Four Quadrant Operation of Dual Converter

Four Quadrant Operation of Dual Converter

Q. Dual Converter

Q. Which converter is suitable for four quadrant operation?

Q. What is meant by four quadrant operation?

Q. How does a dual converter work?

Q. Working Procedure of Dual Converter

The first full converter is capable of operating in two quadrants depending on the value of firing angle α. For the values of a less than 90°, this converter works as a rectifier, there by producing a positive average load voltage and load current and operates in the first quadrant.
Whereas for values of a greater than 90°, it works in the inverting mode, making its average output voltage negative. The load current however remains positive.
Therefore the first full converter operates in the fourth quadrant allowing the energy to flow from load to source making the regenerative braking possible.
Similarly the second full converter operates in the third quadrant of the load voltage load current characteristics for a less than 90°.
The average load voltage and current both are negative. The direction of power flow is from source to load and the dc machine works as a motor.
The converter operates in the third quadrant. The direction of rotation reverses. This converter acts as an inverter for a greater than 90°. The average load voltage is positive but the average load current continues to be negative, therefore the power flow will take place from load to source.
The load acts like source i.e. the motor will act as a generator and regenerative braking will take place.

Figure A

The converter thus works in the second quadrant.
Thus the dual converter works in four quadrants.
Thus the dual converter is capable of operating in four quadrants as shown in Figure.
Following table summarizes the results.

Parameter	Converter I		Converter II
Parameter	α < 90^o	α > 90^o	α > 90^o	α > 90^o
1. Mode of Operation	Rectifier	Inverter	Rectifier	Inverter
2.Average Output Voltage	Positive	Negative	Negative	Positive
3. Average Output Current	Positive	Positive	Negative	Negative
4.Flow of power	Source to load (Forward Motoring)	Load to Source (Refer Fig. B)	Source to load (Reverse Motoring)	Load to Source (Regenerative Braking)
5.Quadrant of Operation	I	IV	III	II
6.Direction of rotation	Clockwise (Refer Fig. a) In Figure B	Clockwise (Refer Fig. b) In Figure B	Counter clock (Refer Fig. c) In Figure B	Counter-clockwise (Refer Fig. d) In Figure B

Figure B

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