In this active rectifier, the circuit operates in a buck mode. This means that the output voltage is now less than the input voltage. For this example, it is assumed that the load circuit has a very large inductor in it, therefore making the load current look continuous. 

As in the case of the VR there are 8 different switching states. The voltage that these states produce depends on the sector that the circuit is operating in. There are 6 different sectors over one fundamental period. If you use the red line on the fundamental voltage and current graph and move it along you will see the sector change. Also shown are the vectors that the 8 different switch combinations to. It is interesting to note that 4 of the positions result in a zero vector, i.e. have the same affect. 

In a particular sector, move the red line through the switching pattern to see how the switch state is able to change the path that the current is taking. 

By adjusting the input voltage magnitude for all 3-phases simultaneously, it can be seen how the switching pattern changes.

• Moving the red line in the switching figure to see how the current path direction in the rectifier changes.
• By moving the red line in the fundamental voltage and current plot it can be observed how the different vector sectors are being used. Can you determine what causes the new vector segment to be used?
• The magnitude of the input voltage can be adjusted for all 3-phases by using the red dot on the R phase input voltage. Adjusting this magnitude results in different switch combinations and on times being used to generate the output voltage.