Stator Shape Research Articles

Research on influence of stator shapes and frames of switched reluctance motor to thermal characteristics

This paper describes a comparison of thermal characteristics of stator shapes and frames in switched reluctance motor. It has been published that stator shapes and frame shapes had a large influence on noise and vibration performance, but thermal characteristics haven't been studied. Four differ ent stator shapes were analyzed by using transient magnetic analysis in order to calculate the losses, which were taken into thermal analysis as heat source. Three dimensional finite element th ermal analyses was then carried out to study four different stator s with same basic dimension, and it was found that the square shape was most heat conductive. Frames including conventional axial ribbed aluminum frame, axial ribbed iron casting frame, radial ribbed frame, no ribbed frame were modeled and analyzed. The simulation results could be used to help make a choice between different stators and frames considering both vibration be havior and thermal behavior.

The Improvement of Permeability and Strength in Soft Magnetic Composites Motor Core Using Spark Plasma Sintering Process

The practical uses of soft magnetic composite(SMC) for an electrical motor is presented in this paper. SMC allows obtaining improved stator and core shapes as well as totally new design concepts such as claw pole motor. However, a major disadvantage of soft magnetic composites was their weak strength. In this study, spark plasma sintering (SPS) was utilized to improve the strength of SMC. Advantages of the SPS process over other conventional sintering process are the faster heating and cooling rates ensured and higher pressure applied during the sintering procedure. This allows obtaining high strength products in short periods of time to meet with industrial application without insulation destruction. This paper introduces the development of high strength soft magnetic composite motor core and examples of practical application for industries. The result showed that the SPS process increased the fracture strength, about 1.3 to 1.7 times, of SMC compare to the conventional compaction. Also we derive method to reduce the iron loss in the SPS sintering process using control forming temperature. As the forming temperature decreased from 500°C to 300°C, reduction of iron-loss was obtained from 192W/kg to 21W/kg by using SPS sintering process. Moreover, with increased the SPS sintering process pressure value from 250MPa to 800MPa which is the conventional compaction condition and decreased forming temperature to 200°C, iron-loss was measured. The results showed that iron-loss was obtained 11.42W/kg and it was similar value of conventional compaction results.

焼嵌めによる損失を低減するための電磁鋼板の特性を用いた固定子形状の改善

In a motor with a stator which is inserted in a frame by shrink fit, iron loss increases and the increase has become a serious problem. Therefore, the stator shape has been studied to decrease the compression stress. In this paper, a new approach to decrease the loss is proposed, which makes use of physical properties of electrical steel sheet for tension stress, and new stator shape is shown and evaluated by experimental results to decrease the iron loss caused by the shrink fit.

Characteristics of the Linear Ultrasonic Motor using an Elliptical Shape Stator

A prototype linear ultrasonic motor using normal vibration and tangential vibration modes of an elliptical shape stator was fabricated and studied in this research. The composite structure of the stator is formed by two multilayer piezoelectric actuators clamped in an elliptical elastic body. The geometry of the stator has been computed with the help of the finite element analysis. The dimensions of the stator's structure were determined by making the two resonance frequencies close to each other. Two modes of normal and tangential vibration degenerate at the dimensional ratio of major axis and minor axis diameter equal to about 1.6 for coincidence of two resonance frequencies when the thickness is 6 mm and the width is 3 mm. The construction and some operational characteristics of the linear motor are presented. The maximum moving speed of the prototype was about 180 mm/s when applying 11 Vp driving voltage by using two signal driving method.

Novel Maglev Pump With a Combined Magnetic Bearing

The newly developed pump is a magnetically levitated centrifugal blood pump in which active and passive magnetic bearings are integrated to construct a durable ventricular assist device. The developed maglev centrifugal pump consists of an active magnetic bearing, a passive magnetic bearing, a levitated impeller, and a motor stator. The impeller is set between the active magnetic bearing and the motor stator. The active magnetic bearing uses four electromagnets to control the tilt and the axial position of the impeller. The radial movement of the levitated impeller is restricted with the passive stability dependent upon the top stator and the passive permanent magnetic bearing to reduce the energy consumption and the control system complexity. The top stator was designed based upon a magnetic field analysis to develop the maglev pump with sufficient passive stability in the radial direction. By implementing this analysis design, the oscillating amplitude of the impeller in the radial direction was cut in half when compared with the simple shape stator. This study concluded that the newly developed maglev centrifugal pump displayed excellent levitation performance and sufficient pump performance as a ventricular assist device.

