Search

This paper compares two different identification methods of a static rate-independent energy-based hysteresis model with regard to the dynamic hysteresis loop shape prediction when coupled to the parametric magnetodynamic lamination model. The values of hysteresis model parameters are determined solely based on the quasi-static major loop. A semiphysical approach identifying the reversible and irreversible field components independently and a purely mathematical scheme using a differential evolution optimization algorithm determining all parameters simultaneously are compared. Both variants of parameter identification are analyzed in terms of hysteresis loop shape prediction for quasi-static as well as dynamic loops. [ABSTRACT FROM AUTHOR]

This paper describes a mathematical model for the dynamic magnetic power losses in the laminated steel stator of high-frequency permanent magnet machines, such as brushless dc (BLDC) motors. The model presented is based on a utilization of the dynamic Jiles–Atherton model. Accurate dynamic $B$ – $H$ curve fitting and magnetic power loss derivations have been achieved, where the calculated magnetic losses have shown $\sim 95$ % accuracy from 5 to 2000 Hz over a flux density range of 1.0–1.6 T. This approach has been applied to estimate the magnetic power loss of a small scale high-frequency (>10 000 r/min) BLDC motor, with calculated and measured losses being in close agreement. [ABSTRACT FROM AUTHOR]

The knee point in the B – H curve of a permanent magnet (PM) is considered crucial in electric motor applications. In the case of severe fault conditions, such as overheating or a short circuit in electric motors, the working point might fall below the knee point causing irreversible demagnetization of the PM. Hence, the remanence flux decreases and the motor operation would be reduced or stalled. In this paper, two demagnetization models of PMs are investigated, i.e., a linear model and an exponential model. Demagnetization curves for NdFeB were measured at temperatures varying from room temperature to 180 °C. It was found that all the parameters in the exponential model, including Br , H\mathrm {jc} , \mu r , and the fitting parameter K1 , are temperature dependent. Therefore, an exponential model can be developed as a function of temperature which allows a more efficient implementation within electric motor applications using PMs. However, comparison of the exponential and linear models indicates that the latter has a better accuracy near the knee point for the demagnetization curves of NdFeB magnets. [ABSTRACT FROM AUTHOR]

To develop efficient silicon steel plates and electric machines using silicon steel laminations, the evaluation of excess loss in silicon steel plates is important. In this paper, investigation on excess loss calculation using the finite element method is carried out. The excess loss, which is mainly due to two factors, lack of flux penetration and domain wall pinning, is considered by the proposed approach using the domain wall bowing degree (DWBD), which depends on the above two factors. The DWBD is obtained using nonlinear eddy-current analysis. The correlation between the excess loss and the DWBD can be expressed as an exponential equation. Using the equation, the excess loss can be predicted under harmonic frequency in the range of 50–2000 Hz. These results can be applied to iron loss estimation, especially, when there are harmonics in the power supply. [ABSTRACT FROM PUBLISHER]

Problems involving intense pulsed magnetic fields in soft ferromagnetic materials require the solution of nonlinear partial differential equations with a field-dependent relative differential permeability that must represent the major magnetic properties of the material over an extremely wide range of magnetic fields. With the assumption that hysteresis can be neglected, a simple mathematical model with two exponential terms is described in which four constants can be used to model the magnetic properties of interest in a given problem. The model is constrained to match the initial value, the maximum value, and the saturation flux density. The analysis presented here shows that there are limitations and that not all values of the magnetic properties can be accommodated simultaneously. [ABSTRACT FROM PUBLISHER]