Decoupling Control Analysis of a Flux Reversal Linear Rotary Permanent Magnet Actuator

Kaikai Guo,Youguang Guo,Jingzhao Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

In order to meet the requirement of industrial production, a control system of a novel fux reversal linear rotary permanent magnet actuator (FR-LRPMA) is developed in this paper, and the electromagnetic and motion decoupled process is analyzed in detail. Firstly, the control equation of FR-LRPMA is derived in the nine phase stator coordinate system and dual dq-axis mover coordinate system. Then the control model of FR-LRPMA is built in MATLAB/Simulink using improved space vector pulse width modulation (SVPWM), and the linear, rotary and spiral motions of the proposed actuator are achieved. Finally, the prototype of the actuator is manufactured, and the experiment platform of FR-LRPMA is set up to measure the cogging torque and linear detent force, validating the simulation results. It is concluded that the control system of FR-LRPMA can be converted into two independent single freedom motors by dual dq transformation. The improved SVPWM is efective in the control system, and the method can be used to solve the electromagnetic and motion decoupling problems.

Chaotic behavior of in-line bubbles rising with coalescences in non-Newtonian fluids: A multiscale analysis

Shaokun Jiang,Youguang Ma,Wenyuan Fan,Ke Yang,Huaizhi Li 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

The nonlinear dynamics of in-line bubbles rising with coalescence in non-Newtonian Carboxymethylcellulose sodium (CMC) fluids was studied through the techniques such as the multiresolution signal decomposition and the chaotic time series analysis. The temporary signals of bubble passages collected by an optical sensing device at different heights were investigated by a 12-level wavelet decomposition and the scalewise characteristics of bubble motion were extracted and analyzed. The chaotic time series analysis distinguished the periodicity or the deterministic chaos of bubble motion successsfully. The calculation of Kolmogorov entropy proves that in the ranges of experimental heights and gas flowrates, the bubble rising dynamics becomes more chaotic with the increase of height, and reaches the maximum chaotic extent in a certain height, while with the further increase of height, the chaotic extent decreases slowly. With the increase of gas flowrate, at the lower height, the bubble rising dynamics changes from periodicity to deterministic chaos, and at the higher heights it reaches the maximum chaotic extent in a certain gas flowrate; however,for both cases, it has little change in the higher gas flowrates. Moreover, with the increase of CMC concentration, the bubble rising dynamics becomes less chaotic when the height is beyond a certain value.

Design and Analysis of an Outer Mover Linear-Rotary Vernier Machine

Guo Kaikai,Guo Youguang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

According to the requirements of large torque and high precision linear displacement of the drilling robot, an outer mover (OM) linear-rotary (LR) vernier machine (VM) is proposed with a special support mechanism, which combines an outer rotor VM and a cylindrical OM linear VM. In order to reduce the detent force and improve the displacement accuracy of the linear motion when the proposed motor works at low speed and short stroke conditions, the modular stators and permanent magnet poles are adopted instead of the traditional toroid structure. Since the torque is the main output quantity and the linear motion mainly determines the linear displacement, the design of the rotary unit is taken as the optimization objective fi rstly. Then, the cogging torque and detent force of OMLRVM are added to the optimization objectives. The electromagnetic and mechanical designs of the proposed motor are calculated based on 3-D fi nite element model. Compared with the results of the initial topologies I and II, the end eff ects of rotary and linear units are reduced thanks to the support mechanism, and the amplitudes of cogging torque and detent force are decreased. The idea of combined electromagnetic and mechanical design is an eff ective way to solve the practical application problems in industrial fi eld.

11-kV Series-Connected H-Bridge Multilevel Converter for Direct Grid Connection of Renewable Energy Systems

Islam, Md. Rabiul,Guo, Youguang,Zhu, Jian Guo Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.2

Due to the variable nature of renewable energy resources and power demand by consumers, it is difficult to operate a power system installed with only one type of renewable energy resource. Grid-based renewable generation may be the only solution to overcome this problem. The conventional approach based on a low-voltage converter with power frequency transformer is commonly employed for grid connection of offshore renewable energy systems. Because of the heavy weight and large size of the transformer, the system can be expensive and complex in terms of installation and maintenance. In this paper, an 11-kV series connected H-bridge (SCHB) multilevel voltage source converter (VSC) is proposed to achieve a compact and light direct grid connection of renewable energy systems. This paper presents the design, simulation and analysis of a five level (5L)-SCHB and an eleven level (11L)-SCHB VSC for 11-kV grid-based renewable energy systems. The performance, cost, modulation scheme and harmonic spectra of the converter are analyzed.

