How can we determine ESR of the capacitor and DCR of inductor theoretically in the design of buck converter, without using an LCR meter?
By calculating RMS current through L and C devices and their power dissipation at maximal input voltage. And then solve equation (Output Power)/(PowerDissipation+OutputPower)=GoalEfficiency
u can evaluate the real RMS And Maximal in put voltage in follow the formula
The ESR and DCR are mostly dependent on the package size of the component itself and thus determined entirely experimentally. They are usually on the datasheet and they are one of the deciding factors that goes into choosing the component that goes on the circuit board.
Theoretical design of an SMPS is not the greatest idea since they are so fragile. Theoretical design just doesn't take everything into account properly such as temperature, altitude, frequency, and so many other things.
As already mentioned if you have the components then you should be able to track down their datasheets. ESR is a very important parameter to consider when selecting a capacitor for a power supply. If you have not chosen yet I would go for a Tantalum capacitor. They are more expensive, but have lower ESRs.
1) Film capacitors here, their loss is very low but still heat up
ESR*Irms^2=power loss.
Some 0.1W/cm^2 largest section of the capacitor.
ESR = impedance*tan(delta)
At low frequency (500kHz), ESR may be proportional to the root of frequency. The values depend on construction: film material and metallising. Most of them are self-healing: they do not contain much metal.
The losses are so low that mainly calorimetric measurements are the solution.
I did make calorimeters, but another way could be to empty a capacitor and put a resistor inside to characterise the thermal resistance to ambient...
I did make such dummies for characterising transformer shapes.
put DK4141 inductors in google
2) Electrolytic capacitors:
tan(delta) about 10-20% for 100-120Hz, above 10kHz they rather behave as "resistors", see data sheets. The ESR increases with a factor 2-3 at the end of life.
3) Solid Tantalum electrolytes?
Tantalum has to be avoided if possible as it is a mineral which delivers money for fighting in Africa.
Manufacturers of aluminium electrolytic capacitors have the special series i.e. EXR of Hitano, for which they define ESR. I have checked it placing capacitor in the output of buck converter and measuring the current and the output ripple voltage. It was the best way to determine the ESR.
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