Papers by Author: Xu Dong Wang

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: Capacitor matching in single-phase capacitor-run induction motor (SPCRIM) is investigated in this paper. Combining symmetrical components method with resultant current method, capacitor value is calculated. Relationship between turn ratio of main winding and auxiliary winding, main winding current, auxiliary winding current and capacitor value is analyzed by simulation. SPCRIM is optimized on the ground of the theoretically calculated capacitor value and turn ratio of the main and auxiliary windings with FEA (Finite Element Analysis). Results show that calculated capacitor value contributes to the determination of turn ratio of the main winding and auxiliary winding, and with appropriately calculated capacitor value and turn ratio, small winding current can be got.

Abstract: Asynchronous motor vector control is one of hot research problems. In this paper, according to the variable-frequency speed control principle, combining with Variable Voltage Variable Frequency (VVVF) vector control strategies, the asynchronous motor vector control simulation model is built based on the toolbox of Matlab/Simulink in order to study on the characteristics of asynchronous motor vector control. The dynamic characteristics including no-load, load, acceleration and deceleration were researched. The results verified the validity and feasibility of the proposed simulation model for synchronous motor vector control.

Abstract: This paper investigates the detent force modeling of a slotted iron core type vertical permanent magnet linear synchronous motor (PMLSM) for ropeless elevator applications. Variable network non-linear magnetic equivalent circuit model is established to predict the detent force of PMLSM. The topology structure of equivalent magnetic circuit is developed and the permeances are derived and calculated. The end effect of two end teeth is essential for analysis of detent force and it is focused in the modeling. Magnetic saturation of primary iron-core also be taken into account. In final some 3-D finite-element numerical calculation results are used to validate the feasibility of the proposed method.

Abstract: In this paper, a model of unit motor (16p15s) which is used for vertical elevator has been set up. And a modification of the primary geometry has been presented. In the new geometry, pole shoes are affixed to the primary poles. The finite element analysis (FEA) of various width of pole and different width of pole shoe have been carried out in this paper. The results show that the force profile of the proposed PMLSM has been improved. The minimum force ripple occurs in a suitable width of the pole shoes. And the back EMF constant is analyzed, too.

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: A novel Detent-force-based Magnetic Suspension System (DMSS) is presented. The topological structure and operating principle of DMSS are analyzed. The characteristics of the axial, radial force and magnetic field and torsion moment are studied with FEA method respectively. Simulation results show that the DMSS can generate larger levitation force than common levitation systems, and its levitation mode is a passive suspension in the axial direction and torsion without external control.

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.