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Electrical Power Engineering 3 Power Electronics

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Electrical Power Engineering 3 Power Electronics Dr Ewen Macpherson Dr Sasa Djokic Dr Markus Mueller Electrical Power Engineering 3 Power Systems 14 lectures Power ... – PowerPoint PPT presentation

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Title: Electrical Power Engineering 3 Power Electronics


1
Electrical Power Engineering 3Power Electronics
  • Dr Ewen Macpherson
  • Dr Sasa Djokic
  • Dr Markus Mueller

2
Electrical Power Engineering 3
  • Power Systems
  • 14 lectures
  • Power Electronics
  • 10 lectures
  • Powerway
  • lab exercise, 2 mornings
  • Castaway
  • power system design exercise, weeks 6-11

3
Electrical Power Engineering 3
  • Assessment
  • 60 Exam (Power Systems, Power Electronics)
  • 15 Powerway
  • 25 Castaway

4
Electrical Power Engineering 3
  • Powerway
  • Starts week 2
  • 2 mornings total
  • Groups of 8-12
  • Work in pairs

Check when you are due to attend! Prepare
Beforehand
5
Electrical Power Engineering 3
  • Castaway
  • Design power system expansion in Sri Lanka
  • Starts week 6
  • Groups of 5 (approx.)
  • Power System simulation (Powerworld)
  • Costings required
  • Presentation week 11

6
Power ElectronicsDr Ewen Macpherson
  • Lectures
  • Monday 2-3 (every week)
  • Examples Class
  • Friday 2-3 (every 3rd week)
  • Tutorials
  • Wednesday 12-1 (weeks 4/5 and 9/10)

7
Power Electronics
  • Recommended Text
  • Power Electronics Converters, Applications
    Design
  • Mohan, Undeland Robbins (Wiley)
  • (also used for Power Electronics 4)

8
Power Electronics uses Semiconductor Devices to
process power (1W to 10,000MW)
9
Devices
Diode p-n 8,000A, 6,500V
Bipolar transistor n-p-n (rarely used)
Thyristor p-n-p-n 7,000A, 12,000V
Triac 150A, 1,500V
Power MOSFET 100A, 1,200V
IGBT (insulated gate bipolar transistor) 2,400A, 6,500V
GTO (gate turn off thyristor) 4,000A, 6,500V
10
Circuits
  • Rectifier converts ac ? dc
  • Inverter converts dc ? ac
  • (dc) chopper converts dc ? dc
  • ac controller converts ac ? ac
  • General term for all Converter

11
Applications
  • Motor Speed Control

Speed controlled by varying Vdc
12
Applications
  • Uninterruptible Power Supplies (UPS)
  • For critical loads where a mains failure is
    unacceptable
  • Computers
  • Safety systems (oil rigs)
  • Emergency lighting (hospitals, cinemas)

13
Applications
  • Uninterruptible Power Supplies

14
Applications
  • High Voltage DC Power Transmission (HVDC)
  • AC normally used, except
  • bulk power transmission, long distances
  • submarine cables
  • 2000 MW cross-channel link, France-UK
  • 500 MW Scotland-Ireland link

15
Applications
  • High Voltage DC Power Transmission (HVDC)

16
Applications
  • Electronic Power Supplies
  • All electronic equipment needs a power supply

Worldwide market 20 billion?
17
ThyristorSCR Silicon Controlled Rectifier
  • 4 layer (p-n-p-n) device
  • Switched on by applying gate pulse
  • Stays on when gate signal removed, if current
    flowing through it
  • Like a diode, current only flows in one direction

18
Thyristor
  • Reverse bias
  • blocking
  • reverse breakdown voltage exceeded - dies!

19
Thyristor
  • Forward bias
  • blocking
  • forward breakover voltage exceeded turns on

20
Thyristor
  • Forward bias gate pulse applied
  • turns on
  • stays on

21
Thyristor Example Circuit
  • Short gate pulse (3V, 20us, 50mA to 1A)
  • turns on
  • Gate pulse removed
  • stays on if current gt holding current

22
Thyristor
  • Serious problem
  • Not easily switched off
  • Only switches off when current through it goes to
    zero (or drops below holding current)

23
Power MOSFET
  • Voltage controlled device
  • Remove gate drive to turn off
  • Very low gate current
  • Very high speed (up to 10MHz)
  • Up to 100A, 1,200V

24
Gate Turn Off Thyristor (GTO)
  • Current controlled device
  • Turned off by negative gate pulse
  • Very high gain at turn-on
  • Low gain at turn-off (typically 4)
  • Low frequency (up to 3 kHz)
  • Up to 6.5kV, 4kA

25
Insulated Gate Bipolar Transistor (IGBT)
  • Combines high gate impedance of MOSFET with high
    current capability of BJT
  • Medium frequency (up to 100 kHz)
  • Up to 2.4 kA, 6.5 kV
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