Special Machines

Permanent Magnet DC Motor

A DC Motor whose poles are made of Permanent Magnets is known as Permanent Magnet DC (PMDC) Motor. The magnets are radially magnetized and are mounted on the inner periphery of the cylindrical steel stator. The stator of the motor serves as  a return path for the magnetic flux. The rotor has a DC armature, …

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Reluctance Torque

Reluctance torque or alignment torque is experienced by a ferromagnetic object placed in an external magnetic field, which causes the object to line up with the external magnetic field. An external magnetic field induces an internal magnetic field in the object and because of this torque is produced. The torque is generated between the two …

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Amplidyne

Amplidyne is the most common version of the Metadyne. It consists of the basic metadyne in which a compensating winding is connected in series with the power output brush terminals. The compensating winding cancels out the d axis MMF, which opposes the control field MMF. The schematic diagram of the Amplidyne is shown below. The …

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Metadyne

Metadyne is a special machine which consists of two pairs of brushes or has an additional set of brushes on the d axis. This arrangement enables the armature MMF to provide most of the excitation and achieve higher power gains. In this, the brushes of the quadrature axis (q axis) are short-circuited, and direct axis …

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Hybrid Stepper Motor

Meaning and Working of Hybrid Stepper Motor The word Hybrid means combination or mixture. The Hybrid Stepper Motor is a combination of the features of the Variable Reluctance Stepper Motor and Permanent Magnet Stepper Motor. In the center of the rotor, an axial permanent magnet is provided. It is magnetized to produce a pair of …

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Permanent Magnet Stepper Motor

The Permanent Magnet Stepper Motor has a stator construction similar to that of the single stack variable reluctance motor. The rotor consists of permanent magnet poles of high retentivity steel and is cylindrical in shape. The concentrating windings on diametrically opposite poles are connected in series to form a two phase winding on the stator. …

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