Lab 3

DC-DC Converters:
1. Introduction and Background:
DC-DC converter converts voltage from dc to dc. DC converter is like a transformer that can both step up
and step down voltage but for dc only. DC converters use switching devices like IGBTs, MOSFETs, GTOs,
BJTs etc. There can be ripples in output voltage just like in the case of rectifiers, that’s why filters might
be used to filter out harmonics. Some of the performance parameters for dc converters are ripple factor,
THD, HD and conversion efficiency [1].

2. DC-DC Boost Converter:

In Boost converter average dc output voltage (Va ¿ is greater than input dc voltage. Circuit uses two
switches, one is controlled switch that can be MOSFET, IJBT etc. and other uncontrolled switch that is a
diode. Circuit has two mode of operations. In first mode, controlled switch is turned on and current
flows through inductor and energy is stored in it. In second mode, controlled switch is turned off, and
current that was previously flowing through controlled switch flows through L, C, diode and load. For
our circuit, we have used

Rload=5 Ohms, L=5 mH, C= 0.00011 F.

Figure 1: Boost Converter

2.1. Methodology:
Circuit is simulated in Simulink (MATLAB) and results are also calculated using formulas from lecture
notes. At the end, calculated and simulated results are compared.
Equations used to calculate average output voltage, inductor ripple current and capacitor ripple voltage
for Boost converter for R and RL load are following

Vs
Vo ( avg )=
1−k
Vs
∆ I ( inductor )= kT
L
kIa
∆ Vc=
fC
2.2. Resistive Load:
Table 1: Resistive Load

Item Calculated Observed Calculated Observed

Vdc(source) 25 25 25 25
fsw 100 kHz 100 kHz 100 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.25 0.25
Vdc 50 49.22 33.3 32.56
∆Vdc(load) 0.45 0.4 0.15 0.124
∆Idc(inductor) 0.025 0.076 0.0125 0.025

2.3. RL Load:
Table 2: RL Load

Item Calculated Observed Calculated Observed

Vdc(source) 25 25 25 25
fsw 100 kHz 100 kHz 100 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.25 0.25
Vdc 50 33.3
∆Vdc(load) 0.45 0.15
∆Idc(inductor) 0.025 0.0125

2.4. Resistive Load and Changing Frequency:

Table 3: Resistive Load with changing switching frequency

Item Observed Observed Observed Observed

Vdc(source) 25 25 25 25
fsw 1 kHz 5 kHz 10 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
Vdc 64.6 53.4 51.22 49.22
∆Vdc(load) 40 9 4.4 0.4
 ∆Idc(inductor) 7.8 1.85 0.83 0.025

2.5. Resistive Load and Changing Output Capacitance:

Table 4: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

Cout (F) 0.0011 0.00011 0.000011 0.0000011
Vdc(source) 25 25 25 25
fsw 100 kHz 100 kHz 100 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
Vdc 49.16 49.22 49.28 56.89
∆Vdc(load) 0.0375 0.38 5.8 39
∆Idc(inductor) 0.0075 0.077 1.18 8

2.6. Resistive Load and Changing Inductance:

Table 5: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

L (H) 0.2875 m 10u 28.75u 2.875u
Vdc(source) 25 25 25 25
fsw 100 kHz 100 kHz 100 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
Vdc 49.22 50.72 49.24 50.69
∆Vdc(load) 0.398 7 0.42 1.2
∆Idc(inductor) 0.078 1.4 0.085 0.225

2.7. Conclusion:
Boost converter steps up input DC voltage. Value of output DC voltage depends upon duty cycle. Duty
cycle can be varied by changing turn on time or switching frequency. As duty cycle is decreased, output
voltage also decreases. Output voltage also increases by decreasing switching frequency. Ripple in
output voltage and inductor current depend upon value of output capacitance and inductance value
respectively. If value of filter capacitance is decreased, ripple in output voltage is increased. Similarly, if
value of inductance is decreased, ripple current also increases.

