EXPERIMENT-3
PSPICE Simulation of single phase AC voltage controller with PWM controlfor RL loads
…………………………………………………………………………………
AIM: To analyze the single phase AC Voltage controller with RL loads.
APPARATUS: PSPICE software, personal computer.
THEORY:
By connecting anti parallel pair of SCR’s in series with the load . The voltage applied to the load can be controlled. This type of power controller is known as an AC voltage regulator. Therefore AC voltage regulator converts fixed mains voltage directly to variable alternating voltage without a change in the frequency.
CIRCUIT DIAGRAM FOR RL-LOAD:
Fig 1 single phase ac voltage controller
OPERATION FOR RL-LOAD:
During 0 to Π, T1 is forward biased. At ωt=α,T1is triggered and i0 = iT1 starts building up through the load. At Π , load and source voltages are zero but the current is not zero because of the presence of the inductance in the load circuit. At β>Π, load current reduces to zero. Angle β is called extinction angle. After Π , T1 reverse biased but does not turn off becausei0 is not zero. At β only, when i0 is zero, T1 is turned off as it is already reverse biased. After the commutation of T1 at β , a voltage of magnitude Vmsinβ at once appears as a reverse bias across T1 and as a forward bias across T2 . From β to (Π+α), no current exists in the power circuit. T2 is turned on at (Π+α)>β, current i0 = iT2 starts building up through the load in the reverse direction. At 2Π, load and source voltages are zero but the current is not zero.
At (Π+α+γ),iT2=0 and T2 is turned off because as it is already reverse biased. At (Π+α+γ), Vmsin(Π+α+γ) appears as a forward T1 and as a reverse bias across T2. From (Π+α+γ) to (2Π+α), no current exists in the power circuit. At (2Π+α), T1 is turned on and current starts building up as before.
SUB CIRCUIT FOR THYRISTOR MODEL:
PSPICE is the software used for laboratory purpose.different types of analysis are possible with PSPICE like DC analysis ,AC analysis and transient analysis. PSPICE allows one to define a small circuit as a sub circuit which can be called upon in several places in the main circuit .The general form of sub circuit is SUBCKT SUBNAME[two or more nodes].
Fig 2: Sub circuit for thyristors
A sub circuit must end with end statement.in this program the thyristor sub circuit consists of diode dependent current controlled current source and voltage controlled switch are used.the sub circuit represents the equivalent circuit of the thyristor.By using the END,.TRAN we can analyse the performance and different waveforms of the single phase full converter.
EXPRESSIONS FOR RL LOAD:
EXPRESSIONS FOR HARMONICS:
For n=3,5,……….
SAMPLE CALCULATIONS:
CIRCUIT DIAGRAM:
GATE PULSES:
PROGRAM:
VS 10 SIN (0 169.7V 60HZ)
VG1 2 4 PULSE (0V 10V 4166.0US 1NS 1NS 100US 16666.7US)
VG2 3 1 PULSE (0V 10V 12500.US 1NS 1NS 100US 16666.7US)
R 4 5 2.5
L 5 6 6.5MH
VX 6 0 DC 0V
C 4 0 1245.94UF
CS 1 7 .1UF
RS 7 4 750
XT1 1 4 2 4 ASCR
XT2 4 1 3 1 ASCR
.SUBCKT ASCR 1 2 3 2
S1 1 5 6 2 SMOD
RG 3 4 50
VX 4 2 DC 0V
VY 5 2 DC 0V
RT 2 6 1
CT 6 2 10UF
F1 2 6 POLY(2) VX VY 0 50 11
.MODEL SMOD VSWITCH(RON=.01 ROFF=10E+5 VON=.1V VOFF=0V)
.ENDS ASCR
.TRAN 1US 33.33MS
.PROBE
.OPTIONS (ABSTOL=1.0N RELTOL=1.0M VNTOL=1.0M ITL5=10000)
.FOUR 60HZ I(VX)
.END
MODEL GRAPHS.
