Control Method for DC-DC Boost Converter Based on Inductor Current

Transcription

1 From the electedwork of nnovative Reearch Publication RP ndia Winter November 1, 15 Control Method for C-C Boot Converter Baed on nductor Current an Bao Chau Available at:

2 Control Method for C-C Boot Converter Baed on nductor Current an Bao Chau Faculty of Electrical & Electronic Engineering, y Tu Trong Technical College, Ho Chi Minh City, iet Nam Correponding cvbltt@gmail.com Abtract Thi paper introduce a new control method for C-C Boot converter that i the control method baed on inductor current on the bai of balance of power. The imulation reult have proven to be that: propoed control method enured the accuracy and output voltage ripple i within the required limit. Keyword C-C converter, C-C Boot converter, P controller, inductor current converter baed on the inductor current. With thi method we might not need to build the tranfer function of the converter The tructure of the paper i preented a follow: part overview introduce the converter C-C Boot. Part preent the mathematical model of C-C Boot converter. Control method baed on the inductor current for C-C Boot converter i given in part. Part i the imulation reult and ection conclude.. ntroduction The C-C voltage converter in general and C-C Boot voltage converter in particular ha played a very important role in the creation of a C voltage that ha an amplitude a requeted and very mall output voltage ripple [1-3]. The input of Boot converter input i uually a C reource upplied by the olar battery ource, o it doen't have the ability to adjut. Moreover, thi ource i influenced by light intenity and temperature of the environment. o it will have low amplitude and change contantly. Boot converter have the tak of creating a C voltage at the output i larger and more table C voltage at the input. Normally, the C-C converter are controlled according to the output voltage [4-1]. The output voltage i compared with the reference voltage. With thi control, we need to build the tranfer function of the converter. To adjut the deired output voltage we ue pule width modulation technique PWM to change the time on-off of the witch. The output voltage of the converter i monitored by the voltage ubtraction, the voltage at the poitive pole i igned with the reference voltage and the negative pole aigned with the feedback voltage, when it archived error will be paed to the controller, the tranfer function of the converter and the create pule to cloe/open the MOFET. However, according to the tructure of the C-C Boot converter, the electric current through the inductor depending on the input voltage, output voltage and load reitance [11]. Moreover, according to the principle of balance of power, then the conumption power will equal to the generated power or input power will equal to the output power. o when the input voltage of the converter and load reitor do not change, then the electric current through the inductor will depend on the output voltage. o, we can control the output voltage by adjuting the electric current through the inductor. Therefore, thi article give a new control method for C-C Boot. Mathematical Model of C-C Boot Converter The tructure of C-C Boot converter hown a in figure 1. JET@15 Page 511 K Figure 1. Topology of C-C Boot converter Mathematical model of C-C Boot converter built in [11] and ummarized a follow: When K cloed: Equivalent circuit of the C-C Boot converter i hown a in figure. v Figure. Equivalent circuit of C-C Boot converter when K cloed According to Kirchoff law, we have: di v (1) dt The rate of change of current i a contant. Therefore, the change in inductor current i computed from t T olving for Δ for the witch cloed a follow i i C ()

3 T ( i ) cloe (3) When K open: Equivalent circuit of C-C Boot converter i hown a in figure 3. v Figure 3. Equivalent circuit of C-C Boot converter when K open imilarly, we have: di v (4) dt di or dt The rate of change of current i a contant. Therefore, the change in inductor current i computed from t (1 )T olving for Δ for the witch open a follow ( )(1 )T ( i ) open (6) For teady-tate operation, the net change in inductor current mut be zero. From (3) and (6) we have equation a follow: i ) ( ) (7) olving for o ( cloe open (5) T ( )(1 )T (8) ( 1 ) (1 ) (9) (1) 1 Equating input and output power, we have: [ /(1 )] R (11) R R (1 ) oloving Eq. (11) we find out a follow: (1 ) R R Maximum and imum inductor current are detered by uing the value and the change in current ( i ). cloe and max (1) T (13) (1 ) R T (14) (1 ) R Equation (14) wa developed with the aumption that the inductor current i continuou, meaning that it i alway poitive. A condition neceary for continuou inductor current i for to be poitive. Therefore, the boundary between continuou and dicontinuou inductor current i detered from T (15) (1 ) R or T (1 ) R f From (16) we calculated a follow: (f) (16) (1 ) R (17) (1 ) R (18) f Output voltage ripple can calculated from capacitor current : Find out Q T C (19) R i output voltage ripple RCf where f i the witching frequency () C (1) Rf. Control method baed on nductor Current The method control cheme baed on output voltage hown a in Fig. 4 Ref X - P controller Compar ator G Boot Figure 4. Control method cheme baed on output voltage out Where G Boot i tranfer function of converter G Boot n the method control baed on output voltage cheme [4-1] hown in Fig. 4, the converter output voltage i ened and ubtracted from a reference voltage in an error amplifier. The out JET@15 Page 51

