• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.868-872
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• 2016

This paper presents the design of a BLDC motor driver applicable to various valve control systems using smart devices. BLDC motors are relatively small in size and have better performance than other motors. They help in reducing maintenance cost, installation costs and power consumption in plant facilities. The proposed driver is specially designed for BLDC motors using Smart Communication Platform. It adds smart features in the valve control system using BLDC motors such as multi-management, control, networking and monitoring in real time with the help of smart devices.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.780-785
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• 2014

To assess the deterioration condition of stator insulation, diagnostic and AC dielectric strength tests were performed on five high voltage (HV) motors (2,000 HP, 6.6 kV) for boiler feed-water pump (BFP). Two HV motors for BFP were installed per unit. Following the long term rewinding program, the diagnostic test was performed on five 6.6 kV motors during the planning maintenance period. After completing diagnostic test, AC dielectric strength test was done on the stator windings of HV motors. The AC dielectric strength test was conducted at 15 kV for one minute. Dielectric strength test and diagnostics test results confirmed that the stator insulation was judged to be in serviceable condition in the five 6.6 kV motors.

• Journal of Power Electronics
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• v.3 no.1
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• pp.49-54
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• 2003

A novel control scheme of using a single electronic drive to synchronize two synchronous motors is investigated analytically. The developed control strategy extends the conventional vector control technology, Specifically, it utilizes the property that the motion of two motors can be independently controlled by the q-axis currents provided the desired q-axis currents can be achieved by adjusting physical armature currents. The latter part is indeed guaranteed by adding a position offset to one of the motors. This work has a potential of cost saving in practice where the cost of drive is a major concern.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1277-1282
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• 2014

Concentrated flux interior permanent magnet (CFIPM) motors have the advantage that their utilization of flux linkage is more efficient than that of general IPM motors and CFIPM motors are suitable for washing machine motors, which demand low-speed, high-torque specifications. However, low efficiency occurs in the low-speed high-torque mode considering the high-speed operation for spin mode. This paper proposes a magnet overhang structure between the rotor core that reduces leakage flux and improves efficiency for a CFIPM in wash mode. Optimization of the 3D design of magnet overhang structures is performed to improve the efficiency with the same quantity of permanent magnets. The validity of the optimal design is experimentally verified through the fabrication of prototypes.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.3
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• pp.115-123
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• 1985

A two phase chopper system with two separate groups of DC motors for regenerative braking is dealt with in this article. The main circuit consists of two sets of chopping parts, four diodes and two separate groups of DC motors. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output, it has the following advantages`(1). Ripple frequency of smoothing reactor current becomes twice as high as that of the conventional system, so the continuous current range and the ripple ratio are improved greatly. Therefore, the efficiency becomes even higher, the capacity of commutation equipment is reduced and the inductive interference become less.(2). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt, separately excited and compound motors.

• Journal of Power Electronics
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• v.9 no.1
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• pp.1-17
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• 2009

Permanent magnet brushless DC (PMBLDC) motors are the latest choice of researchers due to their high efficiency, silent operation, compact size, high reliability and low maintenance requirements. These motors are preferred for numerous applications; however, most of them require sensorless control of these motors. The operation of PMBLDC motors requires rotor-position sensing for controlling the winding currents. The sensorless control would need estimation of rotor position from the voltage and current signals, which are easily sensed. This paper presents state of the art PMBLDC motor drives with an emphasis on sensorless control of these motors.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2175-2178
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• 2005

During normal machine operation, partial discharge(PD) measurements were performed with turbine generator analyzer(TGA) in five high voltage motors(rated 6.6kV). These high voltage motors were installed with 80pF capacitive couplers at the terminal box. The PD patterns were displayed two dimensional and three dimensional. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). Off-line PD measurements were conducted on five motors. These motors were energized to 3.81kV. The PD levels in pC were measured with a conventional digital PD detector. The comparison of positive to negative PD indicates whether the defect elements of PD are within the insulation or on the insulation surface. Internal discharges were generated in phase A, B and C of COP-B and pulv.-B, in phase B of Pulv. C and in phase C of Pulv.-D motor. Discharge at conductor surface was discovered in phase A of Pulv. D motor. Slot discharges occurred in three phases of Pulv. E motor.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2046-2047
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• 2007

This paper is about the energy efficiency calculation of operating electric motors in production facilities. The most important 1st step to efficient operation of plants is the evaluation of the energy efficiency of the production facilities in that plant. Through this procedure, we can decide that which facilities i.e. induction motors, in this paper, should do maintenance or not. There are mainly 2 types of energy which are used in production facilities, the one is electric energy and the other is heat energy but in order to make calculation simple, in this paper, we are only focusing on electric energy, efficiency and energy loss of the electric motors under operation conditions. As a case study, we chose electric motors in a certain process in a production facilities, and calculated efficiency and loss by using measured data.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.126-133
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• 2008

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.

• Progress in Superconductivity and Cryogenics
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• v.9 no.2
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• pp.31-34
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• 2007

Superconducting synchronous motors compared with conventional motors can reduce the motor size and enhance the motor efficiency for low-speed and high torque applications under the space constraints for propulsion system. Especially, homopolar superconducting synchronous motors (HSSMs) need less superconductor and lower magnetic flux density in superconductor field coil than air-cored superconducting synchronous motors (ASSMs). In addition, mechanical structure is more simplified and stability is increased because the superconductor field coil of HSSMs is not rotated in operation. In this paper, we present the outline of HSSMs including structure, characteristics and operational principles with the conceptual design of 5MW HSSM.