Influence of machine topology and cross-coupling magnetic saturation on rotor position estimation accuracy in extended back-EMF based sensorless PM brushless AC drives

Zhu, Z Q and Li , Y and Howe, D and Bingham, Chris and Stone, D A (2007) Influence of machine topology and cross-coupling magnetic saturation on rotor position estimation accuracy in extended back-EMF based sensorless PM brushless AC drives. In: Industry Applications Conference, 2007. 42nd IAS Annual Meeting. Conference Record of the 2007 IEEE, 23-27 Sept 2007, New Orleans, USA.

Documents
Influence of machine topology and cross-coupling magnetic saturation on rotor position estimation accuracy in extended back-EMF based sensorless PM brushless AC drives
The influence of the machine topology and dq-axis cross-coupling on the rotor position estimation error in an extended back-EMF based sensorless brushless AC drive is investigated by both finite element analysis and experimentally on four brushless AC machines having different rotor topologies, viz. interior circumferentially magnetized, interior radially magnetized, surface-mounted, and inset magnets. The d- and q- axis apparent self- and mutual-inductances, Ld, Lq, Ldq and Lqd, are predicted by finite element analysis for various d- and q-axis currents. The error in the estimated rotor position of the four machines is investigated and compared when (a) the influence of magnetic saturation is neglected, (b) only the influence of the dq-axis current on Lq is considered, but dq-axis cross-coupling magnetic saturation is neglected, and (c) the influence of dq-axis cross-coupling magnetic saturation is taken into account. It is shown that the error is more strongly influenced by the q-axis current/permeance than the dq-axis current/permeance, since the dq-axis current does not distort the symmetrical field distribution about the q-axis, and that dq-axis cross-coupling magnetic saturation can significantly affect the accuracy of the rotor position estimation. However, by introducing an apparent mutual winding inductance in the extended back-EMF based sensorless method, the error in all four machines under consideration is reduced significantly, to a similar level to that which results with surface-mounted magnet machines.
[img]
[Download]
[img]
Preview
PDF
zhu_1.pdf - Whole Document

3108Kb

Official URL: http://dx.doi.org/10.1109/07IAS.2007.359

Abstract

The influence of the machine topology and dq-axis cross-coupling on the rotor position estimation error in an extended back-EMF based sensorless brushless AC drive is investigated by both finite element analysis and experimentally on four brushless AC machines having different rotor topologies, viz. interior circumferentially magnetized, interior radially magnetized, surface-mounted, and inset magnets. The d- and q- axis apparent self- and mutual-inductances, Ld, Lq, Ldq and Lqd, are predicted by finite element analysis for various d- and q-axis currents. The error in the estimated rotor position of the four machines is investigated and compared when (a) the influence of magnetic saturation is neglected, (b) only the influence of the dq-axis current on Lq is considered, but dq-axis cross-coupling magnetic saturation is neglected, and (c) the influence of dq-axis cross-coupling magnetic saturation is taken into account. It is shown that the error is more strongly influenced by the q-axis current/permeance than the dq-axis current/permeance, since the dq-axis current does not distort the symmetrical field distribution about the q-axis, and that dq-axis cross-coupling magnetic saturation can significantly affect the accuracy of the rotor position estimation. However, by introducing an apparent mutual winding inductance in the extended back-EMF based sensorless method, the error in all four machines under consideration is reduced significantly, to a similar level to that which results with surface-mounted magnet machines.

Item Type:Conference or Workshop Item (Presentation)
Additional Information:The influence of the machine topology and dq-axis cross-coupling on the rotor position estimation error in an extended back-EMF based sensorless brushless AC drive is investigated by both finite element analysis and experimentally on four brushless AC machines having different rotor topologies, viz. interior circumferentially magnetized, interior radially magnetized, surface-mounted, and inset magnets. The d- and q- axis apparent self- and mutual-inductances, Ld, Lq, Ldq and Lqd, are predicted by finite element analysis for various d- and q-axis currents. The error in the estimated rotor position of the four machines is investigated and compared when (a) the influence of magnetic saturation is neglected, (b) only the influence of the dq-axis current on Lq is considered, but dq-axis cross-coupling magnetic saturation is neglected, and (c) the influence of dq-axis cross-coupling magnetic saturation is taken into account. It is shown that the error is more strongly influenced by the q-axis current/permeance than the dq-axis current/permeance, since the dq-axis current does not distort the symmetrical field distribution about the q-axis, and that dq-axis cross-coupling magnetic saturation can significantly affect the accuracy of the rotor position estimation. However, by introducing an apparent mutual winding inductance in the extended back-EMF based sensorless method, the error in all four machines under consideration is reduced significantly, to a similar level to that which results with surface-mounted magnet machines.
Keywords:Permanent Magnet AC Motor, Sensorless control, Brushless AC motor, back-EMF, Cross-coupling
Subjects:H Engineering > H600 Electronic and Electrical Engineering
Divisions:College of Science > School of Engineering
ID Code:2503
Deposited By:INVALID USER
Deposited On:20 May 2010 20:31
Last Modified:13 Mar 2013 08:38

Repository Staff Only: item control page