PALESTINE POLYTECHNIC UNIVERSITY(PPU)
POWER ELECTRONICS
Dr. Sameer Khader
Spring
2005/2006
Diac Circuits
Triac Circuits
Thryristor Circuits
Chapter Seven
Controllable switching devices
Introduction, Classification &Applications,
Practical Firing ( Triggering) Circuits
Chapter 7-A
Thyristor Circuits
1- Construction : Four PNPN layers with special doping in each layer, with purpose to obtain different electron and holes concentrations in these layers. Each one has different potential voltage
P N P NA K
GA
G
KPrinciple of operation :The thyristor constructionPresents three diodes In series ( two forward biased and the third reverse biased).The thyristor will conduct only if D2 forward biased, therefore the current will flow from A to K. This case could be achieved by different ways called switching techniques that should be described hereinafter :
A K
GD3D2D1
Th.
Methods for Switching- on the thyristor The switching process of the thyristor is called “ Firing”, because after Switching process is ceased the firing signal can be removed with purpose to reduce the gate losses .There're several methods applied to realize this purpose :
1-Gate-firing method :by supplying the gate terminal with positive voltage ( this is the most applied method - major method). 2-by suddenly increasing the Anode voltage 3-by increasing the the thyristor temperature over predetermined limit. 4- Photo effect method, which used in photo devices ( Photo thyristor)
Gate-firing method: the firing circuit is shown below: Thyristor
I-V curve
Thyristor Main Parameters:
There’re several parameters related to static & dynamic performance of the thyristor,
these parameters are as follow :
1-VAK- thyristor voltage at steady state 2 V;
2-VBO- -break over voltage , voltage after which thyristor will turning on at constant
gate current ;
3-VBR- break down voltage in reverse biasing state;
4-IH- thyristor holding current :this a minimized load current keeping the thyristor in
conducting state ( if the current goes down the thyristor will switch-off);
5- IL- thyristor latching current :this a minimized load current keeping the thyristor in
conducting state after removing the gate signal ;
6-VGT- minimum gate voltage required to firing the thyristor at given loading condition
, VGT 0.8…12V;
7-IGT- minimum gate current., IGmax- maximum gate current ;
8-di/dt- speed of (increasing/decreasing) of thyristor current ;
9-dv/dt - speed of (increasing/decreasing) of thyristor voltage .
Thyristor Dynamic Performances DC
50 Hz
V2220/-220V
SCR22N5064
R310k 30%D4BAR74
R4100
DC
35.00ms 50.00ms 65.00ms 80.00ms
250.0 V
150.0 V
50.00 V
-50.00 V
-150.0 V
-250.0 V
A: v2_1
35.00ms 50.00ms 65.00ms 80.00ms
1.250 V
0.750 V
0.250 V
-0.250 V
-0.750 V
A: d4_k
35.00ms 50.00ms 65.00ms 80.00ms
2.250 A
1.750 A
1.250 A
0.750 A
0.250 A
-0.250 A
A: r4[i]
35.00ms 50.00ms 65.00ms 80.00ms
250.0 V
150.0 V
50.00 V
-50.00 V
-150.0 V
-250.0 V
A: scr2_1
S3
50 Hz
V585/-85V SCR6
BRX44
+
C31.0uF
R85k 90%
SCR5MCR22-4
R102.5k
R950
0
SCR5_3
SCR5_2
R8_1
SCR5_1
V5_1
0.000ms 15.00ms 30.00ms 45.00ms
100.0 V
50.00 V
0.000 V
-50.00 V
-100.0 V
A: s4_1
