I am working on UC3854 PFC. Input is 80-250V, 50Hz, output is 385V dc. Everything is made like on 250W pfc preregulator on Unitrode UC3854 datasheet, except inductor and power supply for UC3854 (for testing I use external stabilised 18V dc).
For inductor I use ETD35G ferrite core with 250 turns of wire. Core specifications are on this site:
Problem is that pfc preregulator works ok without a load and I have 385V on output, but when i put any load, even very small load like 20k resistor, I get very large input current, like 2A and more, and duty cycle about 90%, and very small output voltage, just few volts.
I checked, and rechecked all components and connections many times but everything is like on Unitrode schematic...
Now I think that problem is in inductor.
Does anybady have experience with UC3854 inductors?
I am very interesting in if that inductor is very critical or pfc can work with several inductors with more or less worse performance?