Thane Heins BI-TOROID TRANSFORMER

[teslaalset]

Thane,

I found a clue why you measure flux in core 3 with the current clamp.
If the secondary coils are loaded to their maximum current, something interesting happens with the flux lines.
In your drawing N_prim/N_sec = 1000/200, meaning I_{sec_max}= I_prim x N_prim/N_sec, so if I simulate these winding ratios and allow the secondary currents to be exactly 5 times as much as the primary current flux direction go outside the core(s)

As long as the secondary currents do no exceed 5 times the primary current, flux lines stay nicely within the core.
Any secondary load current (identical for both secondary coils) up until that maximum current will end up in a flux flow as indicated in my reply #97 on page 7 of this thread.

Have a look what happens if the secondary currents go to their maximum load:

[broli]

teslaalset, could you do me a favor and run some FEMM magic.

The attached image shows the setup. Basically I want you to do a circular line integral of the flux density shown by the black circle in the image. The big toroid is just a ferromagnetic toroid with no current. I also added a setup I made in vizimag which doesn't allow circular line integrals. If you need help with the math I can help so you can make the script that calculates the average flux of the loop.

Of course there's a very good reason to this. Let's assume that the average flux through the toroid is non zero. This means if there was a coil wrapped around it it would generate a voltage. This in turn could make a current. What I've seen in the sim is that it doesn't change the flux of the primary, smaller core.

However if the average flux turns out to be zero, the windings of the toroid will not generate any voltage and thus nothing special happens.

Edit: Had to correct something.

[penno64]

Guys,

Would it be possible to emulate / simulate Thane's effect using this type of core.

I am uncertain how secondary windings 1 and 2 are connected to load.

Any help greatly appreciated, for I would love to re - create this effect.

Regards, Penno

[teslaalset]

teslaalset, could you do me a favor and run some FEMM magic.

The attached image shows the setup. Basically I want you to do a circular line integral of the flux density shown by the black circle in the image. The big toroid is just a ferromagnetic toroid with no current. I also added a setup I made in vizimag which doesn't allow circular line integrals. If you need help with the math I can help so you can make the script that calculates the average flux of the loop.

Of course there's a very good reason to this. Let's assume that the average flux through the toroid is non zero. This means if there was a coil wrapped around it it would generate a voltage. This in turn could make a current. What I've seen in the sim is that it doesn't change the flux of the primary, smaller core.

However if the average flux turns out to be zero, the windings of the toroid will not generate any voltage and thus nothing special happens.

Edit: Had to correct something.

Broli,

Can you clarify a few things, so my understanding is correct?
- the big toroid is only ferrite, no coil ?
- the small toroid is also ferrite, with coil?
- what do you mean with on load/no load in the second and third pictures?

[broli]

Broli,

Can you clarify a few things, so my understanding is correct?
- the big toroid is only ferrite, no coil ?
- the small toroid is also ferrite, with coil?
- what do you mean with load/no load in the second and third pictures?

1) kind of, see 3)
2) yes
3) no load is basically the case you describe in your first question. In the sim that toroid is really a core 1000 perm. with 0 Amps current. With On load I change the current value to say 10amps to simulate induction action. As the toroidal coil would want to oppose the field of the primary.