0.000ms 15.00ms 30.00ms 45.00ms
90.00 V
70.00 V
50.00 V
30.00 V
10.00 V
-10.00 V
A: scr5_1
0.000ms 15.00ms 30.00ms 45.00ms
150.0 W
100.0 W
50.00 W
0.000 W
A: r10[p]
V-source V-source
V-gate V-gate
V-thyris
P-loadP-load
AS2
+ V480V
SCR3BRX45
S1
R55k 60%
+
C21.0uF
SCR4MCR22-3
50 Hz
V3120/-120V
R60.5k
R750
A
S1_2
0
V3_1
V4_1
SCR4_1
R5_3
SCR4_2
C2_1
0.000ms 15.00ms 30.00ms 45.00ms
125.0 V
75.00 V
25.00 V
-25.00 V
-75.00 V
-125.0 V
A: r5_3
0.000ms 15.00ms 30.00ms 45.00ms
2.000 V
0.000 V
-2.000 V
-4.000 V
-6.000 V
A: scr3_1
0.000ms 15.00ms 30.00ms 45.00ms
25.00 V
-25.00 V
-75.00 V
-125.0 V
A: scr4_1
0.000ms 15.00ms 30.00ms 45.00ms
300.0 W
200.0 W
100.0 W
0.000 W
A: r7[p]
V-source
V-gate
V-thyris
P-load
AS2
+ V480V
SCR3BRX45
S1
R55k 60%
+
C21.0uF
SCR4MCR22-3
50 Hz
V3120/-120V
R60.5k
R750
A
R5_3
0
R5_3
V4_1
SCR4_1
R5_3
SCR3_1
SCR3_1
0.000ms 0.300ms 0.600ms 0.900ms
87.00 V
85.00 V
83.00 V
A: s1_1
0.000ms 0.300ms 0.600ms 0.900ms
1.3940 V
1.3938 V
1.3936 V
A: scr3_1
0.000ms 0.300ms 0.600ms 0.900ms
1.65525 V
1.65475 V
1.65425 V
1.65375 V
1.65325 V
1.65275 V
A: scr4_1
0.000ms 0.300ms 0.600ms 0.900ms
138.936 W
138.934 W
138.932 W
138.930 W
138.928 W
A: r7[p]
V-source
V-gate
V-thyris
P-load
AC -circuit
DC -circuit
2-Phase Control Gate Firing Circuits: 1- RC relaxation oscillator
Th2Th1 Th1
Th2
C C
R-load
R1 R1
R2 R2
R-load
Math. Modeling 1- Gate firing circuit using RC relaxation oscillator;2- Gate firing circuits using RC circuit and called Phase control ;These circuits may can use to fire thyristor in AC or DC circuit: in both sources the connected elements must be with the following relations with purpose to realized successful operation: R2<<R1; and R-load << R1; * DC source VBOTh2 < Vs ; and IH2 < Vs/R1; ** AC source VBOTh2 < Vm; and IH2 < Vm/R1; Vs(t)=Vm.sin (t);
Vc t( ) Vs 1 e
t
Vs
R1 CR1
Vc tp( ) VBOTh2VBOTh2
tp R1 C lnVs
Vs VBOTh2R1
Vs
Vs VBOTh2
The thyristor Th2 will
conduct when Vc=VBOTh2; This could be
occurred at t=tp ; this time
called (firing instant)
min sin 1 VTG
Vm
VTG
Vm
max sin 1 Vm
Vm
Vm
Vm
R1minVm
IGTRGK
Vm
IGTRGK
RGKVGT
IGT
VGT
IGT
R1maxVm
IGmaxRGK
Vm
IGmaxRGK
tp360
Ttp
The firing angle of previous firning circuits in AC circuit canDetermine as follow :
9<<90 ( without C)
I-V curve
•In DC source, tp- presents delay time , so by increasing Ig the thyristor allow more current to follow ; therefore increasing the load power ;• In AC source, tp- presents delay angle which corresponds to =tp.360/T, so by increasing Ig, decreases, thus load power increases P()=Pmax . Cos(), where Pmax-maximum allowable power. • may can change from 0 to 90 ( without C) or to 145 (with C) ;• The thyristor gate voltage must be > + 0.85 V at least; VBR > Vm ; ILmin > IL at firing( remains conduct); and ILmin < IH ( swith off) .• By increasing di/dt at given Ig the thyristor capable to carry additional current ILoad .• By increasing Ig, VBO ( ac circuits), which means that the thyristor is fired at earliest time , therefore increasing the load voltage and power .•The gate pulse must removed after successfully firing the thyristor , with aim to reduce the gate losses .
