A Novel Electronically Controllable of Current-Mode Level Shifted Multicarrier PWM Based on MO-CFTA

Transcription

1 RADOENGNEERNG, VOL., NO. 3, SEPEMBER 3 97 A Novel Electroncally Controllable o Current-Mode Level Shted Multcarrer PWM Based on MO-CFA Weerapon KONGNUN, Apnan AURASOPON Department o Electrcal Engneerng, Mahasarakham Unversty, Mahasarakham, hal weerapon.kong@gmal.com, apnan.a@msu.ac.th Abstract. hs paper proposes the applcaton o an electroncally controlled current-mode or a level shted multcarrer PWM generator. he proposed crcut conssts o two multple-output current ollower transconductance amplers (MO-CFAs) or the multple-output trangular generator our current ollower transconductance amplers (CFAs) or the sgnal comparator. he characterstcs o the crcut are as ollows: the current output can be controlled by bas current, the mamum ampltude devaton due to temperature varaton s less than.37 % the power consumpton s appromately.744 W, at ±.5 V supply voltages. he proposed PWM has been vered through PSpce smulaton results whch are n consstent wth the theoretcal analyss. Keywords Current-mode, level shted multcarrer PWM, MO-CFA. or the multlevel voltage source nverters are the multcarrer PWM technque whch has two groups: n the phase shted PWM, the phase derence o trangular carrers s used n modulaton process. Whle the level shted PWM the ampltude derence o trangular carrers s used. However, the most popular smple swtchng scheme or controllng the multlevel voltage source nverters s level shted PWM []. Unequal DC Source Multple DC Source Multlevel Converters Sngle DC Source Cascaded H-Brdge Flyng Capactor Neutral Pont Clamped Equal DC Source Fg.. A classcaton o the multlevel converters.. ntroducton Multlevel voltage source nverters have been wdely used or hgh power applcatons such as water pumpng statons, ehaust gas ans, nducton motor controller, reactve power compensaton, grd ntegraton o renewable energy, more derent applcatons []-[8]. hs s because they have many advantages such as low power dsspaton on power swtches, low harmonc contents low electromagnetc ntererence (EM) outputs. Fg. shows a classcaton o the multlevel voltage source nverter topologes that s dvded at two groups: sngle multple DC source topologes. hese topologes consst o many swtches or generatng the multlevel output voltage. o control the operaton o these swtches, the general basc pulse-wdth modulaton (PWM) such as snusodal PWM or space vector PWM cannot be drectly used. hus, the comple PWM technques have been used can be dvded at two groups: low hgh swtchng requency technques as shown n Fg.. Generally, the swtchng loss the percentage o total harmonc dstorton (HD) are used or selectng the modulaton strateges [9]. However, n some applcatons, the smple modulaton strateges are requred. he smple modulaton technques Fg.. A classcaton o the multlevel modulaton topologes. he level shted multcarrer PWM can be dstngushed n three methods: Phase Dsposton (PD), Phase Opposton Dsposton (POD) Alternatve Phase Opposton Dsposton (APOD) as shown n Fg. 3. he PD method gves the lowest harmonc dstorton at hgh modulaton ndces when compared to the other methods [], []. Moreover, ths method s an optmal soluton

2 98 W. KONGNUN, A. AURASOPON, A NOVEL ELECRONCALLY CONROLLABLE OF CURREN-MODE LEVEL SHFED when used n carrer-based space-vector PWM or threephase nverter [3]. However, n ths paper, all methods wll be eamned n smulaton results.. Basc Concept o MO-CFA Fg. 4(a) shows the symbol o MO-CFA that conssts o nne-port analog two ports or current bas. Whle Fg. 4(b) shows ts equvalent crcut. B B v c c c c- c- c c c c c- v v c- MO-CFA - z - v - z Fg. 3. hree bascs o the multcarrer modulaton topologes. n recent year, most o analog crcut desgn uses a current-mode technque because ths technque has more potental advantages such as wde bwdth, large dynamc range, smple crcut good lnearty [4-]. he m-mode devce current ollower transconductance ampler (CFA) proposed n [] s very sutable or the desgn synthess analog crcut sgnal processng, ts transconductance gan can be controlled by the correspondng bas current. Moreover, usng CFA as an actve element s more desrable n applyng an automatc control. Furthermore, t provdes the system wth smpler crcuts than ts counterparts [3]. From above mentoned, ths paper proposes the applcaton o CFA ts moded-verson, MO-CFA, to generate the level shted multcarrer PWM. he eature o the proposed crcut whch s very smple conssts o two MO-CFAs, our CFAs one grounded capactor. Moreover, the output sgnals are ndependent o temperature. hs paper s organzed as the ollowng sectons. Secton presents basc concept o MO-CFA, saturatonmode on MO-CFA, trangular carrer generaton, comparator prncple o the proposed level shted multcarrer PWM conguraton. Secton 4 shows the smulaton results by PSpce program. n Secton 5, the concluson s presented.. Level Shted Multcarrer PWM Crcut Desgn n ths secton, we present the basc concepts o MO- CFA or trangular carrer generaton CFA or sgnal comparator. Whle, the crcut desgn or the proposed level shted PWM wll be presented n the last subsecton.6. v v z (a) Symbol v z z g m v z g m v z (b) Equvalent crcut Fg. 4. Basc concept o MO-CFA. n an deal case, the relatonshp between current voltage can be ound to be V z Vz, gm V gm V () where c, c, () B B g m, gm V V (3) where g m g m are the transconductance gan o the MO-CFA based on BJ technology, V s the thermal voltage s equal to 6 mv at 7 C, B B are bas currents used to adjust transconductance gan. v - v -

