This paper proposes an improved analytical method to calculate the two-dimensional air gap magnetic field (AGMF) of the permanent magnet array in trapezoidal Halbach permanent magnet linear synchronous motors. The influence of the trapezoidal magnet bottom angle a, equivalent width coefficient aw, height coefficient ah and air gap height coefficient ag on the amplitude and harmonic distortion rate of the air gap central magnetic field is analyzed. Based on the equivalent surface current method (ESCM), an improved equivalent algorithm based on trapezoidal side length is proposed for the trapezoidal Halbach permanent magnet array (THPMA). The equivalent analytical formula of two-dimensional air gap flux density is derived and verified by the finite element method (FEM). Results show that the improved equivalent surface current method (IESCM) is convenient and accurate and is suitable for magnetic field calculation of irregular magnetic poles with arbitrary section shape. Analysis shows that, compared with a rectangular magnet, when the bottom angle a of the magnet is greater than 90∘, AGMF can obtain the maximum peak value of magnetic flux density (Bpeak) and the minimum total harmonics distortion of magnetic flux density (THDB).

Accurate analysis of the air gap magnetic field is the focus of research in the field of precision permanent magnet linear synchronous motors. In this paper, the two-dimensional air gap magnetic field of a secondary trapezoidal Halbach permanent magnet array coreless permanent magnet linear synchronous motor (PMLSM) was taken as our research object. On the basis of the equivalent surface current method, we proposed an improved equivalent analytical algorithm with a trapezoidal side length unit. The equivalent analytical model of the magnetic induction vector of the two-dimensional air gap was established, and the air gap magnetic field of the trapezoidal Halbach array coreless PMLSM was calculated. At the same time, we analyzed the influence of the bottom angle α of a trapezoidal permanent magnet equivalent width coefficient αw, pole height coefficient αh, and air gap height coefficient αg on the amplitude (Bpeak) and total harmonic distortion (THDB) of the central magnetic field in the air gap. The results show that α and αw have a significant influence on the Bpeak and THDB of the central magnetic field air gap. With the synergy of α and αw, we identified the “flux convergence” effect, which makes the maximum range of Bpeak α > 90° and αw < 0.5. We also found the “equilateral” effect, which causes the minimum region of THDB to change linearly. The calculation results of the improved equivalent surface current analytical model established in this paper agree with those verified by the finite element method. The calculation is convenient, and the accuracy of the result is high. This research provides a new method for analyzing the air gap magnetic field of a permanent magnet with a nonrectangular cross-section and lays a theoretical foundation for optimizing the PMLSM pole model.

Electrical motors is the equipment that convert the electrical energy into the mechanical energy. And they are the main source of power for modern industry application. However, the energy efficiency level of the ordinary stepper motors is low, and the rare earth permanent magnet motors are needed to replace them for the needs of higher energy efficiency in the new era. As an important rare earth functional material, rare earth permanent magnet is the most widely used magnetizing material for permanent magnet motors at present. Its comprehensive magnetic performance is excellent, but its temperature coefficient is relatively high. When it is demagnetized by an external magnetic field at high temperature, it is easy to cause irreversible demagnetization, resulting in the reduction of motor torque performance and even the scrapping of the whole machine. Therefore, it is necessary to understand its demagnetization characteristics to effectively overcome or slow it down. Secondly, the loss generated by the permanent magnets is one of the important sources of the eddy current loss of the rotor part, and the in-depth understanding of it will help to reduce this kind of loss. In addition, the radial force generated acting on the stator teeth will cause the teeth to swing, which is also an important source of motor vibration and noise. It is necessary to conduct in-depth research on it. Aiming at the above three aspects, this paper conducts in-depth and systematic analysis and research through simulation calculation. It is very significant to improve the service performance of rare earth permanent magnets for the interior permanent magnet motors, and it is also a beneficial fundamental academic exploration. In this paper, the performance of the permanent magnet is analyzed and designed. It is known that the anti-demagnetization ability of the permanent magnet decreases with the continuous increase of temperature, and the ability of the permanent magnet to generate a magnetic field also decreases. This is mainly due to the internal material of the permanent magnet, which is also our most concerned permanent magnet demagnetization mechanism. The loss of magnetism of the permanent magnet will induce the motor fail to meet the torque output we need, and it will not be able to continue to meet the service lifetime requirements. Due to the permanent magnet demagnetization, the motor needs a higher current to drive, and the higher current will bring higher heat energy and cause the motor to heat up seriously. Therefore, the superposition will shorten the lifetime of the motor and eventually lose its working ability. We conduct research on these issues to protect and prevent the permanent magnets from loss of magnetism.

