connecting high frequencies components

Thread Starter

fazzree

Joined Dec 24, 2012
2
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
 

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kubeek

Joined Sep 20, 2005
5,795
voltage (secondary coils) = max 35Vac
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.
 

Papabravo

Joined Feb 24, 2006
21,227
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.
 

alfacliff

Joined Dec 13, 2013
2,458
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.
 

Papabravo

Joined Feb 24, 2006
21,227
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.
 

takao21203

Joined Apr 28, 2012
3,702
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.
 

Thread Starter

fazzree

Joined Dec 24, 2012
2
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
 

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kubeek

Joined Sep 20, 2005
5,795
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?
 
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