Efficient cooling method helps to improve the output performance of a motor, and liquid cooling is one of the best cooling methods. In this paper, a linear resonant testing platform is proposed to simulate the reciprocating motion of the linear oscillating motor, in which two check valves are adopted to achieve the cooling oil circulating. The thermal model is presented to calculate the thermal distribution of the testing platform in the condition with and without cooling oil for different current inputs. Shear stress model of the oil is built and mixing losses is systematically calculated to analyze the fluid damping characteristics. The relationship of the pressure, driving force, viscous, wall shear stress and mixing losses with the oil velocity is detailedly analyzed. The thermal analysis and fluid mixing losses formulation of the testing platform provide theoretical references for the design optimization and work efficiency improvement of the linear oscillating motor.
Linear motor has potential applications in electric vehicles because of high efficiency and convenient maintenance. However, existing researches are mainly about linear motors, rarely focusing on its loading system. Actually its complicated motion pattern requires accurate and multi-mode load simulation to evaluate output performance comprehensively. In this paper, a novel multi-mode and accurate load simulation system for linear motor is proposed. Dual-array Halbach magnetized voice coil motor is used for desired force loading. Meanwhile, various dual magnet arrays are compared on force stability and axial eccentric force, which leads to an effective solution to linear loading system design.
Abstract As two‐dimensional (2D) materials, bismuth (Bi) has large interlayer spacing along c‐axis (0.395 nm) which provides rich active sites for sodium ions, thus guaranteeing high sodium ion storage activity. However, its poor electrical conductivity, combined with its degraded cycling performance, restricts its practical application. Herein, Bi microsphere coated with nitrogen‐doped carbon (Bi@NC) was synthesized. Owing to the unique Bi crystals and nitrogen‐doped carbon layer, the obtained Bi@NC anode exhibited satisfactory cycling stability and superior rate capability. Moreover, after assembling Bi@NC anode with Na 3 V 2 (PO 4 ) 3 @C cathode to full battery, excellent sodium storage performance was obtained (57 mA h g −1 after 2000 cycles at 1.0 A g −1 ).
Aerospace vehicle is the next-generation space transportation system with horizontal take-off/Landing and reusable features. However, due to its hypersonic speed, super-maneuver and safety performance, conventional servo system can no longer satisfy the harsh requirements of high dynamic response and reliability in aerospace vehicles. In this paper, an electric direct-drive servo system is proposed based on novel limited angle torque motor to achieve fast frequency response and fault-tolerant simultaneously. For the motor, outer-rotor topology with compound Halbach array is researched to enhance output performance. In addition, multiple single-phase windings with flat wire are designed to facilitate redundancy configuration in the stator. Firstly, the structure of the novel motor and operation principle of the system is presented. Then, focusing on the topology, electromagnetic finite-element (FE) analysis and comparison are conducted to validate its output advantages. Finally, electric redundancy configuration method is demonstrated. And it is expected to provide a new solution to aerospace servo system.
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