Study on Different Types of Controlling Techniques Used For Interleaved DC-DC Boost Converters

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1 Study on Dfferent Types of Controllng Technques Used For Interleaved DC-DC Boost Converters Mrunal J. Panse 1, Rakesh G. Srvastava 2 1M.Tech 4 th Sem. Student, S.D.C.O.E., Wardha, Maharashtra 2Professor, Dept. of Electrcal Engneerng, D.M.I.E.T.R., Wardha, Maharashtra *** Abstract - DC - DC boost converter were used n many applcatons such as renewable energy sources whch ncludes photovoltac ( PV ) cells and fuel cells. The relablty, effcency and controllablty of PV systems can be ncreased by usng Boost converters. A DC - DC Boost converter provde hgher output voltage but t produces some rpple current. In order to reduce the rpple current so as to mprove the effcency of boost converter, an nterleaved boost converter s used. For mantanng the voltage at output constant rrespectve of varatons n DC nput voltage and load current, a control system must be requred for the nterleaved converter. Ths paper presents a detaled study of varous control technques of DC - DC nterleaved Boost for converson of power from one level to another level. In addton, these control technques are compared n terms of ther advantages and ds-advantages. Key Words: DC-DC Interleaved Boost converter(ibc), PID control, Slde Mode Control ( SMC ) and Sgma Delta ( SDM ) 1. INTRODUCTION In recent years, renewable energy sources have become the fastest growng power sector n the world. Conventonal fossl-fuels take mllons of years to completely restore. It also has lmted reserve capacty and costs for hgh prce. Due to ths reason, renewable energy sources are the possble solutons to the envronmental problems. In research felds, most of the renewable energy sources such as fuel cell stacks and photovoltac cells have receved worldwde attenton. [1] A swtchng converter s a power electronc devces whch s used to transform an nput voltage level nto another level by swtchng acton of semconductor devce. For ths purpose a hgh power dc-dc converter s strongly requred that has found wdespread applcatons lke aerospace, electrc vehcle (EV), portable electronc devce lke pagers and mcroprocessor voltage regulaton. Power electronc based DC DC converter nterfaces for DC energy sources, but these power sources have qute low voltage output. Most of the renewable power sources, have qute lowvoltage output and to ncrease ts output level, t requres seres connecton or voltage booster [4]. DC-DC boost converters are generally employed n equpment, as preregulators [8] [10]. But, due to the nductor of classcal boost converter, the rpple current s ncreased. Interleaved boost converter IBC, s one such converter that can be used for hgh power applcatons. The advantages of nterleaved boost converter are faster transent response, hgh effcency, mproved relablty and decreased electromagnetc emsson. Due to nterleaved operaton ( parallel connecton of two or more boost converter ), IBC proposes both lower current rpple at the nput sde and lower voltage rpple at the output sde. Few lteratures related to the controller desgn so as to obtan hgh performance control of hgh-power nterleaved boost converter can be found [2]. In ths paper dfferent control technques, ncludng lnear and non-lnear control such as current mode control, voltage mode control, PWM wth PID control, slde mode control, dgtal control Sgma-Delta modulator, fuzzy control, for DC- DC boost converter have been studed. Fuzzy controller s non-lnear controller that s effectve but s dffcult as well as expensve for practcal applcaton. Now a days, currentmode controllers and lnear control methods are most frequently used for controllng DC-DC boost converter. 2. MODELLING AND DESIGN OF DC DC BOOST CONVERTER A boost converter s known as step up converter. The crcut of dc dc boost converter s shown n Fg. 1. It step up the nput voltage V and provdes hgh output voltage V o at the output sde, for steady state operaton. It boost the voltage to a hgher level. Hence, V o s always hgher than V. Fg 1 Boost Converter The converter manly consst of L as boost nductor, a power controlled MOSFET swtch S, a dode D and a flter capactor 2018, IRJET Impact Factor value: ISO 9001:2008 Certfed Journal Page 3539

