Jianxun Jin

Core Loss Computation in a Permanent Magnet Transverse Flux Motor With Rotating Fluxes

This paper presents the core loss computation in a permanent magnet transverse flux motor (TFM) with soft magnetic composite stator core and mild steel rotor yoke, in which the magnetic fluxes rotate. The computation is based on modified core loss models and finite element magnetic field analysis [finite element analysis (FEA)]. The coefficients for the core loss models are obtained by curve-fitting measurements on samples, and the magnetic flux density patterns in the motor are obtained by time-stepping FEA while operating conditions are considered. The computations of the motor core losses agree with the measured values on the TFM prototype.

Thrust characteristics of a double-sided high temperature superconducting linear synchronous motor with a high temperature superconducting magnetic suspension system

An electromagnetic design of a double-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet secondary is introduced in this paper. A HTS magnetic suspension system is applied to replace the sliding rail to levitate the secondary mover resulting in the HTSLSM moving without sliding friction. The thrust model of the HTSLSM is built using a magnetic circuit method and the thrust characteristics obtained from the model are compared with finite element analysis and practical testing results. The theoretical analysis on the prototype has also been verified by measurements.

Performance Analysis of an HTS Magnetic Suspension and Propulsion System With a Double-Sided HTS Linear Synchronous Motor

A novel HTS magnetic suspension and propulsion system driven by a double-sided HTS linear synchronous motor (HTSLSM) has been developed, which is suspended by an HTS magnetic suspension subsystem located on the bottom of the HTSLSM secondary mover. The structural design of the suspension and propulsion system is introduced, and then the magnetization characteristics of the HTS bulk magnets for the HTSLSM are studied and compared by different magnetization methods. The finite-element analysis (FEA) model of the HTSLSM is built up by using an equivalent model of the HTS bulk magnet, and the thrust characteristics of the HTSLSM are also simulated based on the FEA model, and verified by measurements on the prototype. Furthermore, the suspension performance of the HTS magnetic suspension subsystem has also been analyzed by a numerical method based on an equivalent current sheet model of the permanent-magnet guideway. The results show that the HTS magnetic suspension and propulsion system has applicable thrust and suspension performance, and can be applied to the practical applications such as a maglev.

Influence of external traveling-wave magnetic field on trapped field of a high temperature superconducting bulk magnet used in a linear synchronous motor

A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) has been developed with a pulse magnetization system to obtain the HTS bulk magnet array with alternating magnetic poles for the motor secondary. In order to identify the trapped field characteristics of the HTS bulk magnet exposed to the external traveling-wave magnetic field generated by the primary of the HTSLSM, a measurement system has been built up and the relevant experiments have been carried out. The relationships between the trapped field attenuation of the HTS bulk magnet and the amplitude, frequency and acting direction of the external traveling-wave magnetic field are experimentally obtained to allow the HTSLSM characteristics to be practically verified.

Development of a new bridge-type chopper for low-voltage SMES applications

In this paper, a new bridge-type chopper having power electronic switches is proposed for low-voltage superconducting magnetic energy storage (SMES) applications. The energy charge and discharge characteristics of a high temperature superconducting (HTS) SMES device, including transient current through the HTS coil, maximum discharge time duration for the load, effective energy utilization factor, are numerically studied using the circuit analysis and iterative calculation methods, and finally verified by measurements on the developed chopper device. One new theoretical modeling in corporation with a simple digital control method is presented. Experimental and numerical comparisons of the bridge-type and conventional choppers show that the new developed bridge-type chopper is favorable for long-time power compensation with very high operation efficiency in the low-voltage power applications.

Virtual Instrument based fuzzy control system for PMLSM drive

A Virtual Instrument (VI) based fuzzy control system for permanent magnet linear synchronous motor (PMLSM) drive is presented in this paper. Mathematic model of the PMLSM is presented and the stepper drive scheme is used in the position loop of PMLSM drive. To improve the performance of PMLSM drive, a LabVIEW based fuzzy controller (FC) is proposed for the position loop of PMLSM drive to deal with the dynamic uncertainty and external load effect. Simulation results demonstrated the feasibility of proposed approach.

Advantage of HTS DC power transmission

High Tc superconducting (HTS) cables and their application to build a DC power transmission system with the advantages of high transport current capability and no resistive transmission loss have been studied. Technical assessments of the DC electrical power transmission system behaviors with the use of the HTS DC cable technology have been carried out. The HTS DC cable and its DC power transmission system models have been built, and the analysis results obtained mainly include the magnetic field distribution of the HTS cable and the HTS DC power transmission system performances.

Parameter determination and performance analysis of a PM synchronous generator by magnetic field finite element analysis

This paper presents the accurate determination of key parameters and performance analysis of a permanent magnet synchronous generator (PMSG) by finite element magnetic field analysis, providing a sound basis for the machine design and optimisation. Parameters such as the winding flux, back electromotive force, and inductances are accurately calculated based on a series of numerical field solutions and improved formulations. An equivalent electrical circuit is employed to derive the equation of the external characteristic, the most important performance of the synchronous generator. The theoretical calculations and analyses have been validated by the experimental results on the PMSG prototype.

Investigation of HTS bulk magnet linear synchronous motors

A high temperature superconducting (HTS) linear synchronous motor (LSM) using HTS bulk magnets as secondary has lots of advantages than conventional permanent magnet (PM) LSM, such as smaller volume, less weight, bigger propulsion and so on. In this paper, the numerical model and equivalent magnetic-circuit of a HTS-LSM are built with results are presented. The magnetic field distribution and thrust force characteristics of the HTS-LSM are studied based on finite element method, and the analysis results are compared for different sizes of HTS bulk. The control strategy of Voltage Space Vector PWM (SVPWM) is applied to the running of the HTS-LSM, and the speed-adjusted system simulation model is also built by Matlab/Simulink lied on the mathematical model of HTS-LSM. This work has important meanings for the further studying of the HTS-LSM technology.

Modeling and Simulation of Flyback DC-DC Converter under Heavy Load

Appropriate simulation models of converters under heavy loads are crucial for designing a high reliability converter system. This paper presents the modeling and simulation of flyback DC-DC converters operating in heavy loads such as over-current and under-voltage modes, based on the concept of energy self-holding. An existing converter, which was once damaged in the experiment due to a short-circuited output, is analyzed by the presented simulation models and is found to be likely damaged under a heavy load. According to the simulated results, the circuit and parameters of the converter are modified. The redesigned converter can work safely in both steady state and heavy load modes.