4 error amplifier produce a control voltage i paed to P controller. The output of P controller i compared to a contant- frequency and amplitude awtooth waveform. The comparator produce a logic or 1 ignal that i fed to driver of controllable witche in the dc-dc converter. The duty ratio of the ignal depend on the value of the control voltage. The frequency of the pule width modulation ignal i the ame a the frequency of the awtooth waveform. Control method baed on inductor current i hown a in Figure 5. A K C R o Time () Figure 6. nput voltage wave form and output voltage wave form 3.6 o 3.4 i ref m 3. P 3 ref carr Time () Figure 5. Control method baed on inductor current ifferent with the control method baed on voltage [5-8], here the reference ignal i the output voltage. n thi control method, the reference ignal i inductor current and it calculated ref form Eq.(14), Which i compared with actual meaured from inductor current. The achieved error between above two ignal i paed to P controller. The output of the P controller will be compared with triangle carrier wave high frequency to generate logic level or 1, to cloe or open witch K. o, to the deire output voltage i contant, then the inductor current alo invariant. The P controller aim to imum error between the reference and actual ignal.. imulation reult and dicuion To demontrate the propoed control method, imulation reult made with PM oftware of the C-C Boot converter. Thee parameter of C-C Boot converter i given a follow: nput voltage: 1C Output voltage: 3C oad reitance: 5Ω Output voltage ripple <.5% witching frequency: 1kHz The value and C are calculated by Eq.() and Eq. (3). P controller with Kp=1, Ki=.1. imulation reult of the C-C Boot converter baed on inductor current are hown a in figure 6 and figure 7. Figure 7. Output voltage ripple From figure 7, we can ee that the output voltage ripple i.16%. From the imulation reult we can ee that: propoed control method atified demand of degree of accuracy and ripple of the output voltage.. Concluion Thi paper ha been given a new method for the C-C Boot converter, which i controlled baed on inductor current. Thi method ha the advantage i not having to earch for tranfer function of the converter and can ued for all C-C converter. The imulation reult have proven to be that: the propoed control method ha atified the requirement of degree of accuracy and ripple of the output voltage when deigning C-C Boot converter. Reference i. A Khohooei, Moghani, mplementation of a ingle nput Fuzzy Controller for a High Power Factor Boot Converter, 7th African Technology innovation conference in Africa. 4: ii. Roetta, G piazzi, P Tenti, B Fabiana, C icitra, Fat- Repone High-Quality Rectifier with liding-mode Control, EEE Tran. on Pwer Electronic. 1994, 9 ( ): iii. J B William, eign of Feedback oop in Unity Power Factor AC to C Converter, Power Electronic pecialit JET@15 Page 513

5 Conference, PEC '89 Record., th Annual EEE.1989: iv. C C ee, Fuzzy ogic in Control ytem: Fuzzy ogic Controller -Part / Part 11, EEE Tran. on ytem, Man and Cybematic. 199, 1 (6): v. ng Ep Fredy, H Martinez, Fuzzy ogic Controller for Boot Converter with Active Power Factor Correction, 7th nternatonal Conference on Power Electronic. 7: vi. C Zhou and Jovanovic, eign Trade-off in Continuou Current-mode Controlled Boot Power-Factor Correction Circuit, eventh nternational High Frequency Power Converion (HFPC) Conf., an iego, CA. 199; 9-. vii. H H Chung, E P W Tam, Y R Hui, evelopment of a fuzzy ogic Controller for Boot Rectifier with Active Power Factor Correction, 3th Annual EEE Power Conference in Electronic pecialit. 1999: viii. A Rubaai, M F Chouikha, eign and Analyi of Fuzzy Controller for C-C Converter, Firt nternational ympoium on Control in Communication and ignal Proceing. 4: ix. A Pandey, Prof B ingh, Comparative Evaluation of ingle phae Unity Power Factor ac-dc Boot Converter Topologie, EEE proc.4, 7 (4): x. A Kilovki, mall-ignal low-frequency analyi of a buck type PWM conductance controller, pecialit Conference in EEE Power Electron. 199: xi. aniel W Hart, Power Electronic, Mc Graw Hill, 11. JET@15 Page 514