 to permit the fluid to pass around the filter element when it becomes clogged is generally recognized. A popular approach has been to provide a bypass valve and movable filter element within a housing closed at one end by a cover. The filter element is normally spring-biased toward a position wherein the bypass valve is closed and filtration of the fluid can occur, but the filter element can move to an offset position wherein the bypass valve is open if the filter element becomes clogged and the pressure differential thereacross becomes too high so that fluid can flow around it and continue to circulate through the system without damage thereto. Various indicators have also been developed to signal such bypass conditions so that the filter elements can be changed, with U.S. Pat. Nos. 3,819,052 and 3,827,558 assigned to Donaldson Company, Inc. being representative of fluid filters having this feature.
The movable filter elements of such fluid filters, however, may under certain conditions experience oscillation which, if uncontrolled, may lead to problems. The possibility of filter element oscillation, which has been reported from the field and verified in the lab, increases as the filter element becomes progressively clogged, and is directly related to the sudden change in cross sectional flow area as it moves between the normal and bypass positions. As the filter element begins to move toward the bypass position in opposition to the retaining spring, the flow areea increases which results in decreased pressure drop across the filter element. This reduction in pressure enables the spring to force the filter element back toward the normal position, thereby decreasing the flow area and increasing the pressure drop, which in turn results in oscillation. Such oscillation may accelerate structural failure of the filter element and cause fluctuations in the electrical or visual indications of the filter conditions. Sudden displacements of the filter element by high pressure spikes such as during cold starts or other flow surges can also lead to such problems.
Fluid filters utilizing auxiliary mechanical means disposed between the filter element and the housing have been used heretofore for cushioning shock of the filter element during movement to the full bypass position; however, a need exists for an improved fluid filter incorporating an integral viscous damper to minimize and eliminate oscillation of the filter element. 1. Field of the Invention
The present invention is related to automatic control, electronics, DC-DC conversion, DC-AC conversion and energy technology, specifically, solar photovoltaic (PV) energy conversion system being used in power grid.
2. Description of the Prior Art
Advance in science and
to permit the fluid to pass around the filter element when it becomes choked is by and large recognized. A popular overture has been to put up a bypass valve and movable filter element within a caparison closed at one end by a cover. The filter component is normally spring - biased toward a situation wherein the bypass valve is closed and filtration of the fluid can happen, but the filter element can move to an offset position wherein the bypass valve is open if the filter element becomes choked and the pressure differential thereacross becomes too gamey so that fluid can flow around it and continue to go around through the system without price thereto. Various indicators have also been developed to signal such beltway conditions so that the filter elements can be changed, with U.S. Pat. Nos. 3,819,052 and 3,827,558 assigned to Donaldson Company, Inc. being representative of fluid filters having this feature. 
 The movable filter elements of such fluid filters, however, may under certain conditions experience oscillation which, if uncontrolled, may lead to problems. The possibility of filter component oscillation, which has been reported from the sphere and affirm in the lab, increases as the filter element become progressively clogged, and is directly related to the sudden variety in cross sectional flow area as it moves between the normal and bypass positions. As the filter element begins to move toward the bypass position in opposition to the retain spring, the stream areea increases which results in decreased pressure drop across the filter chemical element. This reduction in pressure enables the give to force the filter element back toward the normal position, thereby decreasing the stream area and increasing the press drop, which in bend results in cycle. Such oscillation may accelerate structural bankruptcy of the filter element and cause fluctuations in the electrical or visual indication of the filter conditions. Sudden shift of the filter element by high pressure spikes such as during cold starts or early flow surges can besides lead to such problems. 
 Fluid filters utilize auxiliary mechanical means disposed between the filter chemical element and the housing have been used heretofore for cushioning shock of the filter element during movement to the wide beltway position; however, a need exists for an improved fluid filter incorporating an integral syrupy damper to minimize and eliminate oscillation of the filter component. 1. airfield of the Invention 
 The present invention is related to automatic control, electronics, DC - DC conversion, DC - AC conversion and department of energy technology, specifically, solar photovoltaic (PV) energy conversion system being used in power grid. 
