Electromagnetic calculation and kinematics analysis of multi-DOF motor with air-floation

In view of the fact that the transmission mode of the multi-DOF motor hinders its further development, the gas bearing is applied to the multi-DOF motor to form a new structure of the multi-DOF motor with air-floation (AMM). AMM not only improves the motor’s motion characteristics and transmission performance, but also basically does not cause environmental pollution. AMM uses porous static pressure gas bearing as the support structure, and completes the multi-DOF movement by controlling the energizing strategy of the coils. This paper introduces the structure of AMM, analyzes the basic working principle of AMM, and solves the air gap magnetic field; the kinematics model of the motor is established, the motion of the motor is controlled with the help of virtual simulation software, and the motion trajectory of the motor is obtained through the marked points of the output shaft. Finally, the AMM was verified by experiments, the error of experiment and simulation was controlled at 5%, and the kinematics characteristics of the motor met the design requirements. The research results provide a new idea for the development of multi-DOF motor.

Suppression of Thrust Fluctuation of a New Ironless Tubular Permanent Magnet Synchronous Linear Motor Based on the Halbach Array

The air gap magnetic field (AGMF) is the key factor in determining the ironless tubular permanent magnet synchronous linear motor (ITPMSLM). The distortion of its waveform causes thrust fluctuation during the operation of the motor, resulting in poor machining accuracy of the machine tool. To solve this problem, this paper proposes a new chamfered permanent magnet structure (CPMS) to improve its performance. First, the equivalent magnetic charge method is used to analyze the AGMF, and the analytical expressions of the no-load back EMF and thrust of the new motor are obtained. Second, the AGMF of six kinds of CPMS is analyzed by the Fourier coefficient. Taking the minimum harmonic distortion rate as the optimization objective, the CPMS that makes the AGMF waveform reach the best sinusoidal property is obtained and the no-load back EMF and thrust of the new motor are analyzed. Then, the new motor is compared with the ITPMSLM of rectangle permanent magnet structures (RPMS). Finally, according to the CPMS, the test prototype is built and tested under different working conditions. The research results show that when the outer circumference is 45o chamfered, the ratio of permanent magnet thickness h2 to the chamfered thickness h1 is 0.8; the sinusoidal property of AGMF is the best, and this structure can effectively reduce the motor thrust fluctuation rates to less than 0.01%, which verifies the effectiveness of the CPMS in improving the sinusoidal property in the AGMF and restraining the thrust fluctuation of the ITPMLSM.

Torque ripple optimization for synchronous reluctance motors based on a virtual permanent magnet harmonic machine model

The torque ripple is affected by both the stator and the rotor magnetic field harmonics. In synchronous reluctance motors (SynRM), there are only rotor permeance harmonics existing on the rotor side for the absence of the rotor windings. Since the asymmetric rotor flux barriers are widely applied in the SynRM rotor, it is difficult to calculate the rotor permeance accurately by the analytical method. In this article, the effects of the rotor permeance harmonics on the air-gap magnetic field are studied by a virtual permanent magnet harmonic machine (VPMHM), which is a finite-element (FE) based magnetostatic analysis model. The air-gap flux density harmonics produced by the SynRM rotor are extracted from the VPMHM model and used as the intermediate variables for the torque ripple optimization. The proposed method does not need to solve the transient process of motor motion. Hence, the time of the optimization process can be significantly shortened. Finally, a full electric cycle is simulated by dynamic FE simulation, and the torque ripple is proved to be effectively reduced.

