Introduction to Power Electronics, Power Diodes, Thyristors and Power Transistors. Different types of Power Converters, Applications of Power Electronics and Peripheral effects.

1. POWER ELECTRONICS – 10EC73
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Presented by,
Ms. Sangeetha B L

2. OUTLINE
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Introduction
Thyristors
Power Transistors
Power Semiconductor Devices
Different types of thyristors
Applications
Types of PE Circuits
Power Diodes
Control characteristics
Peripheral Effects
Examples

3. WHAT IS POWER ELECTRONICS ?
 A field of Electrical Engineering that deals with the
application of power semiconductor devices for the control
and conversion of electric power.
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6. Power electronics divided into 3 areas of specialization.
1. Electronics – solid state devices & circuits
2. Control – steady state & dynamic characteristics
3. Power – static & rotating power equipment
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7. POWER SEMICONDUCTOR DEVICES
1. Uncontrolled turn on & off devices – Power diodes
2. Controlled turn on & off characteristics – Transistors
(BJT, MOSFET, GTO, SITH, IGBT, SIT, MCT)
3. Controlled turn on & uncontrolled turn off – Thyristors
(SCR)
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8. POWER DIODES
1. General Purpose Diodes
 6000V, 4500A; High Reverse recovery time (25us);
1KHz
 Low speed applications (rectifiers & converters)
 2 types : Stud or stud mounted type.
Disk, press pak or hockey puck type
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9. 2. High speed:
 Fast recovery diodes
 6000V, 1100A;
 Reverse recovery times varies between 0.1 & 5us
 High frequency switching of power converters
 Used in low speed applications (choppers & inverters)
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10. 3. Schottky Diodes:
 Low on state voltage and very small recovery time (ns)
 100V, 300A;
 Pn junction is eliminated
 Metal is anode & semiconductor is cathode.
 Have high switching frequencies.
 Drift layer is absent; On – state losses are very low.
 Low voltage converters as feedback & freewheeling diodes.
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11. STRUCTURE OF POWER DIODE
+
V
-
Anode
Cathode
Na =10 cm
19 -3
P
+
Nd =10 cm
-3
Nd =10 cm
19 -3
-314
n+
-
n
epi
substrate
10μm
250μm
Breakdown
Voltage dependent
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12. I – V CHARACTERISTICS
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13. SWITCHING CHARACTERISTICS
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14. APPLICATIONS OF PD
 Uncontrolled rectifiers
 Choppers, inverters & controlled converters
 Commutating circuits for SCRs
 Half controlled converters & half bridge inverters.
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15. THYRISTORS
 Turn on – control signal
 Turn off – power circuit
 Controllable switches are turned on & turned off – controlled
signals.
 Line & Forced Commutated Thyristor
1. SCR
2. GTO
3. RCT
4. SITH
5. GATT
6. LASCR
7. MTO
8. ETO
9. IGCT
10. MCT
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16. SILICON CONTROLLED RECTIFIER
 SCR turns off whenever the current falls to zero or by
making the potential of the anode equal to or less than
the cathode potential.
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17. V – I CHARACTERISTICS
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18. MERITS
 Very small amount of gate drive is required.
 On state losses are reduced
DEMERITS
 Gate has no control once SCR is turned on
 External circuits are required to turn off
APPLICATIONS
 Used for high power low frequency applications
 Controlled rectifiers
 AC regulators, lighting and heating applications
 DC motor drives, large power supplies & electric circuit breakers
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19. GATE TURN – OFF THYRISTORS
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20.  GTO do not require commutation circuit
 Used for forced commutation of converters & 6000V,
6000A.
 Used for Low power applications
 Eliminates the need for forced commutation circuitry
& hence reduces cost
 Gate drive required to turn off is very large
 More power
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21. STATIC INDUCTION THYRISTOR
• Used in medium power converter
circuits with frequency of several
hundred KHz .
• 1200V, 300A
• Turn off gain is very high
• 4500V, 250A
•Low power ratings than GTO &
SITH
MOS-CONTROLLED
THYRISTOR
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22. LIGHT ACTIVATED SCR
 Turned on by light
signal
 Gate is photosensitive
 Isolation
 6000V, 1500A;
switching speed of
200-400us
 High voltage power
systems (HVDC)
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23. REVERSE CONDUCTING THYRISTORS
 Inverse parallel diode. (Anti-
parallel)
 4000V, 2000A & 800A in reverse
conduction
 Switching time 40us
 High speed switching in traction
applications
 Suitable for induction loads
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24. GATE ASSISTED TURN OFF
THYRISTOR – GATT
 Used for high speed switching, medium power
applications
 They require forced turn – off circuits
 1200V, 400A with switching speed of 8us
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25. TRIAC – BIDIRECTIONAL TRIODE
THYRISTOR
 Low power AC applications
 Heat controls, light controls,
motor controls & AC switches.
 Current flow can be controlled
in either direction.
 Turned off by line
commutation of the AC supply
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26. MOS TURN-OFF (MTO) THYRISTOR
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 It is a combination of a
GTO & MOSFET.
 High voltage (upto 10KV)
& high current (upto
4000A)
 High power applications

