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Im recommended to install a 10000uF Aluminium Electrolytic capacitor for a 72 DC-link of an inverter for regenerative purpose. When it comes to details, one manufacturer mentions "inverter" in applications the other mentions general industrial electronics.

Is there any significant difference between these two capacitors.

Cap 1 Cap 2

Since it is based on marketing I couldn't find a way to justify one capacitor or the other.

Which parameters should I check for such application?

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There doesn't appear to be much difference in the headline specifications. They have the same capacitance, voltage, size, rated ripple current and tolerance.

However, there's a big difference in price, which might reflect quality.

Digging a bit deeper, one claims 2000h lifetime at 85C lifetime, the other 12000h. Interestingly it's the cheaper one claims the longer life. As far as I can see, they both use the same criteria for 'end of useful life', which is 55% of initial C remaining and ESR < 3 times initial.

Looking at the ESR, the cheaper one is also much lower, 9mohm versus 21mohm. Given that they are rated for the same ripple current, this means the cheaper one will run a little cooler, which might explain the lifetime difference estimate. Temperature rise due to high ripple current in the capacitor's ESR is a major thing to consider in DC link applications.

So it looks like the cheaper one has the better specs. Unless you know something about the quality of the two manufacturers from experience, you've no reason to pick the more expensive one.

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  • \$\begingroup\$ I see. They are about same IRipple (100Hz, 85°C): TDK: 10A / Vishay: 10.5A but I use it in an inverter, thus I should also consider high frequency ripple current capability: (10kHz, 85°C): TDK = 10A x 1.3 = 13A / Vishay = 10.5A x 1.15 = 12.1A. I dont know where that price difference come from. \$\endgroup\$ – atmnt Dec 19 '18 at 15:14
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Looking at the datasheet of the two capacitors they seem quite similar and none is drastically different from the other with the main difference being the manufacturer, Vishay vs TDK.

Important parameters to look for in capacitors for these applications, apart from capacitance and voltage rating, is ESR, ripple current and temperature rating.

Equivalent Series Resistance (ESR)
ESR is a parasitic resistance that appears as in series with the capacitor. At high currents this will result in self heating of the capacitor and as a limiter of current that can flow in or out from the capacitor. You want to keep this as low as possible.

Ripple current This is denoted as Iac and Ir in the datasheets, the lack of standardization of some of these parameter names is sometimes a bit confusing. This parameter tells a recommended maximum continious AC current at a specified frequency that the capacitor can handle. Bigger ripple current is better if you intend to frequently charge and discharge the capacitor.

Temperature rating Electrolytic capacitors is usually filled with a wet electrolyte and if this starts to dry or leak the capacitor will rapidly degrade. The ability to withstand higher temperatures usually indicates a longer lifespan of the capacitor. Looking at datasheets you usually will find graphs of expected lifetime in different temperatures. Also, here again the ESR comes into play, as even if the capacitor is situated in a not so warm environment the, the power lost due to the ESR will heat the capacitor from the inside and potentially rise the temperature and reduce the lifetime of the capacitor. The ESR also increases with age and hence creates a runaway scenario where the ESR increases as a effect of aging and the higher ESR increases temperature and thus gives a more rapid aging of the capacitor.

Frequency dependence ESR and ripple current recommendations varies with frequency and at the bottom of both data sheets you will find some data about this, more in one and less in the other. With these tables a comparison of behavior at a specific frequency can be done, but as the same set of data is not present in both data sheets this can get a bit speculative.

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  • \$\begingroup\$ I see. They are about same IRipple (100Hz, 85°C): TDK: 10A / Vishay: 10.5A but I use it in an inverter, thus I should also consider high frequency ripple current capability: (10kHz, 85°C): TDK = 10A x 1.3 = 13A / Vishay = 10.5A x 1.15 = 12.1A. I dont know where that price difference come from. \$\endgroup\$ – atmnt Dec 19 '18 at 15:14
  • \$\begingroup\$ If you scroll down in the data sheets you will find graphs and tables of how the ripple current and ESR varies with frequency. \$\endgroup\$ – RobinSt Dec 19 '18 at 18:14

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