Core Losses and Machine Design for Electric/Hybrid Vehicles

随着高速电机被设计成复杂的几何形状，导致复杂的磁通模式，电机的磁芯损耗领域越来越受到关注。磁通可能主要是交替的，但是机器的很大一部分经历了旋转损失，在这个区域做了很少的功。建议的工作分为三个部分。首先是为主要是脉动的波形建立更精确的模型。申请人发现，由于测量的方式，在将损耗分为涡流和迟滞方面产生了基本错误。在典型的Epstein样品中，整个通量在层压中流动，但随着频率的增加，趋肤效应接管，并且在层压厚度内通量密度的大小和相位发生变化。更精确的建模允许考虑这种变化，但这仍然必须转化为对实际损失的更精确计算。最近，在测量机械中转动铁损耗方面已经做了一些基础性的工作。设计并制造了一种新的测试夹具，并进行了有限的测试。这项任务的目的是推进测量，以包括非正弦激励，而通量是旋转的，并包括更广泛的材料和仪表。在建模方面，需要做的基本工作是开发磁通旋转时磁滞和涡流损失的公式，类似于对脉动磁通所做的工作。第三个任务是利用铁芯损耗建模的结果设计一种新的低转矩纹波的同步磁阻电机，不需要倾斜。定子或转子的倾斜增加了制造的复杂性。平均磁通密度也降低了。提出了一种与转子肋的方向有关的新技术，可以在没有倾斜的情况下使转矩脉动最小化。

The area of core losses in electrical machines is of growing interest as higher speed machines are being designed with complicated geometries, leading to complex flux patterns. The fluxes may be primarily alternating, but a significant portion of the machine experiences a rotational loss, an area in which very little work has been done. The work proposed is divided into three sections. The first is to develop more accurate models for waveforms that are primarily pulsating. The applicant has found that fundamental errors are being made in the separation of losses into eddy currents and hysteresis because of how the measurements are made. In typical Epstein specimens the entire flux is measured flowing in the lamination, yet as frequency increases, skin effect takes over and there is a variation in the magnitude and phase of flux density within the thickness of the lamination. More accurate modeling has allowed this variation to be taken into account, but this must still be translated into more accurate calculations of the actual losses. Some fundamental work in the measurement of rotational iron losses in machines have been done recently. A new test fixture has been designed and built and limited tests have been conducted. The purpose of this task is to advance the measurement to include non-sinusoidal excitations, while the flux is rotating and to include a wider range of materials and gauges. On the modeling side, fundamental work needs to be done on developing a formula for hysteresis and eddy current losses while the flux is rotating, similar to what has been done for pulsating fluxes. The third task is to use the results in the core loss modeling to design a new synchronous reluctance motor with low torque ripple, without the need for skewing. Skewing of the stator or rotor increases the manufacturing complexity. Also the average flux density is reduced. A new technique related to the orientation of the ribs in the rotor is proposed which can allow torque ripple minimization in the absence of skewing.