# Converters for Electric Motors

## Bridge Rectifier Circuit Diagram with freewheeling diode

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 converters with freewheeling diode

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 …

## Three phase half controlled bridge circuit

Three phase half controlled bridge circuit: This is obtained by a series connection of a 3 pulse controlled converter and a 3 pulse uncontrolled one. The three arms of the former consist of thyristors and the three arms of the latter comprise diodes. A typical Three phase half controlled bridge circuit is shown in Fig. …

## Two pulse half controlled bridge converter

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 …

## Twelve pulse converter

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. …

## Six Pulse Converter with Interphase Transformer

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 …

## Six pulse bridge converter

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 …

## Six pulse midpoint converter

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

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 bridge converter

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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