27. EMITTER TURN OFF THYRISTOR
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 It is a MOS-GTO hybrid device
that combines the advantage of
both the GTO & MOSFET.
 2 gates : One normal gate for turn
on & one with a series MOSFET
for turn off.
 Current rating upto 4KA & voltage
rating upto 6KV.

28. IGCT
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 It integrates a GCT with a
multilayered PCB gate
drive.
 Turned on by applying the
turn on current to its gate
 Turned off by a
multilayered gate driver
PCB.
 Used in current fed inverter
drives

29. POWER TRANSISTOR:
BIPOLAR JUNCTION TRANSISTOR
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Used in power converters (>10KHz)

30. POWER MOSFET
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•Used in high speed power converters.
•Low power SMPS & Inverters

31. IGBT
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Used in PWM inverters & SMPS

32. STATIC INDUCTION
TRANSISTOR
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 High power, high frequency
device
 Low noise, low distortion,
high audio frequency power
capability
 Suitable for low power, high
frequency application &
microwave amplifiers

33. CONTROL CHARACTERISTICS
1. SCR
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34. 2. GTO/SITH/MTO/ETO/IGCT
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35. 3. BJT
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36. 4. MOSFET & IGBT
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37. Classification of power semiconductor devices
1. Uncontrolled turn on and off (Power Diode)
2. Controlled turn on uncontrolled turn off (Thyristors)
3. Controlled turn on and off characteristic (Power Transistor, BJT,
MOSFET, GTO, IGBT)
4. Continuous gate signal requirement (BJT, MOSFET, IGBT, SIT)
5. Pulse gate requirement (SCR, GTO, MCT)
6. Bipolar voltage-withstanding capability (SCR, GTO)
7. Unipolar voltage-withstanding capability (BJT, MOSFET, GTO,
IGBT, MCT)
8. Bidirectional current capability (TRIAC, RCT)
9. Undirectional current capability (SCR, GTO, BJT, MOSFET, IGBT,
MCT, Diode)
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38. TYPES OF PE CIRCUITS
1. Diode Rectifiers: Converts ac voltage into fixed dc
voltage.
Input voltage to the rectifier Vi could be either
single phase or three phase
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39. 2. AC to DC Converter :
 Phase controlled Rectifier.
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• Use line voltage
for commutation
•HVDC
•DC Motor drives
•Static VAR
compensators
•UPS

40. Battery charger : AC – DC Converter
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41. 3. DC to AC Converter: Inverters.
 Used when main is not available, Low power portable
electronic system
 UPS, aircraft & space PS, HVDC etc.,
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42. Electric drive unit : DC – AC convertor
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43. Example: Renewable Power Generation (PV)
PV Inverter: DC-AC Converter
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44. 4. DC to DC Converter:
 Chopper in case of High power & SMPS in case of small
Power Rating.
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45. 5. AC to AC Converter:
 AC Voltage Controller (Cyclo-converters).
 Used for slow speed, very high power industrial drives
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46. Example: Renewable Power Generation (Wind)
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47. 6. Static Switches:
 Supply to these switches can be ac or dc.
 Ac static switches or dc switches
 Number of conversion stages are cascaded to produce the
desired output
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48. PERIFERAL EFFECTS
 Power converter uses switches to convert input power in
required form.
1. Switching voltage or current pulses are induced in the
power supply
2. Harmonics are induced in power supply due to improper
waveforms.
3. Load contains voltage or current spikes and harmonics
4. Interference is radiated (RFI & EMI) due to switching of
devices.
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