2 C confgured n parallel to a resstve load R. The swtch s set to ON and OFF state at a swtchng frequency f s = 1/T wth duty rato D = ton/t, where ton s the tme nterval when swtch S s at ON state [3]. It s a class of swtchng mode power supply (SMPS) contanng at least two semconductors swtches (a dode and a transstor) and at least one energy storage element. The capactor s connected at the output sde as the rpples present n output voltage s reduced [5] Boost converter s sad to operate n two modes, they are as follows : 1) Mode 1 : When the swtch S s closed.e. ON state, causes the current n the boost nductor ncreases lnearly, storng energy n ts magnetc feld. Durng ths mode of operaton, the load s completely solated from source, as shown n Fg. 2 Fg 2 Swtch S n ON state Transstor swtchng perod s gven as, T on DT p (1) Voltage across the nductor, d L V (2) dt 2) Mode 2 : When the transstor swtch S s open.e. OFF-state, energy stored n the nductor s released through the fly-back dode D to the nput RC crcut. Voltage across the boost nductor L and the source V, charges the capactor C and also supples the energy to the load R [6]. The conducton path s as shown n Fg. 3 Fg - 3 Swtch S n OFF state Transstor swtchng perod s gven as, T off D )T p (3) Voltage across the nductor, d L - (V Vo ) (4) dt When the swtch s open, the voltage across the nductor s: v L V V (5) o After rearrangng the equatons (1),(2),(3) and (4),we get Δ L V (6) DT p Δ L Vo V (7) (1 D)Tp Hence when the swtch s held OFF, the change n nductor current can be computed as shown n eqn. (8) Vo V ΔL (1 D)T (8) p L On solvng equaton (6) and (8), t yelds Vo 1 (9) V 1 D Equaton (9) reflects the fact that a large duty rato s requred for a large voltage boost. Therefore, n order to mantan acceptably small output rpple voltages, a prohbtvely large capactance s requred to ensure that the output voltage does not sag. Also, snce both dc and ac current are beng sourced through the nductor, the nductor must be desgned such that the cores wll not saturate durng hgh power operaton. Thus, t s concluded that boost converter requres large output flter capactor to reduce current rpple and hence not sutable for hgh power generaton. Due to the dsadvantages of boost converter lsted above, there arse the need for effcent boost converter whch can mprove the effcency and n other hand t should gve low nput and output rpples. The nventon of Interleaved Boost Converter satsfes the above demand. 3. INTERLEAVED BOOST CONVERTER Interleaved boost converter s a promsng nterface between dstrbuted energy sources such as fuel cells, PV, battery and the DC bus of nverters. Due to nterleavng operaton, IBC exhbts both lower current rpple at the nput sde and lower voltage rpple at the output sde. Therefore, the sze and losses of the flterng stages can be reduced, and swtchng losses can be sgnfcantly decreased [7]. Parallelng two or more swtchng devces s a wdely utlzed approach to ncrease the current handlng capablty of swtches. The advantages of the parallel converters scheme s to mplct proper desgn, dynamc response, robustness and tght steady state[13-15]. The power stage of the converter conssts of semconductor swtches and magnetc components. The drawback such as unbalanced current sharng between semconductor swtches and magnetc saturaton s partally overcome by the power stage parallelng method [17] shown n Fg. 4. The nterleaved boost converters conssts of several dentcal boost converters connected n parallel and controlled by the nterleaved method whch has the same swtchng frequency and phase shft. 2018, IRJET Impact Factor value: ISO 9001:2008 Certfed Journal Page 3540

