A Digital Controller Design Method to Improve Performance of PFC Converter *

Transcription

1 Energy an Power Engineering, 03, 5, 6-66 oi:0.436/epe.03.54b03 Publihe Online July 03 ( A Digital Controller Deign Metho to Improve Performane of PFC Converter * Xiaoqiang Zhang,,Weiping Zhang, Peng Mao,, Deyi Fu Beijing Intitute of Tehnology, Beijing, China North China Univerity of Tehnology, Beijing, China zxq@nut.eu.n Reeive September, 0 ABSTRACT With the rapi evelopment of igital ignal proeing hip in reent year, DSP began to be ue in more withing power upply. The avantage of igital ontrol of their own, making the igital ontrol PFC beome a hotpot reearh. However, ompare with the imulation ytem, the igital ontrol tehnology till ha many problem. In thi paper, the problem of igital PI ompenator a a voltage ompenator i iue, an the Single-pole voltage loop ompenator i ue in igital ontrol PFC iruit. Beaue urrent loop banwith i narrow, a metho to expan urrent loop banwith i put forwar. Output power 300 W of prototype i mae, an experimental reult verify the orretne of the theory. eywor: PI ompenator; Single-pole Compenator; the Banwith of Current Loop. Introution In the PFC iruit, igital PI ontrol algorithm i ue wiely, beaue of it imple truture, eay to implement. Control truture uing the voltage loop, urrent loop ontrol. With the eepening of reearh, many new ontrol trategie an way to improve ytem performane are appeare. In the ontrol algorithm whih appeare a preitive ontrol, fuzzy ontrol, eabeat ontrol, aaptive ontrol. Thee ontrol metho are avane ontrol theory, ha it own avantage, but mot of the more omplex to implement, inreaing the ytem intability fator. For the ontrol of omplex power ytem, the impliity of the algorithm i neeary. In hort, thee algorithm improve the ytem performane to a ertain extent, but overall in term of ome of the other. In the analog ontrol of PFC iruit, PI ompenator i not wiely ue. Aware of thi problem, the analog ontrol PFC iruit of the PI ompenator i eigne to iover the reaon for it not being applie, in orer to fin appliation in the igital PI ompenator ontrol problem, help to improve ytem performane. Thi paper tuie the problem of the traitional PI ompenator a a igital voltage loop ompenator, the one pole ompenator of voltage loop i ue in igital ontrol PFC * Projet upporte by Natural Siene founation of China (N ). The Importation an Development of High-Caliber Talent Projet of Beijing Muniipal Intitution (NO.IDHT03050) iruit. The expanion of igital ontrol PFC iruit urrent loop banwith metho i given. Finally, the orretne of the metho i verifie by experiment.. Performane Compariion of Voltage Loop Compenator In PFC iruit, the output voltage ontain the amount of the eon harmoni, reulting in the emergene of the input urrent referene ignal thir harmoni, the input urrent to trak the urrent referene ignal hange, whih alo ontain thir harmoni []. In orer to reue the ontent of thir harmoni, Voltage ompenator gain at 00 Hz to the mall, relevant literature, the ontent of thir harmoni of input urrent i le than 3%, the voltage ompenator output either the eon harmoni ontent of over.5% of the total output. From the above analyi, PFC iruit voltage ripple ompenator eign tanar i gave: ) The voltage ompenator banwith f <00 Hz ) The voltage ompenator gain at 00 Hz at the meet,.5% vea GEA () 0log () v.. PI Compenator of Voltage Loop In the ae of meeting the tanar ripple voltage loop ompenation, the 300 W PFC iruit voltage om- opk Copyright 03 SiRe.

