Because the synchronous reluctance motor (SynRM) does not require a rare-metal-based permanent magnet (PM), the demand for SynRMs is progressively increasing because of the inexpensive design. ...However, due to the disuse of the PM, the average torque of the SynRM is much lower than that of an interior PM synchronous motor. Although many shapes of the flux barrier have been reported for the improvement of the torque characteristics, most of them are derived from the shape optimization method. Since the topology of the rotor and stator core is fixed during shape optimization, there is the possibility of further improving the torque performance using topology optimization (TO). Furthermore, it is very important to reduce the iron loss as well as to improve the torque characteristics to improve the SynRM efficiency. In this article, a sensitivity analysis of the iron loss using the adjoint variable method is proposed. The procedure is successfully implemented for a TO based on a level-set method, and design optimization of the SynRM for reducing iron loss as well as improving the torque characteristics is demonstrated.
In order to provide guidance and reference for developing a ball screw drive system of the high-speed machine tool, this article investigates three basic issues with consideration of dynamics, ...including mechanical characteristics, inertia matching problem, and driving torque characteristics. The axial stiffness and natural frequency of the system are first calculated to verify the correctness of mechanical parts selection, and the stability of the system is ensured by designing an appropriate gain. vvNext, the inertia matching problem between the servo motor and load is analyzed based on the two-inertia-system, and the range of the inertia ratio is determined as an important principle in developing a ball screw drive system. The speed-torque characteristics are further discussed, and a graphical method is proposed to quickly and accurately determine a suitable servo motor. Finally, a complete flow is described, and the ball screw drive systems of a high-speed machine tool for aeroengine casing manufacturing are developed as an application. The actual test results of speed, accuracy, cutting ability, and machining performance indicate that the developed ball screw drive systems have a satisfactory performance, which validate the effectiveness of the comprehensive study.
To solve the nonlinear fitting problem of three-dimensional (3-D) data, an improved multi-dimensional Taylor network (MTN) structure based on the error backpropagation (BP) algorithm is proposed in ...this paper. Compared to the traditional MTN, the so-called BP-MtN has three main characteristics: 1) an additional full connection layer is added after the same dimension output layer of the traditional MTN to describe the dynamic evolution of the nonlinear system state; 2) adding activation function to improve the ability of network fitting; and 3) the weights of the BP-MTN are trained using the BP algorithm. Compared to the traditional artificial neural networks, the improved MTN has a simpler structure without complex calculations, thus can ensure better real-time operation performance. For verification, the measured 3-D nonlinear torque characteristics of a 5kW switched reluctance motor in an electric vehicle application are modeled with the proposed BP-MTN algorithm. Experimental results show that BP-MTN performs well in terms of model training time and fitting capability.
AbstractThis study presents an innovative approach to attitude control in microsatellites by utilizing a spherical magnetohydrodynamic attitude control device (MHD-SACD) for three-axis attitude ...adjustments. A novel method is developed to quantify the output torque generated by this device, analyzing the relationship between torque, voltage, and average fluid velocity. Utilizing the energy conservation principle, an equivalent coupling circuit for the MHD-SACD is derived to assess its power dynamics. This leads to the formulation of the electromagnetic torque equation. Additionally, simulations are conducted to calculate friction torque and resultant output torque. The findings provide a qualitative assessment of the device’s torque characteristics, serving as a reference for future design optimization and setting the stage for subsequent experimental investigations. This study introduces a groundbreaking perspective to the domain of microsatellite attitude control.
Strip-tillage research in developing countries usually relies on commonly used rotary blades designed for conventional full disturbance soil tillage. With the aim of optimising the blade geometry and ...operational settings, this study investigated the effect of three blade geometries (conventional, half-width and straight) at four rotary speeds (125, 250, 375, and 500 rpm) on torque, power and energy characteristics. A single row rotary tiller was fitted with the blades set at a cutting width of 50 mm and depth of 50 mm and tested in a soil bin (sandy loam soil). Analyses of high speed video images and corresponding blade motion revealed that the peak torque occurred at a higher blade penetration depth as the speed increased indicating transformation of the peak torque requirement from due to initial soil failure at a low speed to final soil cutting and throwing at a high speed. The straight blade design required the least torque, average power, peak power, specific energy and effective specific energy at 375–500 rpm which targeted for a small bite length for a fine soil tilth. The straight blade saved 20–25% power when compared with the conventional and half-width blades at 500 rpm. Although, the average power, peak powerand specific energy requirements increased with the rotary speed for all the blades with a steep rise over 375 rpm, the effective specific energy requirement remained almost unchanged for the straight blade indicating its high effectiveness for strip-tillage operations.
