I am currently developing a three-phase VSI inverter model in PLECS using SiC devices and evaluating the inverter efficiency at different load/output power levels.
I am experiencing an issue with the efficiency calculation. As the output power is increased while keeping the DC-link voltage, output voltage, modulation index, switching frequency, and other operating conditions constant, the calculated inverter efficiency decreases continuously. This is different from the efficiency trend I expected.
The semiconductor conduction and switching losses are calculated using the device thermal models in PLECS. I would like to confirm whether my efficiency calculation and loss evaluation method are correct.
Could you please advise on the following:
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What is the recommended method for calculating inverter input power, output power, total semiconductor losses, and efficiency in PLECS?
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Should the input/output power and losses be averaged over a specific number of fundamental cycles to obtain accurate efficiency results?
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Are there any particular settings required in the thermal models or loss calculation blocks when performing a load sweep?
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Is a continuous decrease in efficiency with increasing output power expected under certain operating conditions, or could this indicate an issue with the model or measurement method?
I can provide the PLECS model, thermal description files, and simulation results for further investigation.
Thank you for your assistance.
C3M0025065L_bodydiode.xml (2.7 KB)
C3M0025065L.xml (6.8 KB)
test2.plecs (197.0 KB)