Electronic – High current, low voltage capacitors

bridge-rectifiercapacitorhigh-current

I'm putting together a high current (200A+), low voltage (<5v) rectifier circuit.

I have sufficient bridge rectifiers, but to smooth out the waveform I need a strong enough capacitor bank. Besides opting for capacitors rated at a voltage of 10vdc (double the 5v just to be safe), what other stats or capacitor specs should I be looking for? Just get three one with the highest max operating temperature? The AC wave will be 50hz.

Best Answer

First make a rough spec for ripple from C and ESR.

For \$C=I_C*dt/dV\$
with Vc=5V and let ripple=5% or dV=250mV(pp) and dt= 10ms ( 100Hz) with Ic=200A

\$C=200A*10ms/250V=8mF\$
let dV=2% 100mV from cap
ESR=V/ESR=0.1V/200A=500 μΩ

For a total ripple of 250mV+100mV=350mVpp

ESR*C=T= 500 μΩ * 8mF = 4 μs

Now check Electric Double Layer Capacitors (EDLC), Supercapacitors specs. anything close rated for >5V

enter image description here 8.2uF 50mΩ TOO HIGH by 100x even at $16

Now you know this concept is going to be more expensive than a 1kW PC SMPS PSU.

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