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TMS320F28069F: [InstaSpin]: Speed Control with reference = 0

Borja Gomez88
Intellectual 715 points

Part Number: TMS320F28069F

Hello,

I'm using the InstaSpin Lab3b for speed control of a PMSM. It works well for most of the cases. The speed control performance is very good even below 10% Rated Speed of the motor, but I have a problem when the speed reference is 0. Is you manually spin the motor axle (with no load) the motor start to spin with low speed and high torque (torque sign is oppostite to speed sign) and it doen't stop even if you remove this manually generated force I had expected some oscillation, but not this continuous movement. Is this normal performance in sensorless control? Probably I have some parameters wrong configured? Any clue?

Thank you in advance,

Borja.

  • 0
    TI__Guru** 116860 points

    InstaSPIN-FOC is a sensorless FOC, it's difficult to spin the motor smoothly with zero speed or very low speed near zero. You have to use sensored-FOC if you want to run the motor at zero/very low speed.

  • 0 in reply to Yanming Luo
    Intellectual 715 points

    Hello Yanming,

    Thank you for your repply. I do not pretend to move the motor at low speed, but I would like to know if this effect (you apply force manually to the motor axle and then remove this force the motor continue spinning indefinitely even if the reference speed is zero)  is due to sensorless control or is due to a mistake in the FW from our side (may be any control flag). If the cause is the control itself, Is there any way to avoid it?

    Thank you in advance

    Borja

  • 0 in reply to Borja Gomez88
    TI__Guru** 116860 points

    That's a normal phenomenon. No matter the force angle is enabled or disabled, the rotation direction is not indefinite during the startup from zero speed, because the sensorless-FOC controller doesn't know the precise rotor position and have to align the rotor to zero position. You have to implement an initial position detection technique for the startup or use sensored-FOC solution.