IRJET- Comparative Analysis of Analog PI and Discrete PI Controller with Single Switch Topology Buck Converter for Improving Percentage Regulation and Accuracy
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This document compares analog and discrete PI controllers for regulating the output of a buck converter. It first describes the buck converter circuit and derives its transfer function. It then simulates both continuous and discrete PI controllers in MATLAB to control the buck converter. The results show that the analog PI controller has faster rise time and settling time with less overshoot and variation, while the discrete controller has higher flexibility and simpler design but more jitter and overshoot. In conclusion, each controller type has advantages for different applications depending on the needed performance and complexity.
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 552
Comparative Analysis of Analog PI and Discrete PI controller with
single switch topology Buck Converter for Improving Percentage
Regulation and Accuracy
Harshit Derasari
Department of Instrumentation and Control Engineering, L.D. College of Engineering, Ahmedabad, Gujarat.
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Switch Mode Power Supply (SMPS) plays an
important role in miniaturized energy sources. Switching
power supplies normally consists of two stages in the power
circuit, viz. the input stage and the output dc-dc converter
stage. A switch mode power supply contains the power stage
and the controlling unit. The power stage includes the mainly
power conversion from the input voltage supply to the output
voltage supply and also includesswitching deviceandthefilter
circuits. A major problem associated with this is strong
dependency of DC bus voltage stress with the output load and
input variance. The main perspective of this paper is to avoid
this problem is presented by implementing buck converter
with single switch topology and closed loop feedback with PI
controller. Controller is design for single switch topology DC-
DC Converter. Converter topology is selected in such a way
that the input stage is discontinuouscurrentmode(DCM)buck
converter and the output stage is continuous mode converter
providing wide band width response. Variation into the
standard buck power circuitry stage and consideration of
power stage component needs are included.
Key Words: Buck Converter, PI controller, MATLAB.
1. INTRODUCTION
The switch mode converters are few of the simple power
electronic devices which step down or step up electrical
voltage by switching action. These dc-dc converter useful
with many area of applications like power supplies for
computers, office appliances, appliance control,
communication instruments, motor drives, automobile
applications, aircraft modules, etc.
Controlling and stabilization of dc-dc converters are the
main parts that need to be analyzed. Many control methods
are available for control of switching device operation in dc-
dc converter but the easy working and low cost controller
always will be in demand for most of the industrial
application as well as high performance appliances. Each
different controlling method have its own pro and cons due
to which that particular control methods considered as
suitable control method under static and dynamic
conditions, compared to other controlling methods.
2. INTRODUCTION TO DC-DC BUCK
CONVERTER WITH FEEDBACK CONTROL
LOOP
The semi-conductor components are used as switching
device through which converter is operate at high switching
frequencies. The differentdesignofinductorandcapacitorin
buck converter uses as filter circuitry. The resisting device
act as load in buck converter which can be change to
analyses the behavior in light resistive load and heavy
resistive load. The various input sourcesutilizeslikebattery,
renewable energy sources etc.
Fig. 1 [3] Block diagram of PID controller
The need or duty of compensating circuit/network is to
settle the system as rapid as possible after change in
normalized operating conditions occur. This compensating
circuit/network is the controlling network for converter.
This controlling network consider a portion of output and
compares it withreferenceinput.Furthersignal conditioning
and amplification of error is done, and according to error
corrective action is taken. The controlling action consists of
opposing the variation observed in output.](https://image.slidesharecdn.com/irjet-v6i6110-191109105259/85/IRJET-Comparative-Analysis-of-Analog-PI-and-Discrete-PI-Controller-with-Single-Switch-Topology-Buck-Converter-for-Improving-Percentage-Regulation-and-Accuracy-1-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 553
3. DESIGN AND SIMULATION OF PI
CONTROLLER
Here it is assume that the dc-dc buck converter is in
continuous conduction mode. It includes linear time
invariant components like resistor, inductor and capacitor
together with switches like MOS and diodes, whose
operation is controlled to maintain the desired conversion.
Therefore, equation for inductor voltage and capacitor
current two circuits are considered, one in the on time and
other in the off time of the converter.
Fig. 2 [1] Buck converter circuit when switch turns on
So for on time our equation for inductor voltage and
capacitor current are,
By expanding above equations we get,
Now the above equations can be written as,
They may be written as,
Here, Don = 0.
Now, when switch is off,
Fig. 3 [1] Buck converter circuit when switch turns off
So for off time our equation for inductor voltage and
capacitor current are,
These can also be written as,
Above equations can be rewritten as,
Here Doff = 0.
