Rotor-bearings systems applied widely in industry are nonlinear dynamic systems of multi-degree-of-freedom. Modem concepts on design and maintenance call for quantitative stability analysis. Using trajectory based sta...Rotor-bearings systems applied widely in industry are nonlinear dynamic systems of multi-degree-of-freedom. Modem concepts on design and maintenance call for quantitative stability analysis. Using trajectory based stability-preserving and dimensional-reduction, a quantitative stability analysis method for rotor systems is presented. At first, an n-dimensional nonlinear non-autonomous rotor system is decoupled into n subsystems after numerical integration. Each of them has only onedegree-of-freedom and contains time-varying parameters to represent all other state variables. In this way, n-dimensional trajectory is mapped into a set of one-dimensional trajectories. Dynamic central point （DCP） of a subsystem is then defined on the extended phase plane, namely, force-position plane. Characteristics of curves on the extended phase plane and the DCP＇s kinetic energy difference sequence for general motion in rotor systems are studied. The corresponding stability margins of trajectory are evaluated quantitatively. By means of the margin and its sensitivity analysis, the critical parameters of the period doubling bifurcation and the Hopf bifurcation in a flexible rotor supported by two short journal bearings with nonlinear suspensionare are determined.展开更多
针对直流调速系统,设计了一种模糊自整定的分数阶内模控制器。首先将分数阶理论与内模控制(internal model control,IM C)相结合设计分数阶内模控制器,其参数可根据系统的相角裕度和穿越频率进行解析整定;然后在分析了相角裕度和穿越频...针对直流调速系统,设计了一种模糊自整定的分数阶内模控制器。首先将分数阶理论与内模控制(internal model control,IM C)相结合设计分数阶内模控制器,其参数可根据系统的相角裕度和穿越频率进行解析整定;然后在分析了相角裕度和穿越频率对系统性能影响的基础上,设计出模糊控制器,实现了系统根据转速偏差和偏差变化对控制器参数的在线自整定,克服了系统性能对相角裕度和穿越频率选择的依赖。仿真和试验结果表明模糊自整定分数阶内模控制器可使系统具有良好的动态响应、干扰抑制特性以及克服参数摄动的鲁棒性。展开更多
文摘Rotor-bearings systems applied widely in industry are nonlinear dynamic systems of multi-degree-of-freedom. Modem concepts on design and maintenance call for quantitative stability analysis. Using trajectory based stability-preserving and dimensional-reduction, a quantitative stability analysis method for rotor systems is presented. At first, an n-dimensional nonlinear non-autonomous rotor system is decoupled into n subsystems after numerical integration. Each of them has only onedegree-of-freedom and contains time-varying parameters to represent all other state variables. In this way, n-dimensional trajectory is mapped into a set of one-dimensional trajectories. Dynamic central point （DCP） of a subsystem is then defined on the extended phase plane, namely, force-position plane. Characteristics of curves on the extended phase plane and the DCP＇s kinetic energy difference sequence for general motion in rotor systems are studied. The corresponding stability margins of trajectory are evaluated quantitatively. By means of the margin and its sensitivity analysis, the critical parameters of the period doubling bifurcation and the Hopf bifurcation in a flexible rotor supported by two short journal bearings with nonlinear suspensionare are determined.
文摘针对直流调速系统,设计了一种模糊自整定的分数阶内模控制器。首先将分数阶理论与内模控制(internal model control,IM C)相结合设计分数阶内模控制器,其参数可根据系统的相角裕度和穿越频率进行解析整定;然后在分析了相角裕度和穿越频率对系统性能影响的基础上,设计出模糊控制器,实现了系统根据转速偏差和偏差变化对控制器参数的在线自整定,克服了系统性能对相角裕度和穿越频率选择的依赖。仿真和试验结果表明模糊自整定分数阶内模控制器可使系统具有良好的动态响应、干扰抑制特性以及克服参数摄动的鲁棒性。
