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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Single Stack Variable Reluctance Stepper Motor

A single stack variable reluctance stepper motor has a salient pole stator. The stator has a concentrated windings which are placed over the stator poles. The number of phases of the stator depends upon the connection of the stator coils. There are three or four windings. The rotor is made up of ferromagnetic materials and…

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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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Multi Stack Variable Reluctance Stepper Motor

A Multi Stack or m stack variable reluctance stepper motor is made up of m identical single stack variable reluctance motor. The rotor is mounted on the single shaft. The stator and rotor of the Multi Stack Variable motor have the same number of poles and hence, the same pole pitch. All the stator poles…

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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 poles as North (N) and South (S)…

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Variable Reluctance Stepper Motor

The principle of Variable Reluctance Stepper Motor is based on the property of the flux lines which capture the low reluctance path. The stator and the rotor of the motor are aligned in such a way that the magnetic reluctance is minimum. There are two types of the Variable Reluctance Stepper Motor. They are as…

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Characteristics of a Stepper Motor

The Torque pulse rate Characteristics of a Stepper Motor gives the variation of an electromagnetic torque as a function of stepping rate in pulse per second (PPS). There are two characteristic curves 1 and 2 shown in the figure below. Curve one is denoted by a blue colour line is known as the Pull-in torque. It shows…

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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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