3 RADOENGNEERNG, VOL., NO. 3, SEPEMBER Saturaton-Mode on MO-CFA From the MO-CFA propertes depcted n Secton., when V Z << V, the output currents at ( ) ( - ) ports are equal to V Z B /(V ) V Z B /(V ), respectvely. he DC transer characterstcs o MO-CFA can be appromated by the rst order aylor s seres epanson [5], whch can be eplaned as: 7. (4) tanh... hus, the orgnal can be ound by tanh V z, B V tanh V z B V. (5) Because the z port s loated, thereore, the output voltage at the z port can be appromated: V CC V (6) Z VEE where V CC V EE are the postve negatve supply voltages, respectvely. From (6), t can be clearly seen that V Z >> V. hen tanh(v Z /(V )) n (4) (5) can be appromately smpled to be V z tanh. (7) V he condton o the MO-CFA operates n the saturatonmode when V Z >> V. hus the output currents at termnals can be re-wrtten rom (4) (5) to be B or when VZ V (8) B or when VZ V B or when VZ V (9) B or when VZ V.3 Current-Mode Multple-Output rangular Carrer Generaton he block dagram o the current-mode multple-output trangular generaton whch s employed n the proposed crcut s shown n Fg. 5. t conssts o two MO- CFAs one grounded capactor. he MO-CFA MO-CFA perorm to be Schmtt trgger ntegrator, respectvely. he trangular-wave outputs can be generated va the alternately dschargng chargng o capactor whch s demonstrated n Fg. 6. From the propertes o MO-CFA as descrbed n Secton.., can be ound to be g V m4 z. () Fg. 5. Multple-output trangular generaton. V B V B Vz B B Fg. 6. Output waveorms o the multple-output trangular generaton. hus V z can be epressed to be V he ampltude o outputs V z. () gm4 tr tr6 g V can be obtan by V B3 z tr tr tr3 tr 4 m3 z () V g V V B3 z tr5 tr6 m3 z. (3) V From (), ()-(3) can be rewrtten as B3 tr tr tr3 tr 4 (4) B3 tr5 tr 6. (5) t

4 9 W. KONGNUN, A. AURASOPON, A NOVEL ELECRONCALLY CONROLLABLE OF CURREN-MODE LEVEL SHFED From the DC characterstc o MO-CFA eplaned n Secton., t can be ound that depends on B. hen tr tr6 can be ultmately wrtten to be B B3 tr tr tr3 tr 4 (6) B B3 tr5 tr 6. (7) Perod output requency can obtaned by Vz C 8C BV dvz (8) Vz B B B. (9) 8CB V From (6), (7) (9), t can be clearly seen that the magntude requency o the output current can be electroncally/ndependently controlled. n addton, the ampltude o output currents s ree rom V. Furthermore, the multple-output trangular carrer generaton s very sutable or applyng n the multcarrer PWM more than another research opton [4-37] whch merely have a sngle output..5 Current-Mode PWM Process n ths subsecton, we eplan the current mode PWM process. Fg. 9 shows the PWM sgnal that s generated by trangular carrer comparng wth normaton sgnal. When the ampltude o trangular carrer s hgher than that o normaton sgnal ths produces the negatve PWM sgnal,, whch can be ound as ollowng: 4 re re.4 Current-Mode Comparator Fg. 7 shows the block dagram o the current-mode comparator. he trangular carrer, C, s subtracted rom the normaton sgnal,. ts result s sent to be an nput o the comparator crcut. Equaton () shows the condton o the output current o the comparator crcut, whch can be eplaned by Fg. 8. B5 C O () B5 C Fg. 9. Output waveorms o the proposed PWM (n case O ). he slope o C m m, t t can be ound to be C C BB3, () CV B ( t ) B B3 C re mc CV re B t d t () m re CV. (3) B B3 t dc re t C ( t ) B From Fg. 9 ()-(3), can be epressed as Fg. 7. Current-mode comparator (n case comparator ). O B5 - B5 Fg. 8. DC characterstc o the current-mode comparator. CV 4 t t 4 B B B B3 t t re. (4) From the pecewse lnear appromaton the hgh t t t. hus (4) requency carrer sgnal can be moded to be 4CV t B re. (5) B B B3