From above equations we can see that A on = A off andBoff=
0. For State Space Averaging given that, A = dA1 + (1-d) A2
where, A1 = A2. So that, A = A1 = A2 and B = dB1 + (1-d) B2.
Where, d= Duty cycle
So,](https://image.slidesharecdn.com/irjet-v6i6110-191109105259/85/IRJET-Comparative-Analysis-of-Analog-PI-and-Discrete-PI-Controller-with-Single-Switch-Topology-Buck-Converter-for-Improving-Percentage-Regulation-and-Accuracy-2-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 556
Here, the effect of PI controller for rapid transient response
is discuss through thesimulationresults.Mainlytheproblem
associate with this controlling technique for converter is
variable switching frequency operation with jitter.
Therefore, switching frequency must be maintain constant.
Both different domain of controller have their own pro and
cons.
5. COMPARATIVE ANALYSIS OF PI
CONTROLLER IN TWO DIFFERENT
DOMAIN
Fig. 13 Comparison of resultant output voltages of buck
converter using analog and Discrete PI controller
Specifications Analog PI Discrete PI
Rise time (sec.) 0.0694 0.00030
Settling time (sec.) 0.0869 0.9802
Overshoot (%) 1.6568 85.7375
Peak (v) 5.0804 9.8924
Peak time (sec.) 0.0934 0.0009
Voltage Variation
(%)
3 5
Jitter present Low Comparatively
high
System’s
Flexibility
Low High
Design Complexity More Complex Comparatively
Simple
Table.1 Comparative analysis of PI controller using
hardware configuration in both domain
6. CONCLUSION
The main aim of this paper is toimplementtheactionagenda
for new technique. Here, two realizations for buck converter
based on PI controller are considered, the comparison
between analog PI and discrete PI controllers is described.
The Implementation results observed from no load to full
load condition and 20% Input variation in both controller.
The technology uses in digital controlling scheme is new era
for power management but on other side analogous control
scheme gives more accurate results than other. So, the
implementation and observational results show thateach of
them has its pro and cons as well weaknesses and strengths.
So, the application field can be determine which methodwill
suitable and can be employee.
7. REFRENCES
[1] Nanda R Mude, Prof. Ashish Sahu — “Adaptive control
Schemes for DC- DC Buck Converter”International Journal of
Engineering Research and Applications (IJERA) May-Jun
2012
[2] Abhilash Kumar and Vinay Pathak — “Advance Control
Techniques for Dc-Dc Buck Converter in Improvement of
Performance” International Journal on Emerging
Technologies 7(1): 101-106(2016)
[3] Ghulam Abbas, Hassam Muazzam, Umar Farooq, Jason
Gu, and Muhammad Usman Asad — “Comparative Analysis
of Analog Controllers for DC-DC Buck Converter” Journal of
Automation and Control Engineering Vol. 3, No.6,December
2015
[4] Li-Jen Liu, Yeong-Chau Kuo and Wen-Chieh Cheng —
“Analog PWM and Digital PWM Controller IC for DC/DC
Converters” 2009 Fourth International Conference on
Innovative Computing, Information and Control
[5] Prof Swapna Manurkar — “Controller Design for Buck
Converter Step-by-Step Approach” National Conference on
Innovations and Recent Trends in Engineering and
Technology (NCIRET-2014)
[6] P. Geethanjali, P. Vijaya Priya, M. Kowsalya, J. Raju —
“Design and Simulation of Digital PID Controller for Open
loop and Closed Loop Control of Buck Converter” December
2010 International Journal of Computer Science and
Technology
[7] Sugandhra Pal Singh, Deepak Kumar Singh, Harish
Kumar, Rheesabh Dwivedi — “Designing and Parametric
Variation of PI Controller for Buck Converter for Constant
Voltage Applications” Jul 2014, International Journal of
Engineering Trends and Technology (IJETT)](https://image.slidesharecdn.com/irjet-v6i6110-191109105259/85/IRJET-Comparative-Analysis-of-Analog-PI-and-Discrete-PI-Controller-with-Single-Switch-Topology-Buck-Converter-for-Improving-Percentage-Regulation-and-Accuracy-5-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 557
[8] C. D. Johnson “Process Control Instrumentation
Technology”
[9] Kannan M. Moudgalya – “Digital Control Book](https://image.slidesharecdn.com/irjet-v6i6110-191109105259/85/IRJET-Comparative-Analysis-of-Analog-PI-and-Discrete-PI-Controller-with-Single-Switch-Topology-Buck-Converter-for-Improving-Percentage-Regulation-and-Accuracy-6-320.jpg)
IRJET- Comparative Analysis of Analog PI and Discrete PI Controller with Single Switch Topology Buck Converter for Improving Percentage Regulation and Accuracy
- 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 552 Comparative Analysis of Analog PI and Discrete PI controller with single switch topology Buck Converter for Improving Percentage Regulation and Accuracy Harshit Derasari Department of Instrumentation and Control Engineering, L.D. College of Engineering, Ahmedabad, Gujarat. ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Switch Mode Power Supply (SMPS) plays an important role in miniaturized energy sources. Switching power supplies normally consists of two stages in the power circuit, viz. the input stage and the output dc-dc converter stage. A switch mode power supply contains the power stage and the controlling unit. The power stage includes the mainly power conversion from the input voltage supply to the output voltage supply and also includesswitching deviceandthefilter circuits. A major problem associated with this is strong dependency of DC bus voltage stress with the output load and input variance. The main perspective of this paper is to avoid this problem is presented by implementing buck converter with single switch topology and closed loop feedback with PI controller. Controller is design for single switch topology DC- DC Converter. Converter topology is selected in such a way that the input stage is discontinuouscurrentmode(DCM)buck converter and the output stage is continuous mode converter providing wide band width response. Variation into the standard buck power circuitry stage and consideration of power stage component needs are included. Key Words: Buck Converter, PI controller, MATLAB. 