About Inverter DC capacitor selection
In this paper, we will discuss how to go about choosing a capacitor technology (film or electrolytic) and several of the capacitor parameters, such as nominal capacitance, rated ripple current, and temperature, for power inverter applications of a few hundred watts and up.
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About Inverter DC capacitor selection video introduction
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6 FAQs about [Inverter DC capacitor selection]
Which capacitors are used in inverter applications?
A general approach for ripple current characterization is provided. Based on these characteristics, the two capacitor types suitable for this purpose, the electrolytic and film capacitors, used in inverter applications are reviewed. Capacitor power loss and voltage ripple calculation are provided for both types.
How to sizing capacitors for inverter bus link applications?
The first step in sizing capacitors for inverter bus link applications should be to understand how much bus link capacitance is required for a given inverter design. The biggest design limitation for electrolytic capacitors in inverter applications has been the amount of ripple current that the electrolytic capacitor can sustain.
Why does a DC link capacitor have a ripple current ICAP?
We may infer from Figure 2 that the DC link capacitor’s AC ripple current Icap arises from two main contributors: (1) the incoming current from the energy source and (2) the current drawn by the inverter. Capacitors cannot pass DC current; thus, DC current only flows from the source to the inverter, bypassing the capacitor.
How big should a DC link capacitor be?
With electric vehicles, inverters are typically optimized for two things - power density and efficiency. Thus, DC link should not be any larger than what the requirements call for. The objective of this article is to help you better understand the role of the DC link capacitor and how to properly size it based off your requirements.
What is a DC link capacitor?
The capacitor current will be 0.55-0.65 x the phase current for PM motors with these power factors. The second role of the DC Link capacitor is to smooth DC voltage fluctuations and “stiffen” the DC bus. This is important because any voltage ripple on the DC bus shows up as current ripple in the phase currents, and that leads to torque ripple.
How do I choose a DC-link capacitor?
Other considerations in choosing a DC-Link capacitor include knowing the DC voltage required at the rails, the expected life of the application, the maximum possible ripple current and frequency that the system will experience, and whether the generated ripple current is steady-state or intermittent.