Conclusion
Chapter 7-B
Triac Circuits1- Triac ( Triode Alternating Current Switch ) – presents two parallel connected thyristors with common gate, which energized with positive and negative voltage. The main purpose of the Triac is to control the RMS load voltage, therefore there're several applications such as : * Lighting control ( dimmer circuits); **- Temperature control ;
*** Torque –speed control of induction machines. 2- Symbol:
3- Circuit application:
3- I-V Curve:
Triac Firing Circuits
2.500 V
Triacvoltage
Loadcurrent
Gatevoltage
Load
35.00ms 50.00ms 65.00ms 80.00ms
200.0 V
100.0 V
0.000 V
-100.0 V
-200.0 V
A: r2_2
Triacvoltage
35.00ms 50.00ms 65.00ms 80.00ms
2.500 A
1.500 A
0.500 A
-0.500 A
-1.500 A
-2.500 A
A: r2[i]
Loadcurrent
35.00ms 50.00ms 65.00ms 80.00ms
1.500 V
0.500 V
-0.500 V
-1.500 V
A: d1_k
Gatevoltage
D1100HF120PV
+
C11uF
MAC210-6
R110k 5%
50 Hz
V1220/-220V
BA
R2100
BA
0.000ms 15.00ms 30.00ms 45.00ms
300.0 V 200.0 V 100.0 V 0.000 V-100.0 V-200.0 V-300.0 V
0.000ms 15.00ms 30.00ms 45.00ms
3.000 A 2.000 A 1.000 A 0.000 A-1.000 A-2.000 A-3.000 A
0.000ms 15.00ms 30.00ms 45.00ms
1.500 V 1.000 V 0.500 V 0.000 V-0.500 V-1.000 V-1.500 V
D1100HF120PV
+ C10.3uF
MAC210-6
R110k 20%
50 Hz
V1220/-220V
BA
R2100
BA
1- Phase angle control without diode 2- Phase angle control with diode
Pulse generator
AC source
S1
0.5uF
UJT
2N2646
20V
D
Tr
Q2004L4
C
B
100 Hz
0/15V
A
50 Hz
120/-120V
R59k
R4150
R347
R120
Rload100
D
C
B
A
0.000ms 10.00ms 20.00ms 30.00ms
25.00 V
15.00 V
5.000 V
-5.000 V
-15.00 V
-25.00 V
A: tr_3
0.000ms 10.00ms 20.00ms 30.00ms
125.0 V
75.00 V
25.00 V
-25.00 V
-75.00 V
-125.0 V
A: v3_1
0.000ms 10.00ms 20.00ms 30.00ms
125.0 V
75.00 V
25.00 V
-25.00 V
-75.00 V
-125.0 V
A: tr_2
0.000ms 10.00ms 20.00ms 30.00ms
5.000 V
3.000 V
1.000 V
-1.000 V
-3.000 V
-5.000 V
A: tr_3
0.000ms 10.00ms 20.00ms 30.00ms
250.0 V
150.0 V
50.00 V
-50.00 V
-150.0 V
-250.0 V
A: tr_2
5.000ms 15.00ms 25.00ms 35.00ms
25.00 V
15.00 V
5.000 V
-5.000 V
-15.00 V
-25.00 V
A: c1_2
UJTneedles
Loadvoltag
e
Pulsegenerator
Loadvoltag
e
Capacitorvoltage
Source voltage
3-Triac firing circuits using UJT
B1
B2
Math. Modeling of Triac Circuits Three main circuits are introduced with purpose to fire the Triac device( Phase control with or without diode, with UJT and with Diac device). The presence of diode in the gate circuit remove one half cycle , therefore convert the Triac into Thyristor . In both circuits there are several relations characterized the application
of such a device . These relations are as follow :
Vdc2
T0
T
2
tVm sin t( ) d
Vrms2
T 0
T
2
tVmsin t( )2d
2
T
Prms ( ) Pmax cosPmax
PmaxVrms 0( )
2
RLoad
Vrms
Pdc ( ) Pdcmax cosPdcmax
PdcmaxVdc 0( )
2
RLoad
Vdc 0( )
1- when 0<</2 Vs<Vrms< 0; 2- Vdc=0 for symmetrical firing 3- Vdc0 for asymmetrical firing 4- the exsisting of I nductace , reduced The control rang of Prms=F().UJT – circuit:
tp R1 C lnVBB
VBB Vp tp( )R1
VBB
VBB Vp *
,VBB-base to base UJT’s voltage:, ujt- UJT’s intrinsic factor <=1,Vp- UJT’s peak voltage;, tp-delay time ( firing instant) .
XrRBB
RBB R4
RBB
RBB R4Vp tp( ) ujt Xr VBB 0.6
Vp t tp( ) Vc tp( )t tp
Vc tp( ) VBB 1 e
tp
Chapter 4-C
Diac Circuits1- Diac ( Diode Alternating Current Switch ) – presents two anti-parallel connected diodes with special construction , aiming to maintain relatively high threshold voltage across its terminals . The main purpose of the Diac is to devide the source voltage between its terminals and the load terminals , therefore there're several applications such as : * Firing device in Triac –gate circuit ; **- Over voltage protective device ; 2- Symbol:
3- Circuit modification:
4- I-V Curve:
5- Time-varying performances:
Phase control circuit with Diac & Triac:
Vd Vc x( )x
Vc C( ) Vcm sinxVc C( )Vc
Vcm 2Vs
1 RC2
Vs
RC
c tan 1 RC( )RC
c xc x
The main equations are as follow , and can derives when Vdiac =Vc at given angle.
