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TMS320F28069M: Sensorless control performance in lab5

user5912823
Intellectual 440 points
Part Number: TMS320F28069M

I am using 28069M to implement the sensorless velocity control on my customized control board. Initially, I want to examine the sensorless control performance with example program lab5c, or lab5d, or lab5e provided by TI . I setup the proper parameters according to TI document, for example, in my hardware settings, some of the parameters below are set in user.h:

#define USER_IQ_FULL_SCALE_FREQ_Hz        (800.0)

USER_IQ_FULL_SCALE_VOLTAGE_V           (38.0)

USER_ADC_FULL_SCALE_VOLTAGE_V       (38.7)

USER_IQ_FULL_SCALE_CURRENT_A         (25.0)

USER_ADC_FULL_SCALE_CURRENT_A        (47.2)

USER_PWM_FREQ_kHz                (15.0)

USER_NUM_CTRL_TICKS_PER_SPEED_TICK  (15)

USER_NUM_CTRL_TICKS_PER_TRAJ_TICK   (15)

.....

The rated parameters of motor are 36V/3000rpm/200w. The motor parameters are also set in user.h. The test is under zero load (no any coupling is at the end of motor shaft).

But when I run the example lab5c, or lab5d, or lab5e, the performance is as below:

When run in  In zero speed condition, there is almost no torque generated, the motor shaft can be easily moved by hand. 

When setting  a speed value for example 100rpm, the motor can run but it seems that no much torque generated on the shaft since it can be hold stop easily by hand. Once setting the velocity bandwidth a higher value, it seems a little improvement in terms of torque. Therefore, the overall performance looks not so good, I am not sure what is the best performance for the Spintac sensorless control ?  or is any problem in my settings ? 

  • 0
    TI__Guru** 114310 points

    You might try to use the sensored-foc if you have to run the motor at zero speed or very low speed with a heavy/full load. The sensorless instaspin-foc or instaspin-motrion (lab05a/b/c) is based on the control without using a position sensor also that is difficult to provide the full torque output at low speed.

  • 0
    Intellectual 440 points

    Thank you Yanming,

    I know that the sensorless control performance may not be comparable with sensor based control. But in my test with the example program, the motor is zero load since the motor shaft has no any couplings. And the result is not good, there is almost no much torque.

    But TI document describes that the motor even can start with full load in sensorless mode. In the document, TI gives speed value such as 30rpm with full load, the motor can start successfully in sensorless mode. According to that, in my implementation, I believe there is some thing wrong setting, but I can not find it. So I just want to find the reason why in my test, the performance is as not as good as that in TI's documents. Therefore, if some advises are given for settings will be very helpful for me. 

    Thank you.

  • +1 in reply to user5912823
    TI__Guru** 114310 points

    That means start the motor from zero speed with load, and pass the low speed to a right running speed, not means the motor can stably run at zero or low speed. And you should add the load to the motor by a torque controller or dyno, not by a hand that is difficult to control the load is less than the rated torque of the motor, especially on a low rated torque motor.

    Having an incorrect Rs value (especially a value higher than the actual Rs) will make the start-up behave poorly. You might refer to chapter 14 "Managing Full Load at Startup, Low-Speed and Speed Reversal" in InstaSPIN-FOC and InstaSPIN-MOTION User's Guide,  http://www.ti.com/lit/ug/spruhj1h/spruhj1h.pdf 

    1. Enable forced angle
    2. Enable stator Rs recalibration before startup
  • 0 in reply to Yanming Luo
    Intellectual 440 points

    Ok, thank you. I guess I got some correct information from your comments.