Asymmetrical breakup and size distribution of droplets in a branching microfluidic T-junction

Pengcheng Ma,Taotao Fu,Chunying Zhu,Youguang Ma 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.1

The breakup and distribution of droplets at a branching T-junction were investigated experimentally by a high-speed camera. The effects of two-phase flow rates, two-phase Reynolds number and capillary number of the dispersed phase on droplet volume distribution were studied. The results indicated that the volume distribution ratio  decreases first and then increases with the increase of two-phase flow ratio Qd/Qc. Similarly, as the Reynolds number Rec of the continuous phase increases, the volume distribution ratio  also decreases at first and then increases. The increase of Reynolds number Red of the dispersed phase would lead to a reduction in the volume distribution ratio . Moreover, the increase of the capillary number Cad of dispersed phase could result in an increase in the volume distribution ratio . Correlations for predicting the volume distribution ratio were proposed, and the calculated results show good agreement with experimental data.

Bubble formation in a step-emulsification microdevice: hydrodynamic effects in the cavity

Zhiwei Zhang,Zhongdong Wang,Fengrui Bao,Mengyu Fan,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-

This study focuses on the generation of bubbles in a step-emulsification microdevice via a two-anglephotography method. It's found that the bubble generation mechanism is controlled by the interfacialtension, below a critical capillary number; while controlled by viscous force, inertial force and thedisturbance induced by the bubble swarm, above the critical capillary number. From the two-anglephotography method, a model is established for predicting the bubble size, by taking into account of thedynamic contact angle between gas-liquid interface and wall, and the hydrodynamic feedback of thecavity on bubble formation via the quantification of resistance by the volume fraction of gas in the cavity.

Effects of the resultant force due to two-phase density difference on droplet formation in a step-emulsification microfluidic device

Zhiwei Zhang,Mengyu Fan,Qianqiao Wang,Huaiyu Li,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.110 No.-

This study focuses on the influence of the resultant force caused by the density difference of the twophases on the droplet generation process in a step-emulsification microfluidic device. Threedimensionalvisualization is used to observe the characteristics of droplet generation. According to thedifference in droplet generation form, it can be divided into drip generation mode and suspended generationmode. In the suspended generation mode, the droplets are more inclined to the formation process ofthe expansion of the ellipsoid, whose size in the horizontal direction is larger than the vertical direction;while in the drip generation mode, the shape of the droplet is opposite. The control stage of the dropletgeneration under various operating conditions is determined. As the viscosity of the dispersed phaseincreases, the control stage of the suspended generation mode is the necking stage, and the control stageof the drip generation mode changes from the first stage of three-dimensional expansion to the neckingstage. The model of the droplet generation is proposed by combining mechanical analysis and experimentaltesting data, and the droplet size prediction formula is thereby obtained.

Comparison of formation of bubbles and droplets in step-emulsification microfluidic devices

Wei Zhang,Ziwei Liu,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-

Monodispersed microbubbles and microdroplets are widely used as reaction carriers in microfluidics. Inthis study, the generation processes of bubbles and droplets in a step-emulsification microfluidic deviceare compared to show the similarities and differences in the emulsification process. By changing theplacement of the microdevice, the effects of buoyancy and gravity on the generation of bubbles and dropletsare introduced, and the feedback mechanism of the bubble layer and the effect of droplet accumulationon the emulsification process are clarified. Finally, based on the analysis of the difference of thepinch-off of the dispersed phase between the bubble and the droplet in this configuration, the Plateau-Rayleigh instability processes for the formation of bubble and droplet are revealed by using a highspeedcamera system, and the reasons for the difference of the operating ranges of the gas flow rateand liquid flow rate in the dripping flow regime are explained.

Manipulation of microdroplets at a T-junction: Coalescence and scaling law

Rui Ma,Qindan Zhang,Taotao Fu,Chunying Zhu,Kai Wang,Youguang Ma,Guangsheng Luo 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

The manipulation of a droplet at a microfluidic T-junction is achieved via adding reagents into the droplet with the same solution. Three types for droplet coalescence at the T-junction were observed: tail coalescence, slipping coalescence and unsteady coalescence behaviors with a new droplet formation. The final droplet size decreased (increased) with increasing the capillary number when the flow rate of the dispersed (continuous) phase was fixed. The final droplet size increased with increasing the capillary number of the added phase. The correlations for predicting the coalesced droplet size for tail and slipping coalescence were proposed.

Breakup dynamics of ferrofluid droplet in a microfluidic T-junction

Rui Ma,Taotao Fu,Qindan Zhang,Chunying Zhu,Youguang Ma,Huai Z. Li 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

This paper investigated the breakup dynamics of ferrofluid droplet in a microfluidic T-junction with the magnetic field. Droplet breakup types with permanent obstruction, part obstruction and without obstruction were observed. The droplet breakup processes with permanent and part obstruction could be divided into squeezing, transition and pinch-off stages. The minimum width of droplet neck could be scaled as power-law relationships with time for squeezing stage and with remaining time for the last two stages. The droplet breakup process without obstruction has only last two stages. The results show that the magnetic field could affect the dynamics of droplet breakup.