[Kalita*, 4.(6): June, 2015] ISSN: (I2OR), Publication Impact Factor: (ISRA), Journal Impact Factor: 2.114

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1 IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY ADAPTIVE CONTROL TECHNIQUES FOR DC-DC BUCK CONVERTER Pranjal Kalia*, Manash Proim Saikia, N.H.Singh * Dep. of Eleronis & Communiaion Engineering Dibrugarh Universiy Insiue Of Engineering & Tehnology Dibrugarh, Assam,India Dep. of Eleronis & Communiaion Engineering Dibrugarh Universiy Insiue Of Engineering & Tehnology Dibrugarh, Assam,India Dep. of Eleronis & Communiaion Engineering Dibrugarh Universiy Insiue Of Engineering & Tehnology Dibrugarh, Assam,India ABSTRACT DC-DC onverers are some widely used power eleroni irui ha effiienly onvers an unregulaed DC inpu volage o a regulaed DC oupu volage. This paper demonsraes one of he basi opologies of DC-DC onverer i.e. Buk Converer. This paper oulines he Sae-Spae averaged modelling of he DC-DC Buk onverer. Various onrol ehniques are developed o onrol he DC-DC onverer. Differen onrol ehniques are demonsraed o onrol he DC-DC onverer in his paper. KEYWORDS: PID and PI onrol; SMC (Sliding Mode Conrol); DC-DC Buk Converer. INTRODUCTION The DC-DC onverer are some of he simples power eleroni irui ha onvers soures of dire urren from one volage level o anoher volage level by swihing aion. This an be done by hanging he duy yle of he main swihes in he iruis. The swihes are ransisors and diodes. These onverers are mosly used as a regulaed swihed mode power supplies. Swihed mode DC-DC onverer onvers he unregulaed d inpu o a onrolled d oupu []-[2]. DC-DC onverers have a very large area of appliaions. They are exensively used in personal ompuers, offie equipmen s, appliane onrol, eleommuniaion equipmen s, DC moor drives, auomoive, airrafs, e. The analysis, onrol and sabilizaion of swihing onverers are he main faors ha need o be onsidered. A suiable onrol ehnique mus deal wih he nonlineariy of DC-DC onverers, wide volage and load variaion [].Many onrol mehods are used for onrol of swih mode d-d onverers suh as: Fuzzy Logi Conroller, Sliding Mode Conroller, PID Conroller, PI Conroller. In his paper he properies of PID, PI, Sliding Mode Conroller has been foused [3]. [85]

2 THE DC-DC BUCK CONVERTER Linear Conrol for a Buk Converer Figure : Blok Diagram of Conrolled Buk Converer Operaional priniple A buk onverer is a sep down onverer ha seps down he fixed high volage o a desired low volage. The basi buk onverer shemai diagram is shown in figure 2 has a apaior and an induor along wih wo swihes. The swihes operae a he rae of PWM swihing frequeny. Figure2: Basi Buk Converer In he onverer operaion i is assume ha he onverer operaes in CCM. In CCM mode of operaion he induor urren flow oninuously over he swihing period. In he firs sub irui sae when he swih S is losed, he diode is reversed biased and he energy is ransferred from he soure o he induor and he urren hrough he induor gradually inreases during his ime inerval as shown in figure 2.(a). In he nex sub-irui sae when he swih S2 is losed, he soure is disonneed from he nework. The diode will be forward biased and he urren will flow hrough he freewhelling diode. During he seond ime inerval he urren hrough he irui dereases linearly as he energy in he induor disharges as shown in he figure 2.(b). [86]

3 Figure2.Buk Converer when (a) Swih is ON (b) Swih is OFF MATHEMATICAL MODELLING OF BUCK CONVERTER When he swih is losed (ON-sae) and diode is reverse biased, he induor urren and oupu V () o are i () L dil () Vd( ) Vo( ) d L dv( ) Vo( ) il ( ) & d C R.. () Vo () Vo ( ) v ( ) r il( ) R, apaior volage When he swih is open (OFF-sae) and diode is forward biased, he induor urren L() and oupu volage Vo () are: dil () Vo () d L dv( ) Vo( ) il ( ) &.. (2) d C R Vo () Vo ( ) v ( ) r il( ) R Model Simplifiaion On simplifying he above equaions, he induor urren and apaior volage dynamis an be rewrien as: When he swih is losed (ON-sae) dil () rr R Vd ( ) il( ) v ( ) d L ( R r) L ( R r) L. (3) dv () R il( ) v( ) d ( R r ) C ( R r ) C When he swih is open (OFF-sae) v () i, apaior volage v () [87]

