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TMS320F28069M: Instaspin Motion too high current problem

ismail polat1
Intellectual 265 points
Part Number: TMS320F28069M

Hi,

I'm using F28069M launchpad with custom board. My existing board is not including voltage sensors for back emf sensing. I'm measuring phase currents with lem current transformer(only measures AC) and these sensors connected to phase lines. My feedback source is an incremental encoder. I'm running Lab12b. I have adjusted the spintac gain value. Motor type:pmsm, Rs:1,55 ohm, rated current:2.6A, speed: 3000rpm, power:400W.

I applied these suggestions from these topics:

http://e2e.ti.com/support/microcontrollers/c2000/f/171/t/336283 

http://e2e.ti.com/support/microcontrollers/c2000/f/171/t/336283

Also I read this topic and related topics:

http://e2e.ti.com/support/microcontrollers/c2000/f/171/t/287319 

I'm spinning the motor but it takes too much current. When I applied 48V and 1A current limit from power supply, voltage is decreasing 19V-1A in ctrl offline state and 17V-1A in ctrl online state(speed ~100rpm). However this motor should works with around 150mA under 48V.

I tried change the current scale factor, spintac gain, adc read order, phase order etc. but nothing changed. I'm reading encoder and it looks like working and I'm not using FAST. My questions:

1. Why too much current?

2. Is current ADC data per unit or amps?

3. I can not exceed 150rpm under same conditions why?

4. What is proper way to use the Instaspin Motion for this situation?

Thanks in advance.

Edit: Sorry, I corrected motor type. It's not pmdc it's pmsm. :)

  • 0
    TI__Genius 17175 points
    I am in receipt of your question and hope to provide an answer within 24 hours

    Sean
  • 0 in reply to Sean Bigley
    Intellectual 265 points

    @ Did you find any solution?

  • 0 in reply to ismail polat1
    TI__Guru** 115420 points
    1. Use lab02b/c to identify the motor parameters first, set the identified parameters in user.h for the projects afterward.
    2. Use lab12a to identify the inertia of the motor, set them in user.h for lab12b.

    btw, you should make sure if the following items are set correctly.
    1. The wires of encoder and motor are connected in a correct sequence.
    2. The sign of current converted value is correct since you are using a customization board, not TI EVM board.
  • 0 in reply to Yanming Luo
    Intellectual 265 points
    @Yanming Luo Thanks for your reply. These labs are using FAST observer and FAST is not working without voltage sensors. I'm using motor data sheet values for user.h file. What should I do?
    I changed phase order but it did not solve my problem and motor didn't spin.
    Current value maybe wrong value but I'm not sure about causing from sign. Current value is amps or perunit?
  • 0 in reply to ismail polat1
    TI__Guru** 115420 points
    Both instaSPIN-FOC and instaSPIN-motion need three-phase voltage sampling value to implement motor control, and all control parameters will be converted to per-uint that include current and voltage. You have to change your h/w board to sample both three-phase current and voltage for instaSPIN implementation.
  • 0 in reply to Yanming Luo
    Intellectual 265 points
    AFAIK, voltage sensors are necessary for FAST estimator. However I don't use FAST's features in my project because I have got encoder and motor data sheet. Also, I read some topics that using Instaspin without voltage sensors in ti e2e forum.

    In addition to this, suppose I added the voltage sensors. But my current sensors are current transformer. My current sensor can't measure DC current. Is FAST estimator using DC current for some processes?
  • 0 in reply to ismail polat1
    TI__Guru** 115420 points

    1. Not right, both InstaSPIN-FOC and InstaSPIN-motion must have three-phase voltage sensing signals, not only a dc bus voltage value.
    2. Not used dc bus current, just three-phase current of the motor. Please make sure there is no sensing delay since you are using the current transformer that is not recommended for sensored/sensorless FOC of a motor.

    Btw, it seems like your h/w board can't support the instaSPIN-motion algorithm, you have to change the h/w design if you want to use instaSPIN-motion.