Interdependence of Demagnetization, Loading, and Temperature Rise in a Permanent-Magnet Synchronous Motor

Ruoho, S.; Kolehmainen, J.; Ikaheimo, J.; Arkkio, Antero

doi:10.1109/tmag.2009.2033592

Cited by 221 publications

(102 citation statements)

References 16 publications

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“…Furthermore, a study has been made on working point ripple in permanent magnets when the generator is connected to an external electrical circuit [22]. Important previous work on demagnetization include work by Ruoho [19,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

Sjökvist

Eriksson

2017

Energies

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Faults in electrical machines can vary in severity and affect different parts of the machine. This study focuses on various kinds of short-circuits on the terminal side of a generic 20 kW surface mounted permanent magnet synchronous generator and how successive faults affect the performance of the machine. The study was conducted with the commercially available finite element method software COMSOL Multiphysics R , and two time-dependent models for demagnetization of permanent magnets were compared, one using only internal models and the other using a proprietary external function. The study is simulation based and the two models were compared to a previously experimentally verified stationary model. Results showed that the power output decreased by more than 30% after five successive faults. In addition, the no-load voltage had become unsymmetrical, which was explained by the uneven demagnetization of the permanent magnets. The permanent magnet with the lowest reduction in average remanence was decreased by 0.8%, while the highest average reduction was 23.8% in another permanent magnet. The internal simulation model was about four times faster than the external model, but slightly overestimated the demagnetization.

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Section: Introductionmentioning

confidence: 99%

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

Sjökvist

Eriksson

2017

Energies

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“…[4][5][6] Especially when traction machines operate under extreme conditions, such as overload and deep flux-weakening, the PMs suffer from high irreversible demagnetization risk. [7][8][9][10] In this condition, the output torque capability will be reduced to some extent, which impacts the continuous high-reliability operation of the vehicles. However, during the design process of the conventional PM machines, the anti-demagnetization investigations of the PMs are often ignored.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10] In the Ref. 6, the demagnetization characteristics of the PM-assisted synchronous reluctance motor are investigated under different current loads, revealing that the PM is demagnetized seriously when 2.5 times rated current is fed.…”

Section: Introductionmentioning

confidence: 99%

Demagnetization investigation of a partitioned rotor flux switching machine with hybrid permanent magnet

et al. 2017

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In this paper, the partitioned rotor flux switching permanent magnet machine with ferrite permanent magnet is proposed. By the adoption of the partitioned rotor configuration, the stator flux leakage is eliminated and the permanent magnet utilization is improved. The ferrite permanent magnet machine often suffers from irreversible demagnetization due to the inherent relatively low coercivity of ferrite permanent magnet. To mitigate the machine irreversible demagnetization risk, an improved partitioned rotor flux switching permanent magnet machine with hybrid permanent magnet topology is also proposed. Two little pieces of rare-earth permanent magnet are installed at the corners of ferrite permanent magnet, thus forming the hybrid permanent magnet topology. And the demagnetization mechanisms of both machines are clarified by the magnetic equivalent circuit method, which prove that the rare-earth permanent magnet offer magnetic protection function for the ferrite permanent magnet. Furthermore, by the 2-D finite element analysis, the demagnetization characteristics and the electromagnetic performances of the two machines are quantitively assessed, revealing that the demagnetization risk is reduced significantly. Both theoretical analysis and simulation results verify that the improved machine can not only maintain low-cost design, but also possess enhanced demagnetization withstand capability and competitive electromagnetic performances as expected. © 2017 Author (s)

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“…It is well known and taken into account in machine simulations that the properties of permanent magnets change with temperature, which in turn changes the machine performance [1]. But the temperature influence on electric steels is commonly neglected in simulations and the electrical machine design process, even if the temperature fluctuation and maximum value are often higher in the stator, compared to the permanent magnets located on the rotor.…”

Section: Introductionmentioning

confidence: 99%

Temperature Influence of NiFe Steel Laminations on the Characteristics of Small Slotless Permanent Magnet Machines

et al. 2013

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Abstract-High performance electrical machines can operate at temperatures of 100• C and beyond in rotor and stator cores. However, magnetic properties are generally measured at room temperatures around 23• C to 25• C according to the standards, even if it is known that the magnetization of some materials is substantially influenced by increasing temperatures. This paper investigates the thermal influence on the magnetic properties and iron losses in the stator cores of small slot-less permanent magnet synchronous machines (PMSMs). The stator stack is made of thin nickel iron (NiFe) lamination sheets. Magnetic measurements of the stator core are conducted for different frequencies and flux densities at several temperatures between 25• C and 105• C. The obtained measurement data is afterwards used in finite element method (FEM) simulations to investigate the influence of the magnetic property change on the machine performance. For the PMSM in consideration, the FEM simulations show that an increased stator core temperature reduces the electromagnetic torque considerably; approximately 1/3 of the torque reduction due to increased rotor magnet and stator core temperatures (from 25• C to 100 • C) can be attributed to the increased stator core temperature.

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Interdependence of Demagnetization, Loading, and Temperature Rise in a Permanent-Magnet Synchronous Motor

Cited by 221 publications

References 16 publications

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

Demagnetization investigation of a partitioned rotor flux switching machine with hybrid permanent magnet

Temperature Influence of NiFe Steel Laminations on the Characteristics of Small Slotless Permanent Magnet Machines

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