• 전기의세계
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• 제25권4호
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• pp.68-72
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• 1976

This study is initiated to solve the problem that the development of an electric machine to drive heavy horse-power load required in the rural district, where only single phase supply is available, is very urgent. As a method for this purpose, the single/three phase converter by single phase induction machine with a tapped auxiliary winding, running unloaded mechanically under single-phase source and supplying three-phase output to a loaded 3-phase induction motor, is devised and the pilot machine is put into test. Analysis based on hybrid equivalent circuit for the phase converter and symmertical component theory for the 3-phase load motor and practical experiment result in that optimum auxiliary winding ratio is to be 1.25 rather than theoretical .root.3/2 in order to keep the voltage unbalance ratio of 3-phase output from the converter as low as possible in both cases of starting and running the load motor.

• 전력전자학회논문지
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• 제6권2호
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• pp.191-201
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• 2001

현재 산업용, 가정용 전동기의 수요는 급증하고 있다. 이는 스위칭 소자와 제어기술의 현저한 진보가 있었기 때문이며 이중 BLDC 전동기의 사용이 증가하고 있다. 그러나 일반적으로 사용되고 있는 3상 BLDC 전동기 맥동토크가 크고 속도변화에 민감하며 높은 속도에 적용하는데 한계가 있다. 이러한 문제를 해결하기 위해서는 전동기의 상과 극수, 슬롯수를 증가시켜야만 한다. 그래서 현재 다상 BLDC 전동기의 연구가 진행중에 있다. 하지만 다상 BLDC에서는 높은 스위칭 주파수로 인해서 일반적으로 쓰고 있는 히스테리시스 전류제어기를 제안하였고 7상 BLDC 전동기에 적용하여 시뮬레이션과 실험을 통해서 타당성을 입증하였다.

• 전기학회논문지
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• 제66권2호
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• pp.447-452
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• 2017

The stator phase winding of a linear pulse motor, which is a new type of linear motor, is comprised of two phases and is structurally characterized by a stacking method in which the winding of one phase is laid on top of the winding of another phase. Such a structural characteristic induces a difference in the flux linkage resulting from the flux of each stator phase winding in the same condition. The difference in the induced flux linkage acts as a kind of thrust ripple component in terms of the generated thrust. Thus, in order to maintain consistent thrust force, a method is required to solve the problem caused by the structural singularity. Hence, in this study, we present a technique for reducing the thrust force ripple generated by the stacking of the stator phase windings of a linear pulse motor through the generation of a compensating current reference value of the current controller in order to keep the torque constant. The proposed compensating algorithm is validated by simulations and experimental results.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.216-220
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• 2007

This paper deals with the characteristic analysis of the single phase switched reluctance motor based on the converter coupled FE analysis. The converter comprises a rectifier, LC filter and switching power device. A computational technique for the converter coupled FE analysis is introduced and its validity is proven by the experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.393-400
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• 1992

The DC(Direct-Current) servo motor has widely used for many application areas, FA(Factory Automation), OA(Office Automation) and home applications. But DC servo motor needs periodical inspection because it has brush and commutator. Recently, AC servo motor has expanded it's application areas due to for the development of the power semi-conductor and control technology. But it has large torque ripple for it's small number of commutation. And it also has cogging torque due to permanent magenet rotor. Therefore it can't run balence rotarion. Many torque ripple reduction methods are published. In this paper, phase advanced method adopted for torque ripple reduction of AC servo motor. In this research, AC servo motor torque characteristic variation surveied under the phase advance control through the computer simulation. Under the simulation, the load inertia varied from 0.0001[Kg.m$^{2}$] to 0.0314[Kg.m$^{2}$]. The result os nonlinear simulation, torque and speed ripple of AC servo motor under the phase advance control reduced approximately 50[%] and 10[%]. And maximum torque of AC servo motor under phase advance control condition increased about 5[%] as compare with fixed switching time.

• Journal of Power Electronics
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• 제19권3호
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• pp.761-770
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• 2019

This paper proposes a hybrid phase windings excitation method for improving the efficiency of a 7-phase brushless DC (BLDC) motor in the electric propulsion system of a ship. The electrical losses of a BLDC motor system depend on the operating region and the number of excited phase windings (2-phase, 4-phase or general 6-phase windings). In this paper the operating region and torque/speed characteristics according to the motor rotation speed and propeller load are analyzed for a number of excitation methods. In addition, it analyzes the electrical losses of the system under each of the excitation methods in the entire operating region of the motor. In every sampling time, the proposed control method calculates the electrical loss of the system for each of the excitation methods and operates a 7-phase BLDC motor by selecting the excitation method that results a decreased electrical loss at the operating speed. The usefulness of the proposed control algorithm is verified through experimental results.

• 전기학회논문지
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• 제65권2호
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• pp.304-310
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• 2016

This paper proposes a fault diagnosis method for an open-fault in inverter driving five-phase induction motor. The five-phase induction motor has a high output torque and small torque ripple in comparison to three-phase. The best advantage of the five-phase induction motor is fault diagnosis and tolerant control using redundancy of phases. This paper uses an inverter as a power converter for driving a five-phase induction motor. If a switch of inverter occurs to the open-fault, this problem is the influence on the output current and output torque. To solve this problem, there is need of an accurate diagnosis and fault switch distinction. Therefore, this paper propose a fault detection method of the open-fault switches for the fault diagnosis. First, analyzing the pattern for the open-circuit fault of one phase. next, analyzing the pattern for the open-circuit fault of each inverter switches. Through the pattern analysis, It defines the scope of each of the failure switch. Thereafter, By using an algorithm that proposes to perform a fault diagnosis method. The proposed algorithm is verified from the experiment with the 1.5 kW five-phase induction motor.

• 대한물리의학회지
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• 제7권2호
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• pp.213-221
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• 2012

Purpose : The purpose of this study was to investigate the effect of Vojta therapy on Gross Motor Function Measurement(GMFM) and Selective Voluntary Motor Control (SVMC) in children with Spastic diplegia. Methods : During this experiment, the subject of four children diagnosed with spastic diplegia was tested using ABA design for Single-subject Experimental Research Design. The procedure consisted of baseline, intervention and follow-up phase which was held thirty minutes each for three times a week for a total of 24 times. Gross motor function was measured using GMFM and selective voluntary motor control was measured using SCALE. Results : According to this study, the gross motor function and selective voluntