Upload
others
View
7
Download
0
Embed Size (px)
Citation preview
International Journal of Scientific & Engineering Research Volume 10, Issue 1, January-2019 601 ISSN 2229-5518
IJSER © 2019 http://www.ijser.org
Theoretical, Experimental Comparison and Mathematical Modeling of AC-AC 3-phase
Thyristor Anudeep.Vurity, Harshith.Ch, S.Narendar
Abstract— This paper deals with the theoretical, experimental comparison and mathematical modeling of AC-AC 3-phase PAS series Thyristors. The ‘Parallel and Series’ or (PAS) - Series thyristors use a maximum current input of 600 Amps and their load is a balanced 3-phase delta connected load. By giving various command voltages at the gate terminal, we can control their input power. An experiment is conducted on “PAS Series Thyristors” to find out the measured outputs, after simulating the models of the firing circuits of these thyristors in simulation programs such as MATLAB and PSpice. A comparison was made between the simulated and the measured output voltages, with the variation of command input. After many calculations, a mathematical model was derived between the command voltage and the RMS output voltage. It was seen from the results that the experimental and the simulated results were in close agreement at all input command voltage values.
Index Terms— PAS Series Thyristor, Thermocouple, Power controller, Firing circuit, Simulink model, Curve Fitting, PSpice Simulation, RMS Voltage.
—————————— ——————————
1 INTRODUCTION e all know how the thyristors are used in the control of the output voltage by varying their input voltage given to the gate terminal at different intervals of time. This is simulat-
ed in an ideal condition using simulating softwares such as PSpice and MATLAB which will mathematically calculate the ideal volt-age outputs of such a network.
However, in reality, that’s not the case, as the voltage sup-ply in either single phase or three phase is never constant and varies by some threshold. There are also other constraints which must be taken into consideration such as losses and other external factors. This results in the real output to be slightly varied compared to the output calculated through these simulating softwares. Hence, this paper deals with find-ing out how much is the variance between the two, using mathematical modelling of the networks involved and curve fitting the results in order to obtain a relation between the two results so that it can be used to accurately predict the results of the desired equipment, saving time and energy in this process.
2 LOAD SIMULATION SYSTEM The load simulation system is used to simulate the working of the AC-AC 3-Phase thyristor. It is generally a closed loop feedback control system. The Voltages are measured using various types of Voltmeters (mostly digital). The heart of the system is the balanced 3-phase delta connected load which on the application of a controlled supply input, gives desired heat
output, which is used to heat the aerospace component for the simulation purposes. To give a controlled input supply to the load, it is essen-tial to have a power controller as well. The open loop control system mainly consists of the following subsystems –
• 3-Phase delta connected load • Power controller for the load
2.1 3-Phase Delta Connected Load The present system uses Line-controlled delta connection. The basic circuit for a 3-phase converter consists of a pair of anti-parallel thyristors in each phase with the necessary firing cir-cuits. The circuit has three identical branches each in one phase con-nected to one of the three phase voltages. It can be seen that the circuit has three arms, one for each phase having a pair of thyristors connected in anti-parallel scheme. During each phase half cycle in the different phases, one SCR from each unit conducts. Since we are using a purely resistive load, it dissipates energy in both the half-cycles of the AC supply. [1]
2.3 Power Controller
Fig.1 Single-phase Full-wave AC voltage controller Controlled power to an EIRH (Electric Infra-red Heater) is
given by this element, which is a 3-phase AC-AC converter
W
———————————————— • Author name is Anudeep.Vurity currently pursuing U.G program in
Electrical and Electronics Engineering in Jawaharlal Nehru Techonologi-cal University, India, Ph-+91-8985501324. E-mail: [email protected]
• Co-Author name is Harshith.CH is currently pursuing U.G program in Electrical and Electronics Engineering in JNTU, India, E-mail: [email protected]
IJSER
International Journal of Scientific & Engineering Research Volume 10, Issue 1, January-2019 602 ISSN 2229-5518
IJSER © 2019 http://www.ijser.org
based on phase control of SCRs. An AC voltage controller op-erating in single phase supply is shown in Fig 1. The load used is resistive in nature. The circuit uses two thyristors which are connected in parallel but are opposite in direction to each oth-er. Here, the firing angle of these devices can be controlled separately in order to get the needed output voltage. For get-ting an AC voltage at the output, the firing angle of the two devices must remain equal. The operation is similar to that of a rectifier, except that instead of removing or reversing the negative half-cycle it is also controlled individually. The wave-forms of the output voltage against the input current are shown in below. [2]
Fig.2 Waveforms of Full-wave AC voltage controller operating in single phase
The RMS value of the output voltage (L-N) is given by
(1)
The line voltage (L-L) for a three phase system is given by (2) The present system uses Line-controlled ∆ connection. The basic circuit for a 3-phase converter is as shown in the figure above. It consists of a pair of anti-parallel thyristors in each phase with the necessary firing circuits. [2]
3 EXPERIMENTAL PROCEDURE • A command voltage was applied in the form of DC
voltage.
