| Too high idle power - Click HERE for Original Thread |
| Danko |
Hello!
I'm making a full bridge mains powered SMPS. It is operating at 170kHz, the mosfets are APT5015BVR, and the mosfet driver ICs are IR2113. The control circuits has a dedicates small 50Hz transformer. it's about 10-15VA.
When I first "launch" it up, I examined the small transformer, and the control circuits. Everything was OK, except the MOSFETs' GATE waveform wasn't as good as I expected.
After this, I feed the "power stage" from my variable voltage labPSU. And here came the problems...
I applied about 25V to the input of the SMPS, and the power consumption was about 0.6A. This means about 15W. There was NO LOAD at the output of the SMPS. I tried to remove the secondary side things (diode bridge), but no results.
Why was the idle power so high? Maybe the MOSFETs were cross-conducting? Or I made some mistake, while I was winding the transformer (ETD49), and I scratched the copper wire's insulation?
The previous prototype worked very good, I measured very good performance.
Here are some images of my 'scope:
The third image was taken from the current sense resistor. Thoose spikes show about 18-20A current-spike. :eek: :eek:
Here are the images in higher resolution:
http://sziget.mine.nu/~danko/aramko...16/dscn9444.jpg
http://sziget.mine.nu/~danko/aramko...16/dscn9446.jpg
http://sziget.mine.nu/~danko/aramko...16/dscn9447.jpg
What can cause this? |
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| Eva |
| That seems like bare cross conduction due to a lack of dead time. |
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| Danko |
Thanks Eva!
I'm going to increase the Dead-Time.
sss:
When I take thoose pictures, there were no snubber in the SMPS, but the place for them is on the PCB. |
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| subwo1 |
| Watch out for current phase inconstancies which make maintaining correct dead times between bridge legs trickier. |
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