3. DC-DC Buck Converter:

Buck converter is used to step down DC voltage. Buck converter also has two mode of operations. In first
mode of operation, switch is turned on and input voltage appears across load. In second mode of
operation, switch is turned off and energy of capacitor is dissipated through diode in load.

Rload=5 Ohms, L=3 mH, C= 30 µF.

Figure 2: Buck Converter

3.1. Methodology:
Circuit is simulated in Simulink (MATLAB) and results are also calculated using formulas from lecture
notes. At the end, calculated and simulated results are compared.

Equations used to calculate average output voltage, inductor ripple current and capacitor ripple voltage
for Boost converter for R load are following

Vo ( avg )=k × Vs
Vs ( 1−k ) k
∆ I ( inductor )=
fL
k ( 1−k ) Vs
∆ Vc= 2
8 LC f

3.2. Resistive Load:

 Table 6: Resistive Load

Item Calculated Observed Calculated Observed

Vdc(source) 50 50 50 50
fsw 10kHz 10kHz 10kHz 10kHz
D (duty cycle) 0.5 0.5 0.75 0.75
Vdc 25 25.02 37.5 37.55
∆Vdc(load) 0.174 0.17 0.13 0.13
∆Idc(inductor) 0.42 0.0325 0.3125 0.027

3.3. Resistive Load and Changing Frequency:

Table 7: Resistive Load with changing switching frequency

Item Observed Observed Observed Observed

Vdc(source) 50 50 50 50
fsw 1 kHz 10 kHz 50 kHz 100 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
Vdc 19.34 25.02 25 25
∆Vdc(load) 15 0.17 0.005 0.0017
∆Idc(inductor) 3 .03 0.0012 0.0004

3.4. Resistive Load and Changing Output Capacitance:

Table 8: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

Cout (µF) 0.3 1 3 30
Vdc(source) 50 50 50 50
fsw 10 kHz 10 kHz 10 kHz 10 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
Vdc 24.61 24.46 24.57 25
∆Vdc(load) 2 1.9 1.2 0.13
∆Idc(inductor) 0.4 0.35 0.2 0.0027

3.5. Resistive Load and Changing Inductance:

Table 9: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

L (H) 0.03 m 0.3 m 3m 30 m
Vdc(source) 50 50 50 50
fsw 10 kHz 10 kHz 10 kHz 10 kHz
D (duty cycle) 0.5 0.5 0.5 0.5
 Vdc 35.65 25.12 25.02 25.02
∆Vdc(load) 12 2 0.2 1.17
∆Idc(inductor) 2.5 0.4 0.04 0.0325

3.6. Conclusion:
Buck converter steps down input voltage. Value of output DC voltage depends upon duty cycle. By
increasing duty cycle (k), we get higher DC voltage and vice versa. By changing switching frequency,
ripples in output voltage and inductor current also change. As value of filter capacitance is increased,
ripple in output voltage and current are decreased. Same is the case for inductance value.

4. DC-DC Buck-Boost Converter:

A buck-boost regulator can both step up and step down DC voltage. Polarity of output voltage is
opposite of input voltage. Circuit has two mode of operations, in first mode when switch is on, inductor
is charged by source voltage and in the meantime, capacitor is discharged through load. In 2 nd mode of
operation, when switch is off, inductor energy charges capacitor and dissipates through load.

Figure 3: Buck-Boost Converter

4.1. Methodology:
Circuit is simulated in Simulink (MATLAB) and results are also calculated using formulas from lecture
notes. At the end, calculated and simulated results are compared.

