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Robust Magnet Polarity Estimation for
Initialization of PM Synchronous Machines
With Near-Zero Saliency
授課老師: 王明賢
學
生 : 黃秉宏
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Outline

Abstract

I. Introduction

II. Overview of Initial Position and Magnet Polarity Estimation

III. PMSM Terminal Attributes for Self-Sensing

IV. Limits To Magnet Polarity Estimation Robustness

V. Methods to Improve Magnet Polarity Estimation Robustness

VI. Eeperimental Results

VII. Conclusion

Reference
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Abstract
 This
paper investigates magnet polarity
estimation of PMSM.
 Angular offset is a secondary limitation
to the polarity estimation robustness.
 By estimating and decoupling the dcoffset vector and the angular offset, the
robustness is improved,and applicability
to a wide set of the machines is enabled.
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I. Introduction

PMSMs require initial rotor position and magnet
polarity to be identified prior to energizing them for
smooth startup.
Some techniques that do not rely on absolute
positiontransducers inject high-frequency transient
[1]–[8] or harmonic signals [9]–[14] to excite and
estimate machine saliency location.
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II. Overview of Initial Position and
Magnet Polarity Estimation
 A.
PMSM Response to Carrier Frequency
Excitation
 B.
Multiple Saliencies
 C.
Signal Extraction
 D.
Dual-Vector-Tracking State Filter
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A. PMSM Response to Carrier
Frequency Excitation
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B. Multiple Saliencies
A spatial Fourier series expansion (4) can be used to model the carriersignal excitation response of machines with multiple saliencies [15],[17].
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C. Signal Extraction
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D. Dual-Vector-Tracking State Filte
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III. PMSM Terminal Attributes for
Self-Sensing
 A.
Machine Characterization
 B. Example Saliency Images
 C. Aggregate Results of Saliency Image
Attributes
 D. Angular Offsets
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IV. Limits To Magnet Polarity
Estimation Robustness
 A.
Initial Position Estimation Accuracy
 B. Maximizing the SNR of the Polarity Signal
 C. Combined Effects Limiting Polarity
Estimation Robustness
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V. Methods to Improve Magnet
Polarity Estimation Robustness
 A.
Noise Mitigation
 B.
Angular Offset and Stationary Saliency
Decoupling and Automatic Identification
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VI. Eeperimental Results
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VII. Conclusion

PMSM attributes for self-sensing span a wide-enough
range to significantly limit magnet polarity estimation
robustness on some machines.

This evaluation of eight PMSMs confirms that
stationarysaliency (dc-offset) vector is the major contributor
to unreliable polarity detection. Stationary saliencies
reaching 50%–90% of the primary saliency magnitude are
not unusual for the second harmonic of positive-sequence
carrier currents. This corresponds to SNR between 1.1
and 2 for certain rotor positions
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VIII.Reference
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