Hyun Rok Cha

Design of outer rotor IPM type PMSM for 3 wheel electric vehicle

In this paper, the optimization design of outer rotor IPM type PMSM was carried out for electric vehicle traction having 3 wheel system. The half round shape was proposed to reduce the cogging torque due to IPM machine characteristics. The object of optimization design is to find out most effective factor in reducing the torque ripple which may occurs the noise, vibration and uncomfortable riding of EV. In order to satisfy the low cogging torque, some design parameter such as air-gap, number of slot, poles, and slot open size was evaluated. From the simulation results of the outer rotor type IPM, we find out that the combination of slot open and depth of magnet is most important factor for reducing the cogging torque and high performance in low speed operational area. Moreover, the prototype of designed outer rotor IPM type PMSM was carried out and verified their properties.

Consensus of generalized integrators

We study a generalized integrator consensus network, each node of which is a single-integrator cascaded with some heterogeneous non-integrator internal dynamics. Under the assumption that the interconnection graph is undirected and connected, we first investigate the convergence property of the consensus network and show that the interconnection is beneficial for the enhancement of the convergence rate if the non-integrator internal dynamics of each node is strictly passive. We then show that the interconnection is also advantageous for the disturbance attenuation in the consensus network.

A Control of the MMF Space Harmonic Parasitic Torques in the concentrated winding AC Machine Using Skew angle Optimization

In this study, the authors proposed a method of controlling harmonic parasitic torque in concentrated winding induction motor and validated its theorys practicality through the experiment. To control harmonic, the rotor was skewed at an angle and to determine optimum skew angle, three dimensional electromagnetic analysis was performed. The result of analysis demonstrated larger than 20 degree skew angle, which was not conventional in distributed winding, was favorable in the proposed concentrated winding induction motor. In this investigation, 27 degree skew angle was optimal for the proposed designed motor. Additionally, in the case AC motor was designed per the proposed theory in this study, the proposed design can be manufactured more cost effectively than conventional distributed winding

A factors affecting compressibility of ultrasonic compaction for high efficiency electrical motor core fabricated soft magnetic composite

This paper deals with the compressibility of ultrasonic compaction. The object is to find out the most effective factor in increasing the density of the compaction for high efficiency electrical motor with soft magnetic composite under ultrasonic action. To make clear the effects of the ultrasonic vibration on the target process and obtain general knowledge usable for the practical design, several model experiments were proposed and carried out. The improvement in the resultant density was studied as function of the compression pressure, the vibration amplitude/frequency and the input power. Throgh the experiments, the fundamental information such as densification mechanism under ultrasonic action and the optimum design parameter for the high densification were figured out.

A Considering Method of Density Distribution Factor for the Ceramic Motor with Soft Magnetic Composite Core

In this paper, we suggested the new standards of motor design in using of Soft magnetic composite (SMC) material. Previous motor design in using of SMC material executed the same procedures of silicon steel. These procedures assumed that all places of material have the same density distribution and B-H curves. But we showed that the SMC material has inequality density distribution. By using powder forming analysis with FEM analysis, we showed that difference of density distribution could not be avoided because of the shear stress on powder, surface of the mold and punch. Therefore the magnetic characteristic was not the same in all places of material. So, we suggested the new method of motor design which considered the inequality density distribution in using of SMC material. And we compared previous method results and new method results and showed the differences of the result values. The density deviation of the SMC motor core was 5.8% and efficiency deviation was 3%. Especially the output value was different above 11% when we got the results by using previous method.

Insulation and Magnetic Properties of Iron Powder Coated by Wet Chemical Method

Magnetic core components are often made from laminated sheet steel, but they are difficult to manufacture in near net shape, resulting in large core losses at higher frequencies. In this study, the pure iron powder was treated with aqueous phosphoric acid to produce phosphate insulating layer on the surface. After drying the powder, it was mixed with 0.5wt% Zn stearate and compacted in a mold with a diameter of 20mm at 800MPa. The powder compacts were then heat treated at 500°C for 1 hour. The results showed that insulated iron powder was obtained with uniform phosphate layer by chemical reaction. With increased amount of phosphate layer, the core loss and density of compacts were decreased. It was also found that the addition of ethyl alcohol during insulating reaction resulted in improved core loss value.

The Improvement of Permeability and Strength in Soft Magnetic Composites Motor Core Using Spark Plasma Sintering Process

The practical uses of soft magnetic composite(SMC) for an electrical motor is presented in this paper. SMC allows obtaining improved stator and core shapes as well as totally new design concepts such as claw pole motor. However, a major disadvantage of soft magnetic composites was their weak strength. In this study, spark plasma sintering (SPS) was utilized to improve the strength of SMC. Advantages of the SPS process over other conventional sintering process are the faster heating and cooling rates ensured and higher pressure applied during the sintering procedure. This allows obtaining high strength products in short periods of time to meet with industrial application without insulation destruction. This paper introduces the development of high strength soft magnetic composite motor core and examples of practical application for industries. The result showed that the SPS process increased the fracture strength, about 1.3 to 1.7 times, of SMC compare to the conventional compaction. Also we derive method to reduce the iron loss in the SPS sintering process using control forming temperature. As the forming temperature decreased from 500°C to 300°C, reduction of iron-loss was obtained from 192W/kg to 21W/kg by using SPS sintering process. Moreover, with increased the SPS sintering process pressure value from 250MPa to 800MPa which is the conventional compaction condition and decreased forming temperature to 200°C, iron-loss was measured. The results showed that iron-loss was obtained 11.42W/kg and it was similar value of conventional compaction results.