VARFLUX

Advanced Control of Variable Flux Permanent Magnet Synchronous Machines (VFCON)

Funding institution: Ministerio de Ciencia, Innovación y Universiodades.

Participating institutions: University of Oviedo.

Dates: 01/09/2023 – 01/09/2026

Project leader: Daniel Fernández Alonso, David Díaz Reigosa

Research team: Fernando Briz, Diego Laborda, Marcos Orviz, Carlos Suárez, María Martínez

INDEX

ABSTRACT

Permanent magnet synchronous machines (PMSM) have been the focus of significant research effort in recent years due to their superior performance, controllability, efficiency or power density, compared to other types of machines. The continuous demand of more efficient electric systems, safer and more reliable made PMSMs the primary option for traction and generation applications in multiple fields:household applications, electric traction and generation systems, military and aerospace applications. Nevertheless, efficiency of PMSMs is diminished in variable speed systems operating at high speeds as negative d-axis current must be applied in order to counteract permanent magnet (PM) flux linkage, matching the back electromotive force (Back-EMF) with the available voltage in the DC link. This mode of operation is known as flux-weakening and is characterized by an inherent copper and core loss increase; due to continuous application of negative d-axis current and the extra harmonics produced in the airgap field. Extra losses reduce the efficiency and increases the temperature of all machine parts (i.e. electric insulation, magnetization of PM), accelerating its degradation. To avoid the injection of flux weakening current and its subsequent adverse effects, variable flux permanent magnet machines (VFPMSMS, also known as memory motors) have been proposed. These types of machines dynamically change the PM magnetization state (MS) during high speed operation, to reduce the need of flux weakening current what drastically reduce the induced losses. Design optimization of a VF-PMSM becomes a complex task since power density, and the volume of permanent magnet used must be maintain compared to conventional PMSMs. At the same time, the machine must allow magnetization/demagnetization easiness to avoid overrated converters, and high demagnetization withstand capability to torque currents. VF-PMSM design relies also on the PM magnetics, electric and thermal stability. A precise characterization of the PMs is therefore key to achieve a precise, stable and safe control of VF-PMSM which is achieved when the magnetization state of the permanent magnets is accurately estimated. Therefore, the development of new PM magnetization state estimation state is a key factor for the controllability of VF-PMSMs.

OBJECTIVES

The main goal of the project proposal is the design and advanced control of variable flux permanent magnet synchronous machines. This includes monitoring techniques to determine the machine magnetizing state. The proposed techniques will introduce advances both in the design and control of this type of machines. This objectives can be divided in two general goals:

- Evaluation of design methodologies for VF-PMSM to meet electric vehicle traction requirements or railway traction requirements. This includes the analysis of the design space of VF-PMSMs based on machine parameter plane, power conversion properties, and total loss distributions based on an assumed demagnetization characteristic.

- Investigation MS trajectories that can be adopted depending on the machine working condition and MS requirements; this will include the analysis of the injected current for MS manipulation on the final PMs MS, the required energy consumption considering side effects, and the operating capabilities of MS manipulation possible trajectories. Also, this second goal includes monitoring techniques to determine the PMs MS.

EQUIPMENT & RESULTS

FEM Model of a VF-PMSM (left) and detailed model of magnet arangemente per pole (right)

FEM Model and demagnetization coefficient for the designed VF-PMSM

Results of non-uniform demagnetization using FEM

Permanent magnet samples. Composition of hybrid magnets (from left to right): 33% AlNiCo - 66% NdFeB, 66% AlNiCo – 33% NdFeB, 66% SmCo – 33% NdFeB, and 30% AlNiCo – 70% NdFeB.

Power magnetizer equipment used to saturate and characterize magnet samples

Histeresisgrhaph, used to characterizer magnetic materials and comples composition of permanent magnets

Rotor and stator lamination laser-cut of the VF-PMSM according to the machine design.

Test bench design including a torque transducer to evaluate the efficiency of the VF-PMSM

Windind assembly of the VF-PMSM design

Real test bench after full assembly, equipped with a torque transducer and a VR resolver.

