Hi, I have a problem with the selection of voltage stabilizing capacitors, I am a bit lost in the patterns found on the internet and I can not find the right way to calculate this.
Here are all the system parameters:
Switching frequency 4kHz
Maximum voltage 65V
Minimum voltage 0V
Maximum current 25A
The ripple voltage I would like to be max 0.2V
I would like to select capacitance capacitors for 100V in uF.
Important thing is the long life of the capacitors so the calculated value would have to be increased but I do not know how mutch. Capacitors will work 12-15 hours a day for over 5 years and in this time the circiut must work good.
I am worried that in the catalog cards the capacitors ripple current is quite low value for example 2A for 1000uF so I would have to use many such capacitors. Those values in the datasheet are for completely different working parameters than mine, I`m confused.
Anyone know any formula to calculate this, maybe some example?
For finding caps spec'ed for high ripple current, you can filter by that in digikey catalog... I just spent about 2 minutes to get a list of 1500 aluminum electrolytic caps with capacitance between 1000uF and 100000uF and rated for >100V and spec'ed for >25A "high frequency" ripple current.....
For example im looking at SAMWHA HC2A478M35040HA its 4700uF; 100VDC; Ø35x40mm this capacitor has a maximum value of ripple current 5,8A at 120Hz and 85 degrees. So I need to use 5 of them? Maybe more because these values are maximum and i want long life for capacitors.
Input voltage is 60V on average but can vary 50-70V, load is resistive, constant. The source of the voltage is constant and neutral, these are photovoltaic panels. If I use capacitors then I have to add coils to balance the circuit? I remember something like that happening in alternating currents, but is it in a constant current too? When I checked with oscilloscope, circuit 10A and with one 1000uF capacitor, the voltage was constant, the capacitor had a temperature of about 35 degrees and the whole circuit worked very well.
The source gives 60V DC, it is neutral. The load is resistive, resistor. The current in the system will be in the range 0-50A. The switching frequency of the mosfet is 4kHz. There are no significant parameters for the resistor, but it is important that the ripple voltage for photovoltaic panels does not exceed 0.2V. So the capacitors must be so chosen that their lifespan is as long as possible.
In my experience, the 1000uF capacitor can handle 10A currents, but it gets a little warm, I do not know how long it lasts. I saw a professional solution and there were two capacitors 2200uF and one coil for current up to 30A. How to find the capacitors for me and if I need a coil if it's a DC circuit?