The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a cu...The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.展开更多
Control methods of hysteresis current vector control of permanent magnet synchronous servo drive fed by voltage source inverter are examined. Detailed description of the control methods in stationary reference frame w...Control methods of hysteresis current vector control of permanent magnet synchronous servo drive fed by voltage source inverter are examined. Detailed description of the control methods in stationary reference frame with circle, square and hexagon shape tolerance area using adaptive solutions is presented. The theoretical considerations are supported by simulation results.展开更多
The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials...The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials developed based on a single biological structure still have limitations regarding overall performance and design freedom.Herein,a dual-structure element combination model with a butterfly-wing porous structure and moth-eye raised structure arranged in an orderly manner is estab-lished.Carbonyl iron and polyurethane are mixed as wave absorbents,and the model is utilized to make a biomimetic metamaterial(CSMA),which has an absorption rate of more than 90%at 6.07-18 GHz,achieving broadband effective absorption.It has been verified that the two biostructures designed after an ordered arrangement show synergistic effects in the combined model,and the cooperation between the structures induces the formation of current vector vortices,which are able to induce microwave losses to broaden the effective absorbing bandwidth.Further,the model has the combined application performance of polarization insensitivity,strong stability of oblique incidence,and low bistatic RCS.Such a thought based on the combination of multiple components provides an effective strategy for the design of broadband-absorbing metamaterials.展开更多
Finite-control-set model predictive control(FCSMPC)has advantages of multi-objective optimization and easy implementation.To reduce the computational burden and switching frequency,this article proposed a simplified M...Finite-control-set model predictive control(FCSMPC)has advantages of multi-objective optimization and easy implementation.To reduce the computational burden and switching frequency,this article proposed a simplified MPC for dual three-phase permanent magnet synchronous motor(DTPPMSM).The novelty of this method is the decomposition of prediction function and the switching optimization algorithm.Based on the decomposition of prediction function,the current increment vector is obtained,which is employed to select the optimal voltage vector and calculate the duty cycle.Then,the computation burden can be reduced and the current tracking performance can be maintained.Additionally,the switching optimization algorithm was proposed to optimize the voltage vector action sequence,which results in lower switching frequency.Hence,this control strategy can not only reduce the computation burden and switching frequency,but also maintain the steady-state and dynamic performance.The simulation and experimental results are presented to verify the feasibility of the proposed strategy.展开更多
With the advent of Computer Algebra System (CAS) such as Mathematica [1], challenging symbolic longhand calcula-tions can effectively be performed free of error and at ease. Mathematica’s integrated features allow th...With the advent of Computer Algebra System (CAS) such as Mathematica [1], challenging symbolic longhand calcula-tions can effectively be performed free of error and at ease. Mathematica’s integrated features allow the investigator to combine the needed symbolic, numeric and graphic modules all in one interactive environment. This assists the author to focus on interpreting the output rather than exerting the efforts of relating the scattered separate modules. In this note the author, utilizing these three features, explores the magneto-static field and its associated vector potential of a steady looping current. In particular by deploying the numeric features of Mathematica the exact value of the vector potential of the looping current conducive to its 3D graph is presented.展开更多
The solution of Grad-Shafranov equation determines the stationary behavior of fusion plasma inside a tokamak. To solve the equation it is necessary to know the toroidal current density profile. Recent works show that ...The solution of Grad-Shafranov equation determines the stationary behavior of fusion plasma inside a tokamak. To solve the equation it is necessary to know the toroidal current density profile. Recent works show that it is possible to determine a magnetohydrodynamic （MHD） equilibrium with reversed current density （RCD） profiles that presents magnetic islands. In this work we show analytical MHD equilibrium with a RCD profile and analyze the structure of the vacuum vector potential associated with these equilibria using the virtual casing principle.展开更多
为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(d...为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(dead-time voltage vector based MPCC,DTVV-MPCC)。首先介绍了死区时间对MPCC的影响,分析了MPCC中存在的死区电压矢量(dead-time voltage vector,DTVV)的形成过程。其次区分了MPCC性能的有利DTVV和非有利DTVV,并分析了有利DTVV的优势。最后优化了死区作用时间。仿真结果表明该控制方法下的电流稳态控制性能要优于传统的MPCC方法。展开更多
为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和...为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和损耗模型,将齿槽转矩引起的系统转矩脉动作为扩展状态变量,与电流环的反馈电流一起构造系统扩张状态空间方程.在状态估计过程中引入了遗忘因子,提高观测精度和速度.与基于谐波电流注入法抑制齿槽转矩的控制方法进行了控制性能和突变工况对比.结果表明:所提出控制方法在低速时转矩脉动降低了43.5%,电损耗降低了14.8%,能更有效抑制齿槽转矩脉动和提高系统效率.展开更多
基金Project(51507188)supported by the National Natural Science Foundation of China
文摘The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.
