90 degree phase difference in current between inductors

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p75213

Joined May 24, 2011
70
The schematic is a circuit I am designing. The current through the leg with the inductor and capacitor in series must be 90 degrees offset from the other leg. The rectified current pulses through both legs must be equal. How do I calculate the values of the inductor and capacitor in series? The reactance of both legs would have to be equal for the current to be equal.Lenz-Free.png - Disregard the 3rd (secondary) inductor.
 

crutschow

Joined Mar 14, 2008
25,679
That appears to be a transformer, not an inductor. They are not the same (although a transformer does have a magnetizing inductance).
You can select a capacitor to give a 90 degree shift for the inductive magnetizing current but that doesn't give a load phase shift.
If you have a resistive load, there will be a lead phase-shift between the capacitive reactance and the load resistance (somewhere between 0 and 90°).
That phase-shift will change with the load resistance.
What is the purpose of this strange circuit?
 

Thread Starter

p75213

Joined May 24, 2011
70
That appears to be a transformer, not an inductor. They are not the same (although a transformer does have a magnetizing inductance).
You can select a capacitor to give a 90 degree shift for the inductive magnetizing current but that doesn't give a load phase shift.
If you have a resistive load, there will be a lead phase-shift between the capacitive reactance and the load resistance (somewhere between 0 and 90°).
That phase-shift will change with the load resistance.
What is the purpose of this strange circuit?
I can't tell you that. However I would appreciate if you could tell me how to calculate the capacitor.
 

Bordodynov

Joined May 20, 2015
2,698
Since you have included inductance to the rectifier bridge, you can not do it. This is my opinion. There will be a strong bias. What kind of phase are we talking about? After all, after the rectifier bridge there is a nonharmonic signal. Refine your goal. And do not say that the phase shift is the goal. I understand that you have decided that it will be enough to move the phase.
 

Thread Starter

p75213

Joined May 24, 2011
70
Ok. The current (magnetic) pulses from the two out of phase primaries combine to make a magnetic pulse which itself is out of phase with both.
 

Bordodynov

Joined May 20, 2015
2,698
Through a single inductance, a direct current component flows, and through the second inductance there is no direct current. the capacitor does not let direct current flow.
 

crutschow

Joined Mar 14, 2008
25,679
and through the second inductance there is no direct current
True. But there will be pulses of current flowing back and forth through the capacitor since the direct current through the top primary causes the bridge output to be a full-wave rectified voltage.
 

MrAl

Joined Jun 17, 2014
7,849
The schematic is a circuit I am designing. The current through the leg with the inductor and capacitor in series must be 90 degrees offset from the other leg. The rectified current pulses through both legs must be equal. How do I calculate the values of the inductor and capacitor in series? The reactance of both legs would have to be equal for the current to be equal.View attachment 157823 - Disregard the 3rd (secondary) inductor.
Hello there,

Overview: We need to know the design principles you were relying on when you designed this circuit.

Number two this is not a practical circuit and number one this is not a practical design. I'll elaborate.

The bridge rectifier supplies only unipolar pulses to the top inductor, which means that in theory with the circuit as is the top inductor saturates. This would cause the inductance to fall to such a low level it might actually appear like a short circuit. With that you'd see zero output voltage or very very low DC voltage.
To make it a practical circuit (but probably still not a practical design) you would either add some series resistance to the top inductor or at least indicate it's ESR. That would limit the DC current. Without that little feature however the inductor acts like a short circuit so it's not feasible.

What all this means is that you really have to review the design and the goal of this design and probably come up with something better. What you are asking and what the circuit looks like are very different than each other. The circuit does not adhere to the concept of phase because of the full wave bridge rectifier unless you really stretch the definition, and in such a rare case you'd have to suggest how you want to do that. The problem is with the rectifier we are dealing with long term storage of energy when in a true AC circuit only have short term energy storage. Thus phase itself is certainly not enough to describe what is happening we have to see instantaneous results. Even in the cap+inductor part of the circuit the cap would charge up to some DC level and then it would stay charged (ideally) and then there would be no more current flow. If there is some leakage then you have to either show that or specify a resistor that achieves that goal otherwise there's not going to be any change in voltage after a short charge up time.

So look over the circuit and try to come up with something else or else specify what it is you really want to do.

If you are relying on the resonant frequency of the cap+inductor then you will have to analyze this in the time domain, and then an unusual situation will arise when the cap+inductor frequency is out of sync with the line (input) frequency. There could be times of almost no current flow and times when there is very high current flow. There will most likely be a huge DC current in the top inductor anyway though but i suppose the analysis would say for sure.
Maybe you could state some of the design principles you were banking on here and that would tell us what you where thinking about how this SHOULD work.
 
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Ramussons

Joined May 3, 2013
890
Looks like you want to run a stepper motor without the electronics.

