Hao Rong, Baoming Wang, Wei‐Qing Lin, Lichao Sun, Jin‐Cheng Zheng and Miao Lu
The purpose of this paper is to report a simple, room temperature approach to assemble dense, vertically aligned single‐walled carbon nanotubes (SWNTs) between a chip and its…
Abstract
Purpose
The purpose of this paper is to report a simple, room temperature approach to assemble dense, vertically aligned single‐walled carbon nanotubes (SWNTs) between a chip and its substrate acting as a kind of thermal interface material by virtue of better mechanical and thermal properties.
Design/methodology/approach
Two silicon chips, with shallow trenches about 2 μm deep on the surface, were pressed together face to face with the trench direction perpendicular to each other. SWNT aqueous solution was driven into the gap between the two chips by capillary force. Later, the sample was baked to remove the moisture completely.
Findings
SWNTs beams were found to be assembled in the gap and have their two ends bonding with the interface of the two chips, respectively. The shear strength of the two chips was measured, and the thermal conductivity of the stacked chip‐SWNTs‐chip was tested using a laser flash method. In result, shear strength up to about 100 kPa, and an average thermal conductivity of 19.3 W·m−1·K−1 were demonstrated.
Originality/value
The paper proposes an approach to grown dense SWNT array bridging a chip and its substrate, and these SWNTs have potential capability to provide mechanical strength and higher thermal conductance instead of commercial thermal interface materials.
Details
Keywords
Xilian Wang, Baoming Ge and Jin Wang
The novel bearingless switched reluctance motor (BSRM) is proposed recently, which is different from the conventional BSRM in the stator structure and suspension winding…
Abstract
Purpose
The novel bearingless switched reluctance motor (BSRM) is proposed recently, which is different from the conventional BSRM in the stator structure and suspension winding arrangement. The reduced number of suspension windings makes the novel BSRM much simpler, so that the control circuit and algorithm are greatly simplified when compared to those of the conventional BSRM. This paper for the first time proposes the novel BSRM's analytic model, including the mathematical relationships among the winding currents, rotor angle, radial forces, and motor torque, to further achieve the suspending forces and torque control. The paper aims to discuss these issues.
Design/methodology/approach
The magnetic equivalent circuit method is employed to obtain the self-inductances and mutual-inductances of the motor torque windings (main windings) and suspension windings (control windings). The straight flux paths are combined with the elliptical fringing flux paths to calculate the air-gap permeances, and the stored magnetic energy. Then, the mathematical expressions of radial forces and torque are derived. A novel BSRM prototype is analyzed through using the proposed analytical model and the finite element model. The results of both methods are compared to verify the proposed mathematical model.
Findings
The proposed mathematical model of the novel BSRM considering unsaturated magnetic circuits is verified by finite-element analysis results.
Research limitations/implications
The mathematical model represents the situation of magnetic circuit unsaturated and is not suitable for the magnetic circuit saturation. It cannot be used to control the motor which is working in the deep magnetic circuit saturation region.
Practical implications
Building mathematical model is a necessary step for the motor's suspension and rotating control. The built model provides the fundamental for the preliminary control algorithm and experimental study of this novel BSRM.
Originality/value
For the first time, the novel BSRM's mathematical model is proposed. It provides necessary fundamental for the motor's further analysis, design, and suspending and rotating controls.
Details
Keywords
Xilian Wang, Baoming Ge, Zhaoli Wu and Fernando J.T.E. Ferreira
This paper seeks to propose a novel bearingless switched reluctance motor (BSRM).
Abstract
Purpose
This paper seeks to propose a novel bearingless switched reluctance motor (BSRM).
Design/methodology/approach
The operating principle and structure characteristics of the proposed three‐phase 12/8‐pole BSRM is analyzed in detail. Finite element method‐based calculations are applied to a prototype and some important characteristics are obtained, including radial force, static torque, air‐gap magnetic flux density, and effect of control winding current on the torque, where magnetic saturation is taken into account by using a nonlinear B‐H curve.
Findings
On the basis of the simulated results, it can be concluded that the proposed BSRM presents an excellent performance in the suspending force and in the torque. The analyzed results show that the two control‐winding currents can effectively control the radial suspending forces and produce negligible effect on the motor torque, which is mainly produced by the main‐winding currents.