文摘Control methods of hysteresis current vector control of permanent magnet synchronous servo drive fed by voltage source inverter are examined. Detailed description of the control methods in stationary reference frame with circle, square and hexagon shape tolerance area using adaptive solutions is presented. The theoretical considerations are supported by simulation results.
文摘The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts,and the design ideas of wave-absorbing metamaterials have been greatly broadened.How-ever,stealth materials developed based on a single biological structure still have limitations regarding overall performance and design freedom.Herein,a dual-structure element combination model with a butterfly-wing porous structure and moth-eye raised structure arranged in an orderly manner is estab-lished.Carbonyl iron and polyurethane are mixed as wave absorbents,and the model is utilized to make a biomimetic metamaterial(CSMA),which has an absorption rate of more than 90%at 6.07-18 GHz,achieving broadband effective absorption.It has been verified that the two biostructures designed after an ordered arrangement show synergistic effects in the combined model,and the cooperation between the structures induces the formation of current vector vortices,which are able to induce microwave losses to broaden the effective absorbing bandwidth.Further,the model has the combined application performance of polarization insensitivity,strong stability of oblique incidence,and low bistatic RCS.Such a thought based on the combination of multiple components provides an effective strategy for the design of broadband-absorbing metamaterials.
基金supported by the National Natural Science Foundation of China under Grant 5227705。
文摘Finite-control-set model predictive control(FCSMPC)has advantages of multi-objective optimization and easy implementation.To reduce the computational burden and switching frequency,this article proposed a simplified MPC for dual three-phase permanent magnet synchronous motor(DTPPMSM).The novelty of this method is the decomposition of prediction function and the switching optimization algorithm.Based on the decomposition of prediction function,the current increment vector is obtained,which is employed to select the optimal voltage vector and calculate the duty cycle.Then,the computation burden can be reduced and the current tracking performance can be maintained.Additionally,the switching optimization algorithm was proposed to optimize the voltage vector action sequence,which results in lower switching frequency.Hence,this control strategy can not only reduce the computation burden and switching frequency,but also maintain the steady-state and dynamic performance.The simulation and experimental results are presented to verify the feasibility of the proposed strategy.
文摘With the advent of Computer Algebra System (CAS) such as Mathematica [1], challenging symbolic longhand calcula-tions can effectively be performed free of error and at ease. Mathematica’s integrated features allow the investigator to combine the needed symbolic, numeric and graphic modules all in one interactive environment. This assists the author to focus on interpreting the output rather than exerting the efforts of relating the scattered separate modules. In this note the author, utilizing these three features, explores the magneto-static field and its associated vector potential of a steady looping current. In particular by deploying the numeric features of Mathematica the exact value of the vector potential of the looping current conducive to its 3D graph is presented.
基金State University of Campinas and CNPq (brazili anagency) for financial support
文摘The solution of Grad-Shafranov equation determines the stationary behavior of fusion plasma inside a tokamak. To solve the equation it is necessary to know the toroidal current density profile. Recent works show that it is possible to determine a magnetohydrodynamic （MHD） equilibrium with reversed current density （RCD） profiles that presents magnetic islands. In this work we show analytical MHD equilibrium with a RCD profile and analyze the structure of the vacuum vector potential associated with these equilibria using the virtual casing principle.
文摘为了减少模型预测控制中因死区时间引起的电压和定子电流的误差,在永磁同步电机(permanent magnet synchronous motor,PMSM)模型预测电流控制(model predictive current control,MPCC)基础上采用了一种基于死区电压矢量的优化MPCC方法(dead-time voltage vector based MPCC,DTVV-MPCC)。首先介绍了死区时间对MPCC的影响,分析了MPCC中存在的死区电压矢量(dead-time voltage vector,DTVV)的形成过程。其次区分了MPCC性能的有利DTVV和非有利DTVV,并分析了有利DTVV的优势。最后优化了死区作用时间。仿真结果表明该控制方法下的电流稳态控制性能要优于传统的MPCC方法。
文摘为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和损耗模型,将齿槽转矩引起的系统转矩脉动作为扩展状态变量,与电流环的反馈电流一起构造系统扩张状态空间方程.在状态估计过程中引入了遗忘因子,提高观测精度和速度.与基于谐波电流注入法抑制齿槽转矩的控制方法进行了控制性能和突变工况对比.结果表明:所提出控制方法在低速时转矩脉动降低了43.5%,电损耗降低了14.8%,能更有效抑制齿槽转矩脉动和提高系统效率.