5 RADOENGNEERNG, VOL., NO. 3, SEPEMBER 3 9 hereby, the duty cycle o O can be obtaned by t. re D B B3 (6) Smlarly, the duty cycle o O,, can be ound to be 4 B t D, (7) B B3 t D3 B B3 t D4 re B B3, (8) (9) where D, D, D 3 D 4 are duty cycle o O, O,,, respectvely. From (6) (9), (t) s equal to 3 re -3 re resultng D D 4 are equal to 5% (t) s equal to re resultng D D 3 are equal to 5%. Whle, B B3 re, equatons (6) (9) can be nally wrtten as t D 4 B B3 (3) B t D. (3) B B3 From the propertes o MO-CFA the operaton o current-mode comparator descrbed n Secton. Secton.5, respectvely, the ampltudes o O,, can be epressed as:.6 Prncple o the Proposed Level Shted Multcarrer PWM From the detal n Subsecton.-.5, we use them to be normaton or desgnng the level shted PWM crcut. Fg. shows the block dagram o the proposed conguraton. t conssts o the multple-output trangular carrer generaton (crcut n Fg. 5) our comparators (crcut n Fg. 7). Fg., 3 llustrate the modulaton process or PD, POD APOD, respectvely. From the process, they requre the derent DC level phase o the trangular carrer sgnals. hese requrements can be adjusted by re selectng the output ports o the crcut n Fg. 5, respectvely. Fg.. Block dagram o the proposed level shted multcarrer PWM. normaton Sgnal O C C C3 C4 O B6 B6 C C (3) O B7 B7 C3 C3 (33) B8 B8 C 4 C 4 (34) From () (3)-(34), t can be ound that the current level o O, O, can be adjusted va bas currents. Furthermore, the ampltude o output currents s deally temperature-nsenstve by reason o lberty V. Fg.. Output waveorms o the PD level shted multcarrer PWM.

6 9 W. KONGNUN, A. AURASOPON, A NOVEL ELECRONCALLY CONROLLABLE OF CURREN-MODE LEVEL SHFED Fg.. Output waveorms o the POD level shted multcarrer PWM. Fg. 3. Output waveorms o the APOD level shted multcarrer PWM. Fg. 4. nternal constructon o MO-CFA. 3. Smulaton Result he perormances o the proposed level shted multcarrer PWM have been conrmed va the smulaton results by PSpce program. he schematc o MO-CFA s shown n Fg. 4. he parameter o PNP NPN transstors employed n the proposed crcut were smulated by usng the parameters o the PRN NRN bpolar transstors o ALA4 transstor array rom A& [38]. DC power supply voltages are equal ±.5 V, C = nf, A = µa, B = µa, B = 5 µa, B3 = 95 µa, = 45 µa, B = B5 = B6 = B7 = B8 = µa. he smulaton results n case o PD, POD APOD are shown n Fgs he output ampltude relatve to the B varaton s llustrated n Fg. 8. t can be clearly seen that the level o output current can be electroncally adjusted by bas currents whch are tuned rom to 8 A. Current (A) Current (A) me (ms) (a) normaton sgnal carrer sgnals me (ms) (b) he output sgnals. Fg. 5. Results o the PD level shted multcarrer PWM.

7 RADOENGNEERNG, VOL., NO. 3, SEPEMBER 3 93 Current (A) - n accordance wth a theoretcal analyss whch s demonstrated n Secton.6. he HD o the proposed PWM s appromately.68 % whch s less than [6], [7], [36]. Current (A) me (ms) (a) normaton sgnal carrer sgnals me (ms) D From (3) Smulated D D From (7) Smulated D D 3 From (8) Smulated D 3 D 4 From (3) Smulated D 4 Current (A) - (b) he output sgnals. Fg. 6. Results o the POD level shted multcarrer PWM. Duty Cycle (%) Current (A) me (ms) (a) normaton sgnal carrer sgnals me (ms) (b) he output sgnals. Fg. 7. Results o the APOD level shted multcarrer PWM. - - Fg. 9. Duty cycles aganst (t). (t) (A) he devaton o the output ampltude relatve to temperature varaton s demonstrated n Fg.. t can be ound that the mamum absolute devaton o the level o output current s less than.37 % or temperature varaton between C. hereore, t can be concluded that the ampltude o output currents s slghtly dependent on wde temperature varaton...5 Ampltude o Output Currents (A) heoretcal Smulated Ampltude Devaton (%) emperature ( o C) B (A) Fg. 8. Ampltude o output versus B. he theoretcal calculaton smulaton o duty cycle s shown n Fg. 9. t can conrm that the results are Fg.. Ampltude o PWM output versus temperature. 4. Concluson A novel current-mode PD, POD APOD level shted multcarrer s benecal because the proposed

