Diagram of an alternator

Alternator – a generator that produces alternating current by converting mechanical energy to electrical energy. Usually, a small rotating machines driven by automotive and other internal combustion engines.

  • Diagram of an alternator – showing the rotating magnet (the Rotor) and the stationary wire winding (the Stator) and the voltage produced as the rotating magnetic field induces a current in the wire.

The first practical alternator was invented by Nikola Tesla in 1891.

How does Alternator Work ? (video 5:19) – video gives elaborated explanation on working of Alternators/ Synchronous generators with help of animation. Functions of slip rings, armature coils, Automatic Voltage regulator (AVR) and pole core are also well explained here.

Charging System – Alternators are used in automobiles to charge the battery and to power all the car’s electric systems when its engine is running. The charging system has three major components. The Battery, Alternator, and the Regulator. The alternator works together with the battery to supply power when the vehicle is running. The output of an alternator is direct current, however AC voltage is actually created and then converted to DC as voltage leaves the alternator on its way to the battery and the electrical loads.

  • Charging System circuit (diagram) – Four wires connect the alternator to the rest of the charging system. ‘B’ is the alternator output wire that supplies current to the battery. ‘IG’ is the ignition input that turns on the alternator/regulator assembly. ‘S’ is used by the regulator to monitor charging voltage at the battery. ‘L’ is the wire the regulator uses to ground the charge warning lamp.

Automotive alternator

What’s the problem?
Alternators produce AC power and this must be rectified to DC for the cars electrical system. Automotive alternators also are fairly fancy when it comes to output voltage regulation.

  • Ask – How are car electrical systems powered? Why do these run off Direct Current (DC)? How is Alternating Current (AC) produced? How can the AC be converted to DC for use in the car’s electrical system?
  • Imagine – To be practical for use in a car, how can the mechanism for producing or capturing and converting energy be relatively small and light. It has to be durable and reliable to ensure that it will work in any conditions where the car might operate – hot, cold, wet,..? Why is voltage regulation important in this application?
  • Design, Build – What are the factors that go into designing and building an alternator for use in a car?
  • Improve – As cars have become more powerful, with more electrical accessories – phone charging, navigation devices, how have alternator designs changed to accommodate these additional demands for power?

That’s engineering

  • alternating current (AC) – an electrical current where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant.
  • diode rectifier bridge – responsible for the conversion or rectification of AC voltage to DC voltage.
  • voltage control – The regulator will attempt to maintain a pre-determined charging system voltage level. When charging system voltage falls below this point, the regulator will increase the field current, thus strengthening the magnetic field, which results in an increase of alternator output.

Engineering ideas

  • alternating current (AC), mechanical energy, electrical energy, magnetic field, voltage, alternator, rectification, voltage control, regulator

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