•Torque requirement was dependent upon rotary speed rather than the blade geometry.•Peak torque requirement was at least twice the average torque for any blade geometry.•Power and specific energy requirements increased with rotary speed (all blades).•Straight blade design saved 20–25% power over conventional blade at 500 rpm.•Effective specific energy remained low for straight blade even at high speed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
In this article, a flux-controllable permanent magnet (FC-PM) motor has been designed and optimized to achieve the optimal torque component distribution under different flux leakage conditions. The ...FC-PM motor can realize flexible adjustment and control of air-gap magnetic field by a reasonable flux bridge design, which further broadens the speed range of the motor effectively. The focus of the research is to analyze and optimize the torque characteristics in combination with typical operation conditions. First, a motor topology is proposed and then the mechanism of flux leakage and the distribution of torque characteristics are studied. Then, according to different flux leakage operation conditions, an optimization method considering the torque component distribution is newly proposed. Based on the proposed optimization method, the optimal motor can be obtained. Finally, the performance of the optimal motor is analyzed and compared with the initial motor. The comparison results indicate that, based on the proposed optimization method, the torque output capability is improved effectively, while the desired leakage flux adjustment range is maintained.
As a auxiliary braking device in vehicle’s downhill process, parallel hydraulic retarder has strict requirements for its rapidity of response performance and accuracy of braking torque. The parallel ...hydraulic retarder uses high-pressure gas as the control medium, which pushes the oil into the working chamber through the high-speed on/off valve. Because the oil filling process of the chamber is an indirect process, the complicated gas–liquid movement during the oil filling period affects the accuracy and response of the braking process. In this paper, the mechanical characteristics of high-speed on/off valve had analyzed by computational fluid dynamics. The oil filling system’s characteristics has analyzed, which had verified by experimental data. Compared with the three dimensional method to directly analyze the response process of the oil charging and discharging system, it has the characteristics of simplicity and fast calculation.The modeling method used in this paper is mainly suitable for hydraulic system which uses air pressure and liquid as control medium. This integration model can obtain the characteristics of valve group more accurately and has certain novelty rather than Theoretical formula calculation. Then the influence of different control pressure and input speed on transient braking response has discussed and analyzed. The results has showed that the shortest opening response time is 1.49 s when the control pressure is 3.2 bar. With the decrease of the oil amount and speed, the oil-discharging response time increases gradually. When the speed is 1800 rpm and the liquid filling rate is 25 %, the oil discharge time reaches 5.48 s.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The cycloid magnetic gear transfers speed through the inner rotor rotation and revolution to get a higher transmission ratio and torque density. The permanent magnets were arranged by Halbach in ...order to improve the magnetic flux leakage and the utilization of permanent magnets,and a prototype was designed and manufactured according to the working principle. The magnetic field distribution and static torque characteristics of the cycloid permanent magnetic gear were researched by finite element simulation. Comparing with the general structure,it shows that the maximum torque density of even value can be increased by about 30% using 90° Halbach structure which has smaller fluctuations. Finally,the transmission torque of different angle were tested by experiments,the results are in accord with simulated results.
This study proposes a novel asymmetric rotor structure with tuning-fork flux barriers for a permanent magnet (PM)-assisted synchronous reluctance machine (PMA-SynRM) to improve the torque ...characteristics. The proposed asymmetrical rotor structure can effectively decrease the flux leakage inside the rotor, as well as ensure the maximum values of the magnetic torque and the reluctance torque are near the same current phase angle as each other to achieve better utility. To realise this, the frozen permeability method is implemented to separate the total torque into the reluctance torque and the magnetic torque via a two-dimensional finite-element method – JMAG-Designer. To achieve the optimal torque characteristics in the proposed model, the Kriging method and a genetic algorithm are used for getting the optimised model. The contribution of this investigation into motor performance is validated by comparing the proposed model with a conventional PMA-SynRM with a symmetric rotor structure. Beyond that, all machine models are the same size, have the same number of magnets and are operated under the same conditions. A prototype of the proposed model is experimentally verified, i.e. the simulation results agree with the experimental results.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
