Optimisation of DC-link capacitors

DC-link capacitors in variable speed drives are used for decoupling the energy source from the output side inverter. Traditionally aluminium electrolytic capacitors are used in the dc-link. New developments of film capacitors however make it possible to use capacitor which are based on this technology too. The economic use of film capacitors implies reduced capacity values and therefore increased ripple voltage. In the paper the parameters which influence voltage ripple in the dc-link of an inverter are analysed.