e-Learning in electrical engineering

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2. Example of function to be achieved: the rectifier

Lecture's plan

Introduction

  1. Structure and command
  2. Example of function to be achieved: the rectifier
  3. Example of function to be achieved: the inverter
  4. Example of function to be achieved: the chopper
  5. Problems to be solved

 

 

We wish to supply a R-L load with a DC voltage starting from a triphased AC source, Y (star) connected (figure 3).

Figure 3

The - terminal of the load is linked to the neutral point of the source.

The + terminal of the load is connected to the three terminals of the source by the way of three semiconductor switches (figure 4).

Figure 4

By closing

  • K1 during the intervals when the e1 voltage is the most positive

  • K2 during the intervals when the e2 voltage is the most positive

  • K3 during the intervals when the e3 voltage is the most positive

we obtain a voltage that is approximatively continuous, because it pulsates around its average value (figure 5).

The absorbed current is closer by a constant current when the inductance of the receiver is greater, because this inductance opposes to the current's variations.

If necessary, in order to obtain across the R a quasi constant voltage, a filter can be belt, by adding a capacitor C (figure 6).

Figure 6

 

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Last update: 2005, September, 30 | Translation: Sergiu Ivanov