OUTPUT PROFILE;
**** 02/11/15 09:28:18 *********** Evaluation PSpice (Nov 1999) **************
**** CIRCUIT DESCRIPTION
******************************************************************************
VS 1 0 SIN(0 169.7V 60HZ)
VG1 2 4 PULSE(0V 10V 4166.0US 1NS 1NS 100US 16666.7US)
VG2 3 1 PULSE(0V 10V 12500.0US 1NS 1NS 100US 16666.7US)
R 4 5 2.5
L 5 6 6.5MH
VX 6 0 DC 0V
C 4 0 1245.94UF
CS 1 7 0.1UF
RS 7 4 750
XT1 1 4 2 4 ASCR
XT2 4 1 3 1 ASCR
.SUBCKT ASCR 1 2 3 2
S1 1 5 6 2 SMOD
RG 3 4 50
VX 4 2 DC 0V
VY 5 2 DC 0V
RT 2 6 1
CT 6 2 10UF
F1 2 6 POLY(2) VX VY 0 50 11
.MODEL SMOD VSWITCH(RON=.01 ROFF=10E+5 VON=.1V VOFF=0V)
.ENDS ASCR
.TRAN 1US 33.33MS
.PROBE
.OPTIONS (ABSTOL=1.0N RELTOL=1.0M VNTOL=1.0M ITL5=10000)
.FOUR 60HZ I(VX)
.END
***02/11/15 09:28:18 *********** Evaluation PSpice (Nov 1999) **************
**** Voltage Controlled Switch MODEL PARAMETERS
******************************************************************************
XT1.SMOD XT2.SMOD
RON .01 .01
ROFF 1.000000E+06 1.000000E+06
VON .1 .1
VOFF 0 0
**** 02/11/15 09:28:18 *********** Evaluation PSpice (Nov 1999) **************
**** INITIAL TRANSIENT SOLUTION TEMPERATURE = 27.000 DEG C
******************************************************************************
NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE
( 1) 0.0000 ( 2) 0.0000 ( 3) 0.0000 ( 4) 0.0000
( 5) 0.0000 ( 6) .0000 ( 7) 0.0000 (XT1.4) 0.0000
(XT1.5) 0.0000 (XT1.6) 0.0000 (XT2.4) 0.0000 (XT2.5) 0.0000
(XT2.6) 0.0000
VOLTAGE SOURCE CURRENTS
NAME CURRENT
VS 0.000E+00
VG1 0.000E+00
VG2 0.000E+00
VX 0.000E+00
XT1.VX 0.000E+00
XT1.VY 0.000E+00
XT2.VX 0.000E+00
XT2.VY 0.000E+00
TOTAL POWER DISSIPATION 0.00E+00 WATTS
**** 02/11/15 09:28:18 *********** Evaluation PSpice (Nov 1999) **************
**** FOURIER ANALYSIS TEMPERATURE = 27.000 DEG C
******************************************************************************
FOURIER COMPONENTS OF TRANSIENT RESPONSE I(VX)
DC COMPONENT = 2.355339E-01
HARMONIC FREQUENCY FOURIER NORMALIZED PHASE NORMALIZED
NO (HZ) COMPONENT COMPONENT (DEG) PHASE (DEG)
1 6.000E+01 4.071E+01 1.000E+00 -9.740E+01 0.000E+00
2 1.200E+02 1.914E-01 4.702E-03 -3.580E+01 1.590E+02
3 1.800E+02 4.780E+00 1.174E-01 1.837E+01 3.106E+02
4 2.400E+02 5.176E-02 1.272E-03 -2.896E+01 3.606E+02
5 3.000E+02 1.623E+00 3.987E-02 -1.675E+02 3.195E+02
6 3.600E+02 3.610E-02 8.868E-04 -4.181E+01 5.426E+02
7 4.200E+02 8.813E-01 2.165E-02 7.013E+00 6.888E+02
8 4.800E+02 2.543E-02 6.248E-04 -2.986E+01 7.493E+02
9 5.400E+02 5.133E-01 1.261E-02 -1.730E+02 7.036E+02
TOTAL HARMONIC DISTORTION = 1.266085E+01 PERCENT
JOB CONCLUDED
TOTAL JOB TIME .08
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