DesignSpark Electrical Logolinkedin
Menu Search
Ask a Question

A New Approach for DC-Link Capacitors

DC links circuits are everywhere.  Any time two AC (alternating current) systems with differing voltages and frequencies are connected, an intermediate DC (direct current) stage can be found. 

This AC/AC converter requires capacitors to store the energy that has been converted from AC into DC before it is then converted back into the new AC voltage. These capacitors must exhibit a number of key characteristics:

  • High voltage rating
  • Low dissipation
  • Low inductance

Traditionally this function has been fulfilled by electrolytic capacitors as a result of their high power density. However, more recently polypropylene film capacitors have found their way into DC-link applications in a number of industries including railroad, renewable energy and robotics.

Polypropylene film capacitors offer a number of advantages over electrolytic types:

  • High voltage capabilities
  • Low inductance
  • Low ESR and flat response up to 50 KHz
  • Wide operating temperature range
  • Improved reliability due to inherent self-healing properties
  • Long life expectancy and excellent mechanical stability

KEMET have introduced the C4AE polypropylene film series, a range of radial capacitors with 2 or 4 leads. This series features a metallised film within a rectangular plastic box which is filled with resin. They are ideal for an array of applications including DC filtering and energy storage.

Connector Geek is Dave in real life. With 29 years in the industry, Dave still likes talking about connectors almost as much as being a Dad to his two kids. He still loves Lego too...

9 Mar 2017, 11:06