Am planning to design a buck converter to charge some 3000F ultracapacitor at 40A. This is the datasheet for the ultracapacitor. https://www.electro-tech-online.com/custompdfs/2013/07/datasheet_k2_series_1015370.pdf . I got 30 of them which will result in a equivalent capacitance of 100F at 75V with a total esr of 8.7mohms(which is very low) . Am planning to use it in a electric car application. These ultracapacitor when charged using a battery or some other source it will act as a short circuit across its charging source. so to charge these capacitors I should develop a buck converter circuit in which its output voltage will vary from 1 to 75V. The reason for variable output voltage is that when the capacitor voltage is at 0V i would charge this capacitor at 1V.
R=V/I ; 1/40 =0.025
To have 40A of charging current the equivalent series resistance of the capacitor must be 0.025ohm . hence i will add a resistor of (0.025-0.0087=0.0163) 16.3mohm in series to the capacitor to allow only a maximum current flow of 40A.
My confusion why there are not many designs of buck converter with variable output voltage, what are the drawbacks in designing such a variable output voltage buck converter.Can it be designed??. I just wanted this charging circuit to be as efficient as possible with very little power stage during transfer cost of the circuit is not a concern since the circuit is designed mostly for very high effiiciency.
Kindly suggest me if there are other ways to charge in a more efficient way
thank you in advance.
R=V/I ; 1/40 =0.025
To have 40A of charging current the equivalent series resistance of the capacitor must be 0.025ohm . hence i will add a resistor of (0.025-0.0087=0.0163) 16.3mohm in series to the capacitor to allow only a maximum current flow of 40A.
My confusion why there are not many designs of buck converter with variable output voltage, what are the drawbacks in designing such a variable output voltage buck converter.Can it be designed??. I just wanted this charging circuit to be as efficient as possible with very little power stage during transfer cost of the circuit is not a concern since the circuit is designed mostly for very high effiiciency.
Kindly suggest me if there are other ways to charge in a more efficient way
thank you in advance.