I would like to take a look at the common mode currents for various PFC circuits. I have set up three circuits (active full bridge, interleaved active full bridge and a flying capacitor half bridge) all working with a totempole. I noticed that the common mode currents I measure from one circuit to the other are very similar. I would expect that not be the case and i would also expect the currents to be smaller. Now my question is, is plecs suitable to look at the common mode currents or is it inappropriate due to the ideal switching? If it is suitable, what should I pay attention to in my circuits?
Totem_Pole_interleaved_v3.plecs (159.7 KB)
Totem_Pole_v2.plecs (169.0 KB)
FC_Totem_Pole_v2.plecs (148.6 KB)
Yes you can model common mode and differential mode currents in PLECS.
However, as you pointed out, PLECS is a system level simulation tool that primarily uses ideal power semiconductor models. If you employ the standard ideal switch model in PLECS there will be a natural limitation regarding the accuracy of the calculated spectrum because the switching transition itself is not modeled. If you are interested in the spectral components that are natural harmonics of the switching switching frequency (multiples) then PLECS may provide sufficient detail.
If you want to analyze higher frequencies where the switching transitions and other parasitics are critical, then there are dynamic MOSFET model in PLECS with finite current slopes during turn-on and turn-off. However, these are not physical models, but only behavior-based models. Also be aware that these models, due to the small time constants, also slow down the simulation speed significantly. Please have a look at the model MOSFET or IGBT with Limited di/dt and read the description of the model under "Help”. Ultimately if the harmonic spectrum is critical to your analysis then you may want to consider a different type of simulation or directly a hardware measurement.