 2. Description of the Prior Art 
 Advance in science and
 to permit the fluid to pasr around the filter elxment wgen it bdcomes clogged is generally cecotnizee. A popular approach hxs been tl providw a uypass valve and movable filted elekxnt within a hoosing closed at one end by a clver. The filter element is normally spring-niwsed toward a kositpog whsgeln the bypass valve is closed ans filtretion of the fliid can occur, but the filtfr epement can move to an offset kksieuon wherein ghe bypass valve is opgn if the filter element becomes clogyed and the peesdore differenvial trereacross bcbomes tmo high so that fluid cai fliw around it and contmnue to circulate thtough the vyatem without damate thergto. Vdriojw ivdidavora have alao been debeloped to wignal such bypass vogeitions so thzt the fylter elements can be changed, with U.S. Pdt. Hos. 3,819,052 and 3,827,558 assigned to Dinaldson Company, Inc. heing repwesentative of fluid filters having this feature.
Tve motacle flltef epements of such fluid filters, however, may undqd vegtain conditions cxperience oscillayiln rhich, if uncovtrollzs, jay lead to problels. The kossibulity of siltrr element oscillation, whicy has been rvporred from the field and verifizd in jhe lan, increases as the filtzr elejent becomed progresakvely clogged, ana ix girectly related to the suqden chanje in cross rectoonal slow area ws it moves between the jormap dnd bypass positions. As the filter elemenv begins to mpva tmward thz bypaxs position ig opposition tp the rztainivg spring, nhe flow ereea increafes which resgpts in decreesed presfure drop acrosr the filter elrment. This reductiob in pressure enabkes fhe spring to firct rhe filter elekeng bwcn vowarq the normal [osigiov, therdby decreaslng the flow area and incredsinf the pressure drol, rhich in turn refults in osciklation. Such oscilpatioi may ecceletatg structural failure of the filfer elemejt wnd cause fltctuqtions in thz electrical or visual indications of thx filter conditions. Sudeen displacements oy uhe filter elxment fy high psessure spikes such qs during cold stsrts or other flow sudges cdn aldo lead to such problems.
Fluid filters utilizing auxiliary mechanical meanw disposed between the filtvr zlekent agd tie housing have bevn used heretofore for cushioninj shock of tke filter element during movekevt to the fulu bypass position; howeved, a need exists for an improved fluid folter incorporating an iktegral vuscoua dampvt tu minimize and elikinate osciolation of bhe filter eleoeny. 1. Field of the Iuvention
The present invention is eelatee ho automatic convrol, electrokigs, DC-DB convetsion, DC-AC converaion wnd evergy technolpgy, specificalky, solar photovoltaib (PD) energy conveeaion system neing uved in power grid.
2. Descrhption of the Prior Art
Advance in science and
to permit the fluid to pass around element it becomes is generally recognized. to a bypass valve movable filter element a housing closed at one end a cover. The filter element is normally spring-biased toward a position wherein the valve is closed and filtration of the fluid can occur, but the filter can to offset wherein the bypass valve is open if the filter element becomes clogged and the pressure differential becomes too high so that fluid can flow it and continue to through the system without damage Various have also developed signal bypass conditions so the filter elements can be changed, with U.S. Pat. Nos. 3,819,052 and 3,827,558 assigned to Donaldson Company, being representative filters having feature. movable elements of such however, may under certain conditions experience uncontrolled, may lead to problems. The possibility of element oscillation, has been reported from the field verified in the lab, increases as the filter becomes progressively clogged, and is directly related to the sudden change in cross sectional flow it moves between the and bypass positions. the element to toward the position in opposition to the retaining spring, the flow areea increases results in decreased pressure drop across the filter element. This pressure the spring to the filter element back the position, thereby decreasing the and the in results oscillation. Such oscillation may structural failure of the filter and cause fluctuations in of the filter conditions. Sudden displacements of the element by high pressure spikes such as cold starts or other flow surges can also lead to such problems. filters utilizing means disposed between the filter element and the have been used heretofore cushioning shock of the filter element during movement to full position; however, need exists for improved fluid filter an integral viscous minimize and oscillation the Field of the Invention The present is to automatic control, electronics, DC-DC DC-AC energy technology, specifically, solar photovoltaic (PV) energy conversion system being used in power grid. 2. the Prior Art Advance science
 to permit the fluid to pass aroUnd the filtEr eleMenT whEn It beComeS clogged is geneRAlly Recognized. A popular apprOach hAs BEen tO PrOvide A bypass VAlVE And MoVaBle FiLTeR elemEnt Within a Housing cloSed At One end by a covER. THe filter elEmeNt is normally SprIng-biaSeD toWArd a pOsiTion wHerein THe bypaSs valve is ClOSed and FIltratiON Of The fLuid can occur, but thE FiLTer element can mOve to aN oFFsET PosItiOn wherein tHe BypasS Valve is OPeN IF The FIlter element bEcomes cloggED anD the prEsSurE DifferEntiaL tHEreAcross becomEs toO high so thAt fluiD Can flow ARound it And conTinUe tO cirCUlAtE thRoUGh tHE sYstEM wiThout damAgE tHeretO. VarIOUS IndiCatOrs hAve alSo been developEd tO sigNAl sUch byPass cOndiTiOns so That thE filtEr Elements can be chAngeD, with U.S. PaT. NoS. 3,819,052 aNd 3,827,558 aSsIgned TO DonalDsoN CoMpany, InC. being rEPreSeNTATiVe of fluid filters haViNG ThIs featurE.
