I still don´t get what you mean with error tolerance...So, how we can calculate that efficiency with error tolerance.
For a graph you need a numper of measurement points.or a graph w.r.t output current.
For a DC input voltage you should calculate with AVERAGE input current.secondly, can we estimate the Iin as IL(avg) in case of boost converter or should it be different ?
You must not "estimate" the input current, you should "measure" the input current.how I can estimate the input current.
Hi,
now you use inductor current.... But you should use average_input_current.
I don´t see the circuit, so I can´t decide if using the inductor current makes sense at all.
--> use input current.
Why?
an inductor is a storage device. It can store energy. In general W = I * I * L / 2
But who says that ALL of the stored energy is given to the output with every pulse?
1)
Maybe the current travels from 760mA to 850mA and back.
Then the max. stored energy is 0.85A * 0.85mA * L / 2 and the min stored energy is 0.76A * 0.76mA * L / 2.. therefore the max "transmitted energy" is the difference of both energies.
And this energy has nothing to do with the average_current of the inductance.
2)
Now this difference energy maybe is not 100% fed to the output side... maybe during switching / or maybe during dead_time of an half bridge a part of the energy is stored BACK to the input side (capacitor).
If so, then this causes a short pulse of negative current flow in the input side. This current is increasing the RMS current, but decreasing the average current.
And with decreasing average current there will be decreasing input power.
***********
Again: measure
* input_average_current
* input_average_voltage
* output_average_current
* and output_average_voltage
...
calculate P_in and P_out and calculate efficiency.
Do this with a lot of different load_currents (= output_average_current) and draw your chart.
Klaus
It is difficult to measure average current when it is in the form of pulses. Here is a simple choke-input filter, which smooths the waveform of current drawn from the supply. This automatically creates an average reading for measuring.
When the supply is a battery or solar panel, this type of LC filter makes a lot of sense.
A capacitor becomes the power source for the On-Off circuit. To select L & C values, start small because you don't gain much by using overly high values.
may I ask about the efficiency of this example
thanks
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