Motor Winding Books Urdu Pdf Free !FREE! Download
CLICK HERE >>> https://blltly.com/2taT9f
Variable reluctance motor (VRM) is a special type of induction motor that can operate at higher speeds than the classically-designed split-phase induction motors. The basic principle of operation is that each winding in the stator is formed of two parts, one part near the center of the stator and one part near the outer edge of the stator. The two portions of each winding are connected by a circuit that is adjustable for adjusting the flux linkage in the stator. The result is that more flux enters the space between the stator and rotor at one speed and less flux at another speed, thus creating a variable reluctance effect. At higher speeds, the variable reluctance motor becomes a variable-speed motor.
Some induction motors have a single fixed field winding and use the rotor to change the flux linkage in the stator. This type of motor is called a variable-speed induction motor and is commonly used in induction heating appliances. Such a motor may be both an induction heater and a variable-speed motor at the same time.
A stepper motor is a specific type of variable reluctance motor. In a stepper motor, the armature coils are in a sequential order. As a result, the number of armature coils that are excited is always the same, and the direction of rotation of the rotor is always the same. In operation, the number of steps per revolution is predetermined by the number of armature coils that are energized.
A permanent magnet synchronous motor (PMSM) is an alternating current motor that rotates in a continuous manner even if no load is connected. The rotor contains a large number of magnets arranged in a circular pattern. The magnetic poles which induce electromotive force in the stator's armature coils are alternately aligned (inclined) or oppositely aligned (disposed) with respect to the direction of the rotor's rotation, creating a flux path along the length of the rotor. When the rotor rotates in a given direction, an increasing number of magnetic poles are aligned with the stator's armature coils, which in turn leads to a change in the number of armature coils that are excited. This effect creates a back electromotive force, which opposes the motor's motion, thus preventing the motor from rotating back in the direction it was moving.
Two-speed windings: the motor may be divided into two sections, for example top and bottom. These sections are often referred to as the top and bottom windings. The winding patterns used in each of the top and bottom windings will differ in some way, for example the winding pattern will be different or the number of turns of wire will be different. Each section may have both a start winding and a main winding, which in turn may have one or more stall windings. The motor may have two contactors. The first contactor may be connected to the start winding, the second contactor may be connected to the stall winding or, if there is only one stall winding, the main winding.
The three-phase electric motor is a composite electric motor that consists of multiple phases with windings attached to a common housing and rotor. Typically, a three-phase motor is either a single-speed or a three-phase induction motor. Synchronous motors are three-phase motors, but are generally more difficult to construct than induction motors due to the multiple windings on the rotor.[21] 827ec27edc