8 94 W. KONGNUN, A. AURASOPON, A NOVEL ELECRONCALLY CONROLLABLE OF CURREN-MODE LEVEL SHFED crcut comprses two MO-CFAs, our CFAs a grounded capactor wthout eternal resstor. he output current can be electroncally controlled s slghtly dependent on wde temperature varaton. he smulaton results conrm that the theoretcal epectaton s possble. Moreover, ths proposed crcut can be mproved n urther research whch needs to use a multcarrer PWM applcaton. Reerences [] RODRGUEZ, J., LA, J., PENG, F. Multlevel nverters: a survey o topologes, controls applcatons. EEE ransacton on ndustral Applcaton,, vol. 49, no. 4, p [] LESNCAR, A., MARQUARD, R. An nnovatve modular multlevel converter topology sutable or a wde power range. n Proceedngs o Power echnology Conerence. 3, vol.3, no. 6. [3] ROSSMANN, W. C., ELLS, R. G. Retrot o ppelne pumpng statons wth 3-hp motors varable-requency. EEE ransactons on ndustral Applcaton, 998, vol. 4, no., p [4] MENZ, R., OPPRECH, F. 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9 RADOENGNEERNG, VOL., NO. 3, SEPEMBER 3 95 [3] LO, Y. K., CHEN, H. C. Swtch-controllable ORA-based square/trangular waveorm generator. EEE rans. on Crc. Syst. Sgnal Processng, 7, vol. 54, no., p. -4. [3] KM, K., CHA, H. W., CHUNG, W. S. OA-R Schmdtt trgger wth ndependently controllable threshold output voltage levels. Electroncs Letters, 997, vol. 33, no. 3, p [33] CHUNG, W. S., KM, H., CHA, H. W., KM, H. J. rangular/square-wave generator wth ndependently controllable requency ampltude. EEE ransactons on nstrumentaton Measurement, 5, vol. 54, no., p [34] CHUNG, W. S., CHA, H. W., KM, H. J. Current-controllable monostable multvbrator usng OAs. EEE rans. on Crcuts Systems,, vol. 49, no. 5, p [35] SRPRUCHYANUN, M., WARDKEN, P. A ull ndependently adjustable, ntegrable smple current controlled oscllator dervatve PWM sgnal generator. ECE rans. Fundam. Electron. Commun. Comput. Sc., 3, vol. E86-A, no., p [36] KUMBUN, J., SRPRUCHYANUN, M. MO-CA-based electroncally controlled current-mode square/trangular wave generator. n Proc. o the st nternatonal Con. on echncal Educaton (CE9)., p [37] SONER, R., JERABEK, J., HERENCSAR, N., PROKOP, R., VRBA, K., PERZELA, J., DOSAL,. Smply adjustable trangular square wave generator employng controlled gan current derental voltage ampler. n Proc. o the 3 th nt.. Con. Radoelektronka. Pardubce (Czech Rep.), 3, p. -6. [38] FREY, D. R. Log-doman lterng: an approach to current-mode lterng. EE Proc. Crcut Devces Syst., 993, vol. 4, p. 46 to 46. About Authors Weerapon KONGNUN was born n Uttaradt, hal n 976. He receved the B. Eng. degree n nstrument Engneerng the M. Eng. degree n Electrcal Engneerng rom Kng Mongkut s nsttute o echnology Ladkrabang (KML) n 999. He was a lecturer at the Department o Electrcal Computer ndustral, Faculty o ndustral echnology, Uttaradt Rajabhat Unversty, Uttaradt, hal snce 4. Hs research nterests nclude electrcal measurement, hgh voltage testng, power electroncs ts applcaton. Apnan AURASOPON was born n Amnat-charoen Provnce, hal n 97. He receved hs B.Eng n Electronc Engneerng rom Northeastern College n 995, M.Eng. Ph.D. n Electrcal Engneerng rom Kng Mongkut s Unversty o echnology honbur n 3 7, respectvely. He was a lecturer at the Department o Electrcal Engneerng, Faculty o Engneerng, Burapha Unversty (BU), Chonbur n 7 transerred to the Faculty o Engneerng, Mahasarakham Unversty (MSU) n 8, where he s Assstant Proessor. Hs research nterests nclude sot-swtched converters, ac choppers, converter systems or mprovng power qualty, applyng electroncs computer or agrculture.