Analysis of the Rotor Magnetomotive Force of Built-In Radial Permanent Magnet Generator for Vehicle

Permanent magnet generator (PMG) for vehicles has attracted more and more attention because of its high efficiency, high power density, and high reliability. However, the weak main air-gap magnetic field can affect the output performance and the normal use of electrical equipment. Aiming at the problem, this paper took the rotor magnetomotive force (MMF), the direct influencing parameter of the main air-gap magnetic field, as the research object, deduced the analytical expression of rotor MMF of the built-in radial PMG in detail, and analyzed its main influencing factors in analytical expression, including the permanent magnet steel (PMS) material, the thickness of PMS in magnetizing direction, the vertical length of the inner side of PMS, and the effective calculation length of PMS. Based on this, the rotor parameters were optimized to obtain the best values. After that, the finite element simulation and prototype test of the optimized generator were carried out. The comparative analysis results showed that the optimized rotor parameters could effectively improve the rotor MMF and optimize the output performance of the generator.

Research air gap on electromagnetic field of high speed motor under the influence of air gap

High speed motor are mainly used in aerospace, petrochemical and NC machining fields. Complex electromagnetic field is distributed in the motor. With the continuous maturity of asynchronous motor technology, research on magnetic field has been rapidly developed. In this paper, the changes of air gap and magnetic field of high speed motor under different working conditions is introduced. The magnetic field model of high-speed motor with Maxwell electromagnetic which established theory through Ansoft finite element software. The distribution of electromagnetic field in the motor is explored. The results show that the magnetic field distribution of induction motor tends to increase with the increase of the air gap magnetic field. Therefore, this study has an important guiding significance for the motor.

End Effect Analysis of a Slot-Less Long-Stator Permanent Magnet Linear Synchronous Motor

The implications of the end effect for flux linkage and thrust ripple in a slot-less long-stator permanent magnet linear synchronous motor (LSPMLSM), are analyzed in this paper. Since it is affected by the end effect, the air-gap magnetic field density under the end permanent magnet is different from that under the non-end permanent magnet, leading to asymmetry in the thrust ripple. For this reason, we establish a dynamic permanent magnet flux linkage model, which proves that the end effect leads to sub-harmonics in the permanent magnet flux linkage. The motor’s magnetic field distribution in the left and right parts is symmetrical. A thrust model taking into account the flux linkage sub-harmonics is established, from which the amplitude and period of the thrust ripple caused by the end effect can be calculated. There is no detent force for the slot-less LSPMLSM, and the end effect is the primary origin of the motor thrust ripple. In order to suppress the end effect, a method of increasing the end iron length is proposed, as a result of which the sub-harmonics in the flux linkage and the motor thrust ripple are effectively suppressed. Experimental and simulation results verify the results of this paper.

Static Eccentricity Fault Analysis of Surface-Mounted Permanent Magnet Electromotor with Skewed Slots Based on 2D FEA

It is of significance to analyze the performance of eccentric electromotor for the research on the electric vehicle wheel drive system’s operational reliabilities. We developed a fast equivalent algorithm in which the two-dimensional finite element calculation results are translated into three-dimensional calculation results. An electromotor with skewed slot was decomposed into straight-slot electromotor units that were series-wound. A prototype electromotor driven by square wave current under healthy and eccentric conditions was calculated, and the computation accuracy of the equivalent algorithm was analyzed. The air-gap magnetic field and induced electromotive force were calculated and contrasted. The study results indicate that the magnetic field distribution and the induced electromotive forces of winding elements with different axis positions were affected transparently by grievous eccentricity, yet the induced electromotive force of one phase winding and average value of torque remained virtually invariable. The reference to reliability analysis of electric vehicle wheel drive system is provided.

Theoretical Computational Model for Cylindrical Permanent Magnet Coupling

Permanent magnet coupling is extensively studied owing to its economic efficiency and stability. In this study, a computational model for cylindrical permanent magnet coupling (CPMC) was designed using the magnetic field division method to divide an air gap magnetic field. An equivalent magnetic circuit model was also designed based on the equivalent magnetic circuit method. The novelty of this study is that both the skin effect and the working point of the permanent magnet are taken into consideration to obtain the magnetic circuit and induce eddy current characteristics of permanent magnet coupling. Furthermore, a computational model was obtained for the transmission torque of the CPMC based on the principles of Faraday’s and Ampere’s laws. Additionally, the accuracy of the model was verified using a finite element simulation model and a test bench.