Reversible Drive using Armature Current Reversal: A schematic of a reversible drive using contactors to reverse the Armature Current Reversal for reversing the rotation is shown kin Fig. 4.81. The contactors F1 and F2 are provided for rotation in the forward direction, whereas R1 and R2 in the reverse direction. This arrangement reverses the current in […]
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Field Oriented Control of Induction Motor: In the slip controlled drives using VSI or CSI discussed in the foregoing sections, the stator voltage or stator current is controlled using slip frequency. They are controlled in magnitude only. The stator current control does not take care of its phase position with respect to flux. The control
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Braking and 4 Quadrants Operation: Subsynchronous converter cascades have been used, till now, in applications requiring one quadrant operation. These can be employed for drives where at least one electrical braking is required. A 4 Quadrants Operation can also be made possible in these cascades, using suitable switching. The braking is obtained by connecting the
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Network Analysis and Synthesis: ABCD Parameters of Two Port Network AC Fundamentals Asymmetrical Network in Network Analysis Attenuator Network Attenuators in Network Analysis Band Pass Filter Band Stop Filter Bode Plot in Network Analysis Bridged T Network Analysis Butterworth Approximation Chebyshev Approximation Circuit Elements Classification of Electrical Network Complex Locus of RLC Networks Composite Filters
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Four Quadrants Converters: Four Quadrants Converters – The converters described in the previous sections are suitable either for one quadrant or two quadrant operation. In the former case stepless speed control is possible by changing the applied voltage. There is no regeneration. In the latter case both speed control and regeneration are possible. The converter
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Six pulse midpoint converter: The converter transformer converts the existing three phase system to a six phase one, since it has six secondary windings. The Six pulse midpoint converter connections are shown in Fig. 3.32. A thyristor having maximum voltage can go into conduction only if it has a firing pulse. The natural firing instant
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Three pulse midpoint converter: These are basically three-phase converters, and are very popular because a 3-phase supply is readily available. 3-phase converters have a greater power capability than single phase converters. With these converters the pulse number of the output voltage superimposing the mean dc voltage can be increased using suitable transformer connections. Increasing the
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Two pulse bridge converter: A two pulse bridge converter is achieved as shown in Fig. 3.22 from two midpoint converters. They are connected in series on the dc side and in parallel on the ac side, It is also a single phase converter. At any given time two diagonally opposite thyristors conduct, one thyristor acting
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Electric Converter: Electric Converter – The speed of a dc motor can be varied by varying the armature voltage or the field current, for which a variable dc supply is required. The speed of an ac motor, on the other hand, can be varied by varying its supply frequency. In order to achieve the rated
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Selection of Power Generation Unit in Load Curve: The load on a Power Generation Unit is seldom constant; it varies from time to time. Obviously, a single generating unit (i.e., alternator) will not be an economical proposition to meet this varying load. It is because a single unit will have very poor efficiency during the
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