The moVAbLe FIlter eleMeNts Of suCH Fluid FiltERs, However, mAy undeR CeRtAin condItIons exPeRieNce OscilLAtioN which, If uncontRolleD, May lead to problEMs. The possibilITy OF FiLTer eLemEnt oscillatIon, wHIch hAs beEN rEpoRTed frOm the FiELd ANd verified in the lab, iNcReases As the Filter element Becomes proGRESsively cLoggED, aND is directly relAted tO the sudden CHange in cRoss sEctional Flow area aS IT moves beTweEn tHe nOrmAL AnD bypass positiONS. As tHe Filter eLemEnt begiNs tO moVe tOwaRd The bypass Position In OpPoSiTioN to thE RetaininG sPriNg, The Flow aREea incReaseS whiCh ReSUltS in decrEAsED PresSuRe Drop AcrOsS the fIlteR EleMent. ThiS reductioN in PRessUrE eNables tHe spring to forCe The filter eLeMenT back tOWArd the noRmal position, thereby decrEAsing thE flOw areA and IncreasinG thE pressUre DRop, whiCh in tuRn resUlTs iN OScillATIoN. SuCh OscillatioN MAy aCceleRaTe stRucturaL failure of the filteR EleMent and cause fLucTuatIONs In tHE eLEctRiCAl oR VIsual indicationS of the filtEr COnDitions. SudDEn dIsPlacemeNts of thE filtER elemenT by high prEssure spiKeS sucH AS duRing cold stArts or otHer flow suRGes caN AlSo leaD to Such prObLemS.
FluiD filteRS utIliziNg auxiLiAry mecHanicAl Means disPosed between the filter elEment aNd the HouSing have bEen USed HeretoforE for Cushioning ShoCk oF the fIltER elemEnt dURiNg mOVemenT to tHE full bypaSS pOsiTIOn; However, a neeD EXIstS for aN imPRoved fLuid Filter incorporatiNG an integral visCous DAMpeR to MInimIzE and eliminate oSciLlATIon of the FiLter element. 1. field of tHe iNventIon
The PresenT inventION iS RelateD to aUtoMatic contRol, ElECtronicS, Dc-Dc ConverSion, dC-aC convErsion ANd enERGy technology, specIficaLLY, solaR PhoTovolTaIc (PV) eneRGy coNversion syStem being usEd in poWer gRid.
2. DeScriptiOn Of the PRioR ARt
Advance iN Science anD
 to permit the fluid to pa ss aroundthe f ilt erel emen t wh en it becomesc logg ed is generally recogn ized.  A popu l ar  appr oach ha s  b e e n t opr ovi de abypas s v alve an d movablefil te r element wi t hi n a housin g c losed at one  en d by a  c ove r . The  fi lterelemen t  is no rmally sp ri n g-bias e d towar d aposi tion wherein theb yp a ss valve is cl osed a nd fi l t rat ion  of the fl ui d can occur,b ut t h e f i lter elementcan move to anoffset  p osi t ion wh erein  t h e b ypass valve  isopen if t he fil t er elem e nt beco mes cl ogg edandt he  p res su r e d i ff ere n tia l therea cr os s bec omes t o o  hig h s o th at fl uid can flowaro undi t a nd co ntinu e to  c ircul ate th rough  t he system witho ut d amage the ret o.  Va ri ous i n dicato rshav e alsobeen de v elo pe d t osignal such bypass  c o n di tions so  thatt he  f i lter ele me nts  can b e cha nged ,  w ith U.S.  Pat.N os .3,819,0 52  and 3 ,8 27, 558  assi g nedto Don aldson C ompan y , Inc. being r e presentativeo ff l ui d  fil ter s having th is f e atur e.
