Haichao Feng

Research on Permanent Magnet Linear Synchronous Motor for Rope-less Hoist System

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.

Detent Force Analysis and Optimization for Vertical Permanent-magnet Linear Synchronous Motor with Fractional-slot Windings

This paper investigates the detent force modeling and optimization of a iron-core type 16-pole 15-slot permanent magnet linear synchronous motor (PMLSM) for ropeless elevator applications. Variable network non-linear magnetic equivalent circuit (VNMEC) model is established to predict the detent force of PMLSM. The topology structure of equivalent magnetic circuit is developed and the permeance are derived and calculated. The end effect of two end teeth is essential for detent force analysis and it is focused in the modeling. Magnetic saturation of primary tooth also is taken into account and nonlinear permanence is calculated. Some 3-D finite-element numerical calculations are used to validate the feasibility of the proposed method. Then proposed VNMEC is employed to calculate and optimize the detent force considering the end tooth dimensions. In final, experimental results are further used to verify the validation of proposed model.

The Research of Sensorless Vector Control for Permanent Magnet Linear Synchronous Motor

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.

Design and Analysis of Permanent Magnet Linear Synchronous Motor with Special Pole Shape

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.

Modeling Analysis and Parameters Calculation of Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor (PMLSM) has several advantages, such as simple structure, small volume, high force, and so on. It is a research focus and difficulties in the research field of motor. Because PMLSM is different from the traditional rotary motors in structure and running state, it is difficult for to build its precise mathematical model by analytical method. The asymmetry of the three-phase winding electromagnetic and electrical parameters of open PMLSM in a low-speed working zone is impossible to take into account. In this paper, the difference between the permanent magnet linear synchronous motor and traditional motors are analyzed. And then, a non-linear, asymmetric and variable parameter space state model is built, considering the structural and running characteristics of PMLSM. The proposed model needs all kinds of parameters of PMLSM, including self- inductance, mutual inductance, flux linkage, etc. So, a finite element calculation and actual measurement of the required parameters of a prototype PMLSM are done, respectively. The influence of air-gap on the inductance parameters was analyzed.

Simulation and Test Study on Direct Force Control for Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor (PMLSM), which has the advantages of simple structure, small volume, high force, is a research focus and difficulties because of the thrust ripple and control problems for PMLSM. In this paper, in order to reduce thrust ripple and improve system control performance, the space voltage vector pulse width modulation technology (SVPWM) was introduced into the directing force control (DFC) strategy of PMLSM. In the running process, the temperature of PMLSM will rise, which changes the resistance of the primary winding. Full consideration of the change of the resistance in the motor running process, the error between the flux observed value and the actual value was analyzed. And then a new flux dynamic compensation algorithm based on flux dynamic compensation was proposed. The novel dynamic compensator was built to improve the observation accuracy of the primary flux, which solved effectively the wrong voltage vector choice and the system control performance failure due to the error of the primary flux. The Simulation and test results show that the PMLSM DFC based on SVPWM and the flux dynamic compensation has better control performance.

Comparison of Performances of PMLSM Fed by Two Power Supplies

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 co-simulation 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.

Aluminum Loss Analysis and Evaluation of Squirrel Induction Motor

In this paper, rotor bar Aluminum Loss of Squirrel Induction Motor running in steady state with full load is investigated. Multi-layered analytical model of rotor bar is employed to analyze the Aluminum loss generated by harmonic current. This model divides the rotor bar into a series of sub-layers with resistance remained constant in each sub-layer considering the skin effect. The bar loss in every layer are analyzed and calculated to get total loss of the whole rotor bar. The finite element analysis is used to verify the results of multi-layered model. A prototype motor Y160L-4 is calculated by combining proposed method and finite element method. The losses with different number of rotor slots are also calculated and discussed. It is useful for loss reduction and efficiency improvement in induction motor design and optimal applications.

Study on Direct Force Control for PMLSM Based on SVPWM and the Flux Dynamic Compensation

Focused on directing force control (DFC) of permanent magnet linear synchronous motor (PMLSM) existing thrust ripple, the space voltage vector pulse width modulation technology (SVPWM) will be introduced into PMLSM DFC strategy in order to reduce thrust ripple and improve system control performance. Full consideration of the motor running process with the rise of temperature, the change of the primary winding resistance caused the error between the flux observed value and the actual value. A new flux dynamic compensation algorithm was proposed. The dynamic compensator was built to improve the observation accuracy of the primary flux, which solved effectively the wrong voltage vector choice and the system control performance failure due to the error of the primary flux. The experimental results show that the PMLSM DFC based on SVPWM and the flux dynamic compensation has better control performance.

Strip/Foil Rolling Mill Stochastic Excitation Model and Its Stability

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.