I am testing a Flyback converter with input 230V ac and output of 12 V at 3.4A.
When I am calculating efficiency from RMS values the efficiency is coming around 40%. I am attaching the waveforms of the same. The switching frequency is 100kHz.
I am noticing that there is excessive heating of output diode. I am assuming this is due to the smaller heat sink (13degree/W coefficient) and heat sink temperature is going upto 90 degree after running for 5minutes after which I switched off the system. Input side I am not observing any heating of Mosfet, snubber etc.
What could be the issue with the design for causing lower efficiency.
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ST’s silicon-carbide diodes take advantage of SiC’s superior physical characteristics over Si, with 4 times better dynamic characteristics and 15% less forward voltage, VF. Their low reverse recovery characteristics make ST’s silicon-carbide diodes a key contributor to energy savings in SMPS...
Thanks Dana. The link solved my problem. I made mistake of using Apparent Power for Calculations instead of real power. As per the power analysis software. Real power input is around 50 W. My output is 39.8 W. So it should be sufficient efficiency (75% to 80%) of typical off-line flyback converter
What you label reactive power is mostly harmonic power. We also see a DC offset in current measurement, but it has no effect on real power measurement as long as it's averaged over full cycles.