LTspice designs, tips, and stuff
LTspice designs, tips, and stuff
I have see many posts on the web asking how to make a current limited voltage source. One easy way to do this is to use a arbitrary behavioral current source and a little math. What you want is this:
I=MIN( gain*error , <current limit> )
or
I=MIN( gain*(Vtarget - V(Vout)) , <current limit> )
Mike has provided a simulator friendly version of MIN with a third parameter:
I=UpLim( gain*(Vtarget - V(Vout)) , <current limit> )
So, for a 1000 volt 0.1 amp current limited voltage source:
I=UpLim(1000000*(1000-V(Vout)), .1, .001)
I have not found much documentation on the third parameter other than:
“defines a zone with quadratic soft limiting” from this page:
http://ltwiki.org/index.php5?title=Undocumented_LTspice
A reference for the behavioral sources can be found at:
Current Limited Voltage Source
Current limited voltage source driving fixed load R3 & RC load R2 & C1.
Valley Fill for Power Factor Correction
A relatively simple way to improve power factor is to use a valley fill circuit. Several more passives than a capacitor hung on the output of a bridge, if you load isn’t too large you can achieve an acceptable power factor. More optimizations can be found here:
https://www.coilws.com/Publications/ImprVF.pdf
Below is the result, red is V(Neutral)-V(Hot) and green is the current through V110VAC
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