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I am working on LTSpice on a project which consists in transferring energy from a PV panel to a load through a transformer, using a controlled bridge at the primary and a diode rectifier at the secondary side of the transformer. I am trying to retrieve the I-V characteristic of the PV panel after the diode rectification, but for that to work it seems that I have to combine a DC sweep analysis (to get the I-V characteristic) and a time analysis (to have the AC square-wave signal that is exchanged between the primary and the secondary side of the transformer).

Is there any way to realize such analysis? Or am I mistaken in what I am trying to accomplish?

I will add a picture of the circuit below.

enter image description here

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    \$\begingroup\$ Sounds a little odd since a DC sweep is going to open up your smoothing capacitor at the end, not mentioning all your other capacitors. Is R1 your load? Are you trying to see the behavior of Vout under various loads? If so, you can .param the resistance value and sweep it over a range using .step. Alternatively, you can replace the resistor with a current source and set it to PWL to sweep it under various currents changing over time instead. Probably a good idea to flag it as load too (checkbox on the right side of the properties window). \$\endgroup\$
    – Ste Kulov
    Commented Jun 4, 2022 at 4:14
  • \$\begingroup\$ @SteKulov I am trying to plot the I-V characterisitc of the PV panel, retrieved after the diode rectifier, for different phase shifts of the control signals in and in2. \$\endgroup\$
    – Sander
    Commented Jun 4, 2022 at 7:11
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    \$\begingroup\$ But...with the load attached? What's the purpose of finding an I-V curve with R1 already there? Also, what information do you expect these I-V curves to tell you? \$\endgroup\$
    – Ste Kulov
    Commented Jun 5, 2022 at 5:59
  • \$\begingroup\$ The load doesn't have to be attached, it was just a tool for the previous simulation... These curves will tell me which phase shift of the command signals will yield the highest MPP \$\endgroup\$
    – Sander
    Commented Jun 5, 2022 at 6:30
  • \$\begingroup\$ Thx for the info. Okay, so you can only get I-V if your circuit doesn't depend with T. One way to accomplish this is to create a DC equivalent for your circuit at the load (e.g. Thevenin equivalent). Another way is if you assume you are in steady state and can't get nudged out of it with different load currents. Then you can do what I said above and after your circuit stabilizes you can use a PWL current source, something like PWL(0 0 +1 0 +1 1) which will wait 1 second first, then sweep up to 1amp during another second of time. Then you can probe Vout to get the V for those I's. \$\endgroup\$
    – Ste Kulov
    Commented Jun 5, 2022 at 6:43

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If this was not a resonant converter, it could be done with reasonable accuracy using a DC sweep (just make one side of the H-bridge 100 % on, and eliminate the core part (2 *20 mH -- connect VL1+ to VL2+ etc.) of the transformer), but since it is a resonant converter, the losses in the switches will depend on the resonant currents and so can't be easily approximated like that.

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  • \$\begingroup\$ So if I want to retrieve the I-V characterisitc of the PV panel at the output of the rectifier for different phase shifts of the command signals in and in2 it is not possible? Since I have to always set one of the side of the H bridge ON all of the time? \$\endgroup\$
    – Sander
    Commented Jun 4, 2022 at 6:55

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