pe&ds slide group 2 2014
TRANSCRIPT
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School of Electrical and Electronic Engineering © Dr. N. Ertugrul
TYPES of DIODES
Higher current and voltage ratings
Fast recovery diodes
Schottky Diodes
Germanium Diodes
GaAs diodes Silicon Carbide Diodes
SiliconDevices
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
IF(AV) = 1.5 to 40 A
PARAMETER GaAs Si
VBR (V) 2500 1400
trr (nsec) 25 50
VF (V) 1.8 1.6
T jmax (oC) 260 150
Jmax (A/cm2) 500 300
Performance ComparisonUltrafast GaAs Power Diodes
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School of Electrical and Electronic Engineering © Dr. N. Ertugrul
States of Diodes
vf
id
A K
+ -
Conducting
A K
+-
id = 0
Blocking
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Conduction Losses of Diodes
i
v
Ideal diodecharacteristic
In an ideal diode:vf = 0
Ploss = 0
A K
+ -vf
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In Practical Diodes
A K
+ -vf
i
v
Operatingpoint
vf = 0
Pd = id . vf = 0
id
vf
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Parallel Connected Power Diodes
To increase the current carrying capability.
D1 D2
R1 R2
L1 L2
Helps current sharing under steady-state condition
COUPLED INDUCTORSHelps current sharing under dynamic conditionIf ID1 rises L1di/dt increasesOpposite polarity voltage across L2
Low impedance path through D2 and current is shifted to D2
The current sharing will be depended upon theirrespective forward voltage drops.
It can be achieved by- connecting current-sharing resistors (losses !)- providing equal inductances, e.g. in the leads- selecting diodes with equal forward voltage drop.
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
Series Connected Power Diodes If a diode cannot meet the required voltage rating
Connected in series to increase the reverse blocking capability.
D1
D2
D1
v
iD2
However, the same type of diodesdiffer due to the tolerance of theirproduction process.
In the forward biasedcondition, both diode
conduct almost the same
amount of current.
In the reversed biased condition, each diode has to carry the same
leakage current. THEREFORE THE BLOCKING VOLTAGESWILL DIFFER.
Vd1 Vd2
-Is
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Series Connected Power Diodes
D1Rs
Cs
D2Rs
Cs
Rs
Rs
For steady-state
voltage sharing.
Voltage sharing under
dynamic condition
(such as switching
loads) can be achieved
by the capacitors.
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
POWER ELECTRONIC
DEVICES :
THYRISTOR
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School of Electrical and Electronic Engineering © Dr. N. Ertugrul
DC
gates DC
6 in ONE
Single
gatespower terminals
2 in ONE
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THYRISTOR FAMILY
SCR
TRIAC RCT GATT FCT ASYMMETRIC MCTGTO
Commonly used Thyristors
•Phase control thyristors
(slow, 50Hz, 60Hz)
• Inverter thyristors (fast, kHz !)
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
G
K
A
THYRISTOR (two transistors model)
G
K
Apnp
npn
IA
IC 2
IB 1
IK
IB 2IG
IC 1
4 LAYER DEVICE
G
K
A
p
n
p
n
p
n
pn
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THYRISTOR - Regeneration
G
K
A
IG
gate signal, IG= IB2
IC 2
IB 2
IG causes IC2 (and IB1 )
IB 1 IB1 causes IC1
IC 1 IC1 increases the original
IB2
two transistor builds each
other up continuous conduction
occur if IC1 > IG(initial) !
