Two pulse converters with freewheeling diode: One quadrant converters can also be obtained by connecting a free wheeling diode across the load terminals. This is possible with both midpoint and bridge converters, as shown in Fig. 3.54. The Two pulse converters with freewheeling diode provides a local path for the load current when the thyristors […]
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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
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Twelve pulse converter: It is clear from the preceding discussion that increasing the pulse number to six greatly improves the performance of the converter. The ac line current has only odd harmonics and the value of g increases to 0.96, indicating that the fundamental content is 96% of the total rms value of the current.
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Six Pulse Converter with Interphase Transformer: The basic connection of a Six Pulse Converter with Interphase Transformer is shown in Fig. 3.38. This is obtained by connecting two three pulse converters in parallel on the dc side. The interphase transformer absorbs the difference of the instantaneous voltages of the two converters. The total load current
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Six pulse bridge converter: The conduction time of a thyristor in a six pulse connection can be increased when the converter is obtained by a series or parallel connection of two three-pulse midpoint converters. A Six pulse bridge converter is obtained by connecting two three pulse converters in series on the dc side and in
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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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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
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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
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