4 dil () rr R il( ) v( ) d ( R r) L ( R r) L. (4) dv () R il( ) v( ) d ( R r ) C ( R r ) C Sae-Spae model of Buk Converer The sae-spae represenaion of he onverer irui an be expressed in he form: dx() Ax BV d d During he swih is ON dx() A2x B2V d d During he swih is OFF Where x, x v ( ) i ( ) 2 L is sae veor and A and B are he sysem maries. The sae maries and inpu veor for boh swihing sae an be expressed as: Rr R ( R r) L ( R r) L 0 A A2, B L, B2 R 0 0 ( R r) C ( R r) C Sae-Spae Averaged model of Buk Converer Here he sae-spae averaging mehod is shown. The duy yle k is a funion of x as well as u. Toal soluion an be obained by sae spae averaging, ha is by summing he erm for eah swihed mode. A A k A ( k) 2 B B k B ( k) 2 On averaging he sysem maries are:.. (5) Rr R k ( R r) L ( R r) L A & BL R 0 ( R r) C ( R r) C (6) The averaged sae equaion and oupu equaion an be expressed as: dil () Rr R k d ( R r) L ( R r) L il () L dv () R v () 0 d ( R r) C ( R r) C Rr () R il y () ( R r ) ( ) v () R r V () d [88]

5 Exraing he Transfer Funion of Buk Converer The buk onverer s small signal onrol-o-oupu ransfer funion, derived by he sandard sae-spae averaging ehnique, is given by: ^ vo() s ( src ) Vd TP () s ^ 2 r d () LC o s s s L RC LC In he ransfer funions, ^ ( s ) & ^ ( s ) are he small variaions of he oupu volage and duy yle respeively. C vo d is he oupu apaiane, L is he induane, and R is he load resisane, is he ESR of C. The onrol-o-oupu ransfer funion is uilized o design he onroller. CONTROL TECHNIQUES USED IN DC-DC BUCK CONVERTER In DC-DC onverer for a given inpu volage, he oupu volage an be onrolled by onrolling he ON or OFF duraion of he swih. Pulse Widh Modulaion (PWM) is one of he mehod in whih onrol irui regulaes he oupu by varying he ON ime of he swih and by fixing he swihing frequeny [5]. r Figure 4: PWM generaion DC-DC onverers are nonlinear in naure and he onroller used mus deal wih wide range of inpu and load variaions as well as i mus ensures sabiliy in any operaing ondiion. There are various onrolling ehniques. This paper fous on PID onroller, PI onroller, Sliding Mode Conroller (SMC) [6],[7],[8] Proporional, Inegral and Derivaive Conroller (PID) In PID onroller, onrol signal is a linear ombinaion of hree signals: () he signal obained by muliplying he he error signal by onsan Kp. (2) he signal obained by differeniaing and muliplying he error signal by onsan Kd. (3) he signal obained by inegraing and muliplying he error signal by onsan Ki.I is given in he form: d u( ) K pe( ) Kd e( ) Ki e( ) d d Taking he laplae ransformaion of above equaion and solving i, an ideal PID onroller ransfer funion an be obained: [89]

6 U ( s) K pe( s) KdsE( s) Ki E( s) s Ki U ( s) E( s) K p Kds s All he hree onsans are adjusable for an aepable performane of he onverer and his adjusmen proess is known as uning. PID onroller redues he error upo an aepable level and provide aepable sabiliy and damping. Proporional, Inegral Conroller (PI) In PI onroller, onrol signal is a linear ombinaion of wo signals: () he signal obained by muliplying he error signal by onsan Kp. (2) he signal obained by inegraing and muliplying he error signal by onsan Ki. I is given by: u( ) K pe( ) Ki e( ) d Taking he laplae ransformaion of above equaion and solving i, an ideal PID onroller ransfer funion an be obained: U ( s) K pe( s) Ki E( s) s Ki U ( s) E( s) K p s The inegral erm in PI onroller redues he seady-sae error o zero whih is no possible wih derivaive erm. As he derivaive erm is more sensiive oward he high-frequeny in inpu so he absene of derivaive erm make he sysem more seady in seady sae in ase of noisy daa. Sliding Mode onrol (SMC) Sliding mode onrol is he only non-linear mehod. Sliding mode onroller is a sysemai approah o solve he sabiliy problem and onsisene performane. Swih mode onroller ould be implemened for swih mode power supplies. Swihing onrol aion is required o drive he non-linear plans sae rajeory ino a speified surfae in he sae spae and o mainain he plans sae rajeory for subsequen ime. The gain of he feedbak pah depends upon he posiion of rajeory w.r. surfae. If he rajeory is above he surfae feedbak pah has one gain and he gain will hange as he rajeory move below he surfae. The surfae is known as sliding surfae [9],[0]. Ideally response is made o slide along a predefined rajeory wih he help of onrol algorihm. The onrol dees he deviaion of aual rajeory from he referene rajeory and orrespondingly hanges he rajeory o resore he raking. Figure5: Blok Diagram of SMC SIMULINK MODEL AND RESULTS [90]

