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A model-free control scheme is proposed for a surface mounted permanent magnet synchronous motor (SMPMSM) drive system with parametric uncertainties and inverter nonlinearity. Using only the input and output data of system, the ultra-local model of SMPMSM system is first set up and the proposed ultra-local model is able to accurately identify the nonparametric model of SMPMSM system with the unknown...
This paper describes the effect of electrical parameters of the double fed induction generator on the transient voltage stability of a DFIG to a simple grid; the DFIG model has been developed in the Matlab/simulink tool. The dynamic behavior of a wind turbine connected to a grid is examined. A three-phase fault is applied close to the wind turbine. The effect of different electrical parameters of...
The sustained oscillation often appears in the induction motor (IM) systems with indirect field-oriented control (IFOC) and essentially caused by the unstable equilibrium points undergoing Hopf bifurcation. In order to stabilize these undesirable oscillations, a convenient time-delayed state feedback method is presented and its accomplishing process is indicated for a tested IM system in detail. It...
According to the large size multi-oil pad hydrostatic bearing, the mathematical model of three-dimensional flow of the gap oil film of the hydrostatic bearing is established in considering the influence of variable viscosity and centrifugal force condition. The finite element method and the finite volume method are used to simulate the flow field of the gap oil film of the large size hydrostatic bearing,...
The gap fluid of hydrostatic thrust bearing is studied in this dissertation. By applying computational fluid dynamics and theory of lubrication, and establishing three-dimensional solid model and mathematical model of the gap fluid of hydrostatic thrust bearing, analyzing synthetically three-dimensional pressure distribution of the gap fluid between hydrostatic guideway and the rotary table by using...
Small signal stability analysis is conducted considering grid connected doubly-fed induction generator (DFIG) type. The modeling of a grid connected DFIG system is first set up and the whole model is formulated by a set of differential algebraic equations (DAE). Then, the mathematical model of rotor-side converter is built with decoupled P-Q control techniques to implement stator active and reactive...
In the hydrostatic thrust bearing with open-loop quantity oil supply system for the heavy NC machine tool, the time-variable oil viscosity and the loads will cause the lubricant film thickness deviating from the optimum value, which reduce the bearing film rigidity and affect the machine tool precision. This paper proposed a controllable hydrostatic thrust bearing, which combined the constant flow...
In this paper, the time-delayed feedback control method is introduced to stabilize unstable equilibrium points undergoing Hopf bifurcation for an induction motor (IM) drive system. Stability criterion of a nonlinear time-delayed system is first established, and then an effective procedure is shown how to stabilize the unstable equilibrium points by suitably select the feedback gain k and the time-delay...
In this paper, a method is presented and achieved to accurately determine Hopf bifurcation point for an induction motor (IM) drive system, and Hopf bifurcation diagram is showed to indicate evolvement of the equilibrium points from steady state to undergoing Hopf bifurcation and then achieving stabilization again. At last, the classical Floquet theory is applied to confirm the limit cyclepsilas stability.
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