Non-invasive, high bandwidth high (400A) current measurement?

Dear Engineers,

We are using 10Kw BLDCs fed by 3 phase inverters. We wish to scope the current waveform in the battery supply cable to the inverter. We have selected the MLX91209 current sensor since it gives a non-invasive solution, and our current peaks will be up to some 400A. One must simply mount the MLX91209 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

Is this a multi-unit, cost sensitive project?
Otherwise use an off the shelf LEM current transducer:

zenerbjt said:

battery supply cable to the inverter.
...
current peaks will be up to some 400A.

Click to expand...

Consider using an ammeter which is similar to a compass. It's non-invasive.

A store-bought unit used to be available at JC Whitney (mail order auto parts). The needle is plastic with a tiny magnet attached. Lay it across a wire and it responds to heavy current. There are two positions to place a wire and two sets of scale markings (one for starter current, one for alternator current). Maximum reading is
600 Amps.

Highest accuracy and bandwidth will be achieved with closed loop hall effect sensor.s They have an op amp that provides feedback to a coil to cancel out most of the core field. This keeps the linearity very good by reducing core flux to minimum. The op amp requires + and - supplies, usually 12-15vdc. Bandwidths are up to 300 KHz.

I've used units from F.W. Bell and Tamura.

Hi,

zenerbjt said:

We wish to scope the current waveform in the battery supply cable to the inverter.

Click to expand...

The inverter should have a capacitor built in ...or a more complex filter, thus the current in the cable should not contain high frequencies.

Battery means DC... I don't recommend a ferrite core measurement without flux_compensation method.

Klaus