• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.80-87
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• 2008

A lot of conventional automotive components driven by mechanical power source are being replaced with electrical ones to comply with the demands of market and customer, therefore the amount of electric energy used in a vehicle will be increased continuously. The increment of electric power demand causes interest on new higher power system such as 42V Power Net, and furthermore necessity for development of energy storage device is highlighted recently. This paper present the design of the BLDC motor for electric air-conditioner in 42V system and compare with the characteristics of several type BLDC motor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.531-538
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• 2007

In this study, an air conditioning system using carbon dioxide as a refrigerant was developed for automotive cabin cooling. Experiments have been carried out to examine the steady state and dynamic characteristics of this system. The system consists of a compressor, a gas cooler, an evaporator, an expansion device, an internal heat exchanger and an accumulator. The compressor is a variable displacement type, driven by the electric motor, and the gas cooler and the evaporator are aluminum extruded heat exchangers of micro channel type. The $CO_2-refrigerant$ charge, the compressor speed, the air inlet temperature of the gas cooler, the air inlet temperature and the air flow rate of the evaporator and the cooling load are varied and the performance of the system is experimentally investigated. As the compressor speed increased, cooling capacity increased, but the coefficient of performance was deteriorated. As the cabin air temperature or the air flow rate to the cabin was set high, both the cooling capacity and the COP increased. In the cool down experiment with 1.0 or 2.0 kW of heat load, the dynamic characteristics of the air-conditioning system were investigated. For a given capacity of compressor, cool down speed was monitored, and the temperature change was acceptable fur low heat load condition.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.52-58
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• 2012

Experimental study was performed to understand the real operation conditions of a showcase working usually in a convenient store and discount store. The purpose of this study was to show the possibility for practical use of cold-heat storage systems being operated for the showcase. To do that, evaporator and condenser temperatures were measured and the compressor electric power consumption were measured simultaneously. To use the ice storage system, the ice making process was typically operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was subcooled using the stored cold-heat after being discharged from the condenser during daytime. So, the cooling performance was increased with the sub-cooling of refrigerant during daytime,hence the actual running time of the compressor could be effectively decreased. Through the experiments, this study showed that the compressor electric power consumption during daytime could be transferred to nighttime for applying the refrigerant sub-cooling. So, for the convenient store, the maximum load transfer rates for each working cooler and showcase were estimated about 31.1% and 19.9% respectively. And for the discount store, the maximum load transfer rates for each refrigeration and freezing showcase were estimated about 34.1% and 49.0% respectively.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.374-375
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• 2019

In this paper, In the whole industry, there is a tendency to replace brushless motors with brushless motors because of the high rate of failure in DC motors with brushes. Accordingly, many methods for driving a brushless motor have been developed and studied. In order to drive the brushless motor, it is essential to know the information about the rotor position of the motor. However, it is not possible to use a position sensor for rotor disconnection due to the structure of an electric compressor brushless DC motor. In this paper, we investigate the rotor position of the motor by using the counter electromotive force included in the voltage of the terminal made by Y connection by using the resistance of each phase without using Hall sensor or encoder generally used to detect the rotor position. A sensorless drive system for a square wave brushless direct current (DC) motor is proposed. To do this, we propose a method to detect the rotor position from the analyzed terminal voltage waveform by performing terminal voltage analysis of each phase for 3-phase, 2-exciton unipolar PWM.

• Solar Energy
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• v.19 no.3
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• pp.63-73
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• 1999

Ice storage systems are used to shift the peak load in day time into night time in summer. This paper describes a system simulation of partial ice storage system composed of an encapsulated ice storage tank, a screw compressor chiller, a heat exchanger, and a brine pump. For the system simulation, a one-dimensional model of ice storage tank is developed and validated by comparison with the performance data from measurements of an ice storage tank installed at a building. The control strategies considered in this study are chiller priority and storage priority being used commercially. The system is simulated with design cooling load of 600 RT peak load in design day and with off-design day cooling load, and the electric energy costs of the two control strategies for the same system size are compared. As a result of calculation, the energy consumption in a week for storage priority is higher than that for chiller priority control. However due to lower cost of night electric charge rate, energy cost for storage priority control is lower than chiller priority.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.21-25
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• 2013