3 Fg - 5 Typcal PID control Structure Fg - 4 Interleaved Boost Converter wth N phase Paralleled Power Stages In a two-phase converter, there are two output stages that are drven 180 degrees out of phase. By splttng the current nto two power paths, conducton (I 2 R) losses can be reduced, ncreasng overall effcency compared to a snglephase converter. In three-cell dc/dc converter archtecture, the cells are swtched wth the same duty rato, but wth a relatve phase shft or tme nterleaved of 120 ntroduced between each cell n order to reduce the magntude of the rpple at the output port of the converter[16]. 4. CONTROL TECHNIQUES To ensure stablty as well as fast transent response of nterleaved Boost Converter Several control technques have been proposed namely - Fuzz Logc controller, Artfcal Neural Network (ANN), PID controller and PI controller. Several Optmzaton technques such as Genetc Algorthm, Partcle Swarm Optmzaton, and Bacteral Foragng Optmzaton have also been proposed. Dfferent control technques, ncludng lnear and nonlnear control, such as current mode control, PID control and sldng mode control (SMC), model predctve control, fuzzy control, hybrd control and sgma-delta modulaton, for DC- DC boost converters have been dscussed. A. Proportonal, Integral, Dfferental Controllers (PID) In varous ndustral applcatons proportonal, ntegral and dfferental controllers organzaton s most commonly use to mprove the performance of the selected control system. Varous combnaton of proportonal (P), ntegral (I) and dfferental (D) controllers are shown below: a) Proportonal and Integral Controllers (PI) b) Proportonal and Dervatve controllers(pd) c) Proportonal Integral and Dervatve Controllers One of the smplest and most wdely used controller for decades s the PID controller. PID stands for proportonal (P), ntegral (I) and dervatve (D) controller. Fg. 5 shows the block dagram of a typcal PID controller. Proportonal dervatve (PD) controller mproves the transent response of the system. Proportonal ntegral (PI) controller reduces steady state error present n the system. The combnaton of PI and PD controller forms the PID controller, t nvolves P, I and D three dfferent constant parameters. Sgnal whch s present n between desred output and actual output s an error sgnal. PID controller operates drectly on error sgnal. Advantages of PID controller are as faster response to change n the control nput; control sgnal ncreases to lead steady state error towards zero and elmnates oscllatons. By tunng the three constant the controller can provde the control acton for the specfc process. the factors on whch the response of the controller depends are the responsveness of controller for error, degree of system oscllaton and the degree at whch controller overshoots the set pont. Advantages of PID controllers PID controller s ndependent of the system model, smple desgn and s applcable for varous felds. Thus, has a predomnant role n ndustral control. Very fast response for change n the control nput control sgnal ncreases to lead steady state error towards zero also elmnates oscllatons. Dsadvantages of PID controllers As the PID controller technque cannot meet ncreasng requrements for fast dynamc response t leads to hgh control precson. If there occurrence of uncertantes then the stablty of ths technque cannot be guaranteed. B. Sldng Mode Control Power electronc converters such as DC-DC converters mostly used. By changng the duty cycle of the swtches n the crcut converter the sources of drect current changes from one voltage to another voltage level. For the nonlnear system t s become a great challenge for desgn and control. Classcal control methods are not sutable for operatng pont varatons and load dsturbances. Large sgnal transent n the startup pont and varatons n the system parameters and large sgnal transent produce n the system output, only due to change n the load, cannot allocate wth these technques. Advantages of sldng mode control Sldng Mode Control s ndependent of dsturbances and constrants. For large dsturbances t can provde fast dynamc response and very smple mplementaton and stablty. Ths can be acheved due to property of actng on all system state varables concurrently. C. Sgma Delta Modulaton Sgma-Delta modulaton (Σ-ΔM or Δ-ΣM) s a technque for convertng analog sgnals nto dgtal data. Σ-ΔM s an 2018, IRJET Impact Factor value: ISO 9001:2008 Certfed Journal Page 3541