2 X. Q. ZHANG ET AL. 63 penator i eigne. Open-loop tranfer funtion Boe plot of voltage loop i hown in Figure, meet the above riteria, the alulate voltage loop banwith i too narrow to meet the ripple onition. The banwith of ompenator i not uitable, whih lea to poor output voltage ynami, the imulation reult hown in Figure, the main reaon i the harateriti of the PI ompenator. A the PI ompenator gain at high frequenie i a ontant, whih make the ripple to meet the requirement of the ae, at the expene of ytem banwith, whih i worth the anle. now the PI ompenator of thi feature, through the voltage loop open-loop tranfer funtion gain at the utoff frequeny of, are: T ( j ) () E After the voltage loop banwith i approximate to meet the onition require to meet the ripple uner the type, p (3) i 400 At the utoff frequeny, voltage loop open-loop tranfer funtion of phae angle: pc tan TE( j) n (4) i p That C n z Let n be the phae fator, when n =, the phae margin i 45 egree. Meet the ripple requirement, z C, at thi time the value of k p ereae, Voltage loop gain ereae at 00Hz,but z an not tay away C, otherwie the phae margin i too mall, the ytem i eay to hok. Therefore, uing a ompromie approah, that i at the expene of phae margin, the voltage at the loop gain at 00 Hz a loe to the require value... Single-pole Voltage Loop Compenator Through the above analyi, PI ompenator in the loop a a voltage ompenator an not meet the output ripple ontraint. In the traitional voltage loop ompenator truture, ingle-pole ompenator i a wiely ue, the iruit truture hown in Figure 3. Through the tuy, Allai, Texa Intrument power of thee well-known ompanie of imilar prout, the wieprea ue of the voltage loop ompenator i ingle-pole ompenator. Thi i mainly about the goo high frequeny attenuation harateriti of ingle-pole ompenator. The Boe plot hown in Figure 4, meet the ripple onition an enure a table ontrol ytem. Through the MATLAB imulation, the voltage loop ompenation tranfer funtion before an after the openloop Boe plot, hown in Figure 5. PSPICE iruit imulation to get through the PFC iruit when the output V O C R R R 3 V EA V ref Figure 3. Single-pole ompenation iruit truture. Figure. Voltage loop Boe plot of open loop tranfer funtion. Magnitue (B) Boe Diagram Phae (eg) Frequeny (Hz) Figure. Output voltage of 300 W PFC iruit. Figure 4. Boe plot of ingle-pole ompenator. Copyright 03 SiRe.

3 64 X. Q. ZHANG ET AL. voltage waveform, hown in Figure 6. Verify the auray of the ompenation eign..3. Feature Compariion of Single-pole Compenator an PI Compenator Calulate by the above analyi, the Boe plot of pole voltage loop ompenator an PI ompenator i hown in Figure 7. Figure 5. Voltage loop Boe plot of open loop tranfer funtion. It an be een from the figure, the ompenator pole at 00 Hz goo attenuation, the PI ompenator gain larger, an thi i the reaon an not meet the ripple requirement. By the voltage loop open-loop tranfer funtion Boe plot, hown in Figure 8. It i lear that ue ingle-pole ompenator iruit attenuation at 00 Hz i goo. From the omparion, thi feature make the PI ompenator applie in the PFC iruit voltage loop pole on the poor performane in the ompenator, but the voltage loop PI ompenator i not without merit. In ummary, inglepole ompenator in the PFC iruit i uperior to the appliation of voltage loop PI ompenator. 3. Metho of Current Loop Banwith Expanion During the igital ontrol, ue to ifferent moe of uty yle upate between igital ontrol an analog ontrol, PWM pule with moulation i equivalent to the ieal ampling with an zero-orer hol evie [], PWM generation proe nee to onier the iue of elay, onier the urrent elay ring truture hown in Figure 9. T e Gpwm ( z) Z( ) (5) Current loop open-loop tranfer funtion: Figure 6. Output voltage of 300W PFC iruit. Figure 8. Compenate voltage loop Boe plot of open loop tranfer funtion. G ( z) i () G ( ) CA z Gpwm z Gi ( z) e Gz ( ) T Figure 7. Boe plot of ingle-pole voltage ompenator an PI ompenator. Figure 9. Diagram of urrent loop. Copyright 03 SiRe.

