1. Converter Classification
ECE 442 Power Electronics

2. First-Quadrant Converter
Load Current iL flows into the load (+)
Load Voltage is +
Rectifier
ECE 442 Power Electronics

3. Second-Quadrant Converter
Load Voltage is +
Load Current iL flows out of the load (-)
Inverter
ECE 442 Power Electronics

4. Second-Quadrant Converter
ECE 442 Power Electronics

5. When the switch is closed
E forces current through L, load voltage vL = 0
ECE 442 Power Electronics

6. When the switch is opened
ECE 442 Power Electronics

7. ECE 442 Power Electronics

8. First and Second Quadrant Converter
ECE 442 Power Electronics

9. S1 and D4 operate as a first-quadrant converter.
S2 and D4D1 operate as a second-quadrant converter
ECE 442 Power Electronics

10. Second Quadrant Operation2
S2 closed S2 open
ECE 442 Power Electronics

11. Third and Fourth Quadrant Converter
The load voltage is always negative, but the load current is either positive or negative
ECE 442 Power Electronics

12. Third Quadrant Operation
S3 closed S3 open iL, vL are always negative
ECE 442 Power Electronics

13. Fourth Quadrant Operation
S2 closed load current +, load voltage – (zero)
S2 open load current +, load voltage negative, (-Vs)
ECE 442 Power Electronics

14. Four-Quadrant Converter
Load Current can be positive or negative
Load Voltage can be positive or negative
For fourth quadrant operation, reverse E.
ECE 442 Power Electronics

15. Summary of a four-quadrant converter
ECE 442 Power Electronics

16. Summary of the conducting devices
ECE 442 Power Electronics