■ FUNDAMENTAL PRINCIPLE
Electromagnetics is a branch of physics that explores the electric and magnetic phenomena. Maxwell's equations provide how electric and magnetic fields are generated, propagated, and interacted by each other and are influenced by objects. The optimal design for the electromagnetic systems such as wireless power transfer (WPT), electric motors can be determined by electromagnetic analysis.
The goal of our research group is to develop the optimization frameworks for the electromagnetic systems and to apply them to the real-world systems. In order to optimize the systems, it is necessary to determine the appropriate design variables, objective function, and constraint functions. The optimization module determines the optimized design to extremize the objective function while satisfying all the constraints with multiple design variables. The analysis module analyses the target model based on the principles of electromagnetics. Through iterations, the design variables are updated, thereby determining the optimized design at the end of optimization.
■ RESEARCH AREA 1: Wireless Power Transfer System
- Size and shape optimization
- An optimization framework for real-world WPT systems is developed through connecting commercial electromagnetic field analysis software and an optimization module using in-house codes. The developed design framework is experimentally validated under the same working conditions.
* S. B. Lee, S. Ahn, and I. G. Jang, “Development of the Optimization Framework for Low-Power Wireless Power Transfer Systems,” IEEE Trans. Microw. Theory Tech., vol. 63, no. 3, pp. 813-820, Mar. 2015.
- Layout (or topology) optimization
- In this research, a novel layout optimization is proposed to determine the optimal layout of the secondary coils when the primary coils are given. To develop the proposed method, the analysis module is built to evaluate electromagnetic field-related measures and coil related measures. Then, the analysis module is connected with the optimization module. As an example, a portable wireless charger is optimized to maximize the induced voltage while satisfying a mass constraint and the optimized design is validated.
* S. B. Lee and I. G. Jang, “Layout Optimization of the Secondary Coils for Wireless Power Transfer Systems,” IEEE Trans. Microw. Theory Tech. under review.
■ RESEARCH AREA 2: Design Optimization for Electric Drive System
- Electric motors consume about 45% of the global electricity , and the motors are applied to various fields such as industrial compressors, fans and hybrid/electric vehicles. In particular, due to greenhouse gases and particle materials emitted by combustion engines, the market share of the hybrid/electric vehicles rapidly increases. However, despite of this market potential, 51% of potential customers hesitate to purchase hybrid/electric vehicles due to their high prices and low performance.
- Our research group aims to improve the performance and reduce cost of various types of motors such as IPMSM (Interior-Permanent Magnet Synchronous Motor), SynRM (Synchronous Reluctance Motor), SRM (Switched Reluctance Motor) by applying the design optimization.
- Design optimization is an effective method to maximize or minimize the objective function (e.g., average torque, torque ripple, rated power, and etc) under multiple constraints (e.g., cost, mass, maximum current of IGBT, battery Voltage). The calculation of vector potential of the electromagnetic field is based on finite element tools (e.g., ANSYS Electronics, COMSOL multiphysics, and etc.). Knowledge of the in-house code (e.g., C ++, Visual Basic, Fortran, and etc) is required for the script-based shape/topology optimization and finite element analysis.
- As the result of optimization, the self-manufactured motor is driven with the advanced motor control such as MTPA (Maximum Torque Per Current), FW (Flux Weakening), MTPV (Maximum Torque Per Voltage). A power analyzer, bidirectional DC supply, 100kW motor dynamo, and vehicle dynamo had been set for the experimental test.
- Relevant Members: Doctoral Course Changwoo Lee/ Master's Course Su Seong Noh
- Relevant Project:
- ▶Development of Hybrid Electric Vehicle Conversion Kit for Diesel Delivery Trucks and
- its Commercialization for Parcel Services (2017.07.-2020.12.)
- ▶Feasibility Study on Eco-friendly Hybrid Diesel-electric Trucks for Parcel Delivery Service