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The rotating magnetic field is the key principle in the operation of induction machines.The induction motor consists of a stator and rotor.In the stator a group of fixed windings are so arranged that a two phase current, for example, produces a magnetic field which rotates at an angular velocity determined by the frequency of the alternating current.
A three-phase power supply provides a rotating magnetic field in an induction motor. Inherent slip – unequal rotation frequency of stator field and the rotor In both induction and synchronous motors , the AC power supplied to the motor's stator creates a magnetic field that rotates in synchronism with the AC oscillations.
In a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. The magnetic core is in two parts; a stator which is stationary, and a rotor, which rotates within it. The magnetic field lines pass in a continuous loop or magnetic circuit from the stator through the rotor and back through the ...
A typical two-phase AC servo-motor has a squirrel cage rotor and a field consisting of two windings: a constant-voltage (AC) main winding. a control-voltage (AC) winding in quadrature (i.e., 90 degrees phase shifted) with the main winding so as to produce a rotating magnetic field. Reversing phase makes the motor reverse.
After expounding the geometric theory of the rotatory magnetic field, he suggested that a simple way of procuring the desired phase-currents would be to branch the circuit of an alternate current into two parts, into one of which should be inserted a resistance without self-induction, into the other a coil of much self-induction but of small ...
In operation, the non-rotating stator winding is connected to an alternating current power source; the alternating current in the stator produces a rotating magnetic field. The rotor winding has current induced in it by the stator field, like a transformer except that the current in the rotor is varying at the stator field rotation rate minus ...
The magnetic field may be produced by permanent magnets or by field coils. In the case of a machine with field coils, a current must flow in the coils to generate (excite) the field, otherwise no power is transferred to or from the rotor. Field coils yield the most flexible form of magnetic flux regulation and de-regulation, but at the expense ...
Free-body diagram of a U-channel synchronous linear motor. The view is perpendicular to the channel axis. The two coils at centre are mechanically connected, and are energized in "quadrature" (meaning a phase difference of 90° (π/2 radians) between the flux of the magnets and the flux of the coils). The bottom and upper coils in this ...