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Transformer and parrellel tank

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LAN_403

Plasma

Sun Dec 29 2019, 03:18AM

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

I'm trying to isolate parrellel resonance circuit using a transformer, but I'm not sure how to size the transformer, as its inductance is in series with the resonance circuit.
Do I have to use phaser diagram with a balanced -j,+j?
Just started looking at this aspect so not much information.

Thanks

Patrick

Sun Dec 29 2019, 03:34AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Can i get a picture of the situation ?

Is this transformer being used in a larger circuit ? or is it the circuit ?

Plasma

Sun Dec 29 2019, 03:44AM

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

I'm planning to have many sub circuit like these three, with only multiple of line current... well the idea.

164035

Patrick

Sun Dec 29 2019, 05:40AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

youre going to need a simulator and every value of capacitance and inductance and resistance:

Parrallel primary feed of:
RLC to primary
RLC to secondary
RLC to tank

Values for each of the three transformers.
RLC to primary 1,2,3
RLC to secondary 1,2,3
RLC to tank 1,2,3

parrallel winding to winding capacitence 1,2,3
series winding to winding capacitence 1,2,3

Cross capacitence from pri to sec 1,2,3
Cross inductance from pri to sec 1,2,3

RL of pri 1,2,3
RL of pri 1,2,3
RL of pri 1,2,3

RC of pri 1,2,3
RC of pri 1,2,3
RC of pri 1,2,3

CL of pri 1,2,3
CL of pri 1,2,3
CL of pri 1,2,3

then:

RL of sec 1,2,3
RL of sec 1,2,3
RL of sec 1,2,3

RC of sec 1,2,3
RC of sec 1,2,3
RC of sec 1,2,3

CL of sec 1,2,3
CL of sec 1,2,3
CL of sec 1,2,3

From what you show it seems that there will be about 200 more iterations and combinations you'll need to have measured values for if you want to predict that circuits behavior.

or find a better way.

hen918

Sun Dec 29 2019, 12:48PM

Registered Member #11591 Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556

Luckily transformers are used all the time in resonant circuits in induction heaters to match impedances. If you can ensure all the transformers attached to the LC have the same impedance looking in, and all your LC tanks have the same resonant frequency, you should be able to match them so they behave as one. I would ignore the parasitic components of the transformers if you can ensure the leakage inductance is much less than the transformed inductance of the LC tank and the magnetising inductance much greater.

Plasma

Mon Dec 30 2019, 03:06AM

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

Thanks, would the LC tanks change with n like L/n and C*n ? Or stay the same LC values.
I did try running one with a transformer, but not much power got transferred. So assumed the resonance frequency changed up or down.
Not quite sure what to ask, I'll do some more thinking.

hen918

Mon Dec 30 2019, 09:07PM

Registered Member #11591 Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556

Step one, build the LC tank so L1*C1 = L2*C2 = L3*C3 ...
If you have the same values exactly, you don't need the transformer.
Ignoring resistance, impedance, Z = sqrt(L/C), so calculate all the impedance of the LCs. Choose an impedance for the primaries of all of your transformer (based on the voltage you will be running it at usually).
use the formula ((Np/Ns)^2) * Zs = Zp, where Zp is your chosen primary-side impedance, Zs is whatever that particular tank impedance is, and Np and Ns are the primary and secondary turn counts for the transformer to choose your transformer winding ratios. Also ensure that Ns causes the secondary magnetising inductance to be much greater than L.

Not sure what the application is, but remember if you change the magnetic field near any of the inductors, the inductance will change and so will the resonant frequency of that particular tank.

Sulaiman

Mon Feb 24 2020, 04:41AM

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

Resonating inductors, transformers and capacitors at line voltages can get a little too exciting,
especially if not thought through.

I suggest a few options ;

1 use a circuit simulator to test your ideas
2 do a few quick checks for feasibility (peak voltages, currents, power etc.)
3 simulate a similar system for lower voltage, whatever you have physically available (e.g. 12 Vac)
4 build and measure then decide what is was that you forgot in your simulation ;)
5 go to #3 until theory matches practice
6 from the ac supply I recommend Fuse, MOV, Fuse
7 ... and some type of 'emergency off' capability :)

This 'simple' project is actually non-trivial.
IF you intend to experiment then what do you envision the transformers to be like ?

This technology was widely used - when I was young

Plasma

Sat Mar 28 2020, 05:41AM

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

Sorry for the late replied.
The transformer was not excaly what you linked to, I'm trying to magically or electrical isolate multiple tanks so the power source doesn't see the muiplte as one tank.

Just got back into this project, but changed it to 50Hz line frequency and got a second hand computer and have installed Ltspice.

Cheers.

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