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To find efficiency of inverter with constant dc input voltage and resistive load

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V Vaishnavi Kumar
V Vaishnavi Kumar on 22 Jun 2013
Answered: Joel Van Sickel on 11 Dec 2020
the input dc current to the inverter is pulsating with ripples, so iuse mean block to measure averaged dc i/p current. the average time is 0.02 seconds as the output frequency is 50 Hz.
Im using unipolar sinusoidal pulse width modulation (PWM) for switching, and getting nearly sinusoidal output.
I use rms block with fundamental frequency 50Hz to measure voltage across and current through resistor.
But he measured input power by multiplying dc voltage and averaged input current is different for different simulation times, the same occurs with output power,
What should be the simulation time, and what are the setting tio be done in the model to find correct efficiency
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Rakesh Patel
Rakesh Patel on 2 Jul 2013
What is switching frequency, solver and its type. In-case of fixed step solver, what is fix step size?

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Answers (1)

Joel Van Sickel
Joel Van Sickel on 11 Dec 2020
Instead of trying to set up those blocks properly, you can measure instaneous power (V*I) and integrate it over a period of time, then divide by that period of time to get the average power. Do this for the exact same period on the output, and you can compare results. This will not be accurate if the time period is to small (as some energy may stored in the converter) but will work if you make sure to allow a number of cycles to be included in the period. Ideally, the time measurement will also be a multiple of your fundamental frequency. 1 second of simulation would be nice for a 50Hz system, but you could start with 10 cycles to get a pretty good estimate.

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