Equations used to calculate average output voltage, inductor ripple current and capacitor ripple voltage
for Boost converter for R load are following.
 −k
Vo ( avg )= Vs
1−k
Vs ×k
∆ I ( inductor )=
fL
k × Ia
∆ Vc=
Cf
4.2. Resistive Load:
Table 10: Resistive Load

Item Calculated Observed Calculated Observed

Vdc(source) 25 25 25 25
fsw 10kHz 10kHz 10kHz 10kHz
D (duty cycle) 0.25 0.25 0.75 0.75
Vdc -8.3 -8.318 -75 -73.81
∆Vdc(load) 0.104 0.09 2.8 2.7
∆Idc(inductor) 0.83 0.08 2.5 2.7

4.3. Resistive Load and Changing Frequency:

Table 11: Resistive Load with changing switching frequency

Item Observed Observed Observed Observed

Vdc(source) 25 25 25 25
fsw 1 kHz 10kHz 50 kHz 100 kHz
D (duty cycle) 0.75 0.75 0.75 0.75
Vdc -80.74 -75 -73.82 73.82
∆Vdc(load) 6.4 2.8 0.5 0.25
∆Idc(inductor) 6.3 2.5 0.5 0.25

4.4. Resistive Load and Changing Output Capacitance:

Table 12: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

Cout (µF) 2 200 2000 5000
Vdc(source) 25 25 25 25
fsw 10 kHz 10 kHz 10kHz 10 kHz
D (duty cycle) 0.75 0.75 0.75 0.75
Vdc -20.27 -73.06 -75 -73.81
∆Vdc(load) 82 27 2.8 1.2
∆Idc(inductor) 82 27 2.5 1.2
 4.5. Resistive Load and Changing Inductance:
Table 13: Resistive Load with changing Capacitance

Item Observed Observed Observed Observed

L (µH) 1 7.5 75 25
Vdc(source) 25 25 25 10kHz
fsw 10 kHz 10 kHz 10 kHz 0.75
D (duty cycle) 0.75 0.75 0.75 -73.81
Vdc -133 -75.5 -73.8 2.7
∆Vdc(load) 6 3 2.8 2.7
∆Idc(inductor) 6 3 2.8 25

4.6. Conclusion:
Buck-Boost converter can both step up and step down DC voltage. When duty cycle is greater than 0.5,
voltage is stepped up and when duty cycle is below 0.5 voltage is stepped down. Changing frequency of
switching has a significant effect on ripple voltage and current. By increasing switching frequency, ripple
voltage and current is decreased. Similarly, increasing capacitance or inductance will also decrease
ripple voltage and current.

Lab 4
Inverters:
 1. Introduction and Background:
Inverter is electronic circuit that converts DC voltage in AC voltage. Inverter can be either single phase or
three phase depending upon output voltage. Depending upon pulse and no of SCRs used inverter can be
single phase two or 04 pulses for single phase output case. Three phase inverter can have 120 or 180-
degree pulse width [2].

2. Single Phase Inverters:

Single phase inverter converts DC voltage into single phase AC voltage. Output should ideally be
sinusoidal but practically, it contains certain harmonics. Single phase inverters are further classified
based on SCRs used and pulse modulation technique.

Methodology:
Circuits are simulated in Simulink MATLAB and theoretical calculations are drawn using formulas from
notes.

For single phase two pulse inverter theoretical calculations are made using following equations.

Vdc
Vo ( rms )=
2
Vo(t )
Io ( t )=
Z
Where,

Z=√ R 2+(wL)2
Further expression of output current requires Fourier solution.

For single phase two pulse inverter theoretical calculations are made using following equations.

Vo ( rms )=Vdc
∞
4 Vdc
Io ( t )= ∑ nπZ
sin ( nwt −θ )
n=1 ,3 , 5 ….

Z=√ R 2+(wL)2

2.1. Single Phase Two Pulse Inverter:

Single phase two pulse inverter uses two SCRs to convert DC into AC. Circuit diagram is shown below.
 Figure 4: Single Phase Two Pulse Inverter

Table 14: RL Load

Vload simulation load current Vload load current

(V) simulation (A) calculated (V) calculated (A)

200 61.35 200

Table 15: RL Load

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 4.947 61.35 86.65 0.1456 0.02649
Voltage (V) 144 200 161.3 0.701 0.2083

