Yumei Du

Research on characteristics of single-sided linear induction motors for urban transit

As a direct electromagnetic driving device without adhesion, the urban transit with single-sided linear induction motor (SLIM) propulsion and wheel on rail support and guidance has many advantages, and has been a part of new type transit. In this paper, a SLIM for urban transit was designed and its characteristics were calculated with improving T-type equivalent circuit model. The specific structure problems of a SLIM such as end effects, half-filled slots for the end windings, skin effect have been taken into account in the design. The prototype has been tested, and the accuracy of the calculation is verified by experimental results.

Study and optimized design of contactless power transformer for high speed maglev train

This paper investigates factors influencing coupling ability of ironless flat winding separable transformer which could work for the contactless power supply system of the high speed maglev train. Basing on 3D finite element method (FEM), the coupling ability to geometrical sizes such as coil length and width, height of air gap and the horizontal displacement of the secondary coils is given. Effect of high frequency on the contactless power supply system is also taken into consideration. The work of this paper provides foundation for the optimized design of high coupling ability ironless flat winding separable transformer.

Design of a medium frequency, high voltage transformer for power electronic transformer

Power electronics transformers (PETs) have better application in smart grid because they have more advantages than conventional transformers with a structure integrating the power electronic equipment and medium frequency transformers (MF transformers). As an important part of PET, the MF transformer undertakes significant functions of voltage conversion, energy transfer and electrical isolation. Its performance determines the efficiency and reliability of the overall system. This paper mainly discusses design procedure and efficiency optimization of MF transformers. The method of computing leakage inductance is also presented to achieve the series resonance. Finally the optimal MF transformer prototype is validated with finite element simulation.

Performance analysis of a linear induction motor based on the finite element method

Single-sided Linear Induction Motors (SLIMs) have been widely applied in transportation recently. For its cut-open magnet circuit along moving direction and different width between primary and secondary, it has longitudinal end effect and transversal edge effect, which bring some effluence to its mutual inductance and secondary resistance. Furthermore, SLIM has normal force for its unsymmetrical structure in vertical direction, which is evident in large slip and current region so as to interfere the propulsion control schemes. According to these SLIM traits, this paper based on the finite element method employed by the commercial software ANSOFT has investigated SLIM transient thrust, normal force, air gap flux density distribution, where the thrust is verified by the measurement. The results indicate that the 2D model can provide comparatively reasonable prediction to the SLIM electromagnetic design and control schemes implementation.

Dynamic characteristics study of single-sided linear induction motor with finite element method

Single-sided linear induction motor (SLIM) is widely used in transportation and other field in need of linear drive for their simple, firm structure and linear motion feature without the translation mechanism. But end effect in SLIM deteriorate the performance for the discontinuous magnetic circuit. This paper analyzes 2-D transient electromagnetic field of SLIM by finite element method (FEM). The electromagnetic field-motion coupling problem was handled by the interpolation linear movement interface method. The torque was calculated by nodal force method. The variation and correlation of eddy current and electromagnetic force with respective frequency is studied in detail as well as flux density. The changing trend of longitudinal end effect in SLIM whole operation process and the influence to dynamic characteristics of SLIM is presented. The conclusions presented in this paper can give good theoretical guidance to the control and design of linear induction motor.

Analysis of contactless power transfer system characteristics influenced by multi-primary multi-secondary contactless transformer

Contactless power transfer (CPT) system is widely used in high power occasion recently. The characteristics of movable loosely coupled transformer (MLCT) in CPT system have powerful influences to the performance of whole system. This paper studies a kind of CPT system with multi-primary multi-secondary contactless transformer. By establishing the equivalent circuit of CPT system, this paper analysis the characteristics of system such as output current, output voltage, output power and efficiency, influenced by the internal resistance, mutual inductance and frequency of multi-primary multi-secondary contactless transformer. Moreover, a further simulation has done to prove the theoretical analysis.

The influence on characteristics of movable loosely coupled transformer from metal units in urban railway system

Contactless power transfer (CPT) system is widely used in high power recently. The characteristics of contactless transformer in CPT system have powerful influences on the performance of whole system. This paper studies the performance on movable loosely coupled transformer (MLCT) for CPT system, which can be used in rail transit system. Making use of 3D finite element methods, this paper investigates how much influence on MLCT produced by metal units in urban railway system, including the fixing units on the vehicle and the metal units on the ground. The results of such studies have great practical significance when the CPT system applied to urban railway system.

Torque ripple reduction in brushless DC motor drives

This paper proposed a novel dual closed loop control of speed and torque method in brushless DC motor (BLDCM) drivers based on genetic algorithm. By defining speed error and torque error as optimum objective functions, using genetic algorithm, the PID parameters can be optimized. In addition, the torque ripple during commutation has been analyzed, and a variable switch conduction mode has been introduced to reduce torque ripple during commutation. The simulation results show that the torque ripple of BLDCM can be eliminated effectively during the commutation period and non-commutation period.

Research on speed sensorless method for permanent magnet linear synchronous motor based on high frequency pulsating voltage signal injection

The position and speed detection of maglev train is critical to train control system. The common methods of speed measurement include speed sensor measurement and speed sensorless measurement. The use of sensorless method can significantly reduce costs and its not influenced by various environmental factors. In this paper, a high frequency pulsating voltage injection method is proposed for the PMLSM, which is used to calculate the speed and position information of the motor. This method is suitable for low speed measurement and it can be used for the permanent magnet linear synchronous motor (PMLSM) with non-salient pole machine. The effectiveness of the method is verified by experiment results.

Speed sensorless control of maglev permanent magnet linear synchronous motor based on sliding mode observer

In order to solve the difficulty of measuring the speed and the position of maglev permanent magnet linear synchronous motor (PMLSM), a speed sensorless back electromotive force (EMF)-based sliding mode is proposed. And to overcome the drawback of the sliding mode technique called chattering phenomenon, a series of improvements are provided.