The firing angle
Additional Firing circuits
C10.5uF
Q12N2646D2
BZG03C30
R46k 10%
SCR210RIA20
S1
50 Hz
V260/-60V
D118DB2
R850
R7250
R650
R550
0.000ms 15.00ms 30.00ms 45.00ms
65.00 V
45.00 V
25.00 V
5.000 V
-15.00 V
-35.00 V
A: d1_3
0.000ms 15.00ms 30.00ms 45.00ms
65.00 V
45.00 V
25.00 V
5.000 V
-15.00 V
-35.00 V
A: r4_3
0.000ms 15.00ms 30.00ms 45.00ms
40.00 V
30.00 V
20.00 V
10.00 V
0.000 V
-10.00 V
A: r4_1
0.000ms 15.00ms 30.00ms 45.00ms
3.500 V
2.500 V
1.500 V
0.500 V
-0.500 V
-1.500 V
A: scr2_2
0.000ms 15.00ms 30.00ms 45.00ms
61.00 V
41.00 V
21.00 V
1.000 V
-19.00 V
-39.00 V
A: scr2_1
0.000ms 15.00ms 30.00ms 45.00ms
71.00 W
51.00 W
31.00 W
11.00 W
-9.000 W
-29.00 W
A: r5[p]
0.000ms 15.00ms 30.00ms 45.00ms
1.250 V
0.750 V
0.250 V
-0.250 V
-0.750 V
-1.250 V
A: scr2_2
0.000ms 15.00ms 30.00ms 45.00ms
60.00 V
40.00 V
20.00 V
0.000 V
-20.00 V
-40.00 V
A: scr2_1
0.000ms 15.00ms 30.00ms 45.00ms
60.00 W
40.00 W
20.00 W
0.000 W
-20.00 W
-40.00 W
A: r5[p]
Source voltage
Zenervoltage
Capacitor voltage
Gate needles
Thyristorvoltage
Loadpower
Gate needles
Thyristorvoltage
Loadpower
1- Practical circuit using UJT:
1- Low =R4.C12- High =R4.C1
T11TO1
D418DB2
50 Hz
V160/-60V
S2
SCR110RIA20
R16k 30%
D3BZG03C30
Q22N2646C2
1.5uF
R1050
R950
R3250
R2150
0.000ms 15.00ms 30.00ms 45.00ms
66.50 V
16.50 V
-33.50 V
A: c2_2
0.000ms
15.00ms
30.00ms 45.00ms
26.50 V
6.500 V
-13.50 V
A: q2_2
0.000ms 15.00ms 30.00ms 45.00ms
2.000 V
1.000 V
0.000 V
A: scr1_2
0.000ms 15.00ms 30.00ms 45.00ms
50.00 V
0.000 V
-50.00 V
A: scr1_1
5.000ms 20.00ms 35.00ms 50.00ms
100.0 W
0.000 W
-100.0 W
A: r10[p]
Gate needles
Capacitor voltage
Thyristorvoltage
Loadpower
UJT Signal at
B2B1
B2
2- Practical circuit using UJT and Isolation Transformer:
5.000ms 20.00ms 35.00ms 50.00ms
7.500 V
2.500 V
-2.500 V
A: c2_2
5.000ms 20.00ms 35.00ms 50.00ms
1.000 V
0.500 V
0.000 V
A: scr1_2
5.000ms 20.00ms 35.00ms 50.00ms
50.50 V
0.500 V
-49.50 V
A: scr1_1
5.000ms 20.00ms 35.00ms 50.00ms
100.5 W
0.500 W
-99.50 W
A: r10[p]
Capacitor voltage
Gate needles
Thyristorvoltage
Loadpower
D11N5402
C42uF
C12uF
Q2MAC15A6
D31N5402
SCR2S2003LS1
SCR1
S2003LS1
S1
50 Hz
V3120/-120V
R10.1k
R80.9k
R747
R60.1k
R50.9k
R40.1k
0.000ms 30.00ms 60.00ms 90.00ms
250.1 V
150.1 V
50.10 V
-49.90 V
-149.9 V
-249.9 V
A: r6_2
0.000ms 30.00ms 60.00ms 90.00ms
250.1 V
150.1 V
50.10 V
-49.90 V
-149.9 V
-249.9 V
A: r8_2
0.000ms 30.00ms 60.00ms 90.00ms
250.1 V
150.1 V
50.10 V
-49.90 V
-149.9 V
-249.9 V
A: r5_1
0.000ms 15.00ms 30.00ms 45.00ms
15.00 V
5.000 V
-5.000 V
-15.00 V
-25.00 V
-35.00 V
A: r6_1
0.000ms 15.00ms 30.00ms 45.00ms
1.250 A
0.750 A
0.250 A
-0.250 A
-0.750 A
-1.250 A
A: r6[i] 0.000ms 15.00ms 30.00ms 45.00ms
150.0 W
100.0 W
50.00 W
0.000 W
-50.00 W
-100.0 W
A: r6[p]
0.000ms 15.00ms 30.00ms 45.00ms
12.49 W
7.490 W
2.490 W
-2.510 W
-7.510 W
-12.51 W
A: c1[p]
3: ON-OFF firing circuit :This circuit illustrates firing techniques used in AC Voltage controller based on so called ON-OFF method, where it’s necessary to fire the thyristor at the beginning of both half-cycles .
