[SOLVED] SMPS efficiency is less than 45%

[Embedded_Geek]

Hello all,

I have designed a flyback smps of rating 5V 2A. The SMPS is based on TinySwitch276.
Unfortunately the efficiency is less than 45%.
1) How can I increase the efficiency?
2) Is it the transformer which is reducing the efficiency?

Thanks in advance,
Embedded_Geek

 

[asdf44]

Find the heat. 10W is going somewhere and is making something hot. What is it?

 

[KlausST]

Hi,

How did you measure the efficiency?
Output power is DC, thus easy to measure.
But how did you measure input power?

Klaus

 

[Embedded_Geek]

I measured the RMS current of the AC input to the SMPS, which was about 102mA. The AC voltage is 230V. Therefore I derived the input power as P = VI = 230*102mA W. Is this not correct?
I measured using true rms clamp meter.

 

[FvM]

Is this not correct?

Not at all. Irms * Vrms = apparent power, not real power. Expect a distortion power factor considerably below unity.

 

[KlausST]

Hi,

Either you use a true effective power meter,
or you run the SMPS on 310V DC.
This gives the efficiency as DC/DC converter. The AC/DC efficiency is slightly less.

Klaus

 

[Embedded_Geek]

Hi,

Either you use a true effective power meter,
or you run the SMPS on 310V DC.
This gives the efficiency as DC/DC converter. The AC/DC efficiency is slightly less.

Klaus

In that case, I can measure after the rectifier in the smps. As the voltage here will be DC. Is this correct?
Thanks.

 

[FvM]

Yes, DC voltage * average DC current = input power.

 

[KlausST]

Hi,

You may input DC at the AC side (before the rectifier)then you will take rectifier loss into account.

Klaus