Electronics > Beginners

Bypassing Loads Under Constant Current Efficiently

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Ian.M:
I'd suggest you repost your inductor question as a new topic with a more appropriate title e.g. "Inductor proximity effects?"

T3sl4co1l:
Mutual coupling between board level components is weak at best (k < 0.05?).  It's hard even to contrive custom parts that have strong coupling, without making them a single component as such.  (Note that embedded inductors and etc. (planar magnetics) can do significantly better, but aren't really components either.)

Capacitors simply have the capacitance between their outer foil/housing, a few pF at most.

Tim

TheDood:
I was simulating different configurations and came across another "throbbing" waveform. I decided to try to get to the bottom of it and found that my frequency calc was not precise enough at only 0.00833s/period. I added a few more sig figs and the "throbbing" went completely away.

Current sim attached if anyone is curious. I'm trying to figure how to calculate power dissipation across the capacitors? The X1 cap shows +/- power dissipation, so the average is misleading? Next step is to switch out rectifier diodes for FETs, right now the biggest power waste is at the bridge, I tried using NMOS's for my return leg of the bridge, tieing the gates to the drain but It didn't work, I think maybe Ill have to implement a few OP-Amps??

T3sl4co1l:
FYI, gate voltage is wrong, those NMOS are in for a big surprise.

Capacitors don't dissipate average power, or capacitance doesn't anyway.  Any ESR you can calculate the dissipation of by taking the current through the component and P = I^2 R.

A synchronous rectifier into a filter choke, isn't so bad, but you need a controller to do it into a capacitor.

Tim

TheDood:

--- Quote from: T3sl4co1l on December 07, 2019, 08:54:01 am ---FYI, gate voltage is wrong, those NMOS are in for a big surprise.

Capacitors don't dissipate average power, or capacitance doesn't anyway.  Any ESR you can calculate the dissipation of by taking the current through the component and P = I^2 R.

A synchronous rectifier into a filter choke, isn't so bad, but you need a controller to do it into a capacitor.

Tim

--- End quote ---

Thanks Tim you're always very helpful, can you help me understand what you're saying, not enough gate V, or too much? I'm only simulating with parts that are preloaded into LTspice to get a general idea, though I just looked up the IRFP4668 and it gives a Vgs(th) of 3V - 5V, and a max of +/- 30V. If I ever were to use a component like this would I want a higher gate V, maybe 12V?

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