4 mprovement of an older Delta modulaton (DM or Δ- modulaton). Delta Modulator s an analog-to-dgtal modulaton technque are generally used for a wde varety of applcatons, ncludng dgtal wreless, dgtal telephony over the Internet (VoIP), and 4th generaton moble communcatons. The SDM conssts of an ntegrator and a quantzer n a feedback loop, as shown n Fg. 7. Fg - 7 Sgma Delta Modulator Block Dagram Advantages of sgma delta modulaton Fast transent response. It provde hgh effcency at low load. Spread spectrum of swtchng nose. It can operate at hgher swtchng frequency and thus can use smaller L and C. 5. PROPOSED WORK The proposed work s based on converson of renewable energy sources nto useful DC or AC power for resdental and ndustral applcatons and to acqure a sutable converter for t. The converter used s three phase nterleaved dc dc boost converter. In the proposed boost converter the voltage at the output of the converter s hgher than the nput. The proposed converter utlzes delta-sgma modulaton to control pulse generator. A thorough and effectve analyss of the converter s carred out n order to acheve the system stablty and to mprove the dynamc performance. The followng block dagram llustrates the proposed work. PV Array 6. CONCLUSION Intreleaved 3 cell Boost Converter Sgma delta (Ʃ ) Modulaton Crcut RL Load Fg - 6 Proposed work block dagram The above paper s a revew of varous control technques of Interleaved DC-DC Boost Converters. Dfferent control technques, ncludng lnear and nonlnear control, such as current mode control, PID control and sldng mode control (SMC), sgma-delta modulator, predctve control, fuzzy control, hybrd control, for DC-DC boost converters have been studed. Non-lnear controllers lke model predctve control (MPC) and fuzzy controllers are dffcult and expensve for practcal applcatons. Current mode controller desgnng s not an easy task and the lnear control effects are lmted. PID Controller technque cannot meet ncreasng requrements for fast dynamc response, hgh control precson and f there are uncertantes then the stablty of ths technque cannot be guaranteed. Slde control method provde stablty, aganst the large dsturbance. It s very smple to mplement and provde fast dynamc response, due to property of actng on all system state varables concurrently. SSDM control loop has very fast response and low rpples. Wth the phase shft of 120, the output of the converter s found to be contnuous. Due to the equal sharng of the load current between cells, relablty s mproved, as the overwork on the semconductor swtches s reduced. REFERENCES [1] Caccato M., Consol A., Attanaso R., and Gennaro F , A mult-stage converter for domestc generaton systems based on fuel cells, In Proc. IEEE Ind. Appl. Soc. Conf., vol. 1, pp [2] Xngy Xu, Lzh Zhu, A DSP Based Controller for, Hgh-Power Interleaved Boost Converters, APEC'03, vol. 1, pp , 9-13 February [3] Maran K. Kazmerczuk, Pulse wdth Modulated DC DC Power Converters, A John Wley and Sons, Ltd, Publcaton [4] Kobayash K., Matsuo H., and Sekne Y.,2006., Novel solar-cell power supply system usng a multple-nput DC DC converter. In IEEE Trans. Ind. Electron., vol. 53, no. 1, pp [5] Lopamudra Mtra, Nbedta San, Closed Loop Control of Solar Powered Boost Converter wth PID Controller, IEEE Internatonal Conference on Power Electroncs, Drves &Energy stem(pedes), 2014 [6] Mrza Faud Adnan, Md. Abdul Mon Onnda, Mrza Muntasr Nshat, Naful Islam, Desgn and Smulaton of a DC DC Boost Converter wth PID controller for Enhanced Performance, IJERT, Vol. 6, 2017 [7] P. A. Dahono, S. Ryad, A. Mudawar and Y. Haroen, Output rpple analyss of multphase DC DC converter. IEEE Int.Conf. Power Electrcal and Drve Systems,Hong Kong, pp , [8] Jang Y., Dllman D. L., and Jovanovc M. M , A new soft swtched PFC boost rectfer wth ntegrated flyback converter for stand-by power, 2018, IRJET Impact Factor value: ISO 9001:2008 Certfed Journal Page 3542

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