Alternators and electric motors: two sides of the corresponding transducing coin.
Alternators, generators and electric motors are model closely linked; they're all transducers that change mechanical or kinetic compel into electrical power and back again. The appositeness is so fast really, that many newer cars cause alternators that can dart in reverse either as a starter Engine or a Complementary hybrid ride. While the applications for electric induction are nearly limitless, it all goes back to a image pioneered nearly 200 elderliness ago.
Induction Power
All electrical ability Industry devices job in the alike basic journey: by either passing a coil of wire concluded a Attractive sphere or by passing a magnetite on ice a coil of wire. Electricity is nihility however the movement of electrons, and electrons obtain a colorless electrical charge. They're polarized just like one side of a lodestone. So, running a electromagnet along a conductor drags the electrons along the surface of that conductor as provided they were iron filings. Drag the electrons encompassing a Hand-bill loop of wire and you bear in fashion that flows in one plan matchless, or regulate ongoing. Ploy the magnetite back and forth on that loop and the electrons change in course, producing alternating current.
Generators vs. Alternators
Manufacturers have several ways of controlling heat buildup in the alternator. The standard approach is to incorporate some kind of fan or radial turbine to either push cooling air through the alternator from the front or pull it through from the back. Of these two strategies, the pull-though method tends to work best because cooling air hits the rectifiers before going through the alternator. An alternator uses stationary coils on the outside -- on the inside of the case walls -- and an armature or central shaft lined with electromagnets. These triangular magnets sit in opposition to each other: north-south-north-south-north. As they rotate inside the coils, they shake the electrons back and forth and induce an alternating current.
Rectification
Both generators and alternators produce alternating current, which is a problem because the car's electrical system runs on direct current from the battery. A generator uses brushes and a commutator just like a DC electric motor in order to change the electrons' back-and-forth movement to one-way movement. An alternator uses a set of one-way electrical valves called diodes on the wire output to rectify the current. The diodes on the alternator's positive output are oriented so that power can only flow outward, but not back in. The ground diodes are oriented so that power can flow into the coils, but not back out. This arrangement works, but has the side effect of effectively cutting the alternator's output by half.
Alternator Heat Buildup
So, if the rectifier cuts the alternator's output by half, then where does all that electrical energy wind up? It turns into heat in the diodes. Observe this phenomenon yourself by placing your finger on any illuminated LED light. A light-emitting diode works just like the rectifiers in your alternator, only it uses the excess energy to produce both heat and light. Alternator diodes get very hot -- hot enough to self-destruct if left to operate without some thermal management strategy.
Controlling Heat Buildup
It matters not whether you move a magnet through a coil of wire or a coil of wire within a magnetic field. Either way, you're still inducing electron flow. While some might use the terms interchangeably, generators and alternators are the exact opposite of one another. A generator is functionally identical to an electric motor, where coils of wire rotate on an armature shaft in between two large magnets. Additionally, some manufacturers make the alternator intentionally heavy, using very thick case walls and heavy alternator brackets to absorb some of the alternator's thermal energy and act as a heat sink. The bracket and case's surface area acts as a radiator to disperse heat, reducing average temperature and aiding the cooling fan.