平面磁路形パラメトリックモータの内側共通磁路形状とモータ特性に関する検討

平面磁路形パラメトリックモータの内側共通磁路形状とモータ特性に関する検討

磁化容易軸不平衡固定子を用いた平面形パラメトリックモータの内側共通磁路幅と特性の関係

We earlier investigated a new type of parametric motor using a laminated iron core, and we showed that the output and efficiency of a prototype motor are comparable to those of conventional single-phase capacitor motors. This paper discusses the relation ship between the width of the inner ring core and the characteristics of a laminated core parametric motor using an asymmetric stator. Parametric oscillation was stabilized, and output and efficiency were significantly improved, by using an asymmetric stator shape.

平面磁路形パラメトリックモータの固定子形状と鉄損の関係

We earlier proposed a parametric motor using a laminated core. This paper discusses, the relationship between stator shape and iron loss in the motor. Square and round outer shapes were used for an experimental stator. The efficiency of the square-stator motor was less than that of the round-stator motor. We investigated the iron loss of the motor and analyzed the distribution of flux density in the stator using the finite element method, to determine the reason for the difference in efficiency. Results showed that the iron loss of the square-stator motor is larger than that of the round-stator motor.

球面超音波モータ用ステータの開発 （第１報） ステータ形状の検討

This paper presents a new type stators for a spherical ultrasonic motor. This motor has three degree-of-freedom in one motor unit. A spherical ultrasonic motor has high performance such as it has high torque at low speeds, high holding torque, a gear is unnecessary and the motor can be driven silently. However, the output characteristics are different from general ultrasonic motors. For that reason it is necessary to investigate the vibration condition of the stator to improve output characteristics of the motor. In this paper a stator shape where the contact face is in the middle of the stator disk is examined using FEM. Experimental results shown an inprovement in the output characteristics about two times in comparison with the usual type stators.

Influence of stator geometry upon vibratory behaviour and electromagnetic performances of switched reluctance motors

The vibrations and the acoustic noise produced by switched reluctance motors (SRMs) are linked to current wave form and to their structural properties. The authors carried out a parametric study to quantify the influence of the stator geometry upon vibratory behaviour of a 6/4 SRM. Their study shows the important influence of stator yoke thickness on vibration reduction compared to the other stator shape parameters. Moreover, a less noisy structure is proposed, based on the simultaneous analysis of electromagnetic performances and elastic characteristics.

Bowed Stators: An Example of CFD Applied to Improve Multistage Compressor Efficiency

Analysis of multistage compressor stator surface static pressure data reveals that the radial growth of suction surface corner separation prematurely separates core flow stator sections, limiting their pressure rise capability and generating endwall loss. Modeling of the stator flowfield, using a three-dimensional Euler analysis, has led to the development of “bowed” stator shapes, which generate radial forces that reduce diffusion rates in the suction surface corners, in order to delay the onset of corner separation. Experimental testing of the bowed stator concept in a three-stage research compressor has confirmed the elimination of suction surface corner separation, the resulting reduction of the endwall loss, and the increase in pressure rise capability of the stator core sections. This results in more robust pressure rise characteristics and substantially improved efficiency over the entire flow range of the compressor. The strong interaction effects of the bowed stator with the viscous endwall flowfield are shown to be predictable using a three-dimensional multistage Navier–Stokes analysis. This permits matching of the rotors to the altered stator exit profiles, in order to avoid potential stability limiting interactions. Application of bowed stators to a high bypass ratio engine eleven-stage high-pressure compressor has resulted in substantial improvement in efficiency, with no stability penalty.

Application of Evolutionary Algorithms and Statistical Analysis in the Numerical Optimization of an Axial Compressor

The purpose of this work is to optimize the stator shape of an axial compressor, in order to maximize the global efficiency of the machine, fixing the rotor shape. We have used a 3D parametric mesh and the CFX-Tascflow code for the flow simulation. To find out the most important variables in this problem, we have run a preliminary series of designs, whose results have been analyzed by a statistic tool. This analysis has helped us to choose the most appropriate variables and their ranges in order to implement the optimization algorithm more efficiently and rapidly. For the simulation of the fluid flow through the machine, we have used a cluster of 12 processors.