Brushless DC Motor Drives(Trapezoidal PMAC): The cross section of a 3-phase 2 pole Brushless DC Motor Drives is shown in Fig. 7.15. It has permanent magnet rotor with wide pole arc. The stator has three concentrated phase windings, which are displaced by 120° and each phase winding spans 60° on each side. The voltages induced […]
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Sinusoidal PMAC Motor: Since the voltages induced in the stator phases of a sinusoidal PMAC motor are sinusoidal, ideally, the three stator phases must be supplied with variable frequency sinusoidal voltages or currents with a phase difference of 120° between them. Behavior of such a motor from a variable frequency voltage source is already described
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Self Controlled Synchronous Motor Drive Employing a Cycloconverter: Self Controlled Synchronous Motor Drive Employing a Cycloconverter as shown in Fig. 7.13. Firing pulses are generated either by comparison of the motor terminal voltages or by rotor position senors as in the case of drive. Cycloconverter control has the advantages of smooth low speed operation, four-quadrant
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Self Controlled Synchronous Motor Drive: A Self Controlled Synchronous Motor Drive employing a load commutated thyristor inverter is shown in Fig. 7.10. In large power drives wound field synchronous motor is used. Medium power drives also employ permanent magnet synchronous motor. The drive employs two converters, which are termed here as source side converter and
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Variable Frequency Control of Multiple Synchronous Motors: A drive operating in true Variable Frequency Control of Multiple Synchronous Motors is shown in Fig. 7.9. Frequency command f* is applied to a voltage source inverter through a delay circuit so that rotor speed is able to track the changes in frequency. A flux control block changes
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Operation of Synchronous Motor: Operation of Synchronous Motor – For any speed other than synchronous speed, the relative speed between air gap flux wave and the rotor is not zero. Consequently, δ varies from 0 to 360°, and torque fluctuates between positive and negative values, but its average value remains zero. Frequency of torque fluctuations
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Synchronous Motors Types: Commonly used Synchronous Motors Types are: wound field, permanent magnet, synchronous reluctance and hysteresis motors. All these motors have a stator with a 3-phase winding, which is connected to an ac source. Fractional horse power synchronous reluctance and hysteresis motors employ a 1-phase stator. Wound field synchronous motor rotor has a dc
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