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LadyN

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Joined: 26/01/2019
Location: United States
Posts: 408

Posted: 08:37pm 28 Jan 2019

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Anyone here worked on Kalman filtering on, say, an Arduino?
I am thinking of starting up with ACS712 Current sensor and hoping to handle noise using Kalman filtering

zaphod

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Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 07:03am 29 Jan 2019

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I have experience of that particular sensor, I don't know what your application is but I used it in a 1Kw switching converter and found it VERY sensitive to external magnetic fields, in the end I replaced it with a LEM that IMOP is a much better device although more expensive and I don't have to filter the LEM at all even though it's in exactly the same situation.

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

LadyN

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Location: United States
Posts: 408

Posted: 10:44pm 29 Jan 2019

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zaphod said I have experience of that particular sensor, I don't know what your application is but I used it in a 1Kw switching converter and found it VERY sensitive to external magnetic fields

OK, do you have the noisy measurements?

What kind of errors/variance were you getting?

zaphod said in the end I replaced it with a LEM that IMOP is a much better device although more expensive and I don't have to filter the LEM at all even though it's in exactly the same situation.

Do you have a link to look at?

zaphod

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Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 11:26am 30 Jan 2019

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Its not a matter of accuracy, it's the sensitivity to noise that I could not filter due to the bandwidth requirements of the design.

The LEM devices are here https://www.lem.com/en/product-list?measurement=52 I happen to use the HLSR series but there are many to choose from.

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

LadyN

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Joined: 26/01/2019
Location: United States
Posts: 408

Posted: 02:37am 31 Jan 2019

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zaphod said Its not a matter of accuracy, it's the sensitivity to noise that I could not filter due to the bandwidth requirements of the design.

I have a LOT to learn, so can you explain this as I don't understand how inability to filter due relates to the bandwidth requirements.

It may happen that your explanation might be a whole book, but in that case can you condense it down to an example and I will try and learn any formula and equations you use in that example.

zaphod said
The LEM devices are here https://www.lem.com/en/product-list?measurement=52 I happen to use the HLSR series but there are many to choose from.

Would it be fair to say that their products, eg: https://www.lem.com/en/ho-200pw0400

Is a PSU and uC wrapped around a sensor like: https://www.aliexpress.com/item/1pcs-lot-free-shipping-LA25-NP-LA35-NP-LA55-P-SP2-LA55-P-HTB100-TP-SP3/32964307267.html

?

Thank you again. VERY MUCH

zaphod

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Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 07:07am 31 Jan 2019

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LadyN said I have a LOT to learn, so can you explain this as I don't understand how inability to filter due relates to the bandwidth requirements.

It may happen that your explanation might be a whole book, but in that case can you condense it down to an example and I will try and learn any formula and equations you use in that example.

The bandwidth required is about 100 times 50hZ in this particular application to ensure accurate reproduction of a 50hZ sine without generating excessive harmonic distortion, any post sensor filter introduces phase lag that is difficult to compensate elsewhere and so it's simply better to eliminate these problems at source (use a better sensor). But if your application is not sensitive to these issues then try a cheap sensor and post filter :)

LadyN said Would it be fair to say that their products, eg: https://www.lem.com/en/ho-200pw0400

Is a PSU and uC wrapped around a sensor like: https://www.aliexpress.com/item/1pcs-lot-free-shipping-LA25-NP-LA35-NP-LA55-P-SP2-LA55-P-HTB100-TP-SP3/32964307267.html

?

Thank you again. VERY MUCH

I have no idea, there is no product information nor specification on that site, I don't use ali express as it tends to be grey market.

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

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