In order to grasp the dynamic behaviors of 4-UPS-UPU high-speed spatial parallel mechanism, the stress of driving limbs and natural frequencies of parallel mechanism were investigated. Based on flexible multi-body dyn...In order to grasp the dynamic behaviors of 4-UPS-UPU high-speed spatial parallel mechanism, the stress of driving limbs and natural frequencies of parallel mechanism were investigated. Based on flexible multi-body dynamics theory, the dynamics model of 4-UPS-UPU high-speed spatial parallel mechanism without considering geometric nonlinearity was derived. The stress of driving limbs and natural frequencies of 4-UPS-UPU parallel mechanism with specific parameters were analyzed. The relationship between the basic parameters of parallel mechanism and its dynamic behaviors, such as stress of driving limbs and natural frequencies of parallel mechanism, were discussed. The numerical simulation results show that the stress and natural frequencies are relatively sensitive to the section parameters of driving limbs, the characteristic parameters of material on driving limbs, and the mass of moving platform. The researches can provide important theoretical base of the analysis of dynamic behaviors and optimal design for high-speed spatial parallel mechanism.展开更多
A method of improving the stability of multiple-motor drive system fed by a 3-leg single inverter has been devised that employs the averages and differences of estimated parameters for field-oriented control. The para...A method of improving the stability of multiple-motor drive system fed by a 3-leg single inverter has been devised that employs the averages and differences of estimated parameters for field-oriented control. The parameters of each motor (stator current, rotor flux, and speed) are estimated using adaptive rotor flux observers to achieve sensorless control. The validity and effective of the proposed method have been demonstrated through simulations and experiments.展开更多
多逆变器并联系统内各逆变器的电流和电压在公共连接点(Point of common coupling,PCC)存在耦合,谐波和扰动会通过电流采样信号对连接到PCC的逆变器的控制产生影响,引起逆变器输出电流波形畸变,进一步增加PCC点的谐波注入,给系统的稳定...多逆变器并联系统内各逆变器的电流和电压在公共连接点(Point of common coupling,PCC)存在耦合,谐波和扰动会通过电流采样信号对连接到PCC的逆变器的控制产生影响,引起逆变器输出电流波形畸变,进一步增加PCC点的谐波注入,给系统的稳定运行带来隐患。针对多逆变器并联系统在PCC存在谐波耦合的问题,提出一种降阶自抗扰控制器(Active disturbance rejection control,ADRC)解耦控制策略,通过等效变换降低观测器所需阶次,消除反馈环节中逆变器电流的耦合分量,实现各逆变器的独立控制,有效地减少逆变器对PCC的谐波电流注入,从而改善电流波形。从环路增益角度分析,所提方法能有效消除耦合电流在控制环路的影响,并通过硬件在环试验验证所提方法能显著减少逆变器输出的高次谐波。展开更多
基金Project(51005138) supported by the National Natural Science Foundation of ChinaProject(BS2012ZZ008) supported by Shandong Young Scientists Award Fund,China+2 种基金Project(J09LD54) supported by the Natural Science Foundation of Shandong Education Department of ChinaProject(2011KYJQ102) supported by the Science Foundation of Shandong University of Science and Technology,ChinaProject(HGDML-1104) supported by Jiangsu Key Laboratory of Digital Manufacturing Technology,China
文摘In order to grasp the dynamic behaviors of 4-UPS-UPU high-speed spatial parallel mechanism, the stress of driving limbs and natural frequencies of parallel mechanism were investigated. Based on flexible multi-body dynamics theory, the dynamics model of 4-UPS-UPU high-speed spatial parallel mechanism without considering geometric nonlinearity was derived. The stress of driving limbs and natural frequencies of 4-UPS-UPU parallel mechanism with specific parameters were analyzed. The relationship between the basic parameters of parallel mechanism and its dynamic behaviors, such as stress of driving limbs and natural frequencies of parallel mechanism, were discussed. The numerical simulation results show that the stress and natural frequencies are relatively sensitive to the section parameters of driving limbs, the characteristic parameters of material on driving limbs, and the mass of moving platform. The researches can provide important theoretical base of the analysis of dynamic behaviors and optimal design for high-speed spatial parallel mechanism.
文摘A method of improving the stability of multiple-motor drive system fed by a 3-leg single inverter has been devised that employs the averages and differences of estimated parameters for field-oriented control. The parameters of each motor (stator current, rotor flux, and speed) are estimated using adaptive rotor flux observers to achieve sensorless control. The validity and effective of the proposed method have been demonstrated through simulations and experiments.
文摘多逆变器并联系统内各逆变器的电流和电压在公共连接点(Point of common coupling,PCC)存在耦合,谐波和扰动会通过电流采样信号对连接到PCC的逆变器的控制产生影响,引起逆变器输出电流波形畸变,进一步增加PCC点的谐波注入,给系统的稳定运行带来隐患。针对多逆变器并联系统在PCC存在谐波耦合的问题,提出一种降阶自抗扰控制器(Active disturbance rejection control,ADRC)解耦控制策略,通过等效变换降低观测器所需阶次,消除反馈环节中逆变器电流的耦合分量,实现各逆变器的独立控制,有效地减少逆变器对PCC的谐波电流注入,从而改善电流波形。从环路增益角度分析,所提方法能有效消除耦合电流在控制环路的影响,并通过硬件在环试验验证所提方法能显著减少逆变器输出的高次谐波。