1. INTRODUCTION The switch mode converters are few of the simple power electronic devices which step down or step up electrical voltage by switching action. These dc-dc converter useful with many area of applications like power supplies for computers, office appliances, appliance control, communication instruments, motor drives, automobile applications, aircraft modules, etc. Controlling and stabilization of dc-dc converters are the main parts that need to be analyzed. Many control methods are available for control of switching device operation in dc- dc converter but the easy working and low cost controller always will be in demand for most of the industrial application as well as high performance appliances. Each different controlling method have its own pro and cons due to which that particular control methods considered as suitable control method under static and dynamic conditions, compared to other controlling methods. 2. INTRODUCTION TO DC-DC BUCK CONVERTER WITH FEEDBACK CONTROL LOOP The semi-conductor components are used as switching device through which converter is operate at high switching frequencies. The differentdesignofinductorandcapacitorin buck converter uses as filter circuitry. The resisting device act as load in buck converter which can be change to analyses the behavior in light resistive load and heavy resistive load. The various input sourcesutilizeslikebattery, renewable energy sources etc. Fig. 1 [3] Block diagram of PID controller The need or duty of compensating circuit/network is to settle the system as rapid as possible after change in normalized operating conditions occur. This compensating circuit/network is the controlling network for converter. This controlling network consider a portion of output and compares it withreferenceinput.Furthersignal conditioning and amplification of error is done, and according to error corrective action is taken. The controlling action consists of opposing the variation observed in output.
- 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 553 3. DESIGN AND SIMULATION OF PI CONTROLLER Here it is assume that the dc-dc buck converter is in continuous conduction mode. It includes linear time invariant components like resistor, inductor and capacitor together with switches like MOS and diodes, whose operation is controlled to maintain the desired conversion. Therefore, equation for inductor voltage and capacitor current two circuits are considered, one in the on time and other in the off time of the converter. Fig. 2 [1] Buck converter circuit when switch turns on So for on time our equation for inductor voltage and capacitor current are, By expanding above equations we get, Now the above equations can be written as, They may be written as, Here, Don = 0. Now, when switch is off, Fig. 3 [1] Buck converter circuit when switch turns off So for off time our equation for inductor voltage and capacitor current are, These can also be written as, Above equations can be rewritten as, Here Doff = 0. From above equations we can see that A on = A off andBoff= 0. For State Space Averaging given that, A = dA1 + (1-d) A2 where, A1 = A2. So that, A = A1 = A2 and B = dB1 + (1-d) B2. Where, d= Duty cycle So,
- 3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 554 , The line-to-output transfer function is H(s)= . Its expression based on average model is In the transfer functions, Vin and Vo are the inputandoutput voltages respectively. Are the small variations of the output voltage, input voltageanddutycycle respectively. d is the duty cycle, C is the output capacitance, L is the inductance, and R is the load resistance. The parameter values of this system are as follows: Input Voltage, Vin 12V Output voltage, Vo 6 V Duty Cycle, D 50% Capacitance, C 220 uF Inductor 10 mH Load resistance, R 10 ohms Now, putting all these values in equation we can derive the system transfer function as follows, Fig. 4 Step response of state- space average model of the system Simulation of PI Controllers in continuous time domain Closed loop implementation PI controller with the circuit of Buck converter were implemented using MATLAB Simulink Fig. 5 closed loop Continuous PI controller implementation for buck converter Simulation of closed loop Continuous PI controller implementation continuously track the desired output voltage which is given as reference and error is given to the PI controller. PI controller gives controller action according to error and PWM is generated which changes thedutycycle for operating the switching device. SimulationofPIControllersinDiscretetime domain Closed loop implementation Discrete PI controller with the circuit of Buck converter were implemented using MATLAB Simulink. Fig. 6 closed loop Discrete PI controller implementation for buck converter Simulation closed loop Discrete PI controller implementation continuously track the desired output voltage which is given as reference and error is given to the PI controller. PI controller gives controller action according to error and PWM is generated with the help of repeating triangular waves which changes the duty cycle according to error and the switching device operated accordingly.