• The controller on application of the command voltage generated a controlled three-phase voltage across the load, depending on the command voltage.The phase voltages (L-N), and line currents were measured us-ing a power analyser.
• Since the specifications of the heaters specified a con-tinuous running duration of 20 seconds at rated volt-age, it was necessary to switch off the heater periodi-cally, after measurements were done. Command DC voltage was increased in steps of 0.5 V ranging from 1V to 5 V, signifying a power increase of 10% at each step.[3] The quantities measured during the load test on the AC controller, have been given in the Table.1
Table.1 Output voltage Vs command voltage
The Fig.3 & Fig.4 graph is generated from MATLAB using equation 1 where alpha is found out using this equation 1. And these figures are compared to Theoretical modeling re-sults.
Fig.3 Firing Angle Vs Command voltage
Fig.4 MS Output Vs Command voltage
IJSER
International Journal of Scientific & Engineering Research Volume 10, Issue 1, January-2019 603 ISSN 2229-5518
IJSER © 2019 http://www.ijser.org
4 THEORETICAL PROCEDURE A single-phase full-wave AC controller was simulated using the SimPowerSystems/Power Electronics block-set in Sim-ulink/MATLAB and also PSpice. The information on the fir-ing pulses and firing angle was taken from the results of the PSpice simulation. The system was simulated for various val-ues of Command Input Voltage ranging from 1V – 5V DC. For the present simulation, following were the parameters tak-en for the thyristor:
Ron = 0.45 mΩ Lon = 0 Vf= 1.4 V
Snubber Circuit – Not present (Rs=∞) These are the corresponding models in PSpice and MATLAB in Fig.5 & Fig.11. Since the system was a balanced three-phase system, it was easier to model it as a single-phase system and extend the results for a three-phase case.
4.1 Simulink Simulation Results
Fig.5 MATLAB Simulation model Hence, only a single-phase model has been simulated. The output result are derived from inputs and a 5V command in-put voltage is shown in Fig.6 [4]
Fig.6 Output at command input voltage 5.0V ms. Fig.7 & Fig.8 shows the results which are generated in MATLAB.
Fig.7 Firing Angle Vs Command Voltage
Fig. 8 RMS output voltage Vs Command Voltage
7.1 PSpice Simulation Results
Fig.9 PAS series thyristor Open-loop firing circuit
The open loop firing circuit in Fig.9 was modeled using PSpice and its response to different values of command input voltage was simulated. The simulation gave the waveform of the pulse signals at the output of the pulse transformer circuitry. The variation of the pulse width leads to the variation of the firing angle. The Fig.10 shows output voltage at gate terminal at 5V of command voltage.[4] Many components are studied and replaced in the model with the help of their datasheets present on-internet.[5][6][7][8][9][10][11].
