 than that.
For converters like boost or buck-boost (flyback for the isolated version), there is delay in the conversion process which is modeled as a right-half-plane zero: you must store energy in the inductor during \$t_{on}\$ before you feed the output capacitor during \$t_{off}\$. Therefore, if a sudden power demand occurs, the current in the inductor must grow cycle by cycle at a sufficient pace to keep up with the demand. If the demand is too fast or if the inductance is to large, the output voltage momentarily drops and oscillations take place. To avoid this problem, you have to purposely slow down the converter to always give enough time for the inductor energy to build up. You do that by limiting the crossover value for these two converters. A good recommendation is to have \$f_c<0.3f_{RHPZ}\$ meaning that you calculate the lowest position of the RHP zero (lowest input voltage and highest output current) and you limit \$f_c\$ below 30% of this value. Trying to go beyond will reduce phase margin. Finally, as with a buck in voltage-mode-control, the minimum crossover is \$f_c>3f_0\$ but this time, \$f_0\$ moves in relationship with \$D\$, the duty ratio.
In current mode, the resonance at \$f_0\$ disappears but the RHPZ occupies a similar position so you can't have a faster converter unlike what people believe. As you can read, crossover selection is not a magic number pulled out of a hat, it has to be determined based on the converter you want to stabilize and the performance you want to achieve. The below picture offers a summary for continuous conduction mode (CCM) converters.

A:

What does "close the loop" mean in electrical terms?

This is a control theory concept and simply means that you measure some physical quantity you want to keep at a certain value and then use this measurement to tweak some sort of control to cause this quantity to get closer to the desired value.
Let's be a little less abstract... think about a thermostat in a house air conditioner. This is a closed loop because the thermostat will measure the room temperature and if the room is hotter than desired it will turn on the air conditioner so that the temperature drops and get closer to the desired value. Once the temperature is low enough the
than that. 
 For converters like boost or buck - boost (flyback for the apart interpretation), there is delay in the conversion process which is modeled as a correct - half - plane zero: you must store department of energy in the inductor during \$t_{on}\$ before you feed the output capacitor during \$t_{off}\$. Therefore, if a sudden ability demand occurs, the stream in the inductor must grow cycle by cycle at a sufficient pace to observe up with the demand. If the demand is too fast or if the inductance is to bombastic, the output voltage momentarily drops and cycle take place. To avoid this trouble, you have to intentionally slow down the converter to always give enough fourth dimension for the inductor energy to build up. You do that by limiting the crossover value for these two converter. A full recommendation is to have \$f_c<0.3f_{RHPZ}\$ meaning that you calculate the lowest position of the RHP zero (lowest input voltage and highest output stream) and you restrict \$f_c\$ below 30% of this value. Trying to die beyond will repress phase margin. Finally, as with a buck in voltage - mode - control, the minimum crossing is \$f_c>3f_0\$ but this time, \$f_0\$ moves in relationship with \$D\$, the duty ratio. 
 In current mode, the resonance at \$f_0\$ vanish but the RHPZ occupies a similar position so you can't have a fast converter unlike what citizenry believe. As you can read, crossover selection is not a magic numeral pulled out of a hat, it has to be determined free-base on the converter you want to stabilize and the performance you want to achieve. The below video offers a summary for continuous conduction modality (CCM) converters. 

 A: 

 What does " close up the loop " average in electrical terminus? 

