Search Results for: motor

DC Chopper: DC Chopper are mainly dc to dc single stage conversion devices which provide a variable voltage on the load side when fed from a constant dc voltage source. The commutation of the current from the thyristors cannot be achieved by means of supply voltage. The necessary reactive power for the converter must be […]

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

Bridge Rectifier Circuit Diagram with freewheeling diodee: A 6 pulse Bridge Rectifier Circuit Diagram with freewheeling diode across the load terminals is shown in Fig. 3.58. As has already been explained, the diode participates in conduction only when the instantaneous load voltage tends to become negative. This occurs for firing angles greater than 60°. For

Two pulse half controlled bridge converter: A Two pulse half controlled bridge converter is obtained by connecting a two pulse controlled midpoint converter in series with an uncontrolled one, as shown in Fig. 3.45. The controlled converter has thyristors T1 and T2 in a com­mon cathode connection whereas the uncontrolled one has diodes D1 and D2 in

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

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

Two pulse mid point converter: Two pulse mid point converter are, in general, single phase converters. The pulse number of the converter indicates the frequency of the ripple voltage superimposing the average dc voltage at the terminals. The schematic of a Two pulse mid point converter is shown in Fig. 3.15. In the figure υs1 and

Phase Controlled Line Commutated Converters: In these Phase Controlled Line Commutated Converters, the commutation voltage, i.e. the voltage required to transfer current from one thyristor to the other, is provided by the supply lines to which the converter is connected. The classification of these Line Commutated Converters is done in several ways. Depending on the

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