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Operating Point Dependent Anisotropies and Assessment for Position-Sensorless Control
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| Author(s) |
Wolfgang HAMMEL |
| Abstract |
Position-sensorless speed and position control of surface mounted permanent magnet synchronous machines(SMPMSMs) is of special interest in industrial automation due to their high efficiency and simpledesign. In the low speed range and at standstill high frequency injection based control schemes areemployed in order to maintain field oriented control.These methods exploit rotor-position dependent anisotropies of the stator inductances which are measuredas a response signal to the injected high frequency excitation. The rotor-position dependency ofthe stator inductances is either caused by a geometrical saliency of the rotor structure of by local magneticsaturation caused by the permanent magnet field.However, a SMPMSM typically has no geometrical saliency and the anisotropy is therefore solely causedby magnetic saturation and is therefore very small. Moreover the inductive anisotropy is also influencedby the presence of the torque producing fundamental wave stator current components. This typicallyresults in nonlinear functions of the differential inductive parameters. The operating point dependentbehavior of the anisotropy must be described and analyzed in order to be able to deduce the correct rotorposition from the measured high frequency response.This paper introduces an operating point dependent description of the anisotropy parameters in a generalapplicable form. A procedure to measure these dependencies is shown and criteria are derived to assessthe observability of the rotor position from the measured anisotropy data. This can be used to compensatefor load torque dependent position errors and also rotor-position dependent harmonic distortions. Finallya new criterion is introduced that allows to assess the stability of a closed loop position observer whichuses the high frequency response as a feedback signal. |
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| Filename: | 0373-epe2016-full-02085312.pdf |
| Filesize: | 938 KB |
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| Type |
Members Only |
| Date |
Last modified 2017-04-13 by System |
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