Papers by Author: Bao Yu Xu

Abstract: Permanent magnet linear synchronous motors (PMLSMs) is the best driving motor for rope-less hoist system because of the advantages of simple structure, small volume, high force, unlimited hoisting height and speed. In this paper, the finite element method (FEM) is adopted to design a PMLSM with 16-pole 15-slot as a unit for rope-less hoist system. Through the FEM analysis, the EMF constant K_e and the force constant K_f of unit motor were got. Then a direct driving elevator prototype drove by the proposed PMLSM was built. Experimental results show the stable operation performance of the experimental device, having good prospects for the development and application.

Abstract: In order to improve the dynamic servo performance of PMLSM, a classical direct torque control (DTC) scheme based on bang-bang control is proposed in the paper. The proposed control method uses the bang-bang hysteresis controller formed a dual-closed loop control system, it contains torque loop and flux loop. The DTC control model was established and the simulation experiment was made. The simulation experiment results show that the DTC can improve the dynamic performance of PMLSM. It can reduce the ripples of speed and torque, so that it can provide more precision and accuracy servo performance.

Abstract: The five-octave mill stochastic dynamics model was established, and then constructed the virtual rolling force excitation, converted random excitation into the rolling force deterministic harmonic excitation by taking advantage of pseudo-excitation method, finally the variance and power spectral density dynamic random changes in the roll gap was Obtained . The results show that the emergence degree of rolled-strip oscillation marks is proportional to random rolling force power spectral density, and in over the five-octave frequency, the roll gap’s dynamic variance no longer change.

Abstract: Based on wavelet transform and artificial neural network, a novel method which takes advantage of both the multi-resolution decomposition of wavelet transform and the classification characteristics of artificial neural network is proposed for fault detection of permanent magnet linear synchronous motor (PMLSM). According to the characteristic of unhealthy PMLSM, the wavelet transform is carried out to decompose and reconstruct winding current signal. Then the energy of each frequency band as faulty features can be detected through spectrum analysis of wavelet coefficients about each frequency band. With normalization method, the feature vectors are constructed from relative energy for energy of each frequency band. The proposed method is applied to the fault detection of PMLSM, and the result of simulation proved that the wavelet neural network can effectively detect different conditions of PMLSM.

Abstract: 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 is researched by solving the Fokker-Planck-Kolmogorov (FPK) equation. The results show that the 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.

Abstract: Direct force control (DFC) with the advantages of simple structure, fast force response, superior control performance, is developed from direct torque control (DTC). So, it is attracting more attention, increasingly becoming a research hot in the control field. It is a valuable research to improve the operation stability of PMLSM by the direct force control. In this paper, based on DFC principle analysis, the force control and flux control theory of DFC is studied according to the mathematical model of PMLSM. The structure and implementation method of DFC is analyzed, and then the DFC system simulation model for PMLSM is built by Matlab/Simulink. The simulation results show the feasibility of the simulation model, with good static and dynamic performance.

Abstract: Rope-less hoist system driven by permanent magnet linear synchronous motor has the advantages of simple structure, small volume, high force, unlimited hoisting height and speed. So, it is attracting more attention, increasingly becoming a research hot and difficult in the vertical hoist field. In this paper, a design scheme of direct driving high-speed elevator is proposed according to the key technical problems of rope-less hoist system driven by PMLSM, and then a small-sized home elevator prototype is built. Experimental results show the safe and stable operation performance of the experimental device, which offers the reference for the further research and the development and application of PMLSM rope-less hoist system.

Abstract: The stochastic excitation power spectral density (PSD) model and ARMA time series model are established based on the stochastic rolling force acquisition data, which is processed into stationary, normal and zero mean from a aluminum hot strip tandem mill. Characteristics of rolling force ARMA time series models are discussed by means of random process theory. The rolling forces PSD function of facilitating engineering application is obtained by utilizing Levenberg-Marquardt combined with generalized global planning algorithm, and the stochastic excitation model is established. It provides the basis for the prediction of rolling force.

Abstract: The dynamic behavior of roller system of a "1+4" hot strip rolling tandem mill were analyzed. The stochastic vertical vibration and the optimum mathematical model were established based on the reliability after the system simplified to some extent. Stochastic optimum has been done to the system according to the optimum mathematical model of the roller system. Its best natural frequency and damping coefficient are obtained by computer simulation under the situation of minimum response of the rollers stationary acceleration when chatter occurs. The results indicate that by optimizing the natural frequency and damping coefficient of the system can greatly improve the dynamic behavior of rollers system and equality of the strip, and are useful to the new design of the rolling mill and the setting up of the rolling parameters.