1. Three-Phase Inverters
Consider three single-phase inverters in parallel, driven 120° apart.

2. Three-Phase Inverter (continued)
Three single-phase full bridge inverters
12 transistors, 12 diodes, 3 transformers
Could it be simpler?

3. Alternative (Preferred) Configuration
6 transistors, 6 diodes conduction for 120° or 180°

4. 180° Conduction
Three transistors ON at a time

5. Summary Table

6. Waveforms for 180 Conduction

7. Phase Voltages for 180 Conduction

8. Waveforms for 180 Conduction

9. Summary Table

10. Mode 1 Operation

11. Mode 1 Operation
Q1, Q5, Q6 conduct

12. Summary Table

13. Mode 2 Operation

14. Mode 2 Operation
Q1, Q2, Q6 conduct

15. Summary Table

16. Mode 3 Operation

17. Mode 3 Operation
Q1, Q2, Q3 conduct

18. Phase Voltages for 180 Conduction

19. Fourier Series for Line-to-Line Voltages

20. For the other Line-to-Line Voltages

21. Line-to-Line rms Voltage

22. rms value of the nth Component
Fundamental Component

23. Line-to-Neutral Voltages

24. Phase Voltages (Y-connected load)

25. Line Current for an RL load

26. DC Supply Current IL=√3Io is the rms load line current
Vo1= fundamental rms output line voltage
Io is the rms load phase current
Θ1 = the load impedance angle at the fundamental frequency

27. Three-Phase Inverter with RL Load