10 Steps for Selecting The Right Film DC Link Capacitor

Ten Steps To Your Film DC Link Capacitor.

Step 1.  Specify your DC bus voltage

Step. 2 Determine the acceptable voltage ripple limit.

Normally the limits vary from 5-10%, however in some rectifier applications they could also be lower than 1% of the DC bus voltage. 

Step 3. Calculate the capacitance required to reach the Uripple level.

Step 4.Calculate the capacitance current

Step 5. Verifying Design Limits

Once the capacitor capacitance and capacitance currents have been identified, it is important to verify that the calculated capacitance is able to handle the calculated current. If not then increase the capacitance to match the current.

Step 6. Select the parts from the Databook.

Step 7. Thermal calculations

The thermal calculations and it's implication can be found in the PEC Application Notes and

Semikube Selection Guide from Semikron GmbH.

Step 8 Lifetime

The lifetime calculations and FIT rates would appear in later blogs however, the above mentioned links have sufficient information on this topic.

Step 9. Capacitance Characteristics

Do not forget to check the performance of the selected capacitor for your operating frequency.

Step 10.Mounting

This is the final but one of the most important steps in the selection process. Do it carefully.