1. Chapter 5 Line-Frequency Diode Rectifiers
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

2. Diode Rectifier Block Diagram
Uncontrolled utility interface (ac to dc)
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

3. Chapter 5 Line-Frequency Diode Rectifiers
A Simple Circuit
Resistive load
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

4. A Simple Circuit (R-L Load)
Current continues to flows for a while even after the input voltage has gone negative
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

5. A Simple Circuit (Load has a dc back-emf)
Current begins to flow when the input voltage exceeds the dc back-emf
Current continues to flows for a while even after the input voltage has gone below the dc back-emf
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

6. Single-Phase Diode Rectifier Bridge
Large capacitor at the dc output for filtering and energy storage
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

7. Diode-Rectifier Bridge Analysis
Two simple (idealized) cases to begin with
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

8. Redrawing Diode-Rectifier Bridge
Two groups, each with two diodes
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

9. Chapter 5 Line-Frequency Diode Rectifiers
Waveforms with a purely resistive load and a purely dc current at the output
In both cases, the dc-side voltage waveform is the same
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

10. Diode-Rectifier Bridge Input Current
Idealized case with a purely dc output current
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

11. Diode-Rectifier Bridge Analysis with AC-Side Inductance
Output current is assumed to be purely dc
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

12. Understanding Current Commutation
Assuming inductance in this circuit to be zero
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

13. Understanding Current Commutation (cont.)
Inductance in this circuit is included
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

14. Current Commutation Waveforms
Shows the volt-seconds needed to commutate current
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

15. Current Commutation in Full-Bridge Rectifier
Shows the necessary volt-seconds
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

16. Understanding Current Commutation
Note the current loops for analysis
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

17. Chapter 5 Line-Frequency Diode Rectifiers
Rectifier with a dc-side voltage
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

18. DC-Side Voltage and Current Relationship
Zero current corresponds to dc voltage equal to the peak of the input ac voltage
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

19. Effect of DC-Side Current on THD, PF and DPF
Very high THD at low current values
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

20. Crest Factor versus the Current Loading
The Crest Factor is very high at low values of current
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

21. Diode-Rectifier with a Capacitor Filter
Power electronics load is represented by an equivalent load resistance
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

22. Diode Rectifier Bridge
Equivalent circuit for analysis on one-half cycle basis
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

23. Diode-Bridge Rectifier: Waveforms
Analysis using MATLAB
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

24. Diode-Bridge Rectifier: Waveforms
Analysis using PSpice
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

25. Input Line-Current Distortion
Analysis using PSpice
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

26. Line-Voltage Distortion
PCC is the point of common coupling
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

27. Line-Voltage Distortion
Distortion in voltage supplied to other loads
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

28. Voltage Doubler Rectifier
In 115-V position, one capacitor at-a-time is charged from the input.
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

29. A Three-Phase, Four-Wire System
A common neutral wire is assumed
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

30. Current in A Three-Phase, Four-Wire System
The current in the neutral wire can be very high
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

31. Three-Phase, Full-Bridge Rectifier
Commonly used
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

32. Three-Phase, Full-Bridge Rectifier: Redrawn
Two groups with three diodes each
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

33. Three-Phase, Full-Bridge Rectifier Waveforms
Output current is assumed to be dc
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

34. Three-Phase, Full-Bridge Rectifier: Input Line-Current
Assuming output current to be purely dc and zero ac-side inductance
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

35. Three-Phase, Full-Bridge Rectifier
Including the ac-side inductance
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

36. 3-Phase Rectifier: Current Commutation
output current is assumed to be purely dc
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

37. Rectifier with a Large Filter Capacitor
Output voltage is assumed to be purely dc
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

38. Three-Phase, Full-Bridge Rectifier
THD, PF and DPF as functions of load current
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

39. Crest Factor versus the Current Loading
The Crest Factor is very high at low values of current
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers

40. Three-Phase Rectifier Waveforms
PSpice-based analysis
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 5 Line-Frequency Diode Rectifiers