Permanent magnet (PM) machines are widely used in industrial processes due to their merits such as high power density and torque and low losses (high efficiency). These machines operate frequently under harsh conditions; therefore, they expose different types of faults. These faults can be diagnosed in initial stages using different techniques and prevent the faults' progress to catastrophic stages. One of the most important PM machine faults in terms of occurrence rate is demagnetization fault, whose causes can be heat, electrical, environmental or combinations. This may lead to efficiency drop, poor performance, and low reliability of the system. This paper attempts to review and summarize the demagnetization fault diagnosis methods in PM machines. First the fault generating factors and their impacts on the performance of the motor are discussed. Then, the recently developed techniques for demagnetization fault under stationary and nonstationary conditions in two separate sections are addressed. Presented methods are compared; their weaknesses and strengths are noted. Finally, suggestions for further research are proposed.

Demagnetization Modeling and Fault Diagnosing Techniques in Permanent Magnet Machines Under Stationary and Nonstationary Conditions: An Overview

This paper reviews the current state of the art of condition monitoring and fault diagnosis techniques for permanent magnet (PM) machines. It also takes into account the past research on this subject as appropriate. The discussion in this paper includes issues related to common abnormalities and specific faults in PM machines and drives, such as magnet damage and demagnetization, rotor eccentricity, unbalanced magnetic pull, open- and short-circuit windings, and switch faults. In this paper, a detailed review is present on the sources of these faults, their analytical model and fault detection tools. Finally, an integrated methodology for condition monitoring of PM machines is discussed.

Fault Diagnosis Techniques for Permanent Magnet AC Machine and Drives—A Review of Current State of the Art

This paper investigates diagnostic techniques for electrical machines with special reference to rotor faults in induction motors. An overview of typical failure mechanisms and their causes is presented. Also recent advances and future perspectives are discussed. To this aim the most recent related works along with important and fundamental papers are reviewed and reported in a comprehensive list of references.

Condition monitoring and diagnosis of rotor faults in induction machines: State of art and future perspectives

This paper proposes how to use the addition of rotor position offsets as perturbation signals for the parameter estimation of permanent-magnet synchronous machines (PMSMs), which can be used for the condition monitoring of rotor permanent magnet and stator winding. During the proposed estimation, two small position offsets are intentionally added into the drive system, and the resulting voltage variation will be recorded for the estimation of rotor flux linkage. With the aid from estimated rotor flux linkage, the stator winding resistance can be subsequently estimated at steady state. This method is experimentally verified on two prototype PMSMs (150 W and 3 kW, respectively) and shows good performance in monitoring the variation of rotor flux linkage and winding resistance.

Position-Offset-Based Parameter Estimation Using the Adaline NN for Condition Monitoring of Permanent-Magnet Synchronous Machines

Nowadays, condition-based maintenance (CBM) and fault diagnosis (FD) of rotating machinery (RM) has a vital role in the modern industrial world. However, the remaining useful life (RUL) of machiner...

https://journals.sagepub.com/doi/pdf/10.1177/1687814021996915

Sounds and acoustic emission-based early fault diagnosis of induction motor: A review study:

Rotor demagnetization effects on permanent magnet synchronous machines

Faults diagnosis in power transformers has been traditionally based on the insulation resistance measurement, polarisation index, analysis of dissolved gasses in oil, dissipation/power factor measurement, and partial discharges within many other alternatives. Originally, all these techniques presented an offline implementation, that is, with the transformer out of service. Currently, some of them, such as partial discharges measurement or gas analysis (gas chromatography), are carried out online in those cases in which the importance of a machine justifies it. These techniques have been recently complemented with new alternatives, such as frequency response analysis, an offline application technique. At the same time, in recent years, development of online diagnostic strategies has been carried out only based in monitoring of electrical variables. These techniques have the advantage of being economical in relation to traditional ones. Its development are incipient and with high growth potential. This study presents a review of the most important techniques and a critical comparison between them.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-gtd.2017.2086

Power transformers monitoring based on electrical measurements: state of the art

The effects of magnet faults on the rotor of permanent magnet synchronous machines are analyzed in the present work. In particular, demagnetization effects are analyzed using the finite element method. Two different stator winding configurations are considered in the analysis, series and parallel connected windings. From this analysis, a fault detection strategy based on the information contained in winding-current spectrum is proposed. A fault severity factor is also proposed to quantify residual magnetism losses (demagnetization) on a single magnet. This factor is practically independent from the motor load conditions. Experimental results are presented to validate the proposal.

Effects of partial rotor demagnetization on permanent magnet synchronous machines

Efficiency optimization in small induction motors using magnetic slot wedges

Fil: Meira, Matias. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernacion. Comision de Investigaciones Cientificas. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires; Argentina

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-gtd.2018.6318

Cristian Ruschetti

Papers

Rotor demagnetization effects on permanent magnet synchronous machines

Power transformers monitoring based on electrical measurements: state of the art

Effects of partial rotor demagnetization on permanent magnet synchronous machines

Efficiency optimization in small induction motors using magnetic slot wedges

Dissolved gas analysis differences between natural esters and mineral oils used in power transformers: a review