Fig.10 Outputs at G1 of R – phase at a Command Voltage of 5V
The firing angle, α can be calculated from the following rela-tionship:
(3)
Where, tp: pulse width of the signal T: time period of the signal
IJSER
International Journal of Scientific & Engineering Research Volume 10, Issue 1, January-2019 604 ISSN 2229-5518
IJSER © 2019 http://www.ijser.org
Fig.11 Simplified PSpice Model of the Firing Circuit
The variation of pulse width, firing angle and RMS value of the output voltage (L-N), with the command input voltage has been presented in Table.2
Table.2 Variation of Pulse width, firing angle and RMS simulated value From the pulse width we got a desired firing angle which is substituted in Eq.1 using MATLAB to get our desired RMS output voltage.
5 Comparison of Simulated Results The experimental and simulated results have been com-pared below. Fig.12 shows the variation of output voltage for both experimental and simulated results and Fig.13 shows the variation of firing angle for both experimental and simulated result.[12]
Fig.12 Variation of Output Voltage with Command Voltage
Fig.13 Variation of Firing angle with Command Voltage
0
V-
7.628mV
15.00V
15.00V
-15.00V
-15.00V
V+15Vdc
15.00V
0V
-14.33V
Q85 Q2N3904
C260.22u
0V
-14.85V
V-
M1
-15.00V
SV7
Implementation = S1
V-
188.5mV
R11
56k
R574.7k
V-
0V
-4.200V
-14.85V
R100
2k
0
5.651V
1.327V
V1
15Vdc
SV9
Implementation = S3
C190.01u
C120.001u
V+
V+
90.00mV
0V
U17
AND2
1
23
0V
U7C
LM339
9
8
312
14
+
-
V+V-
OUT
0
15.00V
5.651V
634.2mV
Q100CD4068B
23459101112
13 1
V-
-14.95V
-4.715V
-14.85V1
C33
0.22u
0V
R40
1k
BG2
15.00V
R49
22R66.8k
R31 56k
0
V+
R4 1000K
R8 120
V+
-14.95V
0V
SV8
Implementation = S2
C290.22u
CD40
68B
-14.95V
-14.95V
U30
NAN2
1
23
0
-15.00V
5.651V
7.628mV
V
V-
3.234V
U16
AND2
1
23
R1
1000k
C280.22u
R101
2k
R30 56k
15.00V
C41u
674.7uV
0V
0
3.234V
R21
56k
R60
10k
C61u
U7B
LM339
7
6
312
1
+
-
V+V-
OUT
R102
2k
V-11.70V
R47
22
-14.33V
1.154mV
0V
D17D1N4007
D23 D1N4007
Q6A
LM339
5
4
312
2
+
-
V+V-
OUT
R35
3.3k
R103
2k
-1.427V
90.00mV
887.5nV
0V
U6C
LM339
9
8
312
14
+
-
V+V-
OUT
15.00VR10
56k
D14D1N4007
0
-14.85V
15.00V
R51
22
R564.7k
RG2
11.70V
15.00V
1.350V
15.00V
188.5mV
0V
15.00V
U12
AND2
1
23
C200.01u
V-
-4.715V
15.00V
-15.00V
C270.22u
D13D1N4007
-15.00V
632.2mV
R45
1k
V+
C100.001u
C300.22u
V11+15Vdc
D11
D1N4148
709.4mV
V
1.428V
R19
56k
R524.7k
D12D1N4007
C81u
R25
1k
-14.95V15.00V
632.2mV
0V
Q1
Q2N3904
D20 D1N4007
C310.22u
0
V+
V+
0V
1.145nV
CN1_2
0V
C180.01u
R554.7k
U14