Source voltag
e
Vg-th1
Vg-th2
V-triac
I-load
P-load
Ic1
Load
S1SCR2
S2003LS1
C22uF
D11N5402
SCR1S2003LS1
C12uF
50 Hz
V1120/-120V R5
4.1kR40.1k R3
0.9kR15.1k
S1SCR2
S2003LS1
C22uF
D11N5402
SCR1S2003LS1
C12uF
50 Hz
V1120/-120V R5
5.1kR40.1k R3
0.9kR15.1k
20.00ms 50.00ms 80.00ms 110.0ms
250.0 V
150.0 V
50.00 V
-50.00 V
-150.0 V
-250.0 V
A: v1_1
20.00ms 50.00ms 80.00ms 110.0ms
250.0 V
150.0 V
50.00 V
-50.00 V
-150.0 V
-250.0 V
A: scr1_2
20.00ms 50.00ms 80.00ms 110.0ms
250.0 W
150.0 W
50.00 W
-50.00 W
-150.0 W
-250.0 W
A: r4[p]
20.00ms 50.00ms 80.00ms 110.0ms
300.0 V
100.0 V
-100.0 V
-300.0 V
A: v1_2
Zero-Voltage switching
S=Off S=ONS S
20.00ms 50.00ms 80.00ms 110.0ms
200.0 V
0.000 V
-200.0 V
A: v1_1
20.00ms 50.00ms 80.00ms 110.0ms
10.00 V
0.000 V
-10.00 V
A: scr1_3
20.00ms 50.00ms 80.00ms 110.0ms
5.000 V
0.000 V
-5.000 V
A: scr1_2
20.00ms 50.00ms 80.00ms 110.0ms
200.0 W
0.000 W
-200.0 W
A: r4[p]
V-source
Vg-th1
Vth1
Load power
Introduction, Classification & Applications
I- Introduction: Power electronic controllable devices found widespread application in variuos industrial fields, depending on the operation function. These devices can classified in two main families : 1- Thyristor family ( including SCR, TRIAC, DIAC , GTO , Phot Thyristor ,……….); 2- Transistor family ( including BJT, UJT, FET, MOSFET,…., SIT,……) .
II- Classification : Power electronic devices may can classified in four main classes , as follow:
Power
Electronics
AC to DC converters
Dc to ACconverters
DC to DC converters
AC to AC converters
Uncontrolled rectifiers ( diodes…)Controlled rectifiers, ( SCR,…)
Inverters ( Thyristorized or Transistorized ) -VFI, CFI & RFI
Choppers( Thyristorized or Transistorized )–Step-down , step-up..
AC Voltage Controller (Thyristorized)Phase-angle control, On-OFF, Cyclo..
III- Applications :AC to DC Converters
-Power supplies , driving a dc motors, battery charger, …
Dc to ACConverters
-Uninterruptible Power Supplies (UPS) ,Brushless dc motor, Lighting , frequency converters …
DC to DC Converters
-Voltage regulators and stabilizers , Speed control of dc motors, temperature control, ….
AC to AC converters
-Speed control of induction machines , RMS voltage control, temperature control, lighting control, frequency changers, cycloconverters,…...
IV- Advantages : - High efficiency of energy conversion; and minimized losses- High switching capability and reliability ,….- Long life time ,little maintenance ,…-Light weight, reduced cost and avoiding of transformer drawbacks ,……-Application in precise systems and hazard operation regions,..
Fig.1A
Fig.2A
Fig.1B
Fig.2B
V-Principal circuits:
Fig.3-A Fig.3-B
Fig.4-BFig.4-A
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