IR2153--cum l-ati folosit

[Marian]

Repede se mai aprind spiritele fratica...

 

-Maxente asa cum Dl Miticamy a explicat, daca exista inductanta dupa diode atunci sigur este forward, ti-am zis si pe privat eu unul n-am intalnit ATX flyback, dar la fel de adevarat este ca asa cum am zis si acolo, asta nu inseamna ca nu exista, ci inseamna doar ca eu nu am lucrat cu destule, deci nu ma pot pronunta intr-o directie sau alta, dar repet, daca exista acea inductanta atunci e forward. Oricum flyback de putere ceva mai mare este o oarecare risipa mai ales la traf ( care in fapt e mai degraba inductanta, 2 inductante cuplate magnetic ).

 

-Asa cum s-a demonstrat chiar la aceasta sectiune, cum mi s-a demonstrat chiar mie ca ma inselam cand sustineam ceva, se poate forward si cu umplere mai mare de 50%, si probabil la fel de bine se poate si flyback, UDAR insa a spus deja care este dezavantajul.

 

-Depanatorul inainte sa-ti dai singur cu dreptul in stangul, asigura-te ca stii ce spui, ( si spune asta unul care are experienta in datul cu stangul in dreptul->eu ). Eu nu l-as contrazice pe Dl Miticamy fara sa fiu al naibii de sigur de argumentele mele, dumnealui este un practician cu experienta la care multi de aici pot doar visa, deci mai incet cu caracterizarile, limiteaza-te la a posta la obiect. Sunt diferente mari intre forward si flyback, si una dintre ele este tocmai faptul ca la forward traful chiar este traf, chestia asta este unul din "detaliile" care permite forward cu puteri comparativ mai mari, mult mai mari.

[maxente]

Deci e clar, sursa e forward

Eu nu vreau sa contrazic pe nimeni, a fost o confuzie de-a mea, nu sunt inginer si invat si eu de pe forumu asta cat ma duce capul

Va inteleg domnule @miticamy ca ati mai tot zis prin diferite posturi si ati tot obosit sa ziceti mereu cum sta treaba cu flyback, dar daca pe mine nu m-a interesat in mod special aceasta topologie nu am stat sa mai studiez si in mintea mea a ramas ca in general astea sunt flyback

Acum mai vine o intrebare: la sursele astea forward e musai intrefier sau nu ?

Tocmai ce am desfacut si traful si nu are nici cel mai mic intrefier !

Pun si poza cu toata placa sursei 

 

Va multumesc pentru raspunsurile date si pentru timpul pierdut sa mai lamuriti un entuziast in ale electronicii !!!

Editat Iulie 13, 2015 de maxente

[sesebe]

La forward intrefierul mai mult strica decit ajuta...deci nu!

[Marian]

Maxente nu la tine m-am referit atunci cand am zis in postarea anterioara despre contrazis, stii cred la cine m-am referit

 

La forward nu e nevoie de intrefier, ci din contra este contraindicat datorita inductantei de scapari mari generate de el, la flyback este necesar pentru ca asa cum zisei, traful este in fapt o inductanta ( de fapt 2 cuplate ), energia se inmagazineaza in traf la Ton si se elibereaza la Toff, trebuie intrefier pentru ca permeabilitatea sa scada suficient incat sa nu apara saturatia.

[giongiu]

@miticamy , am impresia ca in afara de osciloscop nu prea stii nimic , dar astept oscilograme cu flyback factor de umplere peste 50% eventual 100% ... ma intreb cand se mai elimina energia din miezCine crede ca forward duce KW putere viseaza ... cand tot curentul trece unidirectional prin transformator si tranzistor ,cand  tocmai de asta s-au inventat topologiile half-bridge , full-bridge

@miticamy chiar stie ce vorbeste, spre deosebire de tine. Exista surse forward de ordinul Kw, mai toate invertoarele sudura si nu numai. Dar poate am reparat asa ceva in somn, deci visam...Si o sursa forward, de ...doar...2,4Kw... http://danyk.cz/reg60v.html Schema e inspirata cel mai probabil, din invertoare de sudura industriale.http://danyk.cz/zdroje.html Editat Iulie 13, 2015 de giongiu

[Vizitator]

La noi este mai greu de gasit documentatie. E stufos ce am gasit dar este prezentat mai atragator.

http://info.ee.surrey.ac.uk/Workshop/advice/coils/gap/

 

@miticamy , am impresia ca in afara de osciloscop nu prea stii nimic , dar astept oscilograme cu flyback factor de umplere peste 50% eventual 100% ... ma intreb cand se mai elimina energia din miez

 

Acum am citit, si pe langa rusinea ca am fost deconspirat as face totusi un pariu: pui o poza cu pene ca Mircea Badea daca fac acest experiment?

Editat Iulie 13, 2015 de Vizitator

[Vizitator]

Eu am facut masuratorile dar nu am primit raspuns cu privire la pariu.

