connecting high frequencies components

Discussion in 'General Electronics Chat' started by fazzree, Oct 29, 2014.

  1. fazzree

    Thread Starter New Member

    Dec 24, 2012
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    i am working on a inductive energy transfer project. i have a problem.

    my compensation capacitors of my secondary coils always get blown up every time i connect it to the primary coils. and the wire becomes very hot. i need to know any technique to connect all my compensation capacitors together safely without problems. i tried using normal pcb board but it didnt work and i tried connecting it wit just wire(as shown in the picture), it doesnt work as well.

    here is some data : frequency = 50kHz
    current = 11.5A
    voltage (secondary coils) = max 35Vac
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    straps work better than thin wires at higher frequencies. at 50 kHz, you are getting into skin effect.
     
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I suppose these capacitors are part of an LC tank circuit. Am I correct?
    Please show your entire circuit diagram, but my guess is that the voltage at resonance is much higher than you think it is.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    what is the rating for the caps for rf current? some dont handle high frequency current very well.
     
  5. Papabravo

    Expert

    Feb 24, 2006
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    50 kHz is not what I would call RF, more like nervous DC. Quite simply you are exceeding the absolute maximum ratings of the devices.
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    it may not be vhf, but how much had to be done to get smps to work at 30 khz? how about why some electrolytics wont work even at 30 without heating? rf dosnt mean only that which can be transmitted through space, there are transmtters on elf around 15 kHz. passing current at 50 kHz is still different than dc.
     
  7. Papabravo

    Expert

    Feb 24, 2006
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    Twinke twinkle little star,
    Power's equal I squared R.

    True at DC or 50 KHz, it's not magic what is going on here and we still have no schematic; so anything we say without sufficient information is clearly rank speculation.
     
  8. takao21203

    Distinguished Member

    Apr 28, 2012
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    some foil caps are quite inductive- there are two different kinds:

    1: coiled
    2: stacked

    Also I know these capacitors you have, they are rather for high voltage than high currents.
    Current capability is proportional to size somehow.

    How do you know dc voltage doesnt exceed 35 volts? You could shunt it for instance with a suitable power LED (some have forward voltages of 30 volts).

    Maybe you have a short, defective diodes...

    Not showing the schematics- always do that first before opening a thread.
     
  9. fazzree

    Thread Starter New Member

    Dec 24, 2012
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    im sorry for the late reply. ive guessed that the problem is with the capacitors. ive tested all other components and they are all working fine. from what i read the ESR (equivalent series resistance) for my capacitors are too low for my circuit. so it would be great if anyone could suggest a type of capacitor that is suitable for the circuit.

    L = 4microH
    Ck = 2.43microF
     
  10. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    That schematic doesnt say much. What is the black box on the left? What is connected to the right side? What is the purpose of the circuit? What is output and what is input?
     
  11. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Also how did you measure secondary voltage? And did you also measure without load on the LC tank?
     
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