• Journal of Power Electronics
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• v.9 no.3
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• pp.438-446
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• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.853-854
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• 2006

Interior permanent magnet synchronous motor(IPMSM) has higher power density than other PM(permanent Magnet) machines due to reluctance torque in addition to magnetic torque, and the ratio of magnetic and reluctance torque has influences on motor characteristics such as input current, efficiency, power factor, etc. Therefore, this paper presents the output characteristics of IPMSM according to the ratio magnetic and reluctance torque of IPMSM and discuss the design strategy of IPMSM.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.40-42
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• 1999

High-speed brushless permanent magnet machines are good for compressor and aerospace applications, etc, since they are conductive to high efficiency, high power density, small size and low weight. This paper describes a diametrically magnetized PM motor with the rating of 4.3kW and 50000 rpm fur high-speed drive applications. To bear strong stress from high speed, rotor was designed cylindrical structure, was magnetized diametrically permanent magnet. The performance characteristic of motor was evaluated by means of FEA(Finite Element Analysis), no-load test And then, in order to find back-EMF constant, used FEA, search coil.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.22-24
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• 2005

This paper is intended to introduce a set of static and dynamic experiments for a better characterization of the linear permanent magnet oscillatory machine. The experiment have been peformed on two prototypes; one with buried permanent magnets with flux concentration while the other with surface permanent magnets. Though the testing arrangement allows for it, temperature, noise and vibration have not been in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.568-574
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• 2017

This paper proposes a demagnetization fault diagnosis method for interior permanent magnet synchronous motors(IPMSMs). In particular, a demagnetization fault is one of the most frequent electrical faults in IPMSMs. This paper proposes an estimation method for permanent magnet flux. The method is based on linear interpolation. The effectiveness of the proposed method for diagnose demagnetization faults is verified through various operating conditions by finite element simulation.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1051-1053
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• 2003

Flywheel Energy Storage System (FESS) consists of a high-speed flywheel with an integral motor/generator suspended on magnetic bearings and in an evacuated housing. Permanent magnet (PM) machines as the FESS motor/generator are a popular choice. since there are no excitation losses which mean substantial increase in the efficiency. In this paper, the basic design and the steady-state performances of a permanent magnet synchronous high speed motor/generator for FESS are presented.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.945-950
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• 2013

This paper deals with the ellipse permanent magnet machines for the minimization of torque ripple based on electromagnetic field theory. On the basis of a magnetic vector potential and a two dimensional (2-D) polar system, analytical solutions for flux density due to permanent magnet (PM) and current are obtained. In particular, the analytical solutions for mathematical expressions of magnets with different circumferential thicknesses can be solved introducing improved magnetization modeling techniques. The analytical results are validated extensively be nonlinear finite element solutions, a reduction of torque ripple can be achieved.

• Journal of the Korean Institute of Navigation
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• v.21 no.4
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• pp.29-38
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• 1997

Because of the result of a large use of electronic equipments, the occupation density of microwave frequency band is highly increased, and electromagnetic environment is getting more seriously bad. It is sometimes reported that electronic machines are not normally operated on account of the influence of undesired electromagnetic wave, which often gives fatal blow to even human life and thus becomes serious social problems. OATS(Open Area Test Site) is principally used to measure EMI or examine elelctromagnetic emission. Because of various restrictions we often build semi-anechoic chamber which has the function of OATS to measure EMI or EMS other than OATS. If the difference of the site attenuation between semi-anechoic chamber and OATS is within ${\pm}3dB$, the semi-anechoic chamber is recognized as adequate facility to measure EMI or EMS. Accordingly authors evaluate and analyze site attenuation due to absorbent materials, polarization, mutual coupling effects, etc. The calculated and the measured site attenuation in semi-anechoic chamber are compared. As a result good agreement is obtained.

• Journal of Magnetics
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• v.18 no.3
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• pp.361-364
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• 2013

Permanent magnet flux switching motor (PMFSM) is a novel double salient machine which employs PMs instead of field winding for excitation. PMFSM contains only one set of armature winding, thereby features simple control strategy, low cost power inverter and substantial high efficiency. Due to the unique double salient structure and operation principle, the generated cogging torque in PMFSM is critical and quite different compared to the traditional PM machines. This paper presents and investigates various design techniques for reducing cogging torque in PMFSM. Firstly, an analytical model is proposed to study the influence of different methods on cogging torque. Then the optimal design parameters for minimizing cogging torque are determined by the analytical model, which significantly reduces the computational efforts. At last, the cogging torque with different design approaches are simulated by FEA along with the average output electromagnetic torque, which validates the analysis above.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.145-157
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• 1999

Wood dust is created when machines are used to cut or shape wood materials. Industries of high risk of wood dust exposure are sawmills, dimension mills, furniture industries, and carpenters, etc. Health effects associated with wood dust exposure includes dermatitis, allergic respiratory effects and cancer. Health effects of wood dus t are mainly depend on the concentration, dust size and exposure time. This study were carried out to evaluate the concentration and particle size distribution of wood dust during working processes. The subjects of this study were 53 workers exposed to wood dust in 7 furniture factories and 5 musical instruments, and 5 sawmill factories. The average total wood dust concentrations measured by personal cascade impactor were $1.82{\pm}2.31mg/m^3$ in primary manufacture, $3.59{\pm}1.72mg/m^3$ in s econdary manufacture, $5.09{\pm}1.46mg/m^3$ in sanding operation. Mass median diameters of hardwoods dust were $3.36{\mu}m$ in primary manufacture, $4.25{\mu}m$ in secondary manufacture, $4.21{\mu}m$ in sanding operation. softwoods dust were $3.39{\mu}m$ in primary manufacture, $4.34{\mu}m$ in secondary manufacture. Particle size distributions showed a nearly the same pattern in each working processes. The sample concentration of all hardwood dust exceeded the Threshold Limit Value(TLV) and 20.8% of the softwood dust exceeded the Threshold Limit Value. The range of size distribution were $0.5-10{\mu}m$ in the soft and hardwood dust. The respirable dust of soft and hardwood took up 59% and above. Therefore new threshold limit value for wood dust should be needed in Korea. Also, it should be done for various studies on health effects related to occupational exposure of wood dust.