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This work investigates post-demagnetization characteristics of permanent magnet synchronous machines (PMSMs). A combination of closed-form analysis using a magnetic equivalent circuit model and finite element (FE) analysis is used to provide physical insights into the flux paths associated with demagnetizing electromotive force (MMF). Post-demagnetization behavior in several types of PMSMs is studied...
The use of interior permanent magnet synchronous motors (IPMSMs) with rare-earth magnets has recently been on the rise. When IPMSMs are operated to expand the operating speed range by flux-weakening control, irreversible demagnetization might occur in the magnets in the rotor and deteriorate motor characteristics. To prevent this, dysprosium (Dy) is added to rare-earth magnets. However, it is desirable...
The performance of a cage-less 16-kW, 1,500-rpm interior permanent magnet machine developed for a portable generator application is examined when run as a motor under open-loop volts-per-hertz control from an inverter. The analytical and experimental steady-state results show the machine can operate with high power-factor and efficiency. The dynamic results show robust operation in starting and the...
This paper suggests design of variable flux motor for variable speed operation. The calculation method of electrical parameters to meet variable speed condition is suggested, and the basic motor shape is decided using the relationships between the calculated electrical parameters and motor geometry. The difference between corecivity of two types of magnet is used to control flux. To prevent irreversible...
This paper investigates demagnetization characteristics of rare-earth permanent magnets used in electric machines. A test fixture was designed and built to induce controllable local demagnetization in the magnet sample under test. A range of demagnetizing magnetomotive force (MMF) was applied to force the magnet samples to operate at various points along their B-H curves. The degree of demagnetization...
This paper is concerned with the development of a vector controller for a variable flux inset permanent magnet synchronous machine (VF-IPMSM). This variable flux machine (VFM) uses low cost aluminum-nickel-cobalt (AlNiCo) permanent magnets (PMs). The demagnetization of the permanent magnets (PMs) is conducted on the stator winding of the machine hence there is no separate winding for the excitation...
In this paper, we analyze the back electromotive force (BEMF) characteristics according to the magnetization pattern of irreversible demagnetization to determine the fault type for interior permanent-magnet (IPM) type brushless DC (BLDC) motors. We numerically model irreversible demagnetized PMs using space-harmonics analysis. In addition, we analyze the results using the finite element and analytical...
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