شکاف هوایی در موتورهای همگام با مغناطیس دائم داخلی
Abstract
I- Introduction
II- IPMSM Model
III- Grid On/Off Search Method
IV- Simulation Results
V- Structural Analysis
VI- CONCLUSION
REFERENCES
Abstract
Interior permanent-magnet synchronous motors (IPMSMs) have been widely used due to their high-efficiency and high-power densities. Minimization of torque pulsation resulting in vibration and acoustic noise is one of the important design considerations for IPMSMs. In this paper, a grid on/off search method for the rotor profile is proposed to mitigate torque pulsation. Selection of the rotor profile is due to the fact that air gap is the most sensitive parameter in electric machines wherein changes in flux densities can cause substantial differences in the distribution of forces. A layer comprised 20 partitions with a 0.1 mm thickness and 3° wide grids have been introduced to the rotor surface for each pole, and the possible geometries have been analyzed using the finite-element method in ANSYS Maxwell. An optimal design was found that has the lowest torque ripple with a higher average torque compared to the original design. Genetic algorithm has also been applied to the method to automate the coupling between Maxwell and MATLAB, thereby saving the simulation time. Complete structural analysis has been done for both of the original and optimal designs to verify the superiority and feasibility of the proposed design.
INTRODUCTION
INTERIOR permanent-magnet synchronous motors (IPMSMs) have broad applications in electric vehicles, home appliances, and robotics due to their high-power densities, high torque densities, and large speed ranges [1], [2]. Permanent magnets are buried inside the rotor, which leads to an unequal permeability for the d-axis and q-axis leading to magnetic saliency. Given the presence of reaction torque, caused by the magnetomotive force (MMF) of the stator and its interaction with permanent magnets, the torque of IPMSM is a combination of reaction and reluctance torques, which provides a higher torque density and wider speed range during field weakening compared to other conventional machines [3]. However, torque pulsation is one of the most important design considerations in IPMSMs, since it can cause unwanted byproducts such as vibrations and acoustic noise. Mitigation of torque pulsation has been studied by many scholars. There are mainly two categories of methods, namely, control techniques such as the current profiling method [4], [5], and the optimal design method. However, reducing torque pulsation based on power electronics and control method heavily depends on the accuracy of the power electronics circuits as well as the need for high-end microcontrollers to guarantee a timely execution of the control algorithm. This paper proposes a torque ripple minimization method from the design point of view. Many techniques have addressed this topic, such as rotor or stator skewing [6]–[8], magnet skewing and shape optimization [7], slot/pole number combinations [7], [9], [10], optimization of flux barrier such as asymmetric flux barriers [11], rotor shape optimization, such as Kiyoumarsi and Moallem [12], Kioumarsi et al.