TIDM-02010: TMS320F2800137_motor_2_Software_issue

Babaji Nemnar

Part Number: TIDM-02010

Dear Sir,

as we have run motor2.

in that following point how to change.

if i have change speedRef_Hz then speed_Hz change as per value enter but i measure actual speed is different so what is relation please guide ??

please see below my observation:

speedRef_Hz=50.0 ,speed_Hz=50.0750465 but actual speed of motor is 750 RPM (as per tachometer reading)

so guide in which/where is relation between speed_Hz & RPM ??

Please motorVars[1].speed_Hz parameter

over 1 year ago

0 Jiaxin Teng over 1 year ago

TI__Expert 5050 points

Hi Babaji,

What is the pole pairs of the test motor? The relationship between rpm and Hz follows the formula n=60f/p. From the screenshot, the motor speed follows the speedRef_Hz well and looks normal.

Thanks,

Jiaxin

0 Babaji Nemnar over 1 year ago in reply to Jiaxin Teng

Intellectual 335 points

Thank you.

Which c file(source) this formula is mention in software.

0 Jiaxin Teng over 1 year ago in reply to Babaji Nemnar

TI__Expert 5050 points

Hi,

This is general formula to get the synchronous speed of AC motor from frequency.

Thanks,

Jiaxin

0 Babaji Nemnar over 1 year ago in reply to Jiaxin Teng

Intellectual 335 points

Jiaxin Teng said:
This is general formula to get the synchronous speed of AC motor from frequency.

But this is where to mention in software

0 Jiaxin Teng over 1 year ago in reply to Babaji Nemnar

TI__Expert 5050 points

Hi Babaji,

You set the desired frequency reference through software and measured the speed in rpm through tachometer. According to the synchronous motor principle, the motor's rpm is: n (rpm) = 60*frequency/pole pairs. In your case, when you run the motor at 50 Hz, and if the motor has pole pairs equal to 4, then you have the motor running in n=60*50/4=750rpm, which is the same as the tachometer reading.

This equation is not in the software. The motor speed command is given by frequency reference and you need to convert the desired speed in rpm into frequency.

Thanks,

Jiaxin

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TIDM-02010: TMS320F2800137_motor_2_Software_issue