Figure 5: Single Phase Two Pulse Inverter Output Voltage and Current
 Figure 6: Single Phase Two Pulse Inverter’s Gate Pulses

2.2. Single Phase 4 Pulse Inverter:

Four SCRs are used for this circuit; therefore, four pulses are required to operate them. Figure for single
phase 04 pulse inverter is as following.
 Figure 7: Single Phase Four Pulse Inverter

Table 16: RL Load

Vload simulation load current Vload load current

(V) simulation (A) calculated (V) calculated (A)

285.6 121.7 400

Table 17: RL Load

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 1.387 121.7 172.1 0.02243 0.07078
Voltage (V) 76.66 285.6 320.5 0.1086 0.5607

Figure 8: Single Phase Four Pulse Inverter Output Voltage and Current
Figure 9: Single Phase Four Pulse Inverter’s Gate Pulses
 2.3. Single Phase 4 Pulse Inverter over Modulation:
Over modulation is technique of PWM in which output voltage of inverter is increased with it. Over
modulation in PWM occurs, when the width of pulse goes to 0 or/ and 100%
before the modulating signal has reached its maximum or minimum value.
Figure 10: Single Phase Four Pulse Inverter over Modulation
 Table 18: RL Load

Vload simulation load current Vload load current

(V) simulation (A) calculated (V) calculated (A)

318.6 151.8 400

Table 19: RL Load

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 0.915 151.8 214.6 0.1017 0.2559
Voltage (V) 52.08 318.6 399.6 0.4906 2.026

Figure 11: Single Phase Four Pulse Inverter over Modulation Output Voltage and Current
 Figure 12: Single Phase Four Pulse Inverter’s Gate Pulses

2.4. Conclusion:
Single phase inverter provides single phase AC output. Magnitude of output voltage and harmonics in
output quantities depend on modulation techniques and no of switching devices. For two pulses scheme
i.e. using two SCRs output voltage’s magnitude is less compared to 04 pulse technique. Also THD is quite
high compared to other two circuits. Highest value of output and best quality of output is obtained
when over modulation technique is used.
 3. Three Phase Inverters:
These inverters produce three phase output voltage. This circuit uses 06 switching devices to convert DC
voltage in AC voltage. Conduction mode of switches can use either 120 degrees or 180 degrees’
conduction mode. Apart from these SPWM technique can also be used for switching devices.

Methodology:
Circuits are simulated in Simulink MATLAB and theoretical calculations are drawn using formulas from
notes.

For three phase inverter with 120 and 180-degree conduction mode, theoretical calculations are made
using following equations (for Phase values).

For 120-degree mode,

Vo ( rms )=0.4082 Vs
Vo(rms)
Io ( rms )=
R
For 180-degree mode,

Vo ( rms )=0.4714 Vs

Vo(rms)
Io ( rms )=
R
For SPWM case with R load mode,

Vo ( rms )=0.625 Vs
Vo(rms)
Io ( rms )=
R
For SPWM case with RL load mode,

Vo ( rms )=0.625 Vs
Io ( rms ) is calculated by taking rms of ℱ expression

3.1. Three Phase Inverter with 120 and 180 Pulse Width:
In 120-degree mode, each switch conducts for 120 degrees. Conduction sequence of 06 switching
devices will be 16, 12, 23, 34, 45, and 56. For each 60-degree inverter any two of 06 switches will be on
as per sequence listed earlier. In 180-degree conduction mode, 03 switches will conduct simultaneously.
Two switches will be either from upper or lower les and other will be from remaining leg. Switching
sequence will be 612, 123, 234, 345, 456, and 561.
 Figure 13: Three Phase Inverter with 120 and 180 Pulse Width

Table 20: Three Phase Inverter with 120 Pulse Width

Vload simulation load current Vload load current

(V) (Phase) simulation (A) calculated (V) calculated (A)

163.3 16.33 163 16

Table 21: Three Phase Inverter with 120 Pulse Width

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 31.09 16.33 22.05 0.006666 4.414
Voltage (V) 31.09 163.3 220.5 0.06666 44.14
Figure 14: Three Phase Inverter with 120 Pulse Width Output Voltage