The purpose of this study is to provide basic data for the safety assessment of a water purifier when water leaks due to inappropriate maintenance and the examination of the cause of accidents related to the leak. Due to its inspection and management by non-specialists, if a leak occurs in a water purifier with the water level controller being inclined, it may result in the failure of the compressor, power supply line, PCB, etc. The analysis of the thermal diffusion pattern of water purifier compressors using a thermal image camera shows that its maximum temperature was approximately $80^{\circ}C$. In addition, its operating current was a maximum of 13 A and the system's operating current was approximately 1.7 A after the compressor was charged. It was found that the housing type power cable cover of the compressor had the effect of preventing electric shock but has poor flame resistance. Furthermore, the performance of the overload protector, PTC relays, etc., was excellent but they have potential for problems as metallic terminals were exposed, resulting in the potential of a safety related accident. The terminals and their surface damaged by the tracking showed a trace of carbonization and the resistance between terminals was measured to be approximately $8{\Omega}$. In addition, while the tracking was proceeding, the fuse and circuit breaker installed for system protection did not operate.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.804-805
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• 2006

Electric scroll-compressor drives are commonly used for e.g. home appliance cooling units. The recent development of hybrid cars with internal combustion engine in combination with electrical propulsion requires new solutions to be able to cool the passenger compartment of cars at stand-still. Both application areas demand efficient motor drives to reach good economy and efficient use of limited battery power as well as competitive volume/weight for a given output. The BLDC motor is a controllable and efficient solution. A major part of the motor is the soft-magnetic core. The powder based $Somaloy^{(R)}$ material shows high resistivity and induction as the result of engineered iron particles with in-organic coating. The unique features of compacted $Somaloy^{(R)}$ components can be utilized to enhance the shape and total volume of the BLDC motor with at least maintained efficiency compared to the use of traditional laminated steel sheet cores. A careful design of the $Somaloy^{(R)}$ components can also simplify assembly and positively influence the coil configuration. This study shows a comparison between a typical laminated BLDC motor and a redesigned, $Somaloy^{(R)}$ based version adapted for a scroll-compressor application.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.826-827
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• 2008

선형전동기는 위치 및 속도 제어기구로 빠른 속도와 강한 추력 정확한 위치 제어가 가능하다. 선형전동기의 성능 향상 및 소형화를 위해서는 추력의 최대화가 요구되는데, 일반적으로 추력을 계산하는 방법으로 유한요소법, 등가자기회로망법 등이 있다. 본 연구에서는 유한요소법을 이용하여 정자장 해석인 정특성과 과도해석인 동특성을 분석하였다. 향후 정특성과 동특성의 결과를 통해서 시제품의 실험결과와 비교 분석하여 동특성해석에 대한 검증을 수행할 것이다.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.63-67
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• 2002

In this study, the performance of the Stirling type orifice Pulse tube refrigerator (OPTR) with a linear compressor was investigated by experiment. The dynamic pressures at three points and a temperature at the cold heat exchanger are measured to explore the dependency of the orifice on the performance of the OPTR. The experimental results show that the opening of the orifice has significant effects on the no load temperature and cool down characteristics. The Pressure amplitude in Pulse tube decrease as the opening of the orifice increase, but the mass flow rate through the orifice and the electric input Power to the compressor increase. The results show that the operating frequency and charging Pressure does not affect on the no load temperature. The pressure amplitude in pulse tube decrease as the operating frequency increase or the charging Pressure decreased.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.130-135
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• 2013

Recently, the needs of system performances such as working speed and processing accuracy in machine tools have been increased. Especially, the working speed increment generates harmful heat at both moving part of the machine tools and handicrafts. The heat is a main drawback to progress accuracy of the processing. Hence, a oil cooler to control temperature is inevitable for the machine tools. In general, two representative control schemes, hot-gas bypass and variable speed control of a compressor, have been adopted in the oil cooler system. In this paper, the compressor's speed are controlled to keep reference value of temperature at oil outlet. The precision processing of a machine tool is required for an oil cooler guaranteeing ${\pm}0.1^{\circ}C$ temperature control. But the oil cooler with precision temperature control is expensive. Therefore in this paper, instead of a on/off(relay) control method, a PID and phase angle electric power control method is proposed for the precision control of an oil cooler. The proposed controller is implemented and tested at the temperature of $23^{\circ}C$, $24^{\circ}C$ and $25^{\circ}C$.