In drilling operation, drilling NPT caused by top drive mechanical failure and high noisy and energy suffered a lot onsite. This paper introduces a top drive which utilizes a permanent magnet synchronous AC motor to drive the quill directly without a gearbox which can shorten drive chain. Meanwhile, its symmetrical and compact mechanical construction and shorter main and control cables obviously improve installation efficiency and effectively reduce the failure rate. We conducted research through structural design, motor efficiency and heat dissipation, and automation system upgrades to form a set of high-efficiency, high-performance direct drive top drive. Transmission structure aspect: design of direct-drive top drive structure, calculation and verification of main load bearing parts, analysis of top drive failure types and effects. Motor energy efficiency aspect: research on speed measurement method of permanent magnet direct drive motor, precise control method of permanent magnet direct drive motor, and closed phase change heat dissipation technology. Automation enhancement aspect: research on control system architecture, self-diagnosis system, One-click operating system. This study resulted in three research findings including synchronous permanent magnet motor design, One-Click operating system with self-diagnosis and efficient self-circulation heat dissipation technology. The new generation of direct-drive top drive can reduce current required by 100-200A and increase efficiency by 20-30% compared with asynchronous motor, while meeting the requirements of corresponding rated load, rated power, speed and continuous torque. It can realize quill rotation precision less than 1° under load and keep the speed fluctuation reduced from 10.6% to 1.1% by improving the motor dynamic response performance. The One-click control method realized by preset parameters can reduce the driller's repeated operation and visual judgment. The tripping efficiency can be increased by 11.9%, reducing the driller's operation complexity and improving drilling safety. The application of phase-change heat dissipation system can reduce ambient noise to 72dB without external circulating pump. At present, over 10 sets of this new equipment have been delivered and industrial applications have been launched in CNPC Dagang Oilfield, CNPC Weiyuan National Shale-Gas Demonstration Zone and Sinopec NiuYe Shale-Gas Demonstration Zone. Till now nearly 20 wells have been conduct with running trouble-free throughout. Intelligent direct drive top drive of synchronous permanent magnet motor with phase change heat dissipation can not only improve the top drive mechanical transmission efficiency and extend the service life of main components, but also can reduce energy consumption and improve the automation level of top drive, making the top drive further satisfy the high-demanded requirements in drilling operation. We believe that there will be a great demand in deep wells, ultra-deep wells and unconventional oil and gas resources exploitation, which has a broad application prospect and good economic and social benefits.

In this paper, an aerostatic bearing model in the form of microorifice annular array is designed to explore the static performance of aerostatic bearing when the orifice diameter and working air film thickness are of the same order of magnitude. Firstly, the simulation model of the new bearing is established, the pressure distribution of the bearing gas film under the influence of the orifice diameter is analyzed by the CFD method, and the performance of the aerostatic bearing is compared with the traditional toroidal throttling method with the orifice diameter of 0.1 mm; at the same time, the effects of air supply pressure, orifice diameter, and orifice number on the static performance of the bearing under different air film thickness are analyzed; finally, a new bearing is developed, and the simulation results are verified by the experimental test. The results show that when the orifice diameter and the air film thickness are of the same order of magnitude, the maximum stiffness of the aerostatic bearing is significantly improved and the microporous throttled aerostatic bearing is more suitable for the field of high stiffness. The greater the air supply pressure, the greater the bearing capacity and stiffness of the bearing. The number of orifices has an effect on improving the bearing capacity of the bearing, but when the number of orifices is large, the effect will become less obvious. This study can provide a new theoretical reference for the design of aerostatic bearing.

In order to objectively evaluate the influence of qualitative indicators in the denture cleaning machine on the design of the denture cleaning machine, provide scientific decision-making for the design of the denture cleaning machine, and optimize the design plan. The AHP method is used to construct the evaluation model of the denture cleaning machine design scheme with aesthetics, economy, and functionality as the benchmark index. The relative weight of each design element is calculated through calculation, and the product scheme design is carried out after obtaining the design focus according to the index weight. Finally, the TOPSIS method is used to determine the distance between different design schemes and the optimal scheme, to realize the prioritization of various schemes, and to reduce the subjectivity and one-sidedness of design scheme evaluation. Comprehensive AHP and TOPSIS method to complete the design and optimization of the denture cleaning machine plan, providing reference for the design evaluation and optimization of the denture cleaning machine in the future.

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.

The oxygen compressor is one of the key components in the onboard oxygen generating system (OBOGS), with a high-pressure canister for backup. In this paper, a multistage compressor unit with a non-crank mechanism is proposed for the compression of the generated oxygen for storage in the high-pressure canister in the oxygen backup line of the OBOGS. The working principle, control strategy, and the design method of the key components of the non-crank compressor are provided to realize the preliminary design. The experimental study was carried out to investigate the control accuracy and the technical feasibility, including the compression capacity and the cooling performance. Results show that the motion control program could realize the motion scheme of the compressor with an error of less than 2%. The discharge pressure reached a relative stability after around 40 cycles of compression, while the discharge temperature achieved relative stability after approximately 100 cycles. The average discharge pressure at the last stage could meet the pressure requirement under standard working conditions. The average inlet temperature of the oxygen to the gasholder was 25 °C under standard working conditions.

The paper proposes a parallel time advance synchronization mechanism based on the overlap region of ABMS (Agent-based Modeling and Simulation). It is driven by events. Combines with the ABMS overlap region, it could ensure the correct execution event causal logic relationship and improve the simulation parallelism and simulation rate. The simulation results shows that the mechanism could be implemented on the X10 high-performance programming language and obtains a good acceleration effect.