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Title: Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range

Abstract

This paper describes an indirect sensing, or sensorless, method for rotor flux position for brushless permanent magnet (BPM) motors operating over a wide speed range, while keeping maximum torque per ampere and/or maximum efficiency capabilities. The method described is particularly applicable to trapezoidal back emf type of BPM motors. The typical trapezoidal waveform of the motor internal voltages (or back emf) contains a fundamental and higher order frequency harmonics. In particular, the third harmonic component is extracted from the stator phase voltages while the fundamental and other polyphase components are eliminated via a simple summation of the three phase voltages. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. In contrast with indirect sensing methods based on detection of the back-emf signal that require heavy filtering, the third harmonic signal needs only a small amount of filtering to eliminate the switching frequency and its side bands. As a result, the method described here is not sensitive to filtering delays, allowing the motor to achieve a good performance overmore » a wide speed range. Motor starting is also superior with this method since the third harmonic signal can be detected and processed at lower speeds than for the conventional method of back-emf sensing. Moreover, an alternative way to acquire the third harmonic signal without the need to access the stator neutral terminal is discussed. This is particularly interesting with the motor neutral connection is not available or expensive to have access. The third harmonic indirect sensing scheme is implemented in the laboratory and compared to a conventional back-emf sensing method.« less

Authors:
 [1]
  1. Whirlpool Corporate Manufacturing and Technology Development Center, Benton Harbor, MI (United States)
Publication Date:
OSTI Identifier:
442671
Resource Type:
Journal Article
Journal Name:
IEEE Transactions on Industry Applications
Additional Journal Information:
Journal Volume: 32; Journal Issue: 6; Other Information: DN: Presented at the 1994 Industry Applications Society annual meeting, October 2--7, Denver, CO (US); PBD: Nov-Dec 1996
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; MAGNETIC FLUX; ELECTRIC MOTORS; ENERGY EFFICIENCY; CONTROL THEORY; PERMANENT MAGNETS

Citation Formats

Moreira, J C. Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range. United States: N. p., 1996. Web. doi:10.1109/28.556643.
Moreira, J C. Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range. United States. doi:10.1109/28.556643.
Moreira, J C. Fri . "Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range". United States. doi:10.1109/28.556643.
@article{osti_442671,
title = {Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range},
author = {Moreira, J C},
abstractNote = {This paper describes an indirect sensing, or sensorless, method for rotor flux position for brushless permanent magnet (BPM) motors operating over a wide speed range, while keeping maximum torque per ampere and/or maximum efficiency capabilities. The method described is particularly applicable to trapezoidal back emf type of BPM motors. The typical trapezoidal waveform of the motor internal voltages (or back emf) contains a fundamental and higher order frequency harmonics. In particular, the third harmonic component is extracted from the stator phase voltages while the fundamental and other polyphase components are eliminated via a simple summation of the three phase voltages. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition, and is practically free of noise that can be introduced by the inverter switching, making this a robust sensing method. In contrast with indirect sensing methods based on detection of the back-emf signal that require heavy filtering, the third harmonic signal needs only a small amount of filtering to eliminate the switching frequency and its side bands. As a result, the method described here is not sensitive to filtering delays, allowing the motor to achieve a good performance over a wide speed range. Motor starting is also superior with this method since the third harmonic signal can be detected and processed at lower speeds than for the conventional method of back-emf sensing. Moreover, an alternative way to acquire the third harmonic signal without the need to access the stator neutral terminal is discussed. This is particularly interesting with the motor neutral connection is not available or expensive to have access. The third harmonic indirect sensing scheme is implemented in the laboratory and compared to a conventional back-emf sensing method.},
doi = {10.1109/28.556643},
journal = {IEEE Transactions on Industry Applications},
number = 6,
volume = 32,
place = {United States},
year = {1996},
month = {11}
}