IK
IA
must be forward biased
+
-• and it conducts load current IA
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Tyhristor’s Characteristic Curves
v
i
B) On-state characteristic
(Forward conduction)
IG3 > IG2 > IG1 > IG0
A) Forward blockingstate characteristic
C) Off-state characteristic
(Reverse blocking)
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A) Forward Blocking State
The highest
repetitive
peak forward
off-state voltage
Forward
breakdown
voltage
+Load
v
i
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
b) On-State Characteristic(forward conduction)
Holding current, IH
The threshold
voltage
+Load
v
i
On-state
voltage drop
Latching current, IL
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C) Off-State Characteristic(Reverse Blocking)
The highest repetitive peak
reverse -blocking voltageReverse
breakdown
voltage
+Load
v
i
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Requirements to TURN-ON and
TURN-OFF of a Thyristor
To turn-on :
G
K A
•VAK > 0 AND
•VGK > 0 AND
• iT > IL
• iT < IH AND
•VAK = 0 OR
VAK < 0
To turn-off :
G
K A
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Features of (Thyristor)• Very higher rating thyristors are available
• One-way switch
• Controlled turn-on capability
• No controlled turn-off capability (except GTO, MCT)
• dV/dt (off state voltage) limited , (low impedance or
uncontrolled switch on)
• dI/dt (on state current) limited , (very rapid local hot spot
may occur)
• Rugged mature product• Relatively slow switch
• External commutation required
• Simple drive circuit
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
A simple gate drive circuit for a thyristor
• Line commutated
• No isolation
• Not very fine control
MAIN THYRISTOR
A
K
G
armatureof the motor
field coil
field coil
240V
BT101
BYX10
BYX10
270
W
5.6K
1K
W
16
F, 64V
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GATE TURN-OFF (GTO)THYRISTOR
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
A K
G
• Keeping the benefits of thyristor• One way switch• Controlled turn-on capability• Controlled turn-off capability• Slower switching than BJT or IGBT• 3000 A, 4500 V , electric traction
applications (locomotives)
GTO THYRISTOR
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A drive circuit for the GTO THYRISTOR
A
K
G
load
BTW58
R 1470
+13V to 18V
0V
R 2
82
L1
2
C1
470nF
T2
BD334
T1
BC635
AC
Drive circuit
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TRIAC
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TRIAC
i
i i
i
T2 T1
G
i g
i g
i g
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
T2 (+) and G (+)
T2 (+) and G (-)
T2 (-) and G (+)
T2 (-) and G (-)
T1 is reference
TRIAC
T2 T1
G
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• Bidirectional current flow• No turn-off capability
• A positive or a negative gate signal
TRIAC
• As an AC mechanical switch
• (solid state relay)
• The average power control
• ON-OFF control or proportional
• control (temp.cont.)
APPLICATIONS :
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A sample solid state relay circuit
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POWER ELECTRONICDEVICES
TRANSISTORS:
a) BJT
b) MOSFET
c) IGBT)
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TRANSISTORS AS A SWITCH
10 -1 10 0 10 1 10 2 10 4 10 5
Switching frequency (kHz)
Controllable
power
(kVA)
10 -1
10 1
10 2
10 3
10 4
MOSFET
BJT
IGBT
GTO
THYRISTOR
10 5
10 6
1990
2004
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Application ranges of power switching devices
School of Electrical and Electronic Engineering © Dr. N. Ertugrul
a) BIPOLAR JUNCTION TRANSISTOR
•One way controlled
turn-on and turn-off
• Current controlled
• Low on-resistance
• Low switching speed
•High power controlI
C= I
B
IE
= IB
+ IC
npnC
E
B
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BJT Characteristics
Increasing
IB
VCE(+ For NPN
- For PNP)
IC(+ For NPN
- For PNP)
Cut-off region
Residual voltage
S a t u r a t i o n r
e g i o n
1
2
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A Base Drive Circuit for the BJT
BJT andFree Wheeling DiodeDRIVE CIRCUITISOLATION CIRCUIT
+5V
-5V
27
370
2.4K 1K HCPL2200
CD4050
(1/6)optocoupler
0.1
F 2N3467
2N3725BC109
TIP162
+Vdc
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b) MOSFET
•Usually three terminaldevices
•One way controlled
turn-on and turn-off
•Voltage controlled
•High switching speed
•High on-resistance
(in high power MOSFETs)
•Moderate power control
n channel
D
S
G
Id
Vds
Vgs
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MOSFET transistor symbols