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I am trying to measure the efficiency of a DC/DC boost-converter in several operating points as precisely as possible. Right now I am measuring my input-voltage and output-voltage with a multimeter, and the input-current and output-current over a shunt-resistor with a multimeter as well. I think the four multimeters are pretty high quality (Flukes). I then calculate the input power and output power. Unfortunately it seems that my measurements are not precise enough, especially through the multiplication factors of the shunt and the multiplication of voltage and current, the resulting power seem to be off by a couple of percent (determined by repeated measurements of the same operating point).

Is there a better and more precise way to calculate the efficiency of my converter. I would obviously prefer a cheap solution, but if there is no way around it, I could also convince my boss to invest some money.

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  • \$\begingroup\$ Often, the data sheet for the boost controller will show the test circuits that were used by the manufacturer to characterize the performance. Have you checked those? This obviously won't help you if you are developing a custom boost controller, of course. \$\endgroup\$ – kjgregory Jul 8 '14 at 17:00
  • \$\begingroup\$ @KGregory: Yes, I am developing my own boost converter. \$\endgroup\$ – Lucas Jul 8 '14 at 17:51
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The four meter approach is pretty standard, though you should be able to calculate your accuracy based on the specs for the meter and the shunts. If the meters have an averaging function you can use that, possibly along with low pass filtering to get rid of any high frequency measurement noise. Measure the input and output voltages right at the terminals of the supply of course to avoid the IR drops in the connections and cables. Nothing wrong with taking several readings and averaging them manually either.

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  • \$\begingroup\$ Ok, I am glad that this seems to be the standard way of doing it. I suppose I will have to recheck if I am doing it correctly. \$\endgroup\$ – Lucas Jul 8 '14 at 17:52

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