3 vs 2 phase current sensing

I originally planned to use 3 in line current Sensors for my project, but now in the PCB layout i can’t get the layout quite right with 3 sensors, so i just want to use 2 sensors on U and W phase.

As far as I understand the MCU (esp32 in my case) just calculates the missing current from V phase from the two other currents.
Are there any shortcomings to this, that I’m missing.

As always thanks for the help.

From pure systems control point of view, your current estimation error is increased because you calculate the third phase from the combination of the the two, it’s a simple calculation. If you could live with that, no other drawbacks. You could even do this from one phase, but then the error is quite high.

Edit: This is where Kalman filtering could come in handy, because that’s exactly why the filter was designed. I’m not sure however how much work it would take. 2D or 3D Kalman should be fairly straightforward, I think. This is such a mature field, there are numerous papers on that subject.

Hey Franz,

For inline sensing this can work, but I don’t think it would work well for low-side sensing.

Note: We don’t support it yet in the library, but it is also possible to do low-side sensing with a single shunt on all three phases…


Just going to use 2 or 3 phase inline sensing, depending on what i can fit on my board.