Originality/value
In this paper, a novel BSRM is proposed. Instead of the six sets of radial suspending control windings required by conventional three‐phases BSRM, the proposed structure requires only two sets of suspending control windings, regardless of the phase number, leading to a simpler power converter with less power switches, thus lowering the overall system cost.
Details
Keywords
Qingqing Ma, Baoming Ge, Daqiang Bi, Fernando J.T.E. Ferreira and Aníbal T. de Almeida
The purpose of this paper is to propose a new three-phase switched reluctance motor (SRM), and achieve high-torque and low-cost. This new SRM's winding configuration uses the…
Abstract
Purpose
The purpose of this paper is to propose a new three-phase switched reluctance motor (SRM), and achieve high-torque and low-cost. This new SRM's winding configuration uses the double-layer distributed windings, which is different from the conventional SRM's single tooth coils.
Design/methodology/approach
The operating principle of new SRM is analyzed, and the voltage equation and the generated torque are deduced. Finite element method (FEM) and finite element circuit coupled method are utilized to evaluate the new motor's operating performances. The two dimensional (2D) frequency response analysis model is employed in the FEM model. Based on the 2D frequency response analysis model, the magnetic field distribution, self-inductance, and mutual-inductance for the new SRM are analyzed in detail. A co-simulation model using FE analysis package and Matlab-Simulink is proposed to simulate the new SRM drive. The simulated and experimental results verify the new SRM.
Findings
For the new SRM with double-layer distributed windings, a co-simulation method is proposed to analyze its characteristics. The new SRM presents lower torque ripple coefficient and generates larger torque than the conventional SRM, with three-wire and standard full bridge power converter, rather than six-wire and asymmetric half-bridge converter for conventional SRM.
Originality/value
This paper proposes a new SRM with the double-layer distributed windings driven by a standard full bridge inverter. In order to calculate dynamic characteristics of the new SRM, a co-simulation method using FEM and Simulink is proposed to simulate the new SRM drive, where the power inverter and the current chopping control algorithm are implemented.
Details
Keywords
Qingqing Ma, Baoming Ge, Daqiang Bi, Fernando J.T.E. Ferreira and Aníbal T. de Almeida
The S-MCSRM is a two-phase excited switched reluctance motor (SRM), with the short flux path and mutual inductance coupling, which is suitable for the oil submersible pump…
Abstract
Purpose
The S-MCSRM is a two-phase excited switched reluctance motor (SRM), with the short flux path and mutual inductance coupling, which is suitable for the oil submersible pump application owing to large torque and three-wire connection with the standard full-bridge power converter. However, there is not literature to disclose its model due to the complicated mutual inductance coupling. The FEM model is a time-consuming method to analyze this motor. For the first time, this paper aims to propose an S-MCSRM model for performance analysis and control method developing. The proposed model would save simulation time and be a theoretical fundamental for further implementing control algorithm.
Design/methodology/approach
The S-MCSRM's operating principle is analyzed, and the voltage equation and the generated torque are deduced. The FEM is utilized to obtain the five typical magnetization curves that describe the S-MCSRM's magnetic path characteristic. The magnetic co-energy equation, phase torque and total torque equations are obtained. From the basic voltage equation, the S-MCSRM's state space model is built for the dynamic analysis and control purpose. The S-MCSRM is widely analyzed in detail by using the proposed model and comparison with the conventional SRM. JMAG finite element package is used to verify the proposed model.
Findings
The proposed modeling method is validated by the identical results to those from FEM-based JMAG software. The proposed model just takes second-level time, which is far less than minute-level time consuming of FEM method. The S-MCSRM generates larger torque than the conventional SRM, with three-wire and standard full bridge power converter, and it is confirmed that the S-MCSRM is suitable for the oil submersible pump applications.
Originality/value
This paper proposes a new modeling method for the S-MCSRM to exactly analyze the motor's operating performances, and also it is a theoretical fundamental for developing control algorithm. The proposed model saves much time in analysis, calculation, and simulation, when compared to the FEM method. The completed analysis including flux linkages, torque, torque-ripple, and torque-speed characteristic discloses the S-MCSRM's steady-state operating performances, which provides the deep insight for this kind of motor's applications.
