Permanent Magnets Aging in Variable Flux Permanent Magnet Synchronous Machines

Abstract

Permanent magnet synchronous machines (PMSMs) operation above based speed is typically achieved by injecting negative d-axis current to produce flux weakening. However, this increases permanent magnet (PM) losses, penalizing the efficiency and increasing the risk of demagnetization. Variable Flux PMSMs (VF-PMSM) in which PMs are magnetized/demagnetized during normal operation of the drive have been proposed to avoid the use of flux weakening current. However, aging effects due to PM magnetization/demagnetization cycles have not thoroughly studied yet. This paper analyzes the variation of NdFeB PMs properties (i.e. magnetic, electric and thermal properties) resulting from magnetization/demagnetization cycles. 1

High Temperature Magnetic Sensors for the Hot Section of Aeroengines

“…Further work is required to predict sensor health and detect symptoms of signal deterioration. Fernandez et al [45] tested performance of PMs subjected to cyclic magnetization and demagnetization in temperature up to 135°C. They found that magnets' cycle life decreases with operating temperature.…”

Permanent Magnets Aging in Variable Flux Permanent Magnet Synchronous Machines

“…This paper analyzes aging effects on PM magnetic, electric and thermal properties, due to magnetization /demagnetization cycles for PMs used in VF-PMSMs (i.e. NdFeB, SmCo and AlNiCo) [15]. The paper is organized as follows: characterization of PMs is discussed in section II, the experimental setup designed to cycle and characterize PMs is analyzed in Section III, experimental results using magnet samples are provided in Section IV, the effects of PMs aging in VF-PMSM is discussed in section V and the conclusions are finally provided in Section VI.…”