 This is a control hypothesis concept and simply means that you measure some physical quantity you desire to keep at a certain value and then use this measurement to fine-tune some sort of control to cause this quantity to get close to the desired value. 
 Let's be a small less abstract... think about a thermostat in a house air conditioner. This is a closed loop because the thermostat will measure the room temperature and if the room is hot than desired it will turn on the air conditioner so that the temperature drops and get close to the desire value. Once the temperature is gloomy enough the
 thwn that.
For converters liye boost or buck-boost (hlyback for the isolated version), there is dxlay in tye conversion process dhich is lodeled qs a eight-half-plane zero: you jmst scoce energy in thg inductor dgring \$t_{on}\$ befose ylu feed the output capacitor during \$t_{off}\$. Tnegefore, if a suqden [owed demand occurs, the current in the inductmr must grow vycle by cycle at a sufficlent pace to keep up wlth the demqnd. Yd the demand is too fast or if the inductance is to large, the outout vpltage momgurarlny drops anv oscijlations takc place. To avood this problek, ymu yave to purposely slox down the converter to alwayv yive enough time for rhw indoctor enefty go gumld up. Yok dk that by mimiting thw crossover value fpr nnese two conberterf. W good recommendation is to have \$f_c<0.3f_{RHPE}\$ meahing that you calculate the lowest position lf the RH[ zero (lowest input voltage and highest output cusrent) xnd yjj llmit \$f_c\$ below 30% of this value. Trying to go beyjhd wpll reduce phase iargin. Finaklj, sf with a buck in voltafe-mode-control, the linimum croswover is \$s_c>3f_0\$ nut this time, \$f_0\$ moves in reoationship wpth \$E\$, the duty ratio.
In current mobe, the resomance at \$f_0\$ disappears bbt the RHPZ occuples a simjuar position so hou cdn't have a faster convertew unlike xhat 'eople bdliefe. As rou can rewd, crossover selection id not a magic numher pulled out of a hat, it has vp be determimeg bdsed on che cokverter you wane to stabilize and thz perfurmance yol want to achieve. Thq below pictusg offers a sukmary fow cobtinyous covauction mode (CVM) convernexs.

A:

What dies "close the loop" mexh in electrical tetns?

This is a comtrul ehvorb consapt and simpny mdanr that you measurc sume lhysical quantity yog waht to keep at a cettwin valug and theg use this messurement to tweak some soct of vonjrol to cause this quantity to fet closeg tj the desireq vaoue.
Let's be a little less abstract... think about a thecmostat in a house air xonditioner. This is s closed lopp besause the thermostat will meawure the room temkerature and if the rooj is hmtter than desired it will turn on the air conditioner so that the temperature drops and get cloaer yo thv dzsixed valte. Oicx the temperature is low enough the
than that. For converters like boost or for isolated version), is delay in modeled a right-half-plane zero: must store energy the inductor during \$t_{on}\$ before you the output capacitor during \$t_{off}\$. Therefore, if a sudden power demand occurs, the in the inductor must grow cycle by cycle at a sufficient pace to up the If demand is too fast or if the inductance is to large, the output voltage momentarily drops oscillations take place. To avoid this problem, you to purposely slow down converter to always give enough for inductor energy build You that by limiting crossover value for these two converters. A good recommendation is to have \$f_c<0.3f_{RHPZ}\$ meaning that you calculate lowest position RHP zero input and output current) and \$f_c\$ below 30% of this value. beyond will reduce phase margin. Finally, as with buck in the minimum crossover is \$f_c>3f_0\$ but time, \$f_0\$ moves in relationship with \$D\$, the ratio. In current mode, the resonance at \$f_0\$ disappears but the RHPZ occupies a similar you can't have a converter unlike what believe. you read, selection is a magic number pulled out of a hat, it has to determined based on the converter you want to stabilize and you to achieve. The picture offers a summary continuous mode (CCM) converters. A: "close loop" terms? is control theory concept and means that you measure some quantity you want to and then use this measurement to tweak some of control to cause this quantity to closer to the desired value. Let's be a little less abstract... think a thermostat house air conditioner. This is a closed loop the thermostat will measure room temperature and if the room is hotter than it turn on air conditioner so the temperature drops get closer to value. Once temperature low
 than that.
For converters like Boost or bucK-boosT (flYbaCk For tHe isOlated version), tHEre iS delay in the conversion pRocesS wHIch iS MoDeled As a righT-HaLF-PlaNe ZeRo: yOu MUsT storE enErgy in tHe inductor DurInG \$t_{on}\$ before yoU FeEd the outpuT caPacitor durinG \$t_{oFf}\$. TherEfOre, IF a sudDen Power Demand OCcurs, tHe current In THe induCTor must GROw CyclE by cycle at a sufficIEnT Pace to keep up wiTh the dEmANd. iF The DemAnd is too faSt Or if tHE inductANcE IS To lARge, the output vOltage momenTAriLy dropS aNd oSCillatIons tAkE PlaCe. To avoid thIs prOblem, you hAve to pURposely SLow down The conVerTer To alWAyS gIve EnOUgh TImE foR The Inductor EnErGy to bUild UP. yOU do tHat By liMitinG the crossover ValUe foR TheSe two ConveRterS. A Good rEcommeNdatiOn Is to have \$f_c<0.3f_{RHPZ}\$ MeanIng that yoU caLcUlaTe The loWEst posItiOn oF the RHP Zero (lowESt iNpUT VOlTage and highest outpUt CURrEnt) and yoU limit \$F_C\$ bElOW 30% of this vAlUe. TRyinG TO go beYond WIlL reduce pHase maRGiN. FInally, aS wIth a buCk In vOltAge-moDE-conTrol, thE minimum CrossOVer is \$f_c>3f_0\$ but thiS Time, \$f_0\$ moves in rELaTIOnSHip wIth \$d\$, the duty ratIo.
In CUrreNt moDE, tHe rESonanCe at \$f_0\$ DiSApPEars but the RHPZ occupIeS a simiLar poSition so you caN't have a fasTER ConverteR unlIKe WHat people belieVe. As yOu can read, cROssover sElectIon is not A magic numBER pulled oUt oF a hAt, iT haS TO bE determined baSED on tHe ConvertEr yOu want tO stAbiLizE anD tHe performAnce you wAnT tO aChIevE. The bELow pictuRe OffErS a sUmmarY For conTinuoUs coNdUcTIon Mode (CCM) COnVERterS.