Figure 15: Three Phase Inverter with 120 Pulse Width Gate Pulses

Table 22: Three Phase Inverter with 180 Pulse Width

 Vload simulation load current Vload load current
(V) (Phase) simulation (A) calculated (V) calculated (A)

188.6 18.86 188.56 18.86

Table 23: Three Phase Inverter with 180 Pulse Width

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 31.07 18.86 25.47 0.01333 5.089
Voltage (V) 31.07 188.6 254.7 0.1333 50.89
Figure 16: Three Phase Inverter with 180 Pulse Width Output Voltage

Figure 17: Three Phase Inverter with 180 Pulse Width Gate Pulses
 3.2. SPWM Three Phase Inverter with R load:
In Sinusoidal PWM, the width of each pulse is varied in proportion to the amplitude of the sine wave
evaluated at the center of the same pulse. The gating signals are generated by comparing a sinusoidal
reference wave with a triangular carrier wave. These modulated signals are then applied at gates of
three phase inverter’s switching devices.

Figure 18: Three Phase Inverter with SPWM

 Table 24: Three Phase Inverter with SPWM

Vload simulation load current Vload load current

(V) (Phase) simulation (A) calculated (V) calculated (A)

249.7 24.97 250 25

Table 25: Three Phase Inverter with SPWM

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 92.8 24.97 25.88 0.5014 0.2975
Voltage (V) 92.8 249.7 258.8 5.014 2.975
Figure 18: Three Phase Inverter with SPWM Output Voltage

Figure 19: Three Phase Inverter’s Pulse Signals

 3.3. SPWM Three Phase Inverter with RL load:
Three phase inverter with SPWM and RL load is studied in MATLAB Simulink. Circuit of inverter is shown
below.

Figure 20: Three Phase Inverter with SPWM and RL Load

Table 26: Three Phase Inverter with SPWM and RL Load

Vload simulation load current Vload load current

(V) (Phase) simulation (A) calculated (V) calculated (A)
 249.7 19.99 250
Table 27: Three Phase Inverter with SPWM and RL Load

THD from RMS from 1st harmonic 3rd harmonic 5th harmonic
Simulation Simulation from simulation from simulation from simulation
Current (A) 44.07 19.99 25.87 0.4992 0.2939
Voltage (V) 92.81 249.7 258.8 5.014 2.975
Figure 21: Three Phase Inverter with SPWM and RL load Output Voltage

3.4. Conclusion:
Three phase inverter produces higher output voltage. Three techniques are used to apply gate pulse at
switches. These are 120-degree pulse width, 180-degree pulse width and SPWM. 180-degree pulse
width produces higher output voltage than 120-degree pulses. Also for three phase inverter, 5 th
harmonic component is significant while 3rd harmonic component is negligible. With SPWM, overall RMS
output voltage is higher compared to previous modulation schemes but THD component is increased in
this scheme.
 Lab 5
AC-AC Converters:
1. Introduction and Background:
AC-AC voltage controllers are circuits that convert AC input voltage into AC output voltage. They are
different from transformers in respect that, these circuits do not step up AC voltage and these can also
change frequency of AC input voltage along with phase on input voltage. There are different types of AC
controllers based upon method of control like indirect controllers, cycloconverters, matrix converters
etc. [3]

2. Single Phase AC-AC Voltage Controllers:

Single Phase AC Voltage Controller is a device which converts fixed single phase AC directly to
a variable AC without a change in frequency. The input and output of the device is single phase.
Any voltage controller's operating system is dependent on the order in which certain power
switches, or SCR, switch on and off. The SCRs are turned on in such a way that the load is
linked to the AC source for a portion of each input voltage half cycle. Because the load is
connected to the source for that portion of the input AC voltage, the output voltage follows that
portion. The output voltage is managed in this manner.

Methodology:
Circuits are simulated in MATLAB and also theoretical results are obtained with formulas.