7 Lis of Parameers Model Parameer Inpu Volage, Oupu Volage, Induane, I Capaiane, C ESR, r V d V o Values 24V 2V 47H 2F 0. Load Resisane, R 0.Ω Swihing Frequeny, Swih Off u=0 Swih On u= f s 00kHz SIMULATION RESULTS Buk Converer wih PI onroller Figure 7: Oupu Volage of Buk Converer wih PI onroller Buk Converer wih PID onroller [9]

8 2 0 Referene volage Oupu volage Oupu Volage Time(se) Figure 8: Oupu Volage of Buk Converer wih PID onroller Buk Converer wih Sliding Mode Conroller (SMC) x V 0 Oupu Volage Time(se) Figure 9: Oupu Volage of Buk Converer wih Sliding Mode onroller x 0-3 RESULTS Sl.N.o. Types of Ciruis Inpu Volage Oupu Volage Buk onverer wih PI onroller 24V 2V 2 Buk onverer wih PID onroller 24V 2V 3 Buk onverer wih SMC 24V 0V [92]

9 Change in seling ime wih Variaion in he inpu volage of he irui Sl.No. Type of Cirui Referene Volage (V) Inpu Volage (V) Seling Time(se) Buk onverer wih 20V PI onroller 2V 30V 2 Buk onverer wih PID onroller 2V 40V 20V 30V 40V Buk onverer wih SMC 2V 20V 30V 40V CONCLUSION A omparison beween PID, PI and SMC onroller for d-d buk onverer is analysed. The d-d buk onverer is evaluaed under he inpu volage of 24V in simulaion. The oupu volage in PI and PID onroller is almos similar. In omparison of PI and PID wih SMC i is founded ha he seling ime of SMC is large. In ase of large seling ime and more volage auray SMC is preferred over PI and PID onroller. Bu in ase of less auray and omplexiy PI and PID onroller is used. REFERENCES [] Power Eleronis, Mahummad H.Rashid. [2] Power Eleronis Converers, Appliaion and Design, Mohan, Undeland, Riobbins. [3] Nanda R Mude, Prof. Ashish Sahu, Adapive Conrol Shemes For DC- DC Buk Converer, Inernaional Journal of Engineering Researh and Appliaions, Vol. 2, Issue 3,202, pp [4] Vandana Jha and Pankaj Rai, Sae Spae Averaged Modeling of Basi Converer Topologies VSRD- IJEECE, Vol. 2,Issue 8, 202, pp [5] Sumia Dhali,P.Nageshwara Rao,Praveen Mande,K.Venkaeswara Rao, PWM-Based Sliding Mode Conroller for DC-DC Boos Converer Inernaional Journal of Engineering Researh and Appliaions (IJERA), Vol. 2, Issue, 202, pp [6] Sandeep Kumar Singh, Ami Pael, Mohi Kumar Pandey,Kamal Singh, A omparaive analysis of PI and PID onrolled Buk Converer using MATLAB Simulink,Vol.3,Issue,203,pp [7] Hongmei Li and Xiao Ye Sliding-Mode PID Conrol of DC-DC Converer, 5h IEEE Conferene on Indusrial Eleronis and Appliaions. [8] M.Ahmed, M.Kuisma, P. Silvenoinen, Implemening Simple Proedure for Conrolling Swih Mode Power Supply Using Sliding Mode Conrol as a Conrol Tehnique, XIII-h Inernaional Symposium on Elerial Apparaus and ehnologies (Siela). May 2003, pp 9-4, Vol. [9] P. Maavelli, L. Rosseo, G. Spiazzi, and P. Teni, General-purpose sliding-mode onroller for d/d onverer appliaions, IEEE Power Eleronis Speialiss Conf. Re. (PESC), 993, pp [0] V. M. Nguyen and C. Q. Lee, Traking onrol of buk onverer using sliding-mode wih adapive hyseresis, IEEE Power Eleronis Speialiss Conf. Re. (PESC), 995. [93]