You do the phase shift Prior to the rectification. Then you can get Phase Shifted Pulses. But getting a 90 degree shift will be by Trial and Error.
 

MrAl

Joined Jun 17, 2014
7,849
This is what I wish to do. Only with dc pulses applied to a transformer.
Hi,

That's an AC circuit which makes more sense.
If you apply DC to a transformer primary you end up with a huge DC current that is limited only by the resistance of the winding and the possible voltage source internal resistance. That usually does not work because it's just such a high current it saturates the core and blows something out. A pulsing DC would cause the current in the inductor to ratchet up higher and higher so it's almost the same as a pure DC.
That's why i mentioned the resonant frequency of the cap+inductor part of the circuit because i think that's the only saving grace that MIGHT prevent a huge current. I have a feeling that wont work either though because there does not seem to be any way to sync the line frequency with the resonant frequency phase.
If you can come up with another way to do this that would be good.
I have a feeling you are not really trying to drive a multi phase motor with this but if you are just mention that then.
 

shortbus

Joined Sep 30, 2009
8,056
I see some kind of over unity scheme on the horizon. The tip off is the -
No disrespect meant to another member by posting this. But since the topic isn't allowed on this site, other members should be aware of this, and the moderators too.

Doing a quick Google on the TS name gets a lot. Seems he is doing research into over unity and othe topicks and is active on at least one over unity/conspiracy site. Unless there are two people using that screen name. If that is the case I apologize in advance.
http://www.energeticforum.com/members/74996-p75213/
 

MrAl

Joined Jun 17, 2014
7,849
No disrespect meant to another member by posting this. But since the topic isn't allowed on this site, other members should be aware of this, and the moderators too.

Doing a quick Google on the TS name gets a lot. Seems he is doing research into over unity and othe topicks and is active on at least one over unity/conspiracy site. Unless there are two people using that screen name. If that is the case I apologize in advance.
http://www.energeticforum.com/members/74996-p75213/
Hi,

That may help to explain why the question does not make any sense :)
But i wont judge anybody just yet.
 

MrAl

Joined Jun 17, 2014
7,849
Hello again,

I took another look at the original circuit.
What i discovered was that we see second harmonic current and voltage waveforms. This means we get something akin to phase, but it's not consistent when we look at the current in the inductor in series with the cap because that has a resonant frequency of it's own. So we get something that looks like a sine in the lone inductor, but in the other inductor we get a very unusual waveform that does not look like a sine. Now we might add the stipulation that we MUST force the resonant frequency such that it is the same as twice the line frequency, but that would be a highly theoretical assumption that would never work in practice without a separate resonant frequency regulator control which would probably be more complex then the designer really wanted.

The worst part however is still the current limit. The lone inductor acts like a short for DC current so it draws a very large amount of current. With the circuit as is, the only limit on the current is caused by the diodes, mostly the equivalent series resistance of the diodes which although non zero is usually very low.
For example, with a 10v peak AC sine source and diodes that have resistance around 0.15 ohms, we could see an average DC current of around 15 amps, and lowering that resistance to half that value would mean the average DC current would go up to around 30 amps. Since we dont normally use diode resistance to limit (average DC) current, this would probably not be a serious design. Of course each design goal is very much dependent on the designer's application of principles and since we cant say that there is no design on Earth that uses a diode for current limit, we are still subject to learning the basic electrical principles that the original designer had in mind when designing this circuit. For example, if they say they did not count on depending on a diode to limit current, then we know right away that the circuit would not work as intended, but if they state that the diode current limit was one of the main principles that was considered as the design progressed, then we would be subject to analyzing the circuit allowing that principle to prevail and thus we'd have to come up with a solution or another reason why it works or does not work.

After all is said and done, i'd love to hear a description of how the design process went from start to finish and that way we could make a very informed decision. As it stands so far though since we dont use diodes to limit current in this kind of circuit normally it looks bad.

If it does turn out to be one of those EFN (energy from nowhere) circuits that would be very sad :)
In that case though i guess we could take it as just another academic question on circuit analysis and maybe learn something new. After all, no matter how bad it is it is still a circuit :)
 
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nsaspook

Joined Aug 27, 2009
7,750
Thanks, I remember that PF thread now.

From the OP:
None of the above. The idea is to remove the back emf from the secondary to the primary. The result of doing this is to reduce, if not cancel, the increase in amperage draw from the source due to the load on the secondary. Effectively the source only has to supply enough current to maintain the magnetic field in the primary (magnetizing current), no matter the load on the secondary.
mod:
What you are proposing and pursuing is Free Energy, and we don't waste folks time discussing such things here. In this case, it is enveloped in electronics fundamentals, but it is the same as if you were proposing a perpetual motion machine (PMM) waterwheel.
 
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