• Journal of the Korean Society of Industry Convergence
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• v.3 no.3
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• pp.265-273
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• 2000

Basic simulation program for Vuilleumier cycle heat pump was developed that can use precise VMHP design and analysis. VMHP system was divided 11 sections in simulation. Simulation was used adiabatic model analysis and that considered with heat transfer performance for heat exchanger, regenerator loss, conduction loss, shuttle loss, pumping loss and pressure loss by flow friction. Specially, friction loss of connection pipe between heat compression side and heat pump side, leakage of rod seal and piston seal was considered in the analysis.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.22-27
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• 2020

In this paper, a generalized efficiency equation was proposed to estimate the internal loss of the SMPS (switched-mode power supply) with 3 variables. The first variable was an internal loss not related to the load current such as auxiliary power, the second was a loss proportional to the current such as diode loss, and the third was a loss proportional to square of the current such as conduction loss. Especially, theoretical internal losses of the totem pole bridgeless PFC which is widely used for high efficiency SMPS were expressed as output function to compare generalized efficiency equation. In addition, in order to reduce the conduction loss of the switch, when a multiple switch were paralleled, the correlation with the efficiency was analyzed and shown as a graph. In order to confirm the degree of the parallel switch structure on the efficiency improvement, a 2kW class totem pole bridgeless PFC was constructed and the effectiveness of the analysis was confirmed by comparing the generalized efficiency equation and theoretical loss analysis results with experimental data.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.295-304
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• 2004

This paper deals with characteristic analysis method using d-q axis equivalent circuit considering iron loss in a single-phase line-start permanent magnet synchronous motor. The iron loss resistance to account for the iron loss is included in the equivalent circuit to improve the modeling accuracy. Furthermore, for the improved calculation of the iron loss, the iron loss is calculated from the magnetic flux density by 2-dimensional finite element method. The result is represented as the iron loss resistance and connected in parallel with the total induced voltage. Therefore, the currents can be expressed as the summation the output current with the current corresponding to the iron loss. Finally, the steady state characteristic analysis results are compared with the experimental results to verify this approach.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2168-2180
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• 2014

In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.15-19
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• 2005

This paper analyzed the power loss characteristics according to winding thickness and winding method of high frequency transformer. Power loss was analyzed by PExprt using FEM tool. The ferrite core model for analysis be used the EE10 type of TDK cop.. Transformer model objected flyback transformer type applied to flyback converter/inverter. Therefore, analysis results of loss were obtained from inner parameters of DC, AC resistance, leakage inductance, copper loss, core loss, and temperature etc.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.165-173
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• 2013

Core loss has a major effect on heat generation in synchronous motors with surface-mounted permanent magnets (SPMs). It is essential to perform heat transfer analysis considering core loss in SPM because core loss is seriously affected by torque and speed of motors. In the present study, mechanical loss, core loss and coil loss are evaluated by measuring input and output energies under various driving conditions. For a better understanding heat transfer paths in synchronous motors, we developed a lumped thermal system analysis model. Subsequently, heat transfer analysis has been performed based on acquired energy loss, temperature data and thermal resistance with three types of SPM. It is shown that the torque constants decrease by Max. 10% as speed increase. At the rated torque, the core loss is Max. 10.9 times greater than the coil loss and the hysteresis loss of magnets is dominant in total loss.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1503-1510
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• 2017

In this paper, a thermal analysis of a high speed induction motor with a PWM voltage source was performed by considering harmonic loss components. The electromagnetic analysis of the high speed induction motor was conducted using the time-varying finite element method, and its thermal characteristics were carried out using the lump-circuit method. Harmonic losses from tests in the high frequency region were divided into core loss and conductor loss components using various ratios, in order to determine the loss distributions for the thermal analysis. The results from both the calculations and experiment were validated using a high speed induction motor prototype operating at 20,000rpm.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.225-229
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• 2017

This paper describes the loss analysis based on load conditions of the air conditioning compressor motors using variable dc-link voltage. The losses of PMSM (Permanent Magnet Synchronous Motor) should be analyzed by the PWM (Pulse Width Modulation) output of inverter. The harmonic loss by the PWM cannot consider that using the current source analysis of the inverter. In addition, when the voltage of dc-link is variable with the condition of variable speed and load conditions in motor, the losses of motor are also changeable, however it is hard to analyze those losses by only electromagnetic finite element method (FEM). Therefore, this paper proposes the analysis method considering the carrier frequency of the inverter and the varying state of the dc-link voltage through the FEM-control coupled analysis. Using proposed analysis method, additional core loss and eddy current loss of permanent magnet caused by PWM could be analyzed. Finally, the validity of the proposed analysis method is verified through the comparison the result of coupled analysis with experiment.

• Journal of Distribution Science
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• v.15 no.11
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• pp.21-29
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• 2017

Purpose - Relationship between farm and county losses determines whether the county program provides too little, too much, or similar amount of assistance relative to the loss on an individual farm. A review of the literature finds limited analysis of the determinants of this relationship. This paper conducts such an analysis using farm-level yield data. Research design, data, and methodology - Farm-level yield data from Illinois and Kansas farm business management associations are used for to calculate the correlation between farm and county loss and the share of farm loss systemic with county loss, and also for the regression analysis. Results - Average share of farm loss systemic with the county loss lies between 42% and 68%. The correlation between farm and county yield/revenue deviation from expected value is statistically significant in all four models. The coefficient is positive, implying the higher the correlation, the larger the share of farm loss that is systemic with the county loss. Conclusions - The findings of this study are consistent with the existing literature which argues that county variability may not be closely associated with farm variability. The findings of this study thus raise questions about the efficacy of area yield and revenue insurance products in helping farmers manage their risk.

• Journal of Magnetics
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• v.18 no.3
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• pp.268-275
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• 2013

This paper shows the characteristics of performance for interior permanent magnet machine (IPM) considering driving conditions such as maximum torque per ampere (MTPA) and flux-weakening control especially in terms of harmonic loss. In particular, based on finite element analysis (FEA), permanent magnet (PM) eddycurrent loss and the harmonic iron loss have been computed where the models have been intentionally designed to identify the effects of pole-slot combinations on the loss while maintaining the required power for electric vehicle. From the analysis results, it was shown that the rotor iron loss and PM eddy-current loss of machine employing fractional slot winding are extremely large at load condition. Furthermore, it was revealed that the harmonic iron loss at high-speed operation is mainly distributed over stator teeth and rotor surface, which may aggravate cooling system of the rotor structure in the vehicle.