Details
Keywords
Shuo Liu, Baoming Ge, Xinjian Jiang, Haitham Abu-Rub and Fangzheng Peng
– The paper aims to propose a new type of three-phase quasi-Z-source indirect matrix converter (QZSIMC) to extend the voltage gain for application in the induction motor drives.
Abstract
Purpose
The paper aims to propose a new type of three-phase quasi-Z-source indirect matrix converter (QZSIMC) to extend the voltage gain for application in the induction motor drives.
Design/methodology/approach
A unique H-shape quasi-Z-source network is connected between the three-phase voltage source and traditional indirect matrix converter to achieve the voltage boost and buck in a single-stage power conversion. The complete space vector modulation (SVM) method is proposed to control the proposed QZSIMC. The output voltage amplitude of quasi-Z-source network can be boosted by the shoot-through of the front-end rectifier, so the whole system's voltage gain is extended. Meanwhile, the QZSIMC modeling and quasi-Z-source impedance parameter design are developed by using the state space averaging method. The design-oriented analysis based on small signal model is used to investigate the quasi-Z-source impedance parameter's impact on the QZSIMC's dynamic performance. A simulated application example employs a 4-kW induction motor drive to verify the proposed QZSIMC, the developed modulation method and parameter design method.
Findings
The proposed QZSIMC can achieve high voltage gain larger than one and also can fulfill buck function, which widens the induction motor drive's operation range. The simulation results verify the proposed QZSIMC and SVM and also validate the quality performance of the proposed induction motor drive and all theoretical analysis and parameter design method.
Originality/value
The proposed QZSIMC effectively overcomes the limitation of traditional indirect matrix converter, through extending the voltage gain larger than one. The systematic principle, analysis, parameter design, and simulation verification provide the proposed QZSIMC with a feasible approach in practical induction motor drive applications.
Details
Keywords
S. Sangiamsuk, B. Bubphachot, O. Watanabe and S. Rittidech
The purpose of this paper was to study the parameters affecting corrosion of the closed-loop oscillating heat-pipe with check valves (CLOHP/CV) in a system in clear that will be…
Abstract
Purpose
The purpose of this paper was to study the parameters affecting corrosion of the closed-loop oscillating heat-pipe with check valves (CLOHP/CV) in a system in clear that will be basic data to be used in future research. The majority of research focuses on the inner surface corrosion heat-pipe systems. The CLOHP/CV is commonly favored in cooling electronic devices, etc. Despite these common applications, limited reliable experimental research findings are available on the operation of the CLOHP/CV. Because of these reasons, the lack of detailed data, working fluids effect, working temperatures and duration of testing of the CLOHP/CV, this study focuses on determining the actual inner surface corrosion.
Design/methodology/approach
Seven types of copper tubes used in the CLOHP/CV set were sectioned to observe their inner surfaces. Seven different specimens with tube corrosion were examined by a visual inspection, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The technique for detecting metals solution in samples is based on the fact that ground state metals absorb light at specific wavelengths. Metal ions in a solution are converted to atomic state by means of a flame. In this study, concentration of copper particle in the working fluid was found by flame atomic absorption spectroscopy (Flame-AAS) and elements that occurred on inner surface tube were analyzed by EDX.
Findings
The analyses with SEM and EDX testing found that the character corrosion of inner surface of CLOHP/CV was pitting clearly. The analysis with Flame-AAS found that the concentration of copper particles in the distilled water and ethanol as working fluid is more than after 1,000 hours until 3,000 hours because of excess volume of oxygen in working fluid which causes many reactions at the beginning. When the oxygen decreases after 1,000 hours, it causes the reaction to decrease too and get the most concentration of copper particles, i.e. 18.57228 ppm or 0.40859 mg.
Originality/value
Corrosion-dependant maintenance must also be factored into the design. Producing reliable equipment that will become standardized and fixing the time for proper maintenance will require individuals that are knowledgeable about the materials that are going to be used in the design of such equipment. Nowadays, the lack of detailed data of working fluids effect, working temperatures and duration of testing of the CLOHP/CV focuses on determining the actual inner surface corrosion. Therefore, this research aimed to study the parameters affecting corrosion of the CLOHP/CV in a system in clear that will be basic data to be used in future research.