Eu zic sa pun pozele pt ca are nevoie de timp sa stranga atatea pene.

SUS:   tensiunea drena MOS

MIJLOC:  curent prin sursa MOS   2A/div

JOS:  tensiune in secundar   50V/div

 

Nu citisem pagina anterioara, asa ca am mai gasit o corectura de-mi vine sa ma apuc de alta meserie (ma gandisem la taximetrie dar nu am permis de conducere) :

 

Bobina pe tor mai mic folosita la sursa de 3V3 are o functionare diferita.

Face parte dintr-o alta sursa stabilizata bazata pe reglajul punctului in care se satureaza miezul

 

Inteleg ca ai citit cate ceva, dar iar confunzi borcanele. Bobina indicata de mine este exact socul de pe iesire 3,3V. Bobina din amplif. magnetic este mai mica si nu se vede.

Am gasit o poza la Chirio  

Editat Iulie 13, 2015 de Vizitator

[Mircea Crisan]

Maxente nu la tine m-am referit atunci cand am zis in postarea anterioara despre contrazis, stii cred la cine m-am referit

 

La forward nu e nevoie de intrefier, ci din contra este contraindicat datorita inductantei de scapari mari generate de el, la flyback este necesar pentru ca asa cum zisei, traful este in fapt o inductanta ( de fapt 2 cuplate ), energia se inmagazineaza in traf la Ton si se elibereaza la Toff, trebuie intrefier pentru ca permeabilitatea sa scada suficient incat sa nu apara saturatia.

 

Poti sa ne arati o formula din care sa reiasa energia inmagazinata in traf in cazul unui flyback?

Asa cum bine spui nu este traf in cazul unui flyback ci doua inductante cuplate magnetic.

Despre condensatori cunosc formula energiei pe care o pot inmagazina dar la inductante ba.

Intreb si eu din postura de amator.

Te rog sa nu incepi iar cu rezervorul de energie.

 

Spor,

[Marian]

http://www.elforum.info/topic/44160-totul-despresurseteorieschemeaplicatii/?p=484022

[Mircea Crisan]

Cunosc teoria lu' smilex.

Te intreb parerea ta.

Smilex pleaca acolo de la o egalitate dintre o energie magnetica si una electrica.

[maxente]

Stiu ca nu la mine te-ai referit @marian

Poate scoti postarile astea, care devin off topic pentru subiectul asta dar necesare si pentru altii si le pui la alta sectiune sau de ce nu, poate intr-un alt subiect.

[CIBY2]

Ca tot este off-topic, asa ca fapt divers, dintre sursele flyback integrate, TOP24X, de la Power Integration, sunt concepute pentru un duty cycle de 78%! Si in programul lor de proiectare, PI Expert, chiar se aplica aceasta valoare!

TOP-urile 22X, au duty cycle de 67%! LA fel si TOP 20X!

Asa ca limita de 50% pentru flyback, este doar o idee preconceputa!

[Marian]

Mircea care va este nedumerirea de fapt? Sau ce anume din ce am zis eu vi se pare in neregula?

[Vizitator]

Flyback Inductor & Transformer Theory

Flyback circuits repeat a cycle of two or three stages; a charging stage, a discharging stage, and in some applications idle time following a complete discharge. Charging creates a magnetic field. Discharging action results from the collapse of the magnetic field. The typical flyback transformer application is a “unipolar” application. The magnetic field flux density varies up in down in value ( 0 or larger ) but keeps the same ( hence unipolar ) direction.

Charging Stage: The flyback transformer ( or inductor ) draws current from the power source. The current increases over time. The current flow creates a magnetic field flux that also increases over time. Energy is stored within the magnetic field. The associated positive flux change over time induces a voltage in the flyback transformer ( or inductor ) which opposes the source voltage. Typically, a diode and a capacitor are series connected across a flyback transformer winding ( or inductor ). A load resistor is then connected across the capacitor. The diode is oriented to block current flow from the flyback transformer ( or source ) to the capacitor and the load resistor during the charging stage. Controlling the charging time duration (known as duty cycle) in a cycle can control the amount of energy stored during each cycle. Stored energy value, E = ( I x I x L ) / 2, where E is in joules, I = current in amps, L = inductance in Henries. Current is defined by the differential equation V(t) = L x di/dt. Applying this equation to applications with constant source voltage and constant inductance value one obtains the following equation; I = Io + V x t / L , where I = currents in amps, Io = starting current in amps, V = voltage in volts across the flyback transformer winding ( or inductor ), L = inductance in Henries, and t = elapsed time in seconds. Note that increasing L will decrease the current. Stored energy will consequently decrease because effects of the “current squared decrease” will more than offset the effects of the inductance increase. Also be aware that the flyback transformer ( or inductor ) input voltage is less than the source voltage due to switching and resistive voltage drops in the circuit.