4 X. Q. ZHANG ET AL. 65 Zi ( Z ) VOT i ST TE( Z) ( p ) Z LZ j T where Z e Gain of urrent loop open-loop tranfer funtion at the ut off frequeny i an phae margin i 45 egree, in that ae, tuy the relationhip of withing frequeny an voltage loop banwith, then there: VOi where m. L Beaue o S p i (6) TT ( ) min T (7) T (8) in T T (9) where f S, T i elay ( p i ) mt time ontant. A the impat of ampling frequeny an elaying time, the banwith of urrent loop of PFC iruit ha been ontraine aoringly. Analyi type an know, in a ertain iruit parameter, the urrent loop banwith i proportional to ampling frequeny; the urrent loop banwith i inverely proportional elay time. That inreae the ampling frequeny, reuing the elay time an be extene urrent loop banwith, o the urrent loop ynami will be enhane an the input urrent waveform itortion will be reue, thereby improving the power fator. Sample one a withing yle, wave about upate moe of PWM uty yle a hown in Figure 0, thi time elay i a withing yle, that i T (0) T If by inreaing the ampling frequeny, reuing the elay time to expan the urrent loop banwith, ampling metho mut be hange. The ampling metho i beame ampling twie a yle, the uty yle upate a hown in Figure, thi time, n T T () N The relationhip of ampling frequeny an the urrent loop banwith: 4N fs () ( ) mt n p i N i a withing yle DSP timer value, n i the uty yle of the PWM wave equivalent timer value, it value epen on the itribution that uty yle value in the ope of the ount, in the mot ba ae, n = N. Remove thi ituation, elay time of the moe of ampling a ingle-yle mut be le than the moe of ampling twie a ingle-yle [3]. Uner the ame onition, uing a metho of ampling twie a ingle-yle an ignifiantly reue the elay time, an an effetively exten the urrent loop banwith. There are ome relate artile mentione it [4-5]. 4. Experimental Reult During the experimental tuie, 300 W PFC iruit whih i ontrolle by DSP TMS30LF407 i buil on, input voltage 0 V-0 V, withing frequeny i 50 khz, the input inutane i.4 mh, the output filter apaitor i 470uF, output power i 300W, output voltage i 340 V. PI ompenator applie to the igital DSP ontrol 300W PFC iruit, the output voltage an input urrent waveform hown in Figure, the power fator i 0.935, the urrent harmoni ontent i 7.7%. The experimental reult of applying ingle-pole ompenator i hown in Figure 3, the power fator i 0.975,the urrent harmoni ontent i 6.7%. Compare with the igital PI T T Figure 0. Upate moe of the uty yle (ampling a ingle-yle). N T T Copyright 03 SiRe.

5 66 X. Q. ZHANG ET AL. Figure. Upate moe of the uty yle (ampling twie a ingle-yle). ompenator in the300w PFC iruit, the iruit ue ingle-pole ompenator, it urrent harmoni ontent ereae by %, power fator Single-pole voltage loop ompenator in igital iruit, it performane ha been marke a igital PI ompenator. Waveform of output voltage an input urrent ue ingle-pole ompenator ampling twie a ingle-yle i hown in Figure 4. Output voltage i 336 V, the power fator i 0.977, ompare with the iruit that ampling a ingle-yle, power fator i improve 0.05, the urrent harmoni ontent i 5%that inreae by %. (ingle-pole ompenator). Figure 4. Waveform of output voltage an input urrent (ampling twie a ingle-yle). 5. Conluion Figure. Waveform of output voltage an input urrent (PI ompenator). Figure 3. Waveform of output voltage an input urrent In thi paper, the metho of uing ingle-pole ompenator in igital iruit i propoe, the traitional metho of uing PI ompenator i rejete, the problem of PI voltage loop ompenator eign an not meet the requirement of the ripple i olve, reuing the input urrent harmoni ontent, power fator an urrent harmoni ontent ha been a goo improvement. The metho of the urrent loop banwith expaning i propoe, the ynami performane of iruit ha been improve. Thi metho effetively reue the elay time, in orer to ahieve the urrent loop banwith expanion. REFERENCES [] W. P. Zhang, Swithing Converter Moeling an Control, Beijing: China Eletri Power Pre, 006, 0. [] D. Lloy, Average Current Moe Control of Swithing Power Supplie, Texa Intrument Appliation Note (U-34). [3] G. H. Liu, W. Wang an D. G. XU, With Fat Dynami Repone of the Digital Power Fator Corretion Algorithm, China Eletrial Engineering, Vol. 9, No., 009, pp.0-. [4] J. Wang, Y. D. Li an Y. J. Ma, A Marke Inreae in Converter Current Loop Banwith of the New Metho for Eletrial Tranmiion, Vol. 39, No. 6, 009, pp [5] H. J. Wang an M. Yang, Permanent Magnet AC Servo Current Loop Banwith Expanion, Chinee Mehanial an Eletrial Engineering, Vol. 30, No., 00, pp Copyright 03 SiRe.