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Type: Posts; User: iop95

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  1. Closed: Re: Why use diff mode inductors rated for 6A(rms) when Input current is only 833mA(rm

    Same reason... need to not saturate in transient regim.
    If that would happen may lead to destructive demage (present as a shot-circuit for upstream eq.) or at least blown of fuse... if is too fast.
  2. [SOLVED]Closed: Re: LT3741 DCDC Buck Converter operating failure diagnosis

    Ok, I see now...
    Ringing is about 3.5MHz, L2 with Coss Q2 || parasitic capacitance of switching node. No resistance in circuit so very small dammping factor.
    May try to add a 100ohm/3W resistor...
  3. [SOLVED]Closed: Re: LT3741 DCDC Buck Converter operating failure diagnosis

    Problem is ringing of motor inductance on turn-off buck higher MOS (when lower MOS is on) because circuit is not dummped... fastest test, add a resistor 100-150ohm parallel with motor.
    Do you added...
  4. Closed: Re: IGBT Short Circuit Detection using Current sensing

    Fastest response mean to remain in analog zone.
    High current may be detected by looking at derivative... need fast circuits.
    May use few high speed comparators and an precision timer(s) to looking...
  5. [SOLVED]Closed: Re: LT3741 DCDC Buck Converter operating failure diagnosis

    Add a 10k resistor between gate - soruce of each MOS.
    Add few 0.1micro ceramic caps on pin Vin of controller.
    Try to start at lower frequency (200-250kHz) and low load and if no oscillation,...
  6. Closed: Re: Is it possible to make an IGBT to work at duty cycles up to 100%?

    I agree regardind 0% and 100% values for a "switching" converter... these values are extreme cases for turn-off and turn-on for long time.

    Regarding chopper duty cycle, that is in fact a buck...
  7. Closed: Re: Micro controller affected by ripple from bldc motor

    This "If the noise has a radiant component will be more complicated " refer to situation when noise is send by electromagnetic waves (radio).
    As you have long distance between driver and MOSFETs,...
  8. Closed: Re: Is it possible to make an IGBT to work at duty cycles up to 100%?

    Sorry, but may add more details at your question? What you looking for in fact / what is main concern?
    In any switching converter there are a minimum turn-on and turn-off time... can't have...
  9. Closed: Re: Is it possible to make an IGBT to work at duty cycles up to 100%?

    100% duty cycle mean IGBT is turned on for long time... can't speak about a switching converter anymore.
    Many application limit duty cycle to 95-96% because need some time for turn-off... so can't...
  10. Closed: Re: Micro controller affected by ripple from bldc motor

    If can't use a totally separate 3.3V controller power supply (my recomandation) add LC filters on pins 3 and 9 of IR2110.
    Also, may be high dv/dt, so try to increase R1 to 22ohm and add a 10ohm...
  11. Closed: Re: 3 phase 4 wire(480V) AC to 12VDC (100mA) power supply for energy metering applica

    Simple 3 diodes, one on each phase will assure power and redundancy for up 2 lost phases.
    After these add caps/ filter and a flyback topology power supply. For such small power and increased...
  12. Closed: Re: Offline flyback SMPS with bigger core generally has less transformer loss

    Need to see Bmax difference, that is area difference of cores.
    If have same material, will be same loss curve.
    First core (bigger) have effective area A1 and volume V1, second core: A2 and V2....
  13. Closed: Re: LLC converter is preferable for step up operation?

    I made same calculation and best values for f0=100kHz are: Lp=6micro, Lr=0.8micro, Cr=3.4micro; n=0.012 (about 1:84 or 2: 168).
    Fmin (to keep ZVS) = 84kHz; Fmax=115kHz
  14. [SOLVED]Closed: Re: Program for PWM of Resonant DC DC buck converter

    Most of resonant converters are frequency modulated (controlled) not by PWM.
    ZVS is a mode of switching that depend of load, frequency and converter switch capacity (Coss), can't be controlled by a...
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    Closed: Re: DC DC boost converter

    What is panel power and short-circuit current?
    What is converter sw frequency and inductance value?
  16. Closed: Re: LLC converter is preferable for step up operation?

    For such high traformer ratio, LLC will request high Cr and very low Lr values somewhat hard to obtain.
    What is nominal power requested?
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    Closed: Re: adapter-12v/60w Design Issues

    Try a resonant LLC topology HB in ZVS.
    That offer better efficiency.
    Need a good controll design and output overvoltage protection to protect load in case of any failure in controll circuit.
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    Closed: Re: MOSFET Leakage (IRFZ44N)

    Put a 2-5k resistor between GS.
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    Closed: Re: variable current source upto 25A @ 230VAC

    An auto-transformer give 0 - 250V variable voltage source.
  20. Closed: Re: Feedback loop calculation for eight bucks in parallel

    Yes, I agree for n*gm relation but I think a real interleaving (at control level also) disable n-1 amplifiers for time when only one converter is working.
    I'm not sure if IC support such disable...
  21. Closed: Re: Feedback loop calculation for eight bucks in parallel

    If interleaving is correct implemented, may use this schematic, with same FB signal to all IC. Sure, each FB must be routed as close to coresponding output (even all are in parallel).
    Need to add...
  22. Closed: Re: Buck converter doesn't work with a battery as load

    Sure, IC voltage must be limited below maxim value.
    Battery modify buck working equation, for Vout<Vbat no current flow...so no energy in inductance.
  23. Closed: Re: Buck converter doesn't work with a battery as load

    With 12V acc as load, must double voltage V1 and V3 for proper working.
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    Closed: Re: Power supply topology opinion

    Simple flyback.
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    Closed: Re: lead lag power factor calculation

    cos phi is always positive; reactive power may be positive (inductive circuits) or negative (capacitive).
    By convention when is positive - "send" reactive power to grid and when negative, "consume"...
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