No abstract

Permanent magnet linear synchronous motor (PMLSM) for rope-less hoist system, which has the advantages of simple structure, small volume, high force, unlimited hoisting height and speed, is a research focus and difficulties in the vertical hoist field. In this paper, according to the key technical problems of PMLSM for rope-less hoist system, a design scheme of direct driving high-speed elevator is proposed, and then a small-sized home elevator prototype drove by PMLSM is built. Experimental results show the safe and stable operation performance of the experimental device, with good prospects for the development and application of PMLSM rope-less hoist system

Modal analysis is a technology for vibration characteristic research. It is the foundation for structural dynamics analysis. Natural frequency is a very important performance in dynamics analysis. Modal characteristics of the Permanent Magnet Linear Synchronous Motor (PMLSM) for ropeless elevator were investigated by finite element method (FEM). FEM models for modal analysis were built for the primary winding, iron core, fixed block, secondary back iron and permanent block by appropriate structure simplification. The influences on natural frequencies of the PMLSM were analyzed. Natural frequencies and mode shapes were simulated by FEM. The accuracy of the FEM analysis is validated by the modal analysis experiment of hammering method. KEY WORDS: ropless elevator; PMLSM; modal analysis; FEM; natural frequency Ⅰ. INTRODUCTIONCompared with the traditional hoisting system, the ropeless elevator droved by PMLSM is promising. Its main feature is high efficiency, small space, and high security [1] . The ropeless elevator is droved by PMLSM guided by two or more rail，and the rails ensure the directionality of its running and horizontal stability, Whether it is unilateral open-or bilateral closed, the air gap between the primary and secondary of PMLSM will seriously affect the normal force between the mover and the stator, and this would inevitably lead to changes in the system dynamics. During operation, vibration and friction force caused by intrinsic thrust and normal force fluctuations between the primary and secondary of PMLSM seriously affect the dynamic performance of the system, resulting in PMLSM fatigue and shorten its life. In order to improve the density of PMLSM thrust and reduce thrust and normal force fluctuations, the PMLSM for ropeless elevator taking the high density, wide speed, lightweight and low-cost designs, this leads more complicated in structure, lighter in weight and thinner in thickness of PMLSM, all of this result in difficult to increase the stiffness and suppressed the electromagnetic vibration of PMLSM [2] .

Permanent magnet linear synchronous motors (PMLSMs), which have great advantages, such as simple structure, high positioning accuracy, good performance, high thrust force density, high dynamic response, are widely used in high precision direct drive field. As a research focus and difficulty, the force ripper and dynamic characteristic of PMLSM is important for its performance. In this paper, the present research status and characteristics of PMLSM is discussed firstly. Then a 16-pole 15-slot PMLSM is built used finite element method (FEM). Based on the finite element model, the thrust force ripple and minimization technologies, the power factor and efficiency of PMLSM with different load, were solved and analyzed, and an optimized model was got. The analysis result of thrust and magnetic flux density shows that through the new geometry of primary tooth shape, named optimized model, can improve the average thrust and reduce thrust fluctuations. The optimized model also has higher the power factor and efficiency. The back EMF of original and optimized model are also compared and discussed.

No abstract

Permanent Magnet Linear Synchronous Motor has been used widely in the industrial application and transportation system. However, a need of mechanical sensors is a drawback for its control system, which restricts the application range seriously. In order to solve the above drawback, the sensorless vector control method was proposed in the paper. The mathematic model was established for the sensorless vector control of PMLSM, so that it can provide the estimate parameters to realize the sensorless control. According to the extended kalman filter algorithm, the simulation experiment model was constructed to rectify the control performance by estimating the mover speed and position angular instead of the mechanical sensors. The mover speed, position angular and electrical magnet torque were obtained. It is showed that the estimating speed value and position angular value are almost similar as the actual value by using sensorless control method, although it has same disadvantages, such as complex algorithm and a large number of mathematical operations especially the matrix operation. Overall, we can know that the sensorless control method by using extended kalman filter algorithm can substitute the mechanical sensor mode, although it has some disadvatages.

Inverters provided non-sinusoidal voltage or current, and the tooth-slot and winding distribution of the motor could lead to a mass of space harmonic components, severely deteriorating the motor performance. In order to know the cause of electromagnetic thrust and mover velocity fluctuation of low-velocity PMLSM fed by SPWM-VS, the steady-state performances of low-velocity PMLSM are analyzed in this paper. the performances of permanent magnet linear synchronous motor by sinusoidal pulse width module voltage source inverter (SPWM-VI-PMLSM) and sinusoidal voltage source inverter (S-VS) were researched used the field-circuit coupled adaptive time-stepping finite element method. The characteristic of having thick air gap is considered in the field-circuit 2D model. The cosimulation using state equation and time-step finite element equation is used, the time step of the state equation is smaller than that of the time-step finite element equation. PWM-VI-PMLSM and S-VS-PMLSM have the same current periodicity and similar current amplitude. The current of SPWM-VI-PMLSM has various harmonic components distorted as a result of magnetic saturation and non-sinusoidal air gap field. The tangential electromagnetic thrust of SPWM-VI-PMLSM under steady state oscillate with a period decided by pole pitch, and it has various harmonic components dampening thrust fluctuation, Thus S-VS-PMLSM has better performance than SPWM-VI-PMLSM. S-VS-PMLSM and SPWM-VI-PMLSM have the same periodicity of slip fluctuation, the slip value of SPWM-VI-PMLSM is larger than that of S-VS-PMLSM. The simulation results accords with experimental data.

Based on the stochastic rolling force data from aluminum hot strip tandem mill, the ARMA time series model and the stochastic excitation power spectral density (PSD) model are established, and the stochastic rolling forces excitation model is established by utilizing Levenberg-Marquardt combined with generalized global planning algorithm. A two dimensional stochastic nonlinear dynamical model of rolls is presented considering the stochastic factor of the rolling force. The Hamilton function is also described as one dimension diffusion process by using stochastic average method, the singular boundary theory was taken for analyzing the global stochastic stability of the system, and the system’s stochastic stability was researched by solving the Fokker-Planck-Kolmogorov (FPK) equation. The results show that the stochastic excitation model obtained has significance for analyzing and researching stochastic dynamics characteristics to the system, and also generalized energy H in the range of 0.02 to 0.4, the system’s response has the minimum transition probability density, and the system state is not easy to change, therefore the system generalized energy H should be to limit in this range in the design and operation of the rolling mill