Three phase IGBT-based inverter designed to control the VF-PMSM machine

Induced voltage of phase at low speeds for differnt magnetization state values

Induced voltage of phase (magnitude) for different demagnetiziing peak values

REALTED PUBLICATIONS

C. González-Moral, J.M. Guerrero, D. Fernández, D. Reigosa, C. Rivas, F. Briz, “Realizable reference anti-windup implementation for parallel controller structures” IEEE Journal on Emerging and Selected Topics in Power Electronics, 9(4): 5055-5068, Aug. 2021. DOI: 10.1109/JESTPE.2020.3021035
D. Fernandez, Y.-G. Kang, D. F. Laborda, M. Martinez, D. Reigosa and F. Briz, “Permanent Magnet Synchronous Machine Torque Estimation Using Low Cost Hall-Effect Sensors” IEEE Trans. on Ind. Appl., 57(4): 3735-3743, July-Aug. 2021. DOI: 10.1109/TIA.2021.3075924.
Y.G. Kang and D. Reigosa, “Improving Harmonic Rejection Capability of OSG Based on n-th Order Bandpass Filter for Single-Phase System” IEEE Access, 9: 81728-81739, June 2021. DOI: 10.1109/ACCESS.2021.3085236.
D. Reigosa, Y. G. Kang, M. Martinez, D. Fernandez, J.M. Guerrero, and F. Briz, “Sensorless Control of Wound Rotor Synchronous Motors Based on Rotor High-Frequency Signal Injection” IEEE Trans. on Ind. Appl., 57(6): 6034-6043, Nov.-Dec. 2021. DOI: 10.1109/TIA.2021.3100315
M. Martinez, D. F. Laborda, D. Reigosa, D. Fernández, J. M. Guerrero and F. Briz, “SynRM Sensorless Torque Estimation Using High Frequency Signal Injection” IEEE Trans. on Ind. Appl., 57(6): 6083-6092, Nov.-Dec. 2021. DOI: 10.1109/TIA.2021.3111840.
Y.G. Kang, D. Reigosa, “Dq-Transformed Error and Current Sensing Error Effects on Self-Sensing Control” IEEE Journal on Emerging and Selected Topics in Power Electronics, 10(2): 1935-1945, April 2022. DOI: 10.1109/JESTPE.2021.3051942.
M. S. Rafaq, H. Lee, Y. Park, S.-B. Lee, D. Fernandez, D. Reigosa and F. Briz “A Simple Method for Identifying Mass Unbalance using Vibration Measurement in Permanent Magnet Synchronous Motors” IEEE Trans. on Ind. Electr., 69(6): 6441-6444, June 2022. DOI: 10.1109/TIE.2021.3088332
M. S. Rafaq, H.-J. Lee, Y. Park, S. B. Lee, M. Orviz Zapico, D. Fernandez, D. Reigosa, and F. Briz “Airgap Search Coil based Identification of PM Synchronous Motor Defects” IEEE Trans. on Ind. Electr., 69(7): 6551-6560 July, 2022. DOI: 10.1109/TIE.2021.3095810
Y. G. Kang, D. Fernandez, D. Reigosa, “Saliency-based Rotor Spatial Position Displacement Self-Sensing for Self-Bearing Machine” MDPI Sensors (ISSN: 1424-8220), 22 (24), 2022. https://doi.org/10.3390/s22249663.
J. Jeong, H. Lee, M. O. Zapico, S. B. Lee, D. D. Reigosa and F. B. del Blanco, "Trailing Edge PM Demagnetization in Surface PM Synchronous Motors: Analysis and Detection," IEEE Trans. on Ind. Appl., Accepted, publication pending, 2023.
M. O. Zapico, D. D. Reigosa, H. J. Lee, M. S. Rafaq, S. B. Lee and F. B. del Blanco, "Demagnetization Detection and Severity Assessment in PMSMs Using Search Coils Exploiting Machine´s Symmetry," IEEE Trans. on Ind. Appl., Accepted, publication pending, 2023, DOI: 10.1109/TIA.2023.3267772.

Page updated

Report abuse