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EST_getAngle_pu behavior

Harry Kroonen
Prodigy 250 points
Other Parts Discussed in Thread: MOTORWARE

A combined heads-up / request issue:

In Motorware_13, the EST_getAngle_pu function documentation mentions a return value between _IQ_ 0.0 and 1.0, but when running a reverse direction / negative speed, the actual value is between zero and MINUS_1.

Further a request related to this function: The angle value is from 0-1 in electrical angle, for one pole. Is there also a function that includes the number of poles, and will give a 'mechanical angle' in a range (0-1) for a full motor revolution?
(This is not very hard to implement, but in our situation with engine running in torque mode and low speed possibility of reversing caused by changing external load, it is somewhat tricky - Besides, I think this should be a standard function)

Regards,

Harry Kroonen

  • TI__Guru** 119600 points

    thanks, I've filed the NEGATIVE 1 issue.

    Harry Kroonen said:
    Is there also a function that includes the number of poles, and will give a 'mechanical angle' in a range (0-1) for a full motor revolution?

    In InstaSPIN-FOC, or specifically from FAST we only give the mechanical frequency.

    For a mechanical position please see the InstaSPIN-MOTION lab 13 that include position control. There is an electrical to mechanical position converter function.

  • in reply to ChrisClearman
    Guru 12800 points

    Harry,

    You could use the SpinTAC Position Convert, detailed in labs 12x & 13x, and migrate this into your own project.  This takes electrical angle in as an input and will track mechanical revolutions.  It is designed to be used with a mechanical sensor, but you could pass the angle output from FAST as the input and while FAST is producing a good angle it would be able to track the mechanical revolutions.  The output range is configurable so you could have it output mechancical revolutions from -1 to 1 for example.

  • in reply to ChrisClearman
    TI__Guru** 119600 points

    ChrisClearman said:
    In InstaSPIN-FOC, or specifically from FAST we only give the mechanical frequency.

    this image was supposed to display

    ChrisClearman said:
    For a mechanical position please see the InstaSPIN-MOTION lab 13 that include position control. There is an electrical to mechanical position converter function.

    I should clarify that this would only work when the rotor speed is high enough for FAST to be giving an accurate estimate of the rotor flux electrical angle, but you could feed the electrical angle from EST into the SpinTAC position converter (in the labs it uses the encoder). Which means the rotor is not at a position, it is always moving. That's why we didn't create a mechanical angle...for a mechanical angle that may be at slow speed or standstill you need a mechanical sensor (encoder/resolver/sometimes Halls) or a different type of software sensor (like our upcoming Initial Position Detection algos).