How Car Alternators Work
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The Rotor
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When the ignition is turned on, an electrical current is provided from the battery to the voltage regulator by the exciter wire. The current is modulated by the voltage regulator to produce a constant voltage within the rotor, composed of a solid iron core tightly wound in wire. The current creates a magnetic field around the rotor.
The Stator
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Driven by a belt connected to the engine, the rotor spins within the stator. The stator consists of three stationary sets of wire coiled conductors called phases. As the rotor spins inside the stator, the magnetic field sweeps across the stator's phases, creating an electrical alternating current (AC).
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The Rectifier
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The AC current is directed though a series of diodes called the rectifier. A diode lets a current to flow in one direction while blocking flow in the opposite direction, allowing the rectifier to convert alternating current to direct current. The rectifier consists of six diodes, using three diodes to convert negative current and three diodes to convert positive current. The newly converted direct current passes through a separate diode trio and then distributed from the rectifier back to the battery and other components.
The Diode Trio
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The diode trio is composed of three diodes, one per phase, and is located within the rectifier. The diode trio sends DC current from the rectifier back to the voltage regulator which monitors the incoming current and disconnects from the exciter wire as the alternator produces its own electrical current to power the rotor's magnetic field. The alternator is now capable of sustaining itself for as long as the engine is running.
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