POWER ELECTRONICS BASIC COMPONENTS INTRODUCTION PART 2

1. POWER ELECTRONICS
Components like power diode,
SCR, Diac, Triac, GTO etc

2. PNPN DIODE
– Also known as Schokley Diode
– Four layers just like SCR
– But NO gate terminal

4. Characteristic

5. Mostly used
as Switch or as
Relaxation
Oscillator

6. POWER DIODE
Two terminals Anode and
Cathode
Low resistance in Forward &
High resistance in Reverse bias
Thus act as SWITCH in rectifiers

7. Size comparison:
SIMPLE diode & POWER diode

8. Just like our normal diode but with higher
Ratings in 100s of Ampere & 1000s of
Voltage
Size becomes very BIG

9. TRANSISTOR
• Also known as BJT (Bipolar Junction Transistor)
• Two types :NPN & PNP
• NPN મ ાં નીકળે
• PNP મ ાં પ્રવેશે

10. NPN PNP

11. • Ratings of Amp & Volt very high
• Three Terminals : Base, Collector & Emitter
• Three configurations:
– CB
– CC
– CE
• Common Emitter configuration highly used

12. POWER MOSFET
Disadvantages of FET:
•High Drain Resistance
•Low input Impedance
•Slow operation
•MOSFET may be considered as
Advance FET

13. Metal Oxide Semiconductor Field Effect Transistor

14. Two Types
– N Channel
– P Channel
• Main current flows from Drain to Source
• Control by Gate

15. Advantages
• Input Impedance very high
• Low output impedance
• Very high speed
• High Efficiency
• Low noise
• High Thermal Stability
• Widely used in industries

16. SCR
• Unidirectional device
• PNPN layer construction
• Three terminals: Anode, Cathode & Gate
• Conducts only when Gate pulse is applied
• If gate current increases, Firing angle will be
reduced hence more Output & Vice versa
• Used as Controlled switch to operate load at
any percentage

17. Symbol, Construction & Photo

18. GTO
• Gate Turn off Thyristor
• Similar to SCR but with TURN OFF facility
• Can be TURNED ON with positive pulse at gate
• Can be TURNED OFF with High Negative pulse at
gate

19. Symbol & Photo

20. LASCR
• Light Activated Silicon Controlled Rectifier
• Can be operated by LIGHT not with Current
• Similar characteristic like SCR
• As intensity of Light increases, SCR firing will
also increase and vice versa

21. LASCR:
Symbol & Photo

22. RCT
• Reverse Conducting Thyristor
• Reverse Blocking Voltage is ZERO
• Thus Size of Converter and Heat Sink reduced

23. DIAC
• Mostly used with SCR or TRIAC for firing them
• Bidirectional Device

25. TRIAC
Bidirectional
device
Just like two SCRs
connected back to
back in parallel in
opposite direction
Used in
Controlled
Switch &
Rectifiers

28. TRIAC
Symbol & Photo
•Three terminals: MT1, MT2 & Gate
•Most Common in our home to regulate fan
speed

29. Three terminals: MT1, MT2
& Gate
Most Common in our home
to regulate fan speed