• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.780-786
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• 2001

For the compressor speed control of a multi-type air conditioning system, a fuzzy control algorithm was developed. The sum of zone temperature errors and its derivative were used as input variables, and the compressor speed was selected as the output variable. To test the effectiveness of the control algorithm, one outdoor environmental chamber and four indoor environmental chambers were used. In the chambers the zone temperature step change test and the indoor unit change over test were performed. Test results showed that, for the control of compressor speed, the fuzzy control algorithm was more effective than the conventional proportional control algorithm for the energy conservation.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.37-41
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• 2011

This paper presents the capacity-control characteristics in an industrial cooler with a variable speed compressor. The inverter-type compressor is controlled by the rotational speed of the operational frequency. This type of the compressor performs the wide range of load compared to the on-off type. When the load of the system reduces, the rotational speed will be reduced. Thus, the system leads to the less power consumption and extends the longer durability of the compressor. With the variable rotational speed of the compressor the cooling capacity of the cooler is about 1.6-3.6 kW and the capacity control is about 40-100%. The system showed the highest efficiency when the rotational speed is about 45-70 Hz. The results can be used as the basic design data to control an industrial cooler.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.676-681
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• 2002

This paper presents the implementation and experimental investigation of sensorless speed control for a variable-speed PMSM(Permanent Magnet Synchronous Motor) in super-high speed compressor operation. The proposed control scheme consists of two different sensorless algorithms to guarantee the reliable starting operation in low speed region and full torque characteristics using the vector control in high speed region. An automatic switching technique between two control modes is proposed to minimize the speed and torque pulsation during the switching instant of control mode. A testing system of 3.3㎾ PMSM has been built and 90% load test results at 7000r/min are presented to examine the feasibility of proposed sensorless control scheme.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.45-50
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• 2015

This paper suggests the sensor-less speed control of PMSM (Permanent Magnet Synchronous Motor) without the position sensor of oil-free air compressor. It estimated d and q axis back electro motive force using Back-EMF (Electro motive Force) observer to control sensor-less speed of PMSM. Also it used the method that tracks the information of rotor position and speed using PLL (Phase Locked Loop) based on estimated d and q axis Back-EMF. The sensor-less speed control of PMSM for oil air compressor application is carried out with the introduced rotor position and speed tracking method. In this paper, the experimental characterization of the sensor-less drive is provided to verify the accuracy of the estimated position and the performance of sensor-less control is analyzed by results obtained from the experiment. Moreover, the potential of PMSM sensor-less drive in industrial application such as compressor drive is also examined.

• Journal of Power Electronics
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• v.6 no.1
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• pp.29-37
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• 2006

A sensorless control for an IPM (Interior Permanent Magnet) synchronous motor in a single piston rotary compressor is presented in this study. The rotor position is estimated from the d-axis and q-axis current errors between the real system and a motor model of the position estimator. The torque pulsation of the single piston rotary compressor is compensated to reduce speed ripples, as well as, mechanical noise and vibration. The proposed sensorless drive enables the compressor to operate at a lower speed which increases energy savings and reduces mechanical noise. It also gives high speed operations by a flux weakening control for rapid air-cooling and heating of the heat pump air-conditioners.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.298-301
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• 2021

A mechanical angle estimator is presented in this study to achieve the sensorless control of permanent magnet synchronous motor (PMSM) used in driving a reciprocating compressor. Braking the PMSM at a specific mechanical angular position is critical for the silent stoppage of the reciprocating compressor. The performance of conventional mechanical angle observers used in reciprocating compressor drives can be seriously affected according to gains of the speed controller because such observers rely on the magnitude of current ripples. A speed ripple-based mechanical angle estimator is proposed to solve this problem. Experimental results showed the effectiveness of the proposed method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.173-179
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• 1998

An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.

• 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 $25^{\circ}C$.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.264-269
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• 2011

A precision of temperature control in the manufacturing process would be an important factor and become the main key to control production quality. Mostly manufacture machinery used oil as a coolant in their system so an accurate oil temperature control system become an absolute need in industrial field. This paper presents a experiment research to control the oil temperature constant at target point, in this experiment is $35^{\circ}C$ by using an inverter attached in compressor to varying the compressor speed. This control has been completed and tested through an experiment with different heat load of 4kW, 6kW, 7kW, 8kW and 10kW given under temperature constant room conditioned as $25^{\circ}C$. The results had shown the temperature deviation in the refrigerator has around $0.2^{\circ}C$ and the COP is 2.5 gained at 8kW and 10kW.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.282-288
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• 2010

The paper presents the characteristics of capacity control of variable speed water cooler with the electronic expansion valve open/close degree. It is a preliminary study on the optimum control of the water cooler system using a variable speed compressor controlled by inverter. The electronic expansion valve controlled by the variation of compressor speed maintains the constant degree of superheat at the evaporator outlet, which aims to find the degree of superheat obtaining the optimum refrigeration effect. The investigation indicates that there is a point achieving the maximum cooling capacity by the variation of the electronic expansion valve open/close degree with constant compressor speed.