Discharge Stage: The current ( which creates the magnetic field ) from the source is then interrupted by opening a switch, thereby causing the magnetic field to collapse or decrease, hence a reversal in the direction of the magnetic field flux change ( negative flux change over time ). The negative flux change induces a voltage in the opposite direction from that induced during the charging stage. The terms “flyback” or “kickback” originate from the induced voltage reversal that occurs when the supply current is interrupted. The reversed induced voltage(s) tries to create ( induce ) a current flow. The open switch prevents current from flowing through the power supply. With the voltage reversed, the diode now permits current flow through it, hence current flows into the capacitor and the load across the capacitor. If current can flow, then the resulting flow of current is in the direction, which tries to maintain the existing magnetic field. The induced current cannot maintain this field but does slow down the decline of the magnetic field. A slower decline translates to a lower induced flyback voltage. If current cannot flow, the magnetic field will decline very rapidly and consequently create a much higher induced voltage. In effect, the flyback action will create the necessary voltage needed to discharge the energy stored in the flyback transformer or inductor. This principle, along with controlling the duration of the charging stage, allows a flyback inductor to increase or decrease the voltage without the use of a step-up or step-down turns ratio. In the typical flyback circuit, the output capacitor clamps the flyback voltage to the capacitor voltage plus the diode and resistive voltage drops. For a sufficiently large & fully charged capacitor, the clamping capacitor voltage can be treated as a constant value. The equations V(t) = L x di/dt, and I = Io + V x t / L can also be applied to the discharge stage. Use the inductance value of the discharging winding and the time duration of the discharging stage. The time will either be the cycle time minus the charging time ( no idle time ), or the time it takes to fully discharge the magnetic field thereby reaching zero current. The cycle time equals the period which equals 1 / frequency.

Idle Stage: This stage occurs whenever the flyback transformer ( or inductor ) has completely discharged its stored energy. Input and output current ( of the transformer or inductor ) is at zero value.

OTHER PRINCIPLES OF OPERATION

Equal Ampere-Turns Condition: A magnetic field is created by the current flow through the winding(s). The current creates a magnetizing force, H, and a magnetic field flux density B. A core dependent correlation will exist between B and H. B is not usually linear with H. By definition H is proportional to the product of the winding turns and the current flowing through the winding, hence ampere-turns. In classical physics, the magnetic field flux cannot instantaneously change value if the source of the field ( the current flow ) is removed. When the source current is removed from the flyback transformer ( or inductor ) the charging stage ends and the discharge stage begins. The value of the magnetic field will be the same for both stages at that point in time ( cannot instantaneously change to another value ). The same magnetic core is used for both stages, hence if the magnetic field is the same, then the magnetizing force, H, must be the same. Consequently the ampere-turns at the end of the charging stage must equal the ampere-turns at the start of the discharge stage. If there are multiple outputs then the total amperes turns of all outputs at the start of the discharge stage must equal the ampere-turns at the end of the charging stage. The same condition applies at the start of the charging stage. The total ampere-turns of all outputs at the start of the charging stage must equal the ampere-turns at the end of the discharge stage. Note that there are zero ampere-turns at both the start and end of an idle stage when an idle stage exists.

Zero Average Voltage: During steady state operation, the average voltage across the charging winding must equal the average voltage across the discharge winding, or equivalently, the volt-seconds of the charging stage must equal the volt-seconds of the discharge stage. If not, flux density increases over time and the core saturates. Assuming a 1:1 turns ratio, then from V1 x t1 = V2 x t2 one can obtain t1 / t2 = V2 / V1 for both continuous and discontinuous modes of operation. For continuous mode operation, t1 + t2 = 1 / operating frequency.

Conservation of Energy: Power out cannot exceed power in. Sum up output power ( V x I ) of each output at maximum steady state load plus allowances for parasitic output power losses ( diode and resistive losses ). Divide power in watts by operating frequency. The result is the energy in Joules that must be discharged each cycle into the output storage capacitor during steady state operation. It is also the amount of energy that must be added to the flyback transformer ( or inductor ) during the charging stage. The energy being transferred equals ( Ipeak x Ipeak – Imin. x Imin. ) x L /2. If operating in the continuous mode, the stored energy will exceed the energy being transferred because the starting level of stored energy is above zero ( Imin. > 0 ). The flyback transformer ( or inductor ) must be designed to handle the peak stored energy, Ipeak x Ipeak x L / 2. The power source will have to supply the transferred energy plus the parasitic switching and resistive losses of the charging circuit, plus some power allowance for transient conditions. Take this value and divide by the power supply voltage. The result will be the average input current.

[Mircea Crisan]

Flyback Inductor & Transformer Theory

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Charging Stage: The flyback transformer ( or inductor ) draws current from the power source. The current increases over time. The current flow creates a magnetic field flux that also increases over time. Energy is stored within the magnetic field. The associated positive flux change over time induces a voltage in the flyback transformer ( or inductor ) which opposes the source voltage.

 

 

 

 

Asta trebuie specificat de fiecare data pentru a nu se creea confuzii.