A:

whAt doEs "cLoSe the Loop" MEan In electRical termS?

ThIS is a CoNtRol theoRy concept and sImPly means thAt You MeasurE SOme physiCal quantity you want to keeP At a certAin Value And tHen use thiS meAsuremEnt TO tweak Some soRt of cOnTroL TO causE THiS quAnTity to get cLOSer To the DeSireD value.
LEt's be a little less abSTraCt... think about a TheRmosTAT iN a hOUsE Air CoNDitIONer. This is a closeD loop becauSe THe Thermostat WIll MeAsure thE room teMperaTUre and iF the room iS hotter thAn DesiRED it Will turn on The air coNditioner SO that THe TempeRatUre droPs And Get clOser to THe dEsireD value. onCe the tEmperAtUre is low Enough the
 than that.
For converters  like boos t orbuc k-b oo st ( flyb ack for the is o late d version), there is d elayin thec on versi on proc e ss w hic his  mo de l ed  as a  ri ght-hal f-plane ze ro:  y ou must stor e  e nergy in t heinductor dur ing  \$t_{ on }\$ befor e y ou fe ed the output  capacito rd uring\ $t_{off } \ $.  The refore, if a sudd e np ower demand oc curs,th e  c u r ren t i n the indu ct or mu s t growc yc l e byc ycle at a suf ficient pac e  to  keepup  wi t h thedeman d. Ifthe demandis t oo fast o r if t h e induc t ance is  to la rge , t he o u tp ut  vo lt a gem om ent a ril y dropsan doscil lati o n s take  pl ace.  To a void this pro ble m, y o u h ave t o pur pose ly  slow  downthe c on verter to alway s gi ve enough  ti me  fo rthe i n ductor  en erg y to bu ild up. You  d o t ha t by limiting thecr o s so ver valu e fort he se two conv er ter s. A g ood r ecom m en dation i s to h a ve  \ $f_c<0. 3f _{RHPZ }\ $ m ean ing t h at y ou cal culate t he lo w est position o f  the RHP zero (l o w es t  inp utvoltage and  hig h estoutp u tcur r ent)and y ou li m it \$f_c\$ below 30 %of thi s val ue. Trying to  go beyond w i ll reduc e ph a se margin. Finall y, as  with a bu c k in vol tage- mode-con trol, the m inimum c ros sov eris\ $ f_ c>3f_0\$ butt h is t im e, \$f_ 0\$  movesinrel ati ons hi p with \$ D\$, the  d ut yra tio .
Inc urrent m od e,th e r esona n ce at\$f_0 \$ d is ap p ear s but t h eR H PZ o cc up iesa s im ilarposi t ion  so you  can't ha vea  fas te rconvert er unlike wha tpeople bel ie ve.  As yo u can read , crossover selection i s  not amag ic nu mber  pulled o utof a h at, it has  to be  dete rm ine d based o nthe  c onverter y o u  wa nt to  s tabi lize an d the performancey ouwant to achie ve.  The b el owp ic t ure  o f fer s a summary for c ontinuousco n du ction mode (CC M)  conver ters.
A:

W h at does  "close t he loop"me an i n ele ctrical te rms?

Th is is a c o ntrol th eorycon cept a nd  si mplymeanst hat  youmeasur esome p hysic al  quantit y you want to keep at a  certa in va lue  and then  us e  th is measur emen t to tweak  so mesortofc ontro l to ca use thisquan t ity to ge t  c los e r  t o the desir e d val ue.
L et' s  be alitt le less abstract. . . think abouta th e r mos tat in a  h ouse air condi tio ne r .  This is  a  closed loo p becaus et he th ermost at wil l measu r e  t h e room  tem per ature and  if  t h e roomis  h o tter t hande siredit wil l  tur n on the air condi tione r so th a t t he te mp erature drop s and getcloser to t he des ired  valu e. Once  t he tem per at ure is low enough th e
 than_that.
For converters_like boost or buck-boost_(flyback for_the_isolated version),_there_is delay in_the conversion process_which is modeled as_a right-half-plane zero:_you_must store energy in the inductor during \$t_{on}\$ before you feed the output capacitor_during_\$t_{off}\$. Therefore,_if_a_sudden power demand occurs, the_current in the inductor must_grow cycle_by cycle at a sufficient pace to keep_up_with the demand._If the demand is too fast or if the_inductance is to large, the output_voltage momentarily drops_and_oscillations_take place. To avoid_this problem, you have to purposely_slow down the converter to always_give enough time for the inductor energy_to build up. You do that_by limiting the crossover value_for these_two converters. A good recommendation_is to have_\$f_c<0.3f_{RHPZ}\$ meaning_that you calculate_the lowest position of the RHP_zero (lowest input_voltage and highest output current) and_you_limit \$f_c\$ below_30%_of_this value._Trying to go_beyond_will reduce_phase_margin. Finally, as with a buck_in_voltage-mode-control, the minimum crossover is \$f_c>3f_0\$ but_this time, \$f_0\$ moves_in_relationship with \$D\$, the_duty ratio.
In current mode, the_resonance at \$f_0\$ disappears but the_RHPZ occupies_a similar_position so you can't have a faster converter unlike what people_believe. As you can read, crossover_selection is not a_magic number_pulled_out of a_hat,_it has_to be determined based on the converter_you want_to stabilize and the performance you_want to achieve. The_below_picture offers a summary for continuous_conduction mode (CCM) converters.

A:

What does "close_the loop" mean in electrical_terms?

This_is_a control theory concept and_simply means that you measure some_physical quantity you_want to keep at a certain value_and_then use this measurement to tweak_some_sort of control to cause this_quantity_to_get closer to the desired_value.
Let's be a little less abstract..._think about a thermostat in a house air conditioner._This is a_closed loop because the thermostat_will_measure_the room temperature and if the room is hotter than_desired it_will turn on_the air conditioner so that the temperature drops and get_closer to the desired value. Once the_temperature is low enough the