where they block all the ventilation holes and let it bake.
the leading edge of the power pulse on the secondary. I went to 600V diodes but I realize that is a poor subsitute to understand what is going on, say by modifying the winding of the transformer or tweeking the snubber values. Hence my desire to properly simulate, hence my query about coupling constants.
current limiting and the overall feedback which regulates the output voltage.
approaches steady state. I may have left a poor set of K's in the file I attached to my OP. Set all the K's back to .999 and it should look better.
Why don't you measure the actual K's of your transformer?
Interesting, in this configuration, L1 only couples power to L2 and L3 to L4. The coupling between L1 L4, L3 L2, L1 L3 and L2 L4 are not players so there coupling is not important so why not just measure the Ks of L1 L2 and L3 L4? Harry
You might think that, but the coupling between the two secondary windings is important too: During the dead time when both transistors are off, the output current is flowing through both secondary windings and diodes. Then when a transistor turns on, one of the rectifier diodes goes reverse biased, and the current in that secondary winding must instantly transfer to the other secondary winding.
where they block all the ventilation holes and let it bake.
the leading edge of the power pulse on the secondary. I went to 600V diodes but I realize that is a poor subsitute to understand what is going on, say by modifying the winding of the transformer or tweeking the snubber values. Hence my desire to properly simulate, hence my query about coupling constants.
current limiting and the overall feedback which regulates the output voltage.
which approaches steady state. I may have left a poor set of K's in the file I attached to my OP. Set all the K's back to .999 and it should look better.
You're right but I haven't had much luck getting reproducible results. The measurement head we have on our Agilent LCR meter is great for measuring surface mount R's & C's, but it does not work well with the transformer pins. Apparently they offer a head for transformer measurements but we don't have that.
The L values I put in the simulation came from the core spec and the number of turns.
Why do you need a measurement head, just connect four BNC connectors to you LCR meter and the other ends to your DUT. Do a Kelvin connection to a short and let the meter calibrate itself with this new head. You will need separate leads to measure mutual inductance anyway. Cheers, Harry
where they block all the ventilation holes and let it bake.
the leading edge of the power pulse on the secondary. I went to 600V diodes but I realize that is a poor subsitute to understand what is going on, say by modifying the winding of the transformer or tweeking the snubber values. Hence my desire to properly simulate, hence my query about coupling constants.
current limiting and the overall feedback which regulates the output voltage.
which approaches steady state. I may have left a poor set of K's in the file I attached to my OP. Set all the K's back to .999 and it should look better.
measurement head we have on our Agilent LCR meter is great for measuring surface mount R's & C's, but it does not work well with the transformer pins. Apparently they offer a head for transformer measurements but we don't have that.
Which Agilent LCR meter are you using? What measurement frequency are you using? It would probably help to use a frequency no higher than, say,
20 KHz. You should be able to use the classic series aiding/series opposing measruement technique.
For example, to measure the K between L1 and L2, wire L1 and L2 in series and measure the inductance. Then reverse the connection to ONE of L1 or L2 and remeasure the inductance. Subtract the smaller measurement from the larger and divide by 4. That will be the mutual inductance, m12, between L1 and L2; then K12 is m12/SQRT(L1*L2), where L1 and L2 are the self-inductances. Do the same for the other inductor combinations.
The dead time is how the current mode PWM controller (a TI UCC3808 series) regulates. There is a current sense resistor in series with the FET sources that feeds back a signal to the controller chip which is compared with the overall feedback signal. Thus the primary current is controlled on a cycle-by-cycle basis. I guess you could say that the system regulates by varying the duty factor.
where they block all the ventilation holes and let it bake.
on the leading edge of the power pulse on the secondary. I went to 600V diodes but I realize that is a poor subsitute to understand what is going on, say by modifying the winding of the transformer or tweeking the snubber values. Hence my desire to properly simulate, hence my query about coupling constants.
current limiting and the overall feedback which regulates the output voltage.
which approaches steady state. I may have left a poor set of K's in the file I attached to my OP. Set all the K's back to .999 and it should look better.
measurement head we have on our Agilent LCR meter is great for measuring surface mount R's & C's, but it does not work well with the transformer pins. Apparently they offer a head for transformer measurements but we don't have that.
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