S
Spirit
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:
http://www.iskra-feriti.si/index.php?t=mat-list
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?
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:
http://www.iskra-feriti.si/index.php?t=mat-list
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?