# Less Rare-Earth Electromagnetic Design for a High-Performance Permanent Magnet Motor
## 1 Introduction
The most applied magnetization patterns in the design of electric motors are parallel and radial magnetization. The literature shows interest in the study of magnetization patterns [8]. There are many studies regarding surface permanent magnet motors (SPM) [9; 10; 11; 12; 13; 14; 15], including Halbach magnetization for this type. Each pattern has its pros and cons, but results usually show that radial magnetization leads to higher torque values regardless of the magnet material. Similarly, we can find few studies for banana-shaped Interior Permanent magnet Motors (IPM). These references [3; 4; 5; 16; 17; 18] present studies that demonstrate an improvement in mean torque with this topology. [PERSON] et al. [3; 16; 17] studies show different performances are obtained by adjusting the radial direction, which they execute by changing the radius value of the center of magnetization in the molds used. The results in [4; 5] show that these topologies increase the mean torque compared to conventional shapes. [PERSON] et al. [5] radial magnetization application leads to a 6% torque increment than parallel. However, despite the fact that radial magnetization provides the advantage of torque increment, its implementation in the industry has been limited due to its complexity and investment. The reason is that to accomplish it requires the specific adoption of a magnetizing device with molds for a component (part by part) or sub-assembly magnetization [19; 20]. Post-assembly magnetization in the rotor could be another option for achieving a desirable radial magnetization pattern. Nonetheless, this process will also require an analysis to check if the stator windings can withstand the magnetizing current because if not, the magnet's magnetization will be lower [21; 22]. Accordingly, creating the need to build a specific magnetizing device to achieve the required remanence. Typically, for NdFeB, the industry follows the component magnetization manufacturing process [19]. The manufacturing process will require an extra investment for radial magnetization, increasing the unit cost of the magnets [5; 13]. So, the slight torque improvement range (3-6%) compared to parallel magnetization might not compensate for the extra investment. Nevertheless, this torque loss due to parallel magnetization affects the effective usage of the implemented magnet weight in a motor. Thus, the question that arises is how to improve the performance of the banana-shaped motor with parallel magnetization for the effective use of the magnet weight. Effective use of the magnet weight will lead to savings in magnet material, and therefore, less rare-earth. This article proposes an innovative magnetization pattern alternative for banana-shaped magnets that maintains the unit manufacturing cost of the conventional parallel magnetization (presuming the existence of a baseline motor already using parallel magnetization) but increases the motor performance for the same magnet weight. This magnetization pattern proposal is the so-called tilted magnetization that consists of the optimal magnetization angle for the magnets. This optimal angle is found through finite element method (FEM) analysis demonstrating it produces a better motor performance for the baseline motor. To the authors' understanding, this fact has not been reported, making it the contribution of this paper. Therefore, since the proposed tilted magnetization pattern improves the baseline banana-shaped motor performance, it also opens the possibility to achieve a new design considering the optimal use of magnet weight. In summary, this paper presents a new electromagnetic design solution using tilted magnetization that could enable the mass production of banana-shaped NdFeB magnets with new manufacturing techniques such as the PIM technique keeping the unit cost as with the typical application of conventional parallel magnetization.