Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deterio...Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deteriorates the SHL seriously. The shape of the grain and the grain boundary affect the intensity of demagnetization field, and consequently on the SHL. The added elements have effects on the phase structures and distributions in the magnets, which influences the uniform of demagnetization field.展开更多
A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yie...A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yields a combination of desired characteristics including simplified control structure, small ripple torque, high speed accuracy, wide operating speed range, and fast dynamic response. Experimental results confirm excellent characteristics of the motor.展开更多
We have recently developed a new micromagnetie method at finite temperature, where the Hybrid Monte Carlo method is employed to realize the Boltzmann distribution with respect to the magnetic free energy. Hence, the h...We have recently developed a new micromagnetie method at finite temperature, where the Hybrid Monte Carlo method is employed to realize the Boltzmann distribution with respect to the magnetic free energy. Hence, the hysteresis loops and domain structures at arbitrary temperature below the Curie point Tc can be simulated. The Haxnilton equations are used to find the magnetization distributions instead of the Landau-Lifshitz （LL） equations. In our previous work, we applied this method on a simple uniaxial anisotropy nano-paxticle and compared it with the mieromagnetic method using LL equations. In this work, we use this new method to simulate an LIO FePt-C granular thin film at finite temperatures. The polycrystalline Voronoi microstructure is included in the model, and the effects of the misorientation of FePt grains are also simulated.展开更多
We apply the hybrid Monte Carlo （HMC） micromagnetie method to FeCo soft magnetic polycrystalline films and test the new method by comparing with the result worked out by micromagnetics using Landau Lifshitz-Gilbert ...We apply the hybrid Monte Carlo （HMC） micromagnetie method to FeCo soft magnetic polycrystalline films and test the new method by comparing with the result worked out by micromagnetics using Landau Lifshitz-Gilbert equations, and the magnetic properties of FeCo films are understood better by carefully considering the effects of polycrystalline microstructures. The hysteresis loops of the FeCo film from low temperature up to 1100K are simulated by the new HMC micromagnetic method.展开更多
Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this...Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.展开更多
动态电压恢复器(dynamic voltage restorer,DVR)的响应速度是衡量DVR特性的重要指标,锁相环和电压跌落检测算法则是决定其响应速度的2个关键因素,而电网电压畸变、跌落过程中发生的相位跳变和电压不平衡制约着锁相环和检测算法的快速性...动态电压恢复器(dynamic voltage restorer,DVR)的响应速度是衡量DVR特性的重要指标,锁相环和电压跌落检测算法则是决定其响应速度的2个关键因素,而电网电压畸变、跌落过程中发生的相位跳变和电压不平衡制约着锁相环和检测算法的快速性。该文结合最小方差(least error squares,LES)滤波器和改进对称分量法设计了新的软件锁相环和电压跌落检测算法,对这2种方法进行详细的理论推导,阐明各频次的正负序分量解耦的机理。在Matlab/Simulink中搭建仿真模型,与传统锁相环方法和电压跌落检测算法进行对比分析。最后,在电压跌落平台进行工业样机验证,结果表明所提方法可行有效,且具有较高的响应速度。展开更多
汽车前、后轴侧偏刚度与汽车的操纵特性紧密联系,是汽车动力学控制中的重要参数。受轮胎特性变化的影响,在汽车使用中线性侧偏刚度发生变化。针对传统估计方法不利于在量产汽车上应用的问题,在车载传感器配置的基础上,提出应用自适应遗...汽车前、后轴侧偏刚度与汽车的操纵特性紧密联系,是汽车动力学控制中的重要参数。受轮胎特性变化的影响,在汽车使用中线性侧偏刚度发生变化。针对传统估计方法不利于在量产汽车上应用的问题,在车载传感器配置的基础上,提出应用自适应遗忘因子递推最小二乘方法(Forgetting-factor recursive least square method,FFRLS)的前、后轴线性侧偏刚度估计方法。设计出在制动工况下对轮胎特性变化具有鲁棒特性的侧向速度观测方法,由此计算估计模型中的前、后轴侧偏角。提出并应用最大侧向力计算估计模型中的前、后轴侧向力。通过设定合适的估计触发条件实现基于工况的在线参数估计。基于veDYNA的仿真结果表明在轮胎侧偏刚度突变时自适应FFRLS方法相比普通FFRLS方法参数能够更快地收敛。最后在驾驶员在环混合仿真平台环境下,针对触发条件受限的工况通过实时仿真验证了估计算法的有效性。展开更多
基金Project supported by Shanghai Leading Academic Discipline (P1502)
文摘Investigation into the magnets with different squareness of hysteresis loop(SHL) reveals that the microstructure of sintered NdFeB magnets has great effects on the SHL of the magnets. The abnormal grain growth deteriorates the SHL seriously. The shape of the grain and the grain boundary affect the intensity of demagnetization field, and consequently on the SHL. The added elements have effects on the phase structures and distributions in the magnets, which influences the uniform of demagnetization field.
