Hello, Siddartha!

The low frequency ripples are caused by input bridge rectifier that rectify sin wave from the line into two positive "semi-wave" voltages during one period, i.e. we have rectified voltages with frequency two times more than the line one. The high frequency ripples are provided by voltage source inverter operating in switching frequency. Research Gate has a number work in the field you're interested in. Some of it are in the attach.

Best wishes and good luck!

Conference Paper Analytical method to calculate the DC link current stress in...

Hello Alexander,

Thanks for the reply. You mentioned about some attachments. I am not able to view any. Can you please send the files. I want to calculate the low frequency ripple for the capacitor selection.

Hello, Siddartha!

Actually, my answer has two attachments. I can paste links to it.

https://www.google.ru/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwj92aTmlJPLAhUlLZoKHcpZCAkQFggbMAA&url=https%3A%2F%2Fwww.researchgate.net%2Ffile.PostFileLoader.html%3Fid%3D567d04f06307d957588b4594%26assetKey%3DAS%253A310472581025792%25401451033840072&usg=AFQjCNG1JtU0PfuJS7Wi150XJSN4afUpjw&sig2=1w926S6UNqMWM7r2bxFwPg&bvm=bv.115277099,d.bGs

https://www.researchgate.net/publication/273796109_Analytical_method_to_calculate_the_DC_link_current_stress_in_voltage_source_converters

I hope it would be useful for you. 

Conference Paper Analytical method to calculate the DC link current stress in...

Hello, Alexander!

Thank you very much for the link. They were very helpful.