Tae-Kyung Chung

A Research on Iron Loss of IPMSM With a Fractional Number of Slot Per Pole

In this paper, we investigated rotor iron loss of interior permanent magnet synchronous machine (IPMSM), which has distributed armature windings. In order to study the iron loss with the effect of slot-pole combination, two machines for high-speed operation such as electric vehicle were designed. One is fractional slot winding and the other is conventional one. In the analysis, we developed a new iron loss model of electrical machines for high-speed operation. The calculated iron loss was compared with the experimental data. It was clarified that the proposed method can estimate iron loss effectively at high-speed operation. Based on this newly proposed method, we analyzed iron loss of the two machines according to their driving conditions. From the analysis results, it was shown that rotor iron loss of machine employing fractional slot-winding is definitely large at load condition. In addition, it is interesting that the ratio (rotor iron loss/stator iron loss) becomes larger as the speed of the machines increase if the number of slot per pole is fractional.

Harmonic Iron Loss Analysis of Electrical Machines for High-Speed Operation Considering Driving Condition

In this paper, we proposed new harmonic iron loss calculation methods for electrical machines. The new methods based on the concept of variable loss coefficients due to their flux density and frequency estimate harmonic iron loss in the time domain and the frequency domain. In order to verify the performance of the proposed method, we calculated the iron loss with conventional methods. Then, the estimated iron losses were compared with the experimental data. It was clarified that the proposed methods are more effective than the conventional methods at high-speed operation. Based on these newly proposed methods, we analyzed the iron loss of the machine for electric vehicle (EV) according to its driving condition. From the analysis results, it was shown that the harmonic iron losses of stator are larger than before at field-weakening region. In addition, it was revealed that rotor iron loss mainly induced by stator slot ripples does not show strong dependence on the current angle and only varied primarily according to the speed.

A Study on Loss Characteristics of IPMSM for FCEV Considering the Rotating Field

This paper presented the loss characteristics of interior permanent-magnet machines (IPMSM) for a fuel-cell electric vehicle. In order to study the loss characteristics of the machine, one prototype machine having 100 [kW] was designed. In the analysis, to consider the harmonic magnetic field and the rotational variation of flux vectors in the core of the machine effectively, we proposed a new harmonic iron-loss calculation method based on adaptive loss coefficients. To verify the performance of the proposed method, we calculated a no-load iron loss in an IPMSM with conventional methods. Then, the estimated iron losses were compared with the experimental data. It was clarified that the proposed method is more effective than conventional methods at high-speed operation. Based on this proposed method, we investigated the losses of the machine considering operating points according to its speed. From the results, it was shown that the main loss component and the location of iron-loss distribution change depending on operating condition.

Optimal design of electric machine using genetic algorithms coupled with direct method

This paper discusses the development of a new optimization algorithm for DC motor design. In principle, the new algorithm utilizes a mixed method that consists of genetic algorithms in conjunction with direct search method. The genetic algorithms are used for locating the global optimum region while the direct search method is used to achieve objective function convergence. In order to validate the effectiveness, the new algorithm has been applied to an actual DC motor. Field and torque characteristics of the DC motor are computed using the finite element method and the principle of virtual work, respectively.

Design of a short-time rating interior permanent magnet synchronous motor using a niching genetic algorithm

This paper presents an optimal design method of short-time rating interior permanent magnet synchronous motor considering transient temperature rise. FEM results are used to compensate the characteristic equation for more accurate analysis. Temperature rise is calculated by using the thermal equivalent network method, and the niching genetic algorithm adopting restricted competition selection is used for optimization in the process of design. Experimental results of the optimally designed motor show good agreement with the simulation results.

A sensitivity analysis using boundary element method for shape optimization of electromagnetic devices

A design sensitivity analysis for optimal shape design of electromagnetic devices is described. The design sensitivity is explicitly derived for two-dimensional electromagnetic systems by using implicit differentiation and direct boundary element methods. The proposed design sensitivity analysis is applied to the optimal shape designs of the yoke of an electromagnet and magnetic pole, and desired distributions of magnetic induction in the air-gap are then obtained. >

Novel Electromagnetic Actuator Using a Permanent Magnet and an Inter-Locking Mechanism for a Magnetic Switch

The solenoid magnetic actuator has been widely used as an actuator for MS (magnetic switch). Thus, conventional MSs continuously consume electrical power to maintain a closed state. To address this problem, an innovative structure which uses a permanent magnet to generate holding force in the closed state without electrical power is suggested in this paper. Further, the permanent magnet is dedicated to the opening operation and the closing operation by means of its magnetic force. In other words, an eco-friendly MS is proposed in this research. However, this structure has a critical problem in that, if unexpected external force is applied to the MS when in the open state, the MS returns to the closed state by the force of the permanent magnet and remains in the closed state, causing an unintended operation of the load. To solve this problem, a novel inter-locking mechanism is proposed. Hence, we termed the proposed novel MS the MSPI (magnetic switch using a permanent magnet and an inter-locking system). In addition, analysis and design methods for the MSPI are proposed in this paper. The usefulness of the MSPI and the accuracy of the analysis and design methods are confirmed through an experiment.

Optimization of multilayer buried magnet synchronous machine combined with stress and thermal analysis

Optimal design process of multilayer buried magnet synchronous machine combined with mechanical and thermal analysis is presented in this paper. Fast stress and thermal analysis method using electromagnetic analysis information is explained in detail. Through the optimization result and comparison with experimental data, the validity of proposed method is verified

Characteristic Analysis and Design of a Thomson Coil Actuator Using an Analytic Method and a Numerical Method

The Thomson coil actuator (TCA) is a useful switch due to its simple structure and rapid completion time. However, research on the TCA is not widely available. Research on the TCA has been focused on the basic working principles and the characteristic analysis of the TCA. To address these problems, an analysis method and a design method for the TCA are proposed in this paper. Concretely, the analysis and the design method using a numerical method and an analytical method are proposed in this paper. The critical design variables are inspected in detail in this research. The correctness of the proposed methods and the usefulness of the TCA for the high speed switch are verified through an experiment.

Characteristic Analysis of an Traveling Wave Ultrasonic Motor using a Cylindrical Dynamic Contact Model

The traveling wave ultra-sonic motor (TWUSM) is operated through the frictional force between the rotor and the stator. Hence, the contact mechanism must be analyzed to estimate the performance of the motor. However, the nonlinearity of the contact mechanism of the TWUSM makes it difficult to suggest a proper contact model and a characteristic analysis method. To address these problems, a novel contact model is proposed here. It is termed the cylindrical dynamic contact model (CDCM) in this research. A motor performance estimation method is suggested using the CDCM, an analytical method, and a numerical method. The feasibility and usefulness of the suggested characteristic analysis are verified through experimental data.