# How to select high frequency rectifier capacitor?

Can I use aluminium electrolytic capacitor after a full bridge rectifier?

My operation frequency is 200 kHz with output voltage of 100 V.

Based on this paper: "Analysis and Design of Load-Independent Output Current or Output Voltage of a Three-Coil Wireless Power Transfer System", the author has used 940 micro farad output capacitor, which is confusing for me also.

Based on the specifications of the following paper I = 4 A, F = 200 Khz, by assuming Vpp = 1V and using the formula C = I / 2 x f x Vpp, I get C = 10 µF

Please correct me I have miscalculated.

However my calculation is pretty different as can been seen from the value shown in the mentioned paper. Since this paper is IEEE transaction paper I have decided to trust it and use 940 uF capacitor after full bridge rectifier.

As far as I know film capacitor have very good performance in high frequency application however a big size of DC film capactitor (940 uF) is very costly.

Can I use an electrolytic capacitor instead?

I believe aluminium electrolytic capacitors vary significantly with increasing frequency. I have confusion in selection of polarized filter capacitor.

What other type of capacitor is suitable?

• Show us your calculation. It sounds like you're off by several orders of magnitude. Or are you really drawing hundreds of amps through this circuit? Apr 4, 2019 at 12:52
• The capacitance needed is related to the current. What current do you need? Apr 4, 2019 at 12:58
• I estimate he's got an output current of circa 400 amps and this does sound extremely far-fetched. Apr 4, 2019 at 12:59
• Can you show your circuit or block diagram? Is this proposed capacitor an input filter or an output filter? Apr 4, 2019 at 13:59
• There is an exellent tool on this site to draw your schematic. Use it so we can see what your trying to do. Also how did you calculate capacitor value? Apr 4, 2019 at 14:43