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That is because you are driving both tanks. In a real circuit, one tank is driven and it feeds the other, which is connected to the input of the next stage.

When I see resonance splitting in the real world, I see it looking at either tank, I don't have to look at both.
On my end in spice, plotting both tanks, I do not see any splitting in the plot of either tank, or any divergence in the resonance between the plots.

When I see resonance splitting in the real world, I see it looking at either tank, I don't have to look at both.
On my end in spice, plotting both tanks, I do not see any splitting in the plot of either tank, or any divergence in the resonance between the plots.

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Between X and Y. If you don't know how to do that, click and hold on X, then slide to Y and release.

Also, you can see it very well by deleting R2 and looking at the voltage at Y.

Sorry, we crossed messages, I was asking John where and how he's measuring to see the splitting.

Sorry, we crossed messages, I was asking John where and how he's measuring to see the splitting.

I wrote, "Remove R2."

In the first circuit.

Andy

Ok, where/how are you measuring it?

David,

Remove R2.

Andy

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Of course they will move in the same direction. They are identical, so there is no way they can move in opposite directions. You simply can't see splitting by measuring that way.

I'm plotting the voltages on the top of the tank caps.? The series R is supposed to represent the R in the inductors, so this would be equivalent to measuring the ungrounded end of a parallel tank.
What I see here, is that the tuning of BOTH circuits moves in the same direction as I increase the coupling.
More odd, if I reverse the polarity of either inductor, the tune change reverses direction.
Momentarily I'll upload a version which is more like my original.
The tanks are driven from a third inductor very weakly coupled, which more represents the real situation.

I'm plotting the voltages on the top of the tank caps.? The series R is supposed to represent the R in the inductors, so this would be equivalent to measuring the ungrounded end of a parallel tank.
What I see here, is that the tuning of BOTH circuits moves in the same direction as I increase the coupling.
More odd, if I reverse the polarity of either inductor, the tune change reverses direction.
Momentarily I'll upload a version which is more like my original.
The tanks are driven from a third inductor very weakly coupled, which more represents the real situation.

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I don't know what you are measuring, but the voltage between X and Y does show resonance splitting. You have a Q of 628 and a k of 0.01, so Qk = 6.28, which is heavily over-coupled. Change k to 0.001? or less and there is no splitting. You can see better if you reduce Span from 200k to 20k.

Also, look at the Spice error log: Number of points reduced from 100000 to 65535.

?It's best to use '1meg' instead of '1000000'. Less chance of an order-of-magnitude error. Also, you could replace the voltage generator and 1meg resistors by two identical current generators.

Uploaded to the temp files area, I have a sim which I believe should be showing resonance splitting, but so far all it does is move the tuning of both tanks in the same direction(!) when I increase the coupling.
What am I doing wrong??? I also tried driving the tanks with a third inductor weakly coupled to the two tanks, (K = 0.0001) with the same result.

Uploaded to the temp files area, I have a sim which I believe should be showing resonance splitting, but so far all it does is move the tuning of both tanks in the same direction(!) when I increase the coupling.
What am I doing wrong??? I also tried driving the tanks with a third inductor weakly coupled to the two tanks, (K = 0.0001) with the same result.

I have uploaded the files to the Temp folder. No pictures included, with the provided files you can do your own simulation runs anyhow.

I don't know if this helps -- but there are files already in our group for the TPS43060.? Perhaps the TPS43060 and TPS43061 are similar?? Look in this folder:

Files / z_yahoo / Files sorted by message number / msg_115005
/g/LTspice/files/z_yahoo/Files%20sorted%20by%20message%20number/msg_115005/

I think one of the problems with that model was double {{curly braces}} in TI's model.? That doesn't make sense for LTspice.

Andy

Adding a bit more to what Donald already wrote:

What we need are your schematic (.asc file), ALL symbols (.asy files) that didn't come with LTspice, and ALL SPICE models that didn't come with LTspice.? Without these, we can't open your schematic to see what's in it.? Do not include the output files (.raw, .log, or .net unless it's a SPICE model).

As you should know already, the place to upload is the group's "Temp" directory.? The link to it is on the group's main page.? Navigate to that directory first before clicking the "+New" button to start the upload.

If you insist on pictures, they should be uploaded to the group's "Photos" section.? Keep in mind that (1) we can't simulate a screen shot, and (2) with the schematic and models, everyone here can see the results so we probably don't need a photo.? They rarely help.

Please do not use "third party" file storage websites.? This group has its own File and Photo areas.? Use them.

I think you wrote that your simulation worked before, and then it doesn't work right anymore.? I wonder if you have some idea what you changed.? SOMEthing must have changed.? Don't assume that you used the standard settings.??How long ago did you have the working simulation?

Andy

I've concluded that the problem is with the "documents" folder used by my Windows 10? system

I have been able to determine that it was set to?D:\OneDrive\Documents. It didn't exist, and therefore LTspice didn't build the lib properly.?

I added the drive and folder, and now it launches. However, I don't want that to be the W-10 document folder. I changed it to something that I wanted, and now everything works.?

Upload your .asc file (and any library or model files that are not
included in the LTspice installation) to our Temp directory and we might
be able to help.

If there is more than one file, zip them together (.zip, please; NOT rar
or 7z or gz or ...) No need for any .raw, .net, or any other files. And
definitely no useless image files (.jpg or .png or whatever.) They don't
simulate at all :-)

Donald.
--

Good point. The OP asked about increasing speed, so I was thinking in
that direction. In the provided models, I didn't see any means to modify
commutation frequency (though I admit to not looking very hard.)

Donald.
--

Thank you all.

On 2/25/21 1:36 PM, Donald H Locker wrote:

Again, increasing the supply voltage (the V source labelled VHV near the
top right of the schematic; it is set to 24V) will increase the motor
speed (and, consequently, the commutation frequency.)

Changing it to 12V will slow the motor to about half speed; increasing
it to 48V will approximately double the motor speed.

It is a brushless DC motor - speed is controlled primarily by the supply
voltage. Commutation frequency is a function of speed; speed is NOT a
function of commutation frequency. The way to change speed is to change
the supply voltage; commutation frequency will then also change.

Did I mention to change the supply voltage (change it from 24V) to
change the motor's speed?

Donald.

Actually, you CAN control speed with commutation frequency, but only
downwards, if you disengage that automatic commutation system normally
being used, you can get very tight speed control by using a fixed
frequency commutation. You do need to monitor the speed the motor is
going because if something does cause it to drop you may need to adjust
the commutation to keep it from loosing lock.

--
Richard Damon