PGA411Q1EVM: pga411-EVM

DEEPAK VERMA68

Part Number: PGA411Q1EVM

I am using PGA411Q1-EVM board . The data is coming like this for a 8 pole PMSM machine which is not correct. Please see the sampling strategy and see if i have made some mistake.

Scope output :

Red -DAC of PGA411 (AOUT pin)

Green- Mechanical out(output after the first "12bit "gain block)

Yellow- Electrical out

Unlike the red signal the green signal is coming with ripple ( its a 12 bit dac output using my dsp -DAC interface)

What is the problem?

over 6 years ago

0 Sharath Vallamkonda over 6 years ago

TI__Expert 3435 points

Hi Deepak,

Thank you for reaching out. Can you provide more details about the setup? Please provide more details about the Green signal. I am refering to the input for the 12 bit gain block etc. I am out of office until 1st sep, so please expect my next response after that.

Thank you

Sharath.

0 DEEPAK VERMA68 over 5 years ago in reply to Sharath Vallamkonda

Intellectual 410 points

PGA411 (resolver to digital converter) gives 12 bit out that is being sensed through GPIO pins and converted into POSITION value in the range of 0 to 2*pi, this GREEN signal is that value output through my external DAC(PMOD DA4), but unlike the 10 bit DAC inside of the PGA411 board the signal is coming pulsed, that's the problem. It should be like the orange waveform. The magnitude of the peak sawtooth can be different depending on the DAC output but frequency should be same and the ramp should be smooth not with some pulsed waveform

0 Sharath Vallamkonda over 5 years ago in reply to DEEPAK VERMA68

TI__Expert 3435 points

Hi Deepak,

I can understand now. looks like you are referring to ORD pins. Based on the graph, it looks like one or more ORD pins are not being connected properly.

Can you probe all these pins one by one to make sure all of them are toggling according to the rotation of the motor?

Regards

Sharath

0 DEEPAK VERMA68 over 5 years ago in reply to Sharath Vallamkonda

Intellectual 410 points

Sure i ll do and let u know soon.

0 DEEPAK VERMA68 over 5 years ago in reply to DEEPAK VERMA68

Intellectual 410 points

Dear Sharath

I have checked the ord pins they r toggling as per angle out. But still, I am not getting proper waveforms.

Please see if there is some setting for PGA411 -EVM Module.

Yellow is the mechanical angle

Green is the electrical (8 Pole machine )

Rest sampling and all is done as same in the previous posts ( Refer above).

0 Sharath Vallamkonda over 5 years ago in reply to DEEPAK VERMA68

TI__Expert 3435 points

Hi Deepak,

If the ORD signals are switching as per the rotation, then the PGA411 setup has no issues. You might need to debug the external DAC that you are using.

You can monitor what actually is happening at the sudden jump on the signal. May be you can rotate the motor manually and see what exactly happening at the jump to debug it.

Regards

sharath.

0 DEEPAK VERMA68 over 5 years ago in reply to Sharath Vallamkonda

Intellectual 410 points

Thank you all

It was the faulty GPIO pin that was omitting one bit (ORD 8) hence there was that ripple.

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PGA411Q1EVM: pga411-EVM