AND2
1
23
C210.01u
2.341V
R26
1k
Q82 Q2N3904
D15D1N4007
0
-4.200V
1
C24
100u
R23
1k
V-
YG2
5.651V
11.70V 0V
-14.85V
0V
1
0V
R36
24k
V3+11.7Vdc
V
Q6B
LM339
7
6
312
1
+
-
V+V-
OUT
-14.95V
0V
R37
33k
R39
0.0001
0-15.00V
R61
1k
D16D1N4007
Q81 Q2N3904
V-
V+
1.350V
0V
U33
NAN2
1
23
D6
D1N4148
R28 56k
V-15Vdc
D22 D1N4007
R96.8k
U5B
LM339
7
6
312
1
+
-
V+V-
OUT
R342.2k
11.70V
11.70V
D7
D1N4148188.5mV
Q93
Q2N3904
Q2
Q2N3904
0
U32
NAN2
1
23
U6D
LM339
11
10
312
13
+
-
V+V-
OUT
R59
1
C140.001u
CN1_1
674.6uV
-15.00V
R5 120
15.00V
0
C1
0.01u
R13
56k
U5A
LM339
5
4
312
2
+
-
V+V-
OUT
D9
D1N4148-15.00V
-15.00V
15.00V
0V
D21 D1N4007
674.6uV
15.00V
632.2mV
C150.001u
C34
0.22u
R24
1k
0
V+
-14.95V
188.5mV
Q86 Q2N3904
U13
AND2
1
23
D8
D1N4148
R48
22
-14.95V
U29
NAN2
1
23 R53
4.7k
D10
D1N4148
U39
NAN2
1
23
C51u
D18 D1N4007
C35
0.01u
1.327V
0V
Q95
Q2N3904
Q91
Q2N3904
R104
2k
0
C16
0.01u
U5C
LM339
9
8
312
14
+
-
V+V-
OUT
U31
NAN2
1
23
OP1
-15.00V
-15.00V
207.8V
15.00V
1.327V
C21u
-1.402V15.00V
-14.85V
R36.8K
U5D
LM339
11
10
312
13
+
-
V+V-
OUT
Q94
Q2N3904
-14.33V
1.327V
0V
0VV+
R27
1k
11.70V
1.350V
15.00V
634.2mV
C25
100u
R42
1k
15.00V
15.00V
C130.001u
U15
AND2
1
23
-4.715V
11.70V
15.00V
R12
56k
C110.001u
C31u
0
11.70V
3.234V
R15
56k
R63
0.0001
U41
NAN2
1
23
CN1_2
D5
D1N4148
887.5nV
15.00V
632.2mV
R33 56k
R16
56k
V-
Vz
R22
1k
0
0
-15.00V
90.00mV
V+
-14.95V
-4.715V
11.70V
1.351V
0V
0V
0V
R20
56k
R7 1000k
Q84 Q2N3904
0
V-
YG1
OP2CN1_1
15.00V
R2
120
D19 D1N4007
R32 56k
Q96
Q2N3904
0
15.00V
R46
22
U28
NAN2
1
23
V12-15Vdc
V+
R544.7k
11.70V
634.2mV
3.234V
R44
1k
634.2mV
R14
56k
R17
56k
15.00V
-15.00V
0
11.70V
-207.8V
0V
U7A
LM339
5
4
312
2
+
-
V+V-
OUT
V+
15.00V
Vz
0V
Q83 Q2N3904
0
-14.85V
15.00V
90.00mV
1
0
0
15.00V
1.404V
11.70V
C32
0.22u
R43
1k
R41
1k
C17
0.01u
-15.00V
-14.85V
1.145nV
0V
0V
V6
4.2Vdc
Q92
Q2N3904
R50
22
-14.85V
707.7mV
-14.85V
C9
1000u
0
V-
-15.00V
R62
1k
U7D
LM339
11
10
312
13
+
-
V+V-
OUT
R105
2k
-4.715V
R58
10
RG1
15.00V
R29 56k
R18
56k
IJSER
International Journal of Scientific & Engineering Research Volume 10, Issue 1, January-2019 605 ISSN 2229-5518
IJSER © 2019 http://www.ijser.org
Fitting a curve for the variation in both firing angle and output voltage with the command voltage gives us a mathematical relationship between the input and output quantities. Fig.14 shows the curve fit for the variation of output voltage with the command voltage input.[12]
Fig.14 Curve Fit for variation of Output voltage with firing angle and their residuals.
