False Negative Diagnosis of Demagnetization in Direct Drive Permanent Magnet Generators

Demagnetization is a fault occurring in permanent magnet machines, leading to increased vibrations, noise and reduction of efficiency in the short term. However, if not detected early, demagnetization will deteriorate the machine via higher current and temperature increase that will enhance the severity level and lead to a catastrophic failure. Such conditions are extremely costly when they concern direct drive applications, typical in offshore energy harvesting. Prompt diagnosis is required. The stator current analysis has been one of the favorable diagnostic methods due to its non-intrusiveness, low cost and online capabilities. Despite that, this paper proves that the monitoring of the stator current is not always reliable because it directly depends on the geometrical and manufacturing characteristics of the permanent magnet generator. Multiple cases that may lead to false negative diagnostic alarms are revealed in this work for the first time, prompting further research towards alternative diagnostic methods.

[1]  M. Mueller,et al.  The Demagnetization Harmonics Generation Mechanism in Permanent Magnet Machines With Concentrated Windings , 2021, IEEE Transactions on Energy Conversion.

[2]  Sang Bin Lee,et al.  Condition Monitoring of Industrial Electric Machines: State of the Art and Future Challenges , 2020, IEEE Industrial Electronics Magazine.

[3]  Daniel Fernandez,et al.  Online Detection of Rotor Eccentricity and Demagnetization Faults in PMSMs Based on Hall-Effect Field Sensor Measurements , 2019, IEEE Transactions on Industry Applications.

[4]  Zia Ullah,et al.  A Comprehensive Review of Winding Short Circuit Fault and Irreversible Demagnetization Fault Detection in PM Type Machines , 2018, Energies.

[5]  T. Habetler,et al.  Transient Demagnetization Characteristics of Interior Permanent Magnet Synchronous Machines with Stator Inter-Turn Short Circuit Faults for Automotive Applications , 2018, 2018 IEEE Energy Conversion Congress and Exposition (ECCE).

[6]  Dan M. Ionel,et al.  Fault Diagnosis Techniques for Permanent Magnet AC Machine and Drives—A Review of Current State of the Art , 2018, IEEE Transactions on Transportation Electrification.

[7]  Adil Usman,et al.  Review of fault modeling methods for permanent magnet synchronous motors and their comparison , 2017, 2017 IEEE 11th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED).

[8]  Sang Woo Kim,et al.  Detection and Classification of Demagnetization and Interturn Short Faults of IPMSMs , 2017, IEEE Transactions on Industrial Electronics.

[9]  Jawad Faiz,et al.  Demagnetization Modeling and Fault Diagnosing Techniques in Permanent Magnet Machines Under Stationary and Nonstationary Conditions: An Overview , 2017, IEEE Transactions on Industry Applications.

[10]  Alasdair McDonald,et al.  On the Optimization of Generators for Offshore Direct Drive Wind Turbines , 2017, IEEE Transactions on Energy Conversion.

[11]  Elias G. Strangas,et al.  On the Accuracy of Fault Detection and Separation in Permanent Magnet Synchronous Machines Using MCSA/MVSA and LDA , 2016, IEEE Transactions on Energy Conversion.

[12]  Gérard-André Capolino,et al.  Advances in Electrical Machine, Power Electronic, and Drive Condition Monitoring and Fault Detection: State of the Art , 2015, IEEE Transactions on Industrial Electronics.

[13]  Zhi Yang,et al.  Vibration monitoring of PM synchronous machine with partial demagnetization and inter-turn short circuit faults , 2014, 2014 IEEE Transportation Electrification Conference and Expo (ITEC).

[14]  Gyu-Hong Kang,et al.  Irreversible magnet demagnetization analysis of IPM type BLDC motor by stator turn fault , 2012, 2012 7th International Forum on Strategic Technology (IFOST).

[15]  Thomas M. Jahns,et al.  Investigation of the Rotor Demagnetization Characteristics of Interior PM Synchronous Machines During Fault Conditions , 2012, IEEE Transactions on Industry Applications.

[16]  Jonathan Shek,et al.  Designing the c-gen lightweight direct drive generator for wave and tidal energy , 2012 .

[17]  Anton Haumer,et al.  Detection and classification of rotor demagnetization and eccentricity faults for PM synchronous motors , 2011, 2011 IEEE Energy Conversion Congress and Exposition.

[18]  Ji-Yoon Yoo,et al.  Automated Monitoring of Magnet Quality for Permanent-Magnet Synchronous Motors at Standstill , 2010, IEEE Transactions on Industry Applications.

[19]  A. Arkkio,et al.  Interdependence of Demagnetization, Loading, and Temperature Rise in a Permanent-Magnet Synchronous Motor , 2010, IEEE Transactions on Magnetics.

[20]  Markus Mueller,et al.  A Lightweight Low-Speed Permanent Magnet Electrical Generator for Direct-Drive Wind Turbines , 2009, Renewable Energy.

[21]  L. Romeral,et al.  Detection of Demagnetization Faults in Permanent-Magnet Synchronous Motors Under Nonstationary Conditions , 2009, IEEE Transactions on Magnetics.

[22]  J. Lee,et al.  The Design of Permanent Magnet Synchronous Motor Considering Partial Demagnetization on the Permanent Magnet , 2006, INTERMAG 2006 - IEEE International Magnetics Conference.

[23]  Oliver Gutfleisch,et al.  Grain growth effects on the corrosion behavior of nanocrystalline NdFeB magnets , 2002 .