1. Application of Power Electronics
Chapter 10
Application of Power Electronics

2. Application of Power Electronics
10.1 DC motor drivers ( thyristor-DC motor system )
Frequency converters and AC drivers
10.3 Uninterruptible Power Supply ( UPS )
10.4 Switching Power Supply
10.5 Power factor correction (PFC)
10.6 Application in utility power system
10.7 Other applications

3. 10.1 DC motor drivers ( Thyristor-DC motor system )
Rectifier mode of operation
Inverter mode of operation
Reversible DC motor drive system
(four-quadrant operation)

4. 10.1.1 Rectifier mode of operation
Waveforms and equations
(10-1)
where
(for 3-phase half-wave)
Waveforms of 3-phase half-wave rectifier with DC motor load

5. Speed-torque (mechanic) characteristic when load current is continuous
(10-2)
For 3-phase half-wave
(10-3)
(10-4)
For 3-phase bridge
For 3-phase half-wave
(10-5)

6. Speed-torque (mechanic) characteristic when load current is discontinuous
EMF at no load (taking 3-phase half-wave as example)
For a  60º
For a > 60º
For 3-phase half-wave

7. (a1< a2 < a3  60º, a5 > a4 > 60º)
Speed-torque (mechanic) characteristic when load current is discontinuous
For different a
The point of EMF at no load is raised up.
The droop rate becomes steer. (softer than the continuous mode)
For 3-phase half-wave
(a1< a2 < a3  60º, a5 > a4 > 60º)

8. 10.1.2 Inverter mode of operation
Equations
are just the same as in the rectifier mode of operation except that Ud, EM and n become negative. E.g., in 3-phase half-wave
Or in another form
(10-3)
(10-4)
Speed-torque characteristic of a DC motor fed by a thyristor rectifier circuit )
cos ( å + - = R I U E d M b
(10-11) e C n - = 1 å + R I U d b
cos
(10-12)

9. 10.1.3 Reversible DC motor drive system (4-quadrant operation)
Back-to-back connection of two 3-phase bridge circuits

10. 4-quadrant speed-torque characteristic of Reversible DC motor drive system

11. 10.2 Frequency converters and AC drivers
Composite converter:
Combination of two or more converters in cascaded connection
Indirect AC to AC converters
(AC-DC-AC converters)
Composite converters
Indirect DC to DC converters
(Isolated DC to DC converters)

12. Indirect AC to AC converters (AC-DC-AC converters)
Classifications
According to type of the DC links:
AC-DC-AC converters
Voltage-source type
Current-source type
According to whether output voltage and frequency is variable:
AC-DC-AC converters
Variable voltage variable frequency (VVVF)
(AC-DC-AC frequency converters)
Constant voltage constant frequency (CVCF)
In narrow sense, frequency converter only refers to
VVVF AC-DC-AC converter.

13. 10.2.1 Configurations of AC-DC-AC converters
Configurations with one-direction power flow
Voltage-source type
Current-source type

14. Configuration with regenerative energy dissipating circuit
Braking transistor and braking resistor

15. Configurations with regenerative power feedback through inversion-mode thyristor rectifier circuit
Voltage-source type
Current-source type

16. Configurations realizing bi-directional power flow through double-sided PWM converters
Voltage-source type
Current-source type 16

17. 10.2.2 Major Applications of AC-DC-AC frequency converters (VVVF converters)
Adjustable speed AC motor drives
Advantages of AC motors over DC motors
Energy saving on AC motors
High-performance AC motor drives
Control of AC motors driven by AC-DC-AC frequency
converters (VVVF converters)
Constant voltage frequency ratio control
Slip frequency control
Vector control
Direct torque control

18. 10.3 Uninterruptible power supplies (UPS)
Basic configuration of UPS
Major Applications of CVCF converters

19. UPS with back-up energy source

20. UPS with back-up energy source and bypass lines

21. 10.4 Switching Power Supply
Linear power supply
Line frequency AC input
Rectifier
Filter
Series Pass Regulator
Transformer DC
Regulated DC output
Line frequency
Isolation
Switching power supply
Regulated DC output
Line frequency AC input
Inverter
Filter
Transformer DC
High frequency AC
Rectifier AC
High frequency
Isolation
Indirect DC to DC converter

22. Point of load regulation (POL)
Specifically means a particular switching power supply for a large size IC chip, such as a CUP or a memory chip.
Synchronous Buck
Synchronous Boost

23. A typical application of switching power supply
Power system for telecommunication equipment

24. Control of switching power supply
Voltage mode control
Current mode control
Peak current mode control
Average current mode control

25. Voltage mode control

26. Current mode control

27. Peak current mode control

28. Average current mode control

29. 10.5 Power Factor Correction (PFC)
Operation principle of typical PFC circuit
Single-phase boost PFC
3-phases single-switch boost PFC
Single stage PFC

30. Single-phase boost PFC

31. 3-phases single-switch boost PFC

32. Single stage PFC ( )
A typical converter

33. 10.6 Application in utility power system
High voltage DC transmission (HVDC)
Reactive power compensation
Harmonics suppression
Power quality control, FACTS and custom power

34. High voltage DC transmission (HVDC)

35. Reactive power compensation
Thyristor switched capacitor (TSC)
Thyristor controlled reactor (TCR)
Static var generator (SVG)

36. Thyristor switched capacitor (TSC)U

37. TSC waveforms when the capacitor is switched in/outVT 1 2
The voltage across the thyristor must be nearly zero when switching in the capacitor, and the current of the thyristor must be zero when switching out the capacitor.

38. TSC with the electronic switch realized by a thyristor and an anti-parallel diode
The capacitor voltage will be always charged up to the peak of source voltage.
The response to switching-out command could be a little slower (maximum delay is one line-cycle).

39. Thyristor-controlled reactor (TCR)
To control the effective current flowing through the reactor by controlling delay angle, therefore control the reactive power absorbed by the reactor. u a i b c n

40. Static var generator (SVG)
Also called static compensator (STATCOM)
VSC based SVG
CSC based SVG

41. Operation principle of SVG

42. Harmonic suppression Two solutions Power factor correction
Circuit configuration of an Active power factor (APF)
Two solutions
Power factor correction
Harmonic compensation

43. Operation principle of APF

44. Power quality control Power quality problems Power quality controllers
Current harmonics
APF
Reactive power
SVC or SVG
Dynamic voltage restorer
(DVR)
Voltage sag
Universal power quality
controller (UPQC)
Voltage flicker

45. Flexible AC Transmission System (FACTS)
FACTS is actually a general term of application if power electronic to the utility electric power transmission system - for higher controllability and larger transmission capacity.
Typical FACTA devices
SVC
SVG
Thyristor Switched Series Capacitor (TSSC)
Thyristor Controlled Series Compensator (TCSC)
Static Synchronous Series Compensator (SSSC)
Unified Power Flow Controller (UPFC)

46. Custom Power
Custom power is a general term of application of power electronics to the utility electric power distribution system for better quality and higher reliability of the power supplying to different customers.
Typical Custom Power devices
SVC or SVG (D-STATCOM)
DVR
APF
Solid State Transfer Switch (SSTS)

47. 10.7 Other applications Lighting Power supply for different lamps
Power supply for gas discharge lamps is specifically called ballast.
Welding
Typical configuration of an electronic ballast
Typical configuration of a welding power supply