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resonance energy storage experiment

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LAN_403

Plasma

Thu Jul 11 2019, 04:14PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

Hi I'm mucking around with parrellel resonance circuit to store energy. So far I've built a frequency generator that can move around 50khz, its just a hex inverter with a pot to adjust it, driving a full bridge.
I'm trying to keep the input to 12 volt 1 amp.
Still need to get the PRC parts.

Sulaiman

Fri Jul 12 2019, 12:43AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Good Luck !

An L.C resonant circuit also has some R, which will consume your energy.
You will need an unachievably high Q to store energy for a significant period of time.
Even if you achieve a very high electrical Q, some energy will be lost to electromagnetic and electrostatic losses/radiation etc.

Example : suppose that your signal generator can supply 1W of power to your resonant circuit,
initially the voltage and current levels (VAR) in your resonant circuit will build up,
the resonant circuit will have a Q value,
suppose that you make a really good resonant circuit with a Q of 1000
(not easy because it is difficult to make a low-loss high power inductor)
the energy circulating in the resonant circuit will self-limit at QxPin, in this case 1000VAR.
That could be 10Vx100A, 100Vx10A, 1kV.1A etc. dependant upon your design choices.

So, I think that you may be a little disappointed with your results,
but you should attempt this anyway as you will learn many useful things from such a (theoretically) simple circuit.

Please notice that even using a small amplifier/oscillator (1W in my example) a low-loss (high Q) resonant circuit can build up energy to a shocking level.

Plasma

Fri Jul 12 2019, 08:29PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

The. Frequency generator, it seems to work.

The DMM reads 4v AC and 22-55khz 47% duty cycle.

Sulaiman

Sat Jul 13 2019, 02:38AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Consider a diode across each mosfet, something like 1N5822.
And a fuse in series with the bridge output.

There will be a lot of energy sloshing around in your resonant circuit,
enough to destroy your mosfets if things do not go as expected
i.e. under normal conditions ;)

Plasma

Thu Jul 18 2019, 06:09AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

Thanks for the tips Suliman. I had to adjust it abit, and put the square wave generator on its own power supply.
Its a lot more stable.

When I connect the tank circuit, there's no voltage across it, and got less when I added the second stage.

Sulaiman

Thu Jul 18 2019, 08:16AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Can you post a link to your circuit diagram ?
(a photo of a hand drawn circuit diagram will suffice)

Plasma

Thu Jul 18 2019, 02:01PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

The values are different, both inductor's are 47uH and the capacitors are 220nF.

Using a peak detector I get
Stage 1 ,10.50
Stage 2. , 12.81
Stage 3. ,13.50

That's DC, what would the AC voltage be ,I need that to workout the current.
It lowers when I move it out of resonance.

Plasma

Sat Jul 20 2019, 12:04AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

Found some of the problems Suleiman. The resistor to the IC dropped 3v , the p and n MOSFETs went turning fully on, and the same leg would.

I've got a revised circuit, hopefully you can check it.

Sulaiman

Sat Jul 20 2019, 01:10AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Your H-Bridge looks wrong to me.
Have a look at this web page

and build a bridge similar to this

the two optocouplers can each be replaced with an NPN transistor plus 1k to 10k in series with the base.

In the last diagram the connections between the mosfet drains and the outputs is missing !
The load would of course be your resonant circuit(s), not a motor ;)
Your inductors and capacitors resonate at about 50 kHz so I'd use 100R 3W resistors for R1 and R2

During your initial design/testing I would put a 12V (21W or similar) car bulb in series with the bridge output,
this gives an instant indication of (and protection from) excessive current.
It will also indicate when your are at the resonant frequency of your resonant circuit(s)

Plasma

Tue Jul 23 2019, 12:57AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268

I've added a halgyin bulb to the list tonight, I've got 5 3amp fuses and clips from last one. R1 r2 is that for the voltage divider for the N channel MOSFETs? Or for resonance part?
125358

I've pretty much copy pasted, but added 3 amp diode after the P MOSFETs so I can short AC leads without both N MOSFETs turning on.

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