topic Problem While reading AC current using Shunt Type with SADC in Kinetis Microcontrollers

Problem While reading AC current using Shunt Type with SADC

avinashbhavsar — Tue, 16 Oct 2018 09:32:40 GMT

I am working on Energy Meter Micrcontroller IC #MKM34Z256VLQ7

Now I am stuck while reading current parameter from SADC 24 bit and getting SADC count with more variation and not seen any repetition while testing with 0 to 500mv

I have tested rang of 0 to 500mV voltage by applying DC volt and its working well with this with no variation .

But variation occur with the AC voltage given to circuit .

Please help if some have any idea about this .

Hardware reference DRM122.

Re: Problem While reading AC current using Shunt Type with SADC

kerryzhou — Wed, 17 Oct 2018 06:14:00 GMT

Hi Avinash Bhavsar,

You said the DC volt works OK, but the AC volt can't work.

Do you use the oscilloscope to test the AC wave? Test the wave between GNDA to LINE_OUT, and GNDA to LINE_IN, and LINE_IN to LINE_OUT.

You need to make sure the input AC wave is clean, don't have too many noise.

You can test the wave, and also share me your AC wave.

Besides, how do you connect your AC gnd to this KM32 board? From my own experience, the ground signal is also very important.

Have a great day,
Kerry

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Re: Problem While reading AC current using Shunt Type with SADC

avinashbhavsar — Fri, 19 Oct 2018 05:04:44 GMT

Hey Kerry thank you for your reply ,

I am getting some problem when I used to connect the AC signal to my oscilloscope, Instate of that I used the hardware which is given in reference document DRM122, I also attach same copy with above question .

AC gnd to this KM32 board I have attach as like the phase .

Do you have any other way to get this SADC data ?

Thank you .

Avinash Bhavsar

Re: Problem While reading AC current using Shunt Type with SADC

kerryzhou — Mon, 22 Oct 2018 07:17:43 GMT

Hi Avinash Bhavsar,

What's the problem when you connect the AC signal to your oscilloscope?

If the AC voltage is very high to ground, it's better don't connect your oscilloscope power GND, then you can test the AC signal.

Have a great day,
Kerry

Re: Problem While reading AC current using Shunt Type with SADC

avinashbhavsar — Wed, 26 Dec 2018 05:03:57 GMT

Hi kerry Zhou ,

Happy to tell you that Problem is sloved , Hardware is completely ok ,There is problem is AFE driver side .

Thank you .

Avinash .

Re: Problem While reading AC current using Shunt Type with SADC

kerryzhou — Thu, 27 Dec 2018 03:08:32 GMT

Hi Avinash,

Congratulations to you! :smileyhappy:

If have the new question in the future, welcome to create the new question post!

Have a great day,
Kerry