For single phase controller (full wave)

Vo ( rms )=
Vm 1
√2 π √
π−α + (
sin 2 α
2 )
Vo ( rms )
Io ( rms )=
R
2
Po=Io ( rms ) R
Po
PF=
VsIs
For single phase controller (full wave) RL load

Vo ( rms )=
√
Vm 1
√2 π (
( β−α ) +
sin 2 α sin 2 β
2
−
2 )
Here, β is calculated by numerical methods

For Single phase bridge cyclo converter

 Vo ( rms )=
√
Vm 1
√2 π (
π−α +
sin 2 α
2 )
Vo ( rms )
Io ( rms )=
R
2
Po=Io ( rms ) R
Po
PF=
VsIs
For three phase voltage controller

For 0≤α≤60

Vo ( rms )=√ 6 Vs
√(
1 π α sin 2 α
− +
π 6 4 8 )
For 60≤α≤90

Vo ( rms )=√ 6 Vs
√( 1 π 3 sin 2 α √ 3 cos 2 α
π 12
−
16
+
16 )
Vo ( rms )
Io ( rms )=
R
2
Po=3 Io ( rms ) R
Po
PF=
3 VsIs
For star connected configuration,

For 0≤α≤60

Vo ( rms )=Vs 1−
√ 3α 3
+
2π 4π
sin 2 α

For 60≤α≤90

Vo ( rms )=Vs
√ 1 3
+
2 4π
sin 2 α + sin ( 2α +60 )

Vo ( rms )
Io ( rms )=
R
2
Po=3 Io ( rms ) R
Po
PF=
3 VsIs
 2.1. Single Phase:
Single phase voltage controllers use two SCRs that are connected anti parallel to each other but in series
with source voltage. During positive half cycle upper SCR conducts at a particular firing angle. Similarly,
during negative half cycle lower SCR conducts at 180+α.

Figure 22: Single Phase AC-AC Converter (R and RL load)

Table 28: Single Phase AC-AC controller R load with firing angle of 60-degree

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 190.9 19.09 3644.3 220 19.09 4199.8 0.8675
Calculation 197.43 19.74 3896.6 220 19.74 4342.8 0.89
Table 29: Single Phase AC-AC controller RL load with firing angle of 60-degree

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 195.3 15.34 2353.4 220 15.34 3374.8 0.6971
Calculation
Table 30: Single Phase AC-AC controller R load with firing angle of 90-degree
 Load Current Pout Input Current Input
Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 146 14.6 2131.6 220 14.6 3212 0.6637
Calculation 155.56 15.56 2421 220 15.56 3423.2 0.707
Table 31: Single Phase AC-AC controller RL load with firing angle of 90-degree

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 151 10.58 1119.4 220 10.58 2327.6 0.4809
Calculation
Figure 23: Single Phase AC-AC Converter (R and RL load) Output Voltage and Current
 2.2. Single Phase CycloConverter:
A cyclo-converter is a machine that changes AC power from one frequency to another, usually a lower
frequency. Without the use of a middle DC link, it transforms the frequency. The output voltage and
frequency of a cyclo-converter can be varied continuously and independently using a control circuit.

Two bridges of SCRs are connected parallel to voltage source. One is connected to positive and negative
terminals and other is connected oppositely.

Figure 24: Single Phase AC-AC CycloConverter

Table 32: Single Phase AC-AC Cycloconverter with R load and 60 Degree Firing Angle

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 197.3 19.73 3892.7 220 19.73 4340.6 0.8965
Calculation 197.45 19.74 3896.7 220 19.74 4342.8 0.92
Table 33: Single Phase AC-AC Cycloconverter with RL load and 60 Degree Firing Angle

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 201.4 16.08 2585.7 220 16.08 3537.6 0.7308
Calculation
Table 34: Single Phase AC-AC Cycloconverter with R load and 90 Degree Firing Angle