- 4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 555 4. SIMULATION RESULT AND HARDWARE IMPLEMENTATION Fig. 7 Output response of Continuous PI controller for buck converter Fig. 8 Output response of Continuous PI controller for buck converter with change in reference voltage Fig. 9 Output response of Discrete PI controller for buck converter Fig. 10 Output response of Discrete PI controller for buck converter with change in reference voltage Fig. 11 Buck converter with Analog PI controller without load Fig. 12 Buck converter with Discrete PI controller without load
- 5. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 556 Here, the effect of PI controller for rapid transient response is discuss through thesimulationresults.Mainlytheproblem associate with this controlling technique for converter is variable switching frequency operation with jitter. Therefore, switching frequency must be maintain constant. Both different domain of controller have their own pro and cons. 5. COMPARATIVE ANALYSIS OF PI CONTROLLER IN TWO DIFFERENT DOMAIN Fig. 13 Comparison of resultant output voltages of buck converter using analog and Discrete PI controller Specifications Analog PI Discrete PI Rise time (sec.) 0.0694 0.00030 Settling time (sec.) 0.0869 0.9802 Overshoot (%) 1.6568 85.7375 Peak (v) 5.0804 9.8924 Peak time (sec.) 0.0934 0.0009 Voltage Variation (%) 3 5 Jitter present Low Comparatively high System’s Flexibility Low High Design Complexity More Complex Comparatively Simple Table.1 Comparative analysis of PI controller using hardware configuration in both domain 6. CONCLUSION The main aim of this paper is toimplementtheactionagenda for new technique. Here, two realizations for buck converter based on PI controller are considered, the comparison between analog PI and discrete PI controllers is described. The Implementation results observed from no load to full load condition and 20% Input variation in both controller. The technology uses in digital controlling scheme is new era for power management but on other side analogous control scheme gives more accurate results than other. So, the implementation and observational results show thateach of them has its pro and cons as well weaknesses and strengths. So, the application field can be determine which methodwill suitable and can be employee. 7. REFRENCES [1] Nanda R Mude, Prof. Ashish Sahu — “Adaptive control Schemes for DC- DC Buck Converter”International Journal of Engineering Research and Applications (IJERA) May-Jun 2012 [2] Abhilash Kumar and Vinay Pathak — “Advance Control Techniques for Dc-Dc Buck Converter in Improvement of Performance” International Journal on Emerging Technologies 7(1): 101-106(2016) [3] Ghulam Abbas, Hassam Muazzam, Umar Farooq, Jason Gu, and Muhammad Usman Asad — “Comparative Analysis of Analog Controllers for DC-DC Buck Converter” Journal of Automation and Control Engineering Vol. 3, No.6,December 2015 [4] Li-Jen Liu, Yeong-Chau Kuo and Wen-Chieh Cheng — “Analog PWM and Digital PWM Controller IC for DC/DC Converters” 2009 Fourth International Conference on Innovative Computing, Information and Control [5] Prof Swapna Manurkar — “Controller Design for Buck Converter Step-by-Step Approach” National Conference on Innovations and Recent Trends in Engineering and Technology (NCIRET-2014) [6] P. Geethanjali, P. Vijaya Priya, M. Kowsalya, J. Raju — “Design and Simulation of Digital PID Controller for Open loop and Closed Loop Control of Buck Converter” December 2010 International Journal of Computer Science and Technology [7] Sugandhra Pal Singh, Deepak Kumar Singh, Harish Kumar, Rheesabh Dwivedi — “Designing and Parametric Variation of PI Controller for Buck Converter for Constant Voltage Applications” Jul 2014, International Journal of Engineering Trends and Technology (IJETT)
- 6. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 06 | June 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 557 [8] C. D. Johnson “Process Control Instrumentation Technology” [9] Kannan M. Moudgalya – “Digital Control Book