Abstract
This paper investigates the magnetization characteristics of variable flux permanent magnet (VF-PM) by using a simplified C-core magnetizer device with AlNiCo PMs. A combined methodology with magnetic circuit model, finite element analysis and Fourier series fitting hysteresis model is proposed. By means of the magnetic circuit analysis, the basic sizing parameters of the device are designed for the prototype manufacturing. A simple experimental setup including a device prototype, a Gaussmeter and H-bridge-converter-based magnetizing circuit is established. Then several experimental schemes are conducted to research the magnetization characteristics. According to the experimental results, a new numerical hysteresis model of AlNiCo PMs is proposed based on Fourier-fitting functions, which can be employed to correct the hysteresis model parameters used in finite element (FE) simulation. Finally, the correctness of the proposed Fourier-fitting hysteresis model (FFHM) is experimentally verified by the test results.
Highlights
If the initial state of the low coercive force (LCF) permanent magnets (PM) comes from the remagnetization operation, the subsequent demagnetization process follows the hysteresis loop determined by the latest remagnetization
If a continuous demagnetization is performed, the LCF PM working point will follow the recoil line: For example, in the process of demagnetization, if the initial magnetization state (MS) is obtained from magnetization, the operating point moves along R2C2Q1R1, and settles at R2
With the proposed combined methodology, a C-core scitation.org/journal/adv magnetizer device equipped with LCF AlNiCo PM is designed
Summary
Variable flux memory machine (VFMM) equipped with low coercive force (LCF) permanent magnets (PM) such as aluminumnickel-cobalt (AlNiCo), Ferrite and Samarium-cobalt (SmCo), etc. can achieve flexible online flux-adjustment by changing the magnetization state (MS) of LCF PM with a current pulse. The corresponding MS can be memorized based on the specific current pulse level, and the speed range can be further extended. due to short time duration of the magnetizing current, VFMMs require less flux-weakening copper loss in high-speed area, leading to high-efficiency operation within a wide speed range. As a result, VFMM is extensively recognized as a competitive candidate for automotive applications.. The highly nonlinear magnetization characteristics of VF-PMs make the determination of the relation between the current pulse amplitude and the MS relatively complicated.. The highly nonlinear magnetization characteristics of VF-PMs make the determination of the relation between the current pulse amplitude and the MS relatively complicated.1 This brings challenges in research and application of the VFMMs for practical wide-speed-range applications. The well-established hysteresis models of AlNiCo PMs mainly include parallelogram and Preisach models.. The well-established hysteresis models of AlNiCo PMs mainly include parallelogram and Preisach models.20 The former model employs simple linear approximations to characterize the repetitive movement of the LCF PM working point. This paper investigates the magnetization characteristics of VFPMs, and develop a new numerical hysteresis model with a simplified C-core magnetizer device.
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