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Old 05-12-2010, 12:56 PM   #3393 (permalink)
MPaulHolmes
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Maybe something like these bad bad bad boys:
I wish I had the money to use these instead...
The panasonic ts-ed caps should last quite a few years though, since they don't get too hot.

The ESR (equivalent series resistance) creates heat inside the cap while current is rushing in and out. Heat is bad. Those bad boys from above have an equivalent series resistance of 4 mOhms, which is really really really low. The panasonic ones have an ESR of like 250mOhm I think.

The ripple current rating is basically how much current can rush in and out of the cap without it overheating. The bad bad bad boys above can take a very large amount of ripple current each, so like 10 or 20 in parallel would have an extremely high ripple rating. (like 500 amps or something) You only need like around 5% of the max current for ripple rating, so they say. 50% is the worst case scenario.


Quote:
Originally Posted by bigh View Post
Hey Everyone,
I don't have the logic side done as yet, i'm waiting on the next incarnation that will include CAN, but i've got a need to order some parts for my ebike from Digikey, and I figgured I may as well order the powerside capacitors at the same time.

I need some help with Capacitor selection. I've got 4x Powerex CM400DU-12F Modules which i'm going to be using for the build. I have a target voltage of 288v+, which will require 400v+ caps.

adamj12b has said he's using Panasonic TS-ED caps. 6 for each IGBT, 560uF each 400V.
(The Australian Electric Vehicle Asn: IGBT Group buy for open source controllers)

But before I purchase the same caps, I'd like to understand how we select apropriate capacitors. The Soliton1 advertises that it has: "Cutting edge capacitor: State of the art ultra low loss 600V film capacitor. No electrolytics to dry out and fail!"

What kind of film capacitor would they be talking about - I checked wikipedia, and there is a plethora of film caps.

I asked on AEVA what properties I should look for in higher voltage caps, and MCUDogs gave the response: "It's the cap properties, ESR, ripple current and temperature. "

Now i'm asking why these properties?

I'm assuming we want a cap that will operate in high temp environments.


on a side note, I'm going to look at a donor car tonight... oh the excitement (1992 Toyota MR2)!

Thanks,
Haydon
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