文摘A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yields a combination of desired characteristics including simplified control structure, small ripple torque, high speed accuracy, wide operating speed range, and fast dynamic response. Experimental results confirm excellent characteristics of the motor.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171086 and 51371101
文摘We have recently developed a new micromagnetie method at finite temperature, where the Hybrid Monte Carlo method is employed to realize the Boltzmann distribution with respect to the magnetic free energy. Hence, the hysteresis loops and domain structures at arbitrary temperature below the Curie point Tc can be simulated. The Haxnilton equations are used to find the magnetization distributions instead of the Landau-Lifshitz （LL） equations. In our previous work, we applied this method on a simple uniaxial anisotropy nano-paxticle and compared it with the mieromagnetic method using LL equations. In this work, we use this new method to simulate an LIO FePt-C granular thin film at finite temperatures. The polycrystalline Voronoi microstructure is included in the model, and the effects of the misorientation of FePt grains are also simulated.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171086 and 51371101
文摘We apply the hybrid Monte Carlo （HMC） micromagnetie method to FeCo soft magnetic polycrystalline films and test the new method by comparing with the result worked out by micromagnetics using Landau Lifshitz-Gilbert equations, and the magnetic properties of FeCo films are understood better by carefully considering the effects of polycrystalline microstructures. The hysteresis loops of the FeCo film from low temperature up to 1100K are simulated by the new HMC micromagnetic method.
文摘Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.
文摘动态电压恢复器(dynamic voltage restorer,DVR)的响应速度是衡量DVR特性的重要指标,锁相环和电压跌落检测算法则是决定其响应速度的2个关键因素,而电网电压畸变、跌落过程中发生的相位跳变和电压不平衡制约着锁相环和检测算法的快速性。该文结合最小方差(least error squares,LES)滤波器和改进对称分量法设计了新的软件锁相环和电压跌落检测算法,对这2种方法进行详细的理论推导,阐明各频次的正负序分量解耦的机理。在Matlab/Simulink中搭建仿真模型,与传统锁相环方法和电压跌落检测算法进行对比分析。最后,在电压跌落平台进行工业样机验证,结果表明所提方法可行有效,且具有较高的响应速度。
文摘汽车前、后轴侧偏刚度与汽车的操纵特性紧密联系,是汽车动力学控制中的重要参数。受轮胎特性变化的影响,在汽车使用中线性侧偏刚度发生变化。针对传统估计方法不利于在量产汽车上应用的问题,在车载传感器配置的基础上,提出应用自适应遗忘因子递推最小二乘方法(Forgetting-factor recursive least square method,FFRLS)的前、后轴线性侧偏刚度估计方法。设计出在制动工况下对轮胎特性变化具有鲁棒特性的侧向速度观测方法,由此计算估计模型中的前、后轴侧偏角。提出并应用最大侧向力计算估计模型中的前、后轴侧向力。通过设定合适的估计触发条件实现基于工况的在线参数估计。基于veDYNA的仿真结果表明在轮胎侧偏刚度突变时自适应FFRLS方法相比普通FFRLS方法参数能够更快地收敛。最后在驾驶员在环混合仿真平台环境下,针对触发条件受限的工况通过实时仿真验证了估计算法的有效性。
