: Components, Function, and Types
What is an Alternator?
An alternator is an electric power generator that converts mechanical energy it receives from its shaft into electrical energy. In addition to charging the battery, it provides power to different components of the car. It provides current, but establishing the alternating magnetic core is the bridge rectifier with diodes rectifiers is responsible for transforming it into continuous current.
Alternator Parts
- Pulley: Receives the rotation of the engine through the belt.
- Fan: Cools the components of the alternator.
- Hand Drive Enclosure: Protects the entire rotor and shaft. The terminals of the alternator are located here.
- Stator: The fixed part of the alternator where the spools that generate electricity are located.
- Induced: Copper wire forming a coil that generates the magnetic field, which, when added to the rotor current, creates the induced current.
- Rotor: The mobile part of the alternator. It is responsible for creating the inductor magnetic field, which induces the electric current supplied by the alternator. The rotor consists of a shaft on which the magnetic core (inductor set) is mounted. This core is formed by two pieces of steel that carry 6 or 8 poles, resulting in a field with 12 to 16 poles.
- Slip Rings: Receive the current created by the rotor’s magnetic core.
- Brushes: Transmit the current from the slip rings to the rectifier bridge.
- Bridge Rectifier: An element with 6 or 9 LED connections to each of the phases of the alternator, rectifying the alternating current to continuous current.
- Housing Slip Rings: A screw cap that protects the rectifier bridge on the inside.
- Brush Holder: An element that holds the brushes.
- Connection Point: This is where the components that need current from the alternator are fed.
Alternator Connections
Star Connection
In a star connection, one end of each phase of the stator is united at a common point, and the other ends are connected to the rectifier bridge. The intensity obtained is the same as if the windings were connected in series. The line voltage is different from the phase voltage (Ep) obtained.
Delta Connection
In a delta connection, the beginning of each phase is connected to the end of the next phase, and the three connection points are connected to the rectifier bridge. The line voltage is the same as the phase voltage because the terminals are attached to the ends of each phase.
Regulator
The regulator’s role is to maintain a constant alternator voltage, and thus the vehicle’s electrical system, throughout the engine’s speed range, regardless of the load and speed. The alternator voltage depends greatly on the speed and load to which it is subjected. Although these terms of service are continuously variable, the voltage must be regulated to a default value. This limitation protects consumers against overvoltages and prevents overcharging the battery. The voltage regulator regulates the value of the exciting current and thus the magnitude of the rotor magnetic field, depending on the tension generated in the alternator. This maintains a constant voltage across the alternator, regardless of speed and varying loads, up to the maximum current value.