AC Series Motor: A series motor can be run from either dc or ac (single-phase) supply provided that both stator and rotor cores are laminated to limit the iron-loss. Figure 10.43 is the cross-sectional view of a AC Series Motor connected to ac supply. As the armature current alternates, the field polarity alternates in phase […]

Hybrid Stepper Motor: Hybrid Stepper Motor -This is in fact a PM stepper motor with constructional features of toothed and stacked rotor adopted from the variable-reluctance motor. The stator has only one set of winding-excited poles which interact with the two rotor stacks. The permanent magnet is placed axially along the rotor in form of […]

Permanent Magnet Stepper Motor: Figure 10.39 shows the phases (stacks) of a 2-phase, 4-pole permanent magnet stepper motor. The rotor is made of ferrite or rare-earth material which is permanently magnetized. The stator stack of phase b is staggered from that of phase a by an angle of 90° elect. When the phase a is […]

Stepper Motor: The stepper motor is a special type of synchronous motor which is designed to rotate through a specific angle (called a step) for each electrical pulse received by its control unit. Typical step sizes are 7.5°, 15° or larger. The stepper motor is used in digitally controlled position control systems in open loop […]

Two phase Servomotor: Two phase Servomotor – For a low-power (a few hundred watts) control application, a 2-phase (balanced) servomotor is ideally suited as it can be driven by means of a relatively rugged (drift-free) ac amplifier. The motor torque can be easily controlled by varying the magnitude of the ac voltage applied to the […]

Circuit Model of Single phase Induction Motor: Circuit Model of Single phase Induction Motor – The winding unbalance and the fact that both the main and auxiliary windings are fed by the same supply result in unbalanced main and auxiliary fields. The phasor along the winding axes can be split into symmetrical components F̅f and […]

Single phase Synchronous motors: Single phase Synchronous motors – The 3-phase reluctance motor has already been discussed as an unexcited salient-pole synchronous machine in Sec. 8.11. The expression for reluctance torque of a single-phase device was derived in Sec. 4.3 from basic principles of energy conversion. The reluctance motor, in general, results wherever the stator […]

Comparison of Single phase and 3 phase Induction Motors: Comparison of Single phase and 3 phase Induction Motors – In a 3-phase induction motor the maximum torque is independent of the rotor resistance, while the slip at which it occurs increases with the rotor resistance. No such neat result is possible in a single-phase induction […]

Shaded Pole Motor: Shaded Pole Motor – Figure 10.17 shows a typical shaded-pole motor with a squirrel-cage rotor. A small portion of each pole is covered with a short-circuited, single-turn copper coil called the shading coil. The sinusoidally-varying flux created by ac (single-phase) excitation of the main winding induces emf in the shading coil. As […]

Split phase Motor: Split phase Motor -When a motor is provided with two windings, even though these are excited from the same voltage (supply being single-phase), the currents in the two windings can be made out-of-phase by adjustment of the impedance of the auxiliary winding in relation to the main winding. As a result F̅m and […]