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Low-Speed Sensorless Control With Reduced Copper Losses for Saturated PMSynRel Machines
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.ORCID iD: 0000-0002-6283-7661
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.ORCID iD: 0000-0002-0744-2552
2013 (English)In: IEEE transactions on energy conversion, ISSN 0885-8969, Vol. 28, no 4, 841-848 p.Article in journal (Refereed) Published
Abstract [en]

Permanent-magnet-assisted synchronous reluctance (PMSynRel) machines are generally well suited for sensorless operation at all speeds since the rotor topology possesses a magnetic saliency. However, magnetic saturation can result in a vanishing differential saliency which renders sensorless control at certain operating points difficult (or even impossible) at low speed. In this paper, an optimization procedure, based on results from finite-element (FEM)-based simulations, is proposed. As output, current reference trajectories are obtained in which copper losses are kept at minimum, while the capability for sensorless control is still maintained. The results from the FEM-based simulations are in good agreement with the corresponding experimental results. For the experimental prototype in consideration, the torque limit when operating sensorless at low speed is increased substantially from below 45% to around 95% of its rated value with only slightly increased copper losses. Additionally, the impact of position-dependent harmonics on the magnetic cross saturation (affecting the steady-state position estimation error) is found to be substantial. This highlights that this spatial variation should be taken into consideration for accurate prediction of performance during sensorless operation even if the winding of the machine is of the conventional distributed type.

Place, publisher, year, edition, pages
2013. Vol. 28, no 4, 841-848 p.
Keyword [en]
Electric drive, magnetic saturation, permanentmagnet-assisted synchronous reluctance machine (PMSynRel), p osition estimation, sensorless control, signal injection
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Energy Engineering
URN: urn:nbn:se:kth:diva-126089DOI: 10.1109/TEC.2013.2279303ISI: 000327642800006ScopusID: 2-s2.0-84889101225OAI: diva2:641694

QC 20131025

Available from: 2013-08-19 Created: 2013-08-19 Last updated: 2014-01-16Bibliographically approved
In thesis
1. Analysis and Control Aspects of a PMSynRel Drive in a Hybrid Electric Vehicle Application
Open this publication in new window or tab >>Analysis and Control Aspects of a PMSynRel Drive in a Hybrid Electric Vehicle Application
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals withmodeling and control of an electric drive equipped with a permanentmagnet assisted synchronous reluctance (PMSynRel) machine for a plug-in hybrid electric vehicle application.

In the first part of the thesis, a special use of the PMSynRel machine in consideration, known as an integrated charger concept, is investigated. The integrated charger feature allows using the PMSynRel machine as a part of the vehicle’s on-board charging system when charging the battery from the grid. A finite-element based analysis is performed providing important insights into the machine operation during the charging process. Dynamic models are developed that facilitate the controller development and the estimation of the efficiency during charging.

In the second part of the thesis, position sensorless control of the PMSynRel drive when applied in an automotive application is considered and analyzed thoroughly. First, a fundamental-excitation based rotor-position estimation technique is investigated. The study shows that the impact of current dynamics on the resulting torque dynamics has to be considered in some very demanding applications. Second, focus is put on signalinjection based sensorless control methods. Impacts of nonlinearities, such as magnetic saturation, cross-saturation and inductance spatial harmonics, on sensorless control performance are investigated and methods to improve the sensorless control quality are summarized and presented. An approach to determine the feasible region for operating sensorless at low-speeds without directly measuring the differential inductances is proposed. For the PMSynRel drive in consideration, the achievable maximum torque is limited when operating sensorless following the maximum-torque-per-ampere (MTPA) current reference trajectory at low-speeds. An optimization approach is therefore proposed which extends the output torque when operating sensorless while still maintaining a relatively high efficiency. To initialize the sensorless control correctly from standstill, the impact of the saturated magnetic bridges in the rotor is also investigated.

Finally, torsional drive-train oscillations and active damping schemes are considered. An off-vehicle setup for implementing and evaluating different active damping schemes is proposed. Of particular interest for sensorless operation in automotive applications, the impact of slow speed estimation on the possibility to achieve good active damping control is investigated and a design approach that allows the implementation of an active damping scheme using estimated speed is suggested.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. x, 60 p.
TRITA-EE, ISSN 1653-5146 ; 2013:046
Active damping control, electric drive, electric vehicle, hybrid electric vehicle, integrated charger, permanent-magnet assisted synchronous reluctance machine, position estimation, sensorless control
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-139592 (URN)978-91-7501-966-6 (ISBN)
Public defence
2014-01-22, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20140114

Available from: 2014-01-15 Created: 2014-01-15 Last updated: 2014-01-15Bibliographically approved

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