The link between LL resonance and the 3 coils configuration

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cd_sharp posted this 26 June 2018

Hi, everyone! I'll try my best to find out how to practically use the LL resonance between two coils in a POC 3 coils configuration.

The basic circuit I have in mind is this:

The single coil is L1, L2 is on top and L3 is at the bottom, on the other leg.

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cd_sharp posted this 26 June 2018

All the coils are almost equal as wire length and inductance.

Input voltage is 12V. According to the theory, a voltage should be induced in L3 whenever there is current flowing through L1.

The current through L3 is blue, the current through L2 is yellow and the FG voltage is magenta. Let's see what happens:

Notice that the current through L3 flows during the time the MOSFET is off.

What if I disconnect L2?

So, L2 must be off while current flows through L3. It's about timing, we need to let the current through L3 flow, we need to let it's magnetic field grow without the magnetic field of L2 opposing.

I need opinions because I really wish to take this further and obtain some practical results.

Vidura posted this 26 June 2018

Hi cd , mayby you should check the connection on L2, it seems strange that ther is no reacting to the input visible. There are many members which have more experience with POC, but I would suggest to test different positioning also which seems to have effect of changing the timing.

Chris posted this 26 June 2018

@CD - Increase your Off Time to 75%

Polarity of Blue Trace appears to be correct.

Polarity of Yellow appears its not correct, try flipping Drain and Source Terminals over.

Mosfetts and Diodes can very easily be damaged, so keep checking them for failure, especially if you're not getting what you should.

   Chris

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Vidura posted this 27 June 2018

Sorry if I have not expressed very clear my suggestion, I refered with the positioning of the coils to test with narrow moveable coil(s) ,if tere is any response to a resonant effect,when sliding a coil. If you have watched the video I posted in the finding the frequency of circuit-thread you can observe that the timings between the output coils can be altered easyli by adjustment of frequency and dutycycle

Vidura posted this 27 June 2018

Sorry if I have not expressed very clear my suggestion, I refered with the positioning of the coils to test with narrow moveable coil(s) ,if tere is any response to a resonant effect,when sliding a coil. If you have watched the video I posted in the finding the frequency of circuit-thread you can observe that the timings between the output coils can be altered easyli by adjustment of frequency and dutycycle

cd_sharp posted this 27 June 2018

@CD - Increase your Off Time to 75%

Duty cycle is already 25%.

Polarity of Yellow appears its not correct, try flipping Drain and Source Terminals over.

I'll try.

I refered with the positioning of the coils to test with narrow moveable coil(s) ,if tere is any response to a resonant effect,when sliding a coil

I cannot slide them, the 2 bobbins cover the entire free space.

cd_sharp posted this 27 June 2018

I'm not sure what was wrong. Anyway, I did the entire circuit again and here are the results:

If I change the polarity of L2, the LL resonance effect diminishes :

There are a few questions that I cannot answer:

How can the yellow trace go negative, against the diode?

If the interaction between L1 and L3 "generates" current, can we use somehow L2 to "generate" some voltage? Maybe a classical transformer interaction between L2 and L3 can cause the voltage over the load go up. Maybe putting half the number of turns in L2 can do the trick.

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Vidura posted this 27 June 2018

Have you checked the diode? You could try to vary frequency and duty cycle if you find any resonant response.

Vidura posted this 27 June 2018

This prototyping boards you are using sometimes fail a conection when the clips wears out, it has happened to me, maybe if you rebuild on a different location of the board you get the expected results.

cd_sharp posted this 27 June 2018

Have you checked the diode?

Yes.

You could try to vary frequency and duty cycle if you find any resonant response

I always do. The resonant response is the long lasting current flow.

Please give me your answers to these questions:

How can the yellow trace go negative, against the diode?

If the interaction between L1 and L3 "generates" current, can we use somehow L2 to "generate" some voltage? We have current and we need some voltage rising.

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