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 155.5 15.55 2418 220 15.55 3421 .7063
Calculation 155.65 15.56 2421.1 220 15.56 3423.2 .707
Table 35: Single Phase AC-AC Cycloconverter with RL load and 90 Degree Firing Angle

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 160.1 11.53 1329.4 220 11.53 2536.6 0.5238
Calculation
Figure 25: Single Phase AC-AC CycloConverter with R load 60 Degree Firing Angle

2.3. Conclusion:
RMS value of output voltage for controllers depend upon firing angle. As firing angle is increased value
of output voltage decreases. PF of circuit also decreases by increasing firing angle. With inductive load,
input current and useful active power is decreased compared to R load for same firing angle.
 3. Three Phase AC-AC Voltage Controllers:
Three phase AC-AC voltage controller uses total 6 SCRs for conversion. A pair of SCRs connected anti-
parallel are used in each line. Gating sequence are so provided that at a time only two SCRs are turned
on at a time.

Figure 26: Three Phase AC-AC Voltage Controller R load

Table 36: Three Phase AC-AC Controller R Load and Firing Angle of 60

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 202.5 18.43 10.19k 220 18.43 12.16k 0.8378
Calculation 200 20 10.26k 220 18.5 12.2k 0.84
Table 37: Three Phase AC-AC Controller RL Load and Firing Angle of 60

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 207.7 15.01 6.6k 220 15.01 9.9k 0.6824
Calculation
Table 38: Three Phase AC-AC Controller R Load and Firing Angle of 90

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 176.3 11.86 4.22k 220 11.86 7.83k 0.5387
Calculation 180 12 4.32 220 12 7.92k 0.54
Table 39: Three Phase AC-AC Controller RL Load and Firing Angle of 90

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 183.5 8.648 2.24k 220 8.648 5.7k 0.3931
Calculation
Figure 27: 3 Phase AC Voltage Controller with R load 90 Degree Firing Angle

Figure 28: 3 Phase AC Voltage Controller with RL load 60 Degree Firing Angle
 3.1. Conclusion:
Output voltage and PF are inversely related to firing angle. As firing is increased, output voltage and
power factor is decreased. Power factor of converter is further decreased for same firing angle as
compared with R load.

4. Three Phase AC-AC Voltage Controllers (Star- Connected):

For this configuration, SCRS are connected in series with load resistance and all three legs are
connected in star. Isolated neutral configuration is mused for this experiment. All SCRs are turned on in
a sequence for 60 degree interval.

Figure 29: Three Phase AC-AC Voltage Controller (Star-Connected) R load

 Table 40: Three Phase AC-AC Controller (Star) R Load and Firing Angle of 60

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 118.8 18.43 10.19k 220 18.43 12.16k 0.8378
Calculation 119.14 19.63 11.56k 220 19.63 12.95k 0.84
Table 41: Three Phase AC-AC Controller(Star) RL Load and Firing Angle of 60

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 104.9 15.01 6.6k 220 15.01 9.9k 0.6824
Calculation
Table 42: Three Phase AC-AC Controller(Star) R Load and Firing Angle of 90

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 184.6 11.86 4.22k 220 11.86 7.83k 0.5387
Calculation 185.6 12.2 4.46k 220 12.2 8.1k 0.55
Table 43: Three Phase AC-AC Controller(Star) RL Load and Firing Angle of 90

Load Current Pout Input Current Input

Vload (V) (A) (W) Vin (V) (A) VA PF
Simulation 174.9 8.648 2.24k 220 8.648 5.7k 0.3931
Calculation
Figure 29: 3 Phase AC Voltage Controller (Star) with RL load 90 Degree Firing Angle
 4.1. Conclusion:
Output voltage at firing angle of 90-degrees is more compared to a firing angle of 60-degrees. As firing
angle is increased, output voltage is increased but power factor is decreased.
References

[1] M. H. Rashid, Power Electronics: Devices, Circuits and Applications, 1988.

[2] B. P S, Power Electronics.

[3] C. W. Lander, Power Electronics.