MSP430F67661A: It possible to measure phase to phase voltage in the MSP430F67661A.

Hi, Praveen

1. Use a voltage transformer to convert high voltage into low voltage signal.

2. Use a differential arithmetic amplifier circuit to convert the two-phase voltage to a single-ended voltage

3. Use a level lift circuit to convert the voltage to positive voltage and input to MSP430.

3. Thank you for your comments, David Schultz. Please refer to https://www.ti.com/lit/an/slaa577g/slaa577g.pdf, you can directly input the small voltage to F6766's ΣΔADC.

Make sure that final voltage is within MSP430's ADC input range:0 ~ AVCC.

Thanks.

This conflicts with the information I see in section 3.2 of slaa577. Which is mostly an RC network to reduce the input voltage. It states that the input range of the ADC extends to -1V. Which matches the AVss-1 range shown in the data sheet.

That network ties the neutral of a Wye connection to AVss. Not the safest thing and only works if you want to measure each phase voltage with respect to neutral. But of course you can then calculate the phase to phase voltage.

If it is desired to directly measure phase to phase voltage and for more than one phase then you need to design an input network that does two things: 1) reduce the voltage range. 2) Control the common mode voltage.

3) Be safe.

This is the sort of design problem you pay an EE to do.

Hi David Schultz,

Thank you for your reply.

Currently, I am implementing the TI reference design TIDA-00454. However, I am unable to locate the details for Phase to Phase measurements in the reference document.

1. Is it possible to measure Phase to Phase in the TIDA-00454 reference design? If so, how can I achieve this? Do I need to make modifications in the firmware or perform any circuit modifications?

Hi, Praveen

For TIDA-00454, It measures Y network voltage:

Every J11 or J12 or J13 measures the voltage difference between the center of Y (is AGND as reference in schematic) and the one line.

If you want to measure phase to phase voltage, you need to convert Y network measure result to △ network result:

In △ network, results are phase-to-phase voltage.

Regards,

Helic

Dear Helic, 

Thanks for your response, 

How do I want to convert the Y network to △ network, Because using TIDA-00454, I am just going to measure the voltages?

Do I want to make changes in hardware or firmware? 

Hi, Praveen

I think you should try find some information on how to convert Y network result to △ network result.

And implement this part of the conversion function in the MCU firmware.

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If this doesn't work, you need to consider modify hardware of this part:

Regards,

Helic

Hi Helic Chi, 

Thanks for your reply,

Is it possible to do it in TIDA-00454 firmware? Is there any library for phase-to-phase measurement? 

Then what kind of modification, do I want to carry down on the circuit?