4._Fundamentals_of_AC_Machinery_2011

4._Fundamentals_of_AC_Machinery_2011 - Fundamentals of AC...

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4. Fundamentals of AC Machinery 1 Fundamentals of AC Machinery Revised May 17, 2011 EEL 3211 © 2011, H. Zmuda
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 2 AC Machines: We begin this study by first looking at some commonalities that exist for all machines, then look at specific machines such as Synchronous Machines Induction Machines DC machines
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 3 AC Machines: Motors: AC Electrical Energy è Mechanical Energy We apply a current to a wire in the presence of an applied magnetic field which produces a torque – this is motor action. Just like when two permanent magnets are near each other, a force is exerted which makes their magnetic fields want to l line up. z Generators: Mechanical Energy è AC Electrical Energy We move a wire in the presence of an applied magnetic field which induces a voltage – generator action. In each case, the applied magnetic field for AC machines is produced by a field winding .
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 4 AC Machines: Two major classes of AC machines: Synchronous Machines are motors and generators whose field current (or current in the rotor windings) is supplied by a direct connection via a rotating contact to a separate stationary power source. Induction Machines are motors and generators whose field current (current in the rotor windings) is induced in the rotor by magnetic induction (transformer action) and by the relative motion of the rotor and stator. We will consider each machine in detail. First we look at the basic commonalities that govern both types of machines.
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 5 In rotating machines, voltages are generated in windings or groups of coils •by rotating these windings mechanically through a magnetic field, •by mechanically rotating a magnetic field past the winding, •or by designing the magnetic circuit so that the reluctance varies with rotation of the rotor. By any of these methods, the flux linking a specific coil is changed cyclically, and a time-varying voltage is generated. A set of such coils connected together is typically referred to as an armature winding .
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 6 In general, the term armature winding is used to refer to a winding or a set of windings on a rotating machine which carry ac currents. In ac machines such as synchronous or induction machines, the armature winding is typically on the stationary portion of the motor referred to as the stator , and these windings may also be referred to as stator windings. Terminology: The stationary part of a machine is called the stator , while the part that rotates is called to rotor . The field circuits of most synchronous and induction machines are located on their rotors.
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EEL 3211 © 2011, H. Zmuda 4. Fundamentals of AC Machinery 7 With rare exceptions, the armature winding of a synchronous machine is on the stator, and the field winding is on the rotor.
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This note was uploaded on 08/23/2011 for the course EEL 3211 taught by Professor Staff during the Summer '08 term at University of Florida.

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4._Fundamentals_of_AC_Machinery_2011 - Fundamentals of AC...

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