Byung-Song Lee

Development of 1-MW Inductive Power Transfer System for a High-Speed Train

Design and fabrication of a 1-MW inductive power transfer (IPT) system that supplies power to the vehicle in real time without any battery charge is proposed for a high-speed train. The IPT system consists of a 1-MW resonant inverter, a 128-m transmitter, four pickups, including rectifiers, and a wireless feedback network to maintain a constant output voltage of the pickups. The operating frequency of the system is 60 kHz to achieve efficient power transfer with a large air gap. The measured efficiency of the IPT system at the 818-kW output power of the pickups for the 5-cm air gap is 82.7%. The electromagnetic field and the induced voltage at the rail are also measured for safety evaluation. The fabricated IPT system was adapted to the high-speed train, and the train successfully accelerates to a speed of 10 km/h according to startup procedures.

Thrust Performance Improvement of a Linear Induction Motor

The end effect of a linear induction motor (LIM) has been known for several decades, especially in high speed operation. The exit part of the primary is not dealt as extensively as the entry part because of its minor effect. However, the exit part is one of the keys to weaken the dolphin effect, which occurs in high speed operation. In this paper, the concept of the virtual primary core is introduced, and chamfering of the primary outlet teeth is proposed to minimize the longitudinal end effect at the exit zone. For this, LIM for the high-speed train is designed and analyzed by using finite element method. Results confirm that chamfering can improve thrust performance effectively.

A study on the Reduction of the Stator iron loss on Permanent Magnet Synchronous Motor for Light Railway Transit Propulsion System

A study on the iron-loss reduction of 110kW-class Interior Permanent Magnet Synchronous Motor (IPMSM) for Light Railway Transit (LRT) is conducted. In general, the iron loss of IPMSM depends on the characteristics of core material and non-oriented electrical steel is used as a core material of IPMSM. In order to reduce the iron-loss of IPMSM, both non-oriented electrical steel and grain oriented electrical steel are applied as core material. Iron loss of 110kW-class IPMSM can be reduced approximately 40% comparing to an existing IPMSM by applying grain oriented electrical steel to the stator teeth.

A New Design Methodology for a 300-kW, Low Flux Density, Large Air Gap, Online Wireless Power Transfer System

A high-power online wireless power transfer system has been investigated intensively in recent years. However, no literature has focused on the design methodology of the high-power online wireless power transfer system with low flux density, high efficiency, and high control stability. This paper proposed a new design methodology for a 300-kW, over 96 % coil-to-coil efficiency, International Commission on Non-Ionizing Radiation Protections safety regulation compatible online wireless power transfer system. Using finite-element analysis and experimental results, the proposed design methodology has been evaluated.

Investigation of a Thermal Analysis Method for IPMSM in Railway Vehicles

In this paper, research on the thermal analysis method is reported for the characterization of heat generation while operating an Interior Permanent Magnet Synchronous Motor (IPMSM) for railway vehicles. Efficient cooling of the heat generated in the IPMSM is important because the excessive heat generated from the winding, core and permanent magnets increases the difficulty of continuously operating an IPMSM over long time periods. Therefore, in this study, in order to analyze the heat generation characteristics of the IPMSM for advanced research in the application of IPMSMs to cooling devices, the heat transfer coefficients for each component of the IPMSM were derived and the thermal equivalent circuit was configured to perform thermal analyses. Finally, the validation of the suggested thermal analysis method was performed through comparison with the heat experimental data of an IPMSM prototype.

Performance comparison of the railway traction IPM motors between concentrated winding and distributed winding

This paper presents performance comparison between concentrated winding and distributed winding of IPMSM (Interior Permanent Magnet Synchronous Motors) which are recently used for light-weight railway applications. Motors are designed on various schemes and analyzed by using FEM (Finite Element Method) instead of EMCNM (Equivalent Magnetic Circuit Network Method) in order to consider saturation and non-linear magnetic property. The overall performance such as torque, torque ripple, losses, demagnetization, efficiency, power density and so on are investigated in detail at the rated and maximum operating speed. From the analysis results, the concentrated winding IPMSM as well as the distributed winding IPMSM can be a good candidate for a high power railway traction motor.

Characteristic Analysis of Superconducting LSM for the Wheel-rail-guided Very High Speed Train according to Winding Method of the Ground 3-phase Coils

Recently, an interest in a hybrid system combining only the merits of the conventional wheel-rail system and Maglev propulsion system is growing as an alternative to high-speed maglev train. This hybrid-type system is based on wheel-rail method, but it enables to overcome the speed limitation by adhesion because it is operated by a non-contact method using a linear motor as a propulsion system and reduce the overall construction costs by its compatibility with the conventional railway systems. Therefore, the design and characteristic analysis of a coreless-type superconducting Linear Synchronous Motor (LSM) for 600km/h very high speed railway system are conducted in this paper. The designed coreless-type superconducting LSMs are the distributed winding model, the concentrated 1 layer winding model and the concentrated 2 layer winding model, respectively. In addition, the characteristic comparison studies on each LSM are conducted.

Core-loss Reduction on Permanent Magnet for IPMSM with Concentrated Winding

Interior Permanent Magnet Synchronous motors (IPMSM) with concentrated winding are superior to distributed winding in the power density point of view. But it causes huge amount of eddy current losses on the permanent magnet. This paper presents the optimal permanent magnet V-shape on the rotor of an interior permanent magnet synchronous motor to reduce the core losses and improve the performance. Each eddy current loss on permanent magnet has been investigated in detail by using FEM (Finite Element Method) instead of equivalent magnetic circuit network method in order to consider saturation and non-linear magnetic property. Simulation-based design of experiment is also applied to avoid large number of analyses according to each design parameter and consider expected interactions among parameters. Consequently, the optimal design to reduce the core loss on the permanent magnet while maintaining or improving motor performance is proposed by an optimization algorithm using regression equation derived and lastly, it is verified by FEM.

A study on the design parameters of inductive power transformers

As a new concept of energy transmission systems, evolved from existing catenary and pantograph methods, Inductive Power Transformer (IPT) systems have been studied in a variety of applications in the field of railway systems recently, but there are still a lot of technical issues to resolve in order to apply an IPT system to a large system such as high-speed railway. Equivalent circuit parameters and coupling coefficients of IPTs are important design factors for high energy transfer efficiency. This paper investigates the properties of equivalent circuit parameters and coupling coefficients of the U-U type IPT and U-I type IPT using analytical and experimental methods.

Air-gap control system of a linear induction motor for a railway transit

In order to realize a traction system with high efficiency and performance for a railway transit, many researchers have continued to study on a linear induction motor (LIM). However, most of researches are limited in LIM unit design. On a moving LIM, the change of an air-gap (it occurs by a construction tolerance of a secondary reaction plate) can lead to decrease a smoother ride and efficiency of the railway transit system. Therefore, a uniform air-gap operation of the LIM is important issue to improve the system efficiency. However, the researches about the air-gap length control of the LIM have been not advanced a lot due to a technical and high-cost problem. Therefore, in this research, the authors introduce an air-gap control system to control the air-gap length which depends on the flatness of the secondary reaction plate when the LIM is been operating. Then, through a dynamic modeling and analysis of the system, the authors analyze characteristic variations of some parameters (spring coefficient, damping coefficient, displacement, and exiting force) which compose the system, and conduct a research on feasibility of the system.