Control methods for smooth operation of permanent magnet synchronous AC motors

  • Greg Heins

    Student thesis: Doctor of Philosophy (PhD) - CDU


    Many applications require a motor capable of providing a smooth torque output. The use of control methods to ensure smooth operation is attractive because it minimises restrictions on motor design and manufacture. Programmed reference current wave- form (PRCW) methods are a commonly proposed control method as they have the ability to work at a range of speeds and load torques, however their experimental implementation to date has been inconclusive.

    This research compares three published PRCW methods with a standard sinusoidal current waveform. For the test motor considered, all PRCW methods tested are able to reduce the RMS pulsating torque to approximately 3 - 4% down from the 8 - 9% created when using a sinusoidal current. While this is a substantial reduction, the results for all methods were too similar to suggest the clear superiority of any method. One method however, the time domain method, produced slightly better results.

    Further reduction in pulsating torque requires a greater accuracy in motor and controller parameter estimation. To achieve this further reduction, this thesis develops a `pulsating torque decoupling' (PTD) method where the parameters are determined from the pulsating torque itself.

    The use of this technique allows calibration of the critical parameters and produces a further reduction of the pulsating torque to approximately 1%. As with the uncalibrated results, the difference between the different PRCW methods is minimal, with the time domain method producing only slightly less pulsating torque.

    These results suggest PRCW methods can be effective in producing a smooth torque output if the relevant parameters are estimated to a suitable accuracy. The use of the PTD method presented in this thesis can achieve this required accuracy.
    Date of AwardMar 2008
    Original languageEnglish
    SupervisorFriso De Boer (Supervisor)

    Cite this