Converter bank capacitor

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Dear All,

              I am working on boost converter (380V/450W) and (350V/300W) and used the PIXls for the same.  For the 300W converter the value of the bank capacitor it has given as 470uF and for the 450W => 390uF.

               Can we have the design calculation sheet for the same from PIXLs. Also i am calculating the bank capacitor by using the formula

C = 5I/Vp*f, where I - rated current,  Vp - peak output of bridge rectifier anf f is the line frequency. After getting the values out of this formula, how much capacitance i should keep extra for the safe opration. kindly help, is the formula correct for the same. Kindly guide.

You can use the PIXls spreadsheet for HiperPFS Boost family and you'll get the value of CO (output capacitor) from there.

Your expression for output cap should contain the ripple voltage rather than the peak value... However, the Output cap is usually limited by the holdup time requirement and can be calculated from the following expression

CO = 2*PO*(T_HOLDUP) / (VO_TYPICAL^2 - VO_MINIMUM^2)

 

For the extra capacitance, tolerance of cap should be taken into account. And the capacitance of  aluminum cap varies a lot with temperature too. So you have to select the cap based on the tolerance and the cold temperature of your design.

 

Regards