Measuring 400A non invasively....and with high bandwidth......inverter drive

[zenerbjt]

Dear Engineers,

We are using 10Kw BLDCs fed by 3 phase inverters. We wish to scope the current waveform in the battery supply cables to the inverter. We have selected the MLX91209 current sensor since it gives a non-invasive solution, and our current peaks will be some 400A. One must simply mount it into a gap in a ring torroid, and then run the conductor through that same torroid. The MLX91209 then gives a voltage output proportional to the current. It has the same bandwidth as a current sense transformer, near enough.

https://www.melexis.com/en/product/MLX91209/250kHz-Programmable-Hall-Effect-Current-Sensor

However, the Melexis website doesn’t tell how we can get hold of the SUPRA 50 SP ferromagnetic cores for this useage.

Do you know how much these cost? We don’t yet have a reply from MagLab, the named manufacturer.
www.maglab.ch

 

[Visitor]

A new account?

 

[KeepItSimpleStupid]

Here's the datasheet: https://www.maglab.ch/wp-content/uploads/2017/09/Supra50_SP510_Eng_maglabV11.pdf

i forget the company I used to get cores from. They had a good selection and you could buy one if needed. You might have to match the alloy to the composition.

I was working on making a variable inductor that could be controlled with current from another winding.

Melexis devices usually requires a programmer which is expensive

 

[rjenkinsgb]

If it's purely for testing rather than to be built in, you can use an off-the-shelf clip-on and fully calibrated, isolated & cased current probe.

We have one of these for monitoring drives & motors:
**broken link removed**

 

[ChrisP58]

Here is a presorted list of possible ready made sensors.
400 Amp hall effect sensors at DigiKey

 

[zenerbjt]

Here is a presorted list of possible ready made sensors.
400 Amp hall effect sensors at DigiKey

Thanks, as such...
This hall sensor looks good for us…and cheap….

L03S Hall current measurers:
https://www.tamuracorp.com/electronics/jp/pdf/2015/06_L03SxxxD15_e.pdf

…however, it only gives an accurate result if the conductor being measured completely fills the aperture, which is 20mm by 10mm. It doesn’t say what kind of accuracy you’ll get with only a certain percentage of aperture fill factor...

{The TA167 current clamp measurer, as kindly linked by rjenkinsgb doesnt appear to have any such "aperture fill factor discrepancy"
**broken link removed**
)

Also, this device will need a micro to be added so that the "zero current" reading can be calibrated?..(.since there is no inbuilt degaussing facility)

Presumably since we only want DC measurements, we don’t have to give it a +/-15V supply, and can just make do with +15vdc supply, then just be sure we put the cable through the aperture in the right way round?

 

[ronsimpson]

Presumably since we only want DC measurements, we don’t have to give it a +/-15V supply, and can just make do with +15vdc supply

+/- 15V +/-5%

0 and 15V does not equal +15, 0V, -15V. I think you need to try it first.