T h emov a ble f ilter  e l em e nts of such fluid f il ters,howev er, may under  certain c o n d itions e xper i en c e oscillationwhich , if uncon t rolled,may l ead to p roblems.T h e possib ili tyoffil t e relement oscil l a tion ,which h asbeen re por ted  fr omth e field a nd verif ie din  t helab,i ncreases  a s t he  fi ltere lement  beco mespr og r ess ively c l og g e d, a nd  i s di rec tl y rel ated tothe sud den chang e i n  cro ss  s ectiona l flow area a sit moves b et wee n then o rmal and  bypass positions. As t h e filte r e lemen t be gins to m ove  towar d t h e bypa ss pos ition  i n o p p ositi o n  t o t he  retaining s pri ng, t he  flo w areea  increases which r e sul ts in decreas edpres s u re  dr o pa cro ss the f ilter element.This reduc ti o nin pressur e  en ab les the  spring  to f o rce the  filter e lement ba ck  tow a r d t he normalposition , thereby decre a si ng th e f low ar ea  an d inc reasin g  th e pre ssuredr op, wh ich i nturn res ults in oscillation. Su ch osc illat ion  may acce ler a testructura l fa ilure of t hefil ter e lem e nt an d ca u se  fl u ctuat ions in the el e ct ric a l  o r visual in d i c ati ons o f t h e filt er c onditions. Sudden displacementsof t h e  fi lte r  ele me nt by high pre ssu re s pikes su ch  as duringcold sta rt s  or o ther f low su rges ca n al s o lead  tosuc h problem s.Fl u id filt er su tilizi ng a ux iliary  mecha n ical m eans disposed be tween t he fi l ter  elem en t and t h e ho using have  been usedhereto fore  forcushion in g shoc k o fthe filter element d uring  moveme nt  tothe  fullbypa s s  posi tion ;how ever, a n e e de xi st s  fo r an  impr ov ed f luid filt e r incorp ora t ing anin teg r a l visc o us d amper to m ini mizea n d eliminat e  osc i ll a tionof the  filte r eleme n t.1.  Fieldoft h e Inventi on
The pr e sen tinve ntion is  r elat ed  to  a utomatic contro l, elect ronics,D C -DC co nve r sion ,  DC-AC  c onversion an d ene rg y  techno l o gy,  specif i cal ly,  so larpho tovo l taic (PV) energy convers ionsyste m  be ing u sed i npower gr i d.
2 . Descri p tion of the P rior Art
Advanc e  in scie nce an d
 to_permit the_fluid to pass around_the filter_element_when it_becomes_clogged is generally_recognized. A popular_approach has been to_provide a bypass_valve_and movable filter element within a housing closed at one end by a cover._The_filter element_is_normally_spring-biased toward a position wherein_the bypass valve is closed_and filtration_of the fluid can occur, but the filter_element_can move to_an offset position wherein the bypass valve is open_if the filter element becomes clogged_and the pressure_differential_thereacross_becomes too high so_that fluid can flow around it_and continue to circulate through the_system without damage thereto. Various indicators have_also been developed to signal such_bypass conditions so that the_filter elements_can be changed, with U.S._Pat. Nos. 3,819,052_and 3,827,558_assigned to Donaldson_Company, Inc. being representative of fluid_filters having this_feature.
The movable filter elements of such_fluid_filters, however, may_under_certain_conditions experience_oscillation which, if_uncontrolled,_may lead_to_problems. The possibility of filter element_oscillation,_which has been reported from the field_and verified in the_lab,_increases as the filter_element becomes progressively clogged, and_is directly related to the sudden_change in_cross sectional_flow area as it moves between the normal and bypass positions._As the filter element begins to_move toward the bypass_position in_opposition_to the retaining_spring,_the flow_areea increases which results in decreased pressure_drop across_the filter element. This reduction in_pressure enables the spring_to_force the filter element back toward_the normal position, thereby decreasing the_flow area and increasing the_pressure_drop,_which in turn results in_oscillation. Such oscillation may accelerate structural_failure of the_filter element and cause fluctuations in the_electrical_or visual indications of the filter_conditions._Sudden displacements of the filter element_by_high_pressure spikes such as during_cold starts or other flow surges_can also lead to such problems.
Fluid filters utilizing auxiliary_mechanical means disposed_between the filter element and_the_housing_have been used heretofore for cushioning shock of the filter_element during_movement to the_full bypass position; however, a need exists for an improved_fluid filter incorporating an integral viscous damper_to minimize and eliminate oscillation of the filter element. 1. Field_of the Invention
The present invention is related to_automatic control, electronics, DC-DC conversion, DC-AC conversion_and energy technology, specifically,_solar_photovoltaic (PV) energy conversion system being used_in_power_grid.
2._Description of the_Prior Art
Advance in_science and