After mathematically fitting the curve of the variation of firing angle with the command voltage, we then fit the curve for the variation of output voltage with the firing angle. Then we finally fit the curve between output and command voltage. From Fig.14 we got the below equation:
3 20 1.3 41 300 220V V V V= − + + (4)
Where, The variation of the RMS value of the output voltage with the command voltage of the “PAS Series” 3-phase AC-AC thyris-tor can be expressed in the above Equation 4. [13] Vo= Output RMS Voltage=Input Command Voltage
6 Conclusion A load test on the actual hardware was performed, to vali-date the simulated results. The command input voltage was applied to the firing circuit in an open loop configuration. Since the load was a balanced load, the output voltage across only the R-Y phases was measured as being a balanced sys-tem, the other two line voltages, Y-B and B-R would also be equal to that of the R-Y phases. A comparison was made between the simulated and the measured output voltages, with the variation of command input. The simulated output voltages being phase voltages, needed to be multiplied by a factor of √3 to convert it into line voltage, for comparison purpose. A Mathematical model was generated which was very much useful for generating a re-quired-profile without any further calculations. It was seen from the results, that the experimental and the simulated results were in close agreement at all input com-mand voltage values.
ACKNOWLEDGMENT
We are very much thankful to our project guide S.Narendar (Sci-entist ‘D’) who gave us an incredible support for this project within the Thermo-Structural Test Facility of the Defense and Research Development Organization (DRDO).
REFERENCES [1] Dr.P.S.Bimbhra, Power Electronics, Delhi: Khanna publishers,
2002. [2] MATLAB user guide, "Math works," MATHWORK, [Online].
Available: https://in.mathworks.com/. [3] OrCAD-PSpice, "PSpice User Manual," OrCAD. [4] 2N3904-npn TRANSISTOR DATA SHEET, "ALL
DATASHEET.COM," [Online]. Available: https://www.alldatasheet.com/view.jsp?Searchword=2n3904.
[5] CD4068B-CMOS INPUT GATE, "TEXAS INSTURMENTA-TIONS," 2003. [Online]. Available: http://www.ti.com/lit/ds/symlink/cd4068b.pdf.
[6] LM339-opamp, "Texas Instrumentations," december 2014. [Online]. Available: http://www.ti.com/lit/ds/snosbj3e/snosbj3e.pdf.
[7] 1N4148 Diode, "Datasheet 360- IEEE GlobalSpec," TEXAS IN-STRUMENTATION MANUFATURER, [Online]. Available: https://www.datasheets360.com/part/detail/1n4148/5885653563208841037/.
[8] L7815CV-VOLTAGE REGULATOR, "ALL DATASHEET.COM," [Online]. Available: https://www.alldatasheet.com/datasheet-pdf/pdf/22641/STMICROELECTRONICS/L7815CV.html.
[9] MC7915CT ON LINEAR VOLTAGE REGULATOR, "MOUSER ELECTRONICS," [Online]. Available: https://www.mouser.in/Search/Refine.aspx?Keyword=MC7915CT.
[10] HEF4093B-2INPUT NAND GATE SCHMITT TRIGGER, "nex-peria," [Online]. Available: https://assets.nexperia.com/documents/data-sheet/HEF4093B.pdf.
[11] "Power Control Operational Manual," STF-DOFS, DRDL, Hy-derabad, 2011.
[12] "Thyristor Power Controller Calibration," STF-DOFS/DRDL. [13] Jacob Millman and Christos C.Halkias, "Operational amplifer,"
in Integrated Electronics – Analog and Digital Circuits and Sys-tems, Tokyo, 1972, pp. 501-534.
[14] Curve Fitting-Mathematical methods; [15] Wikipedia [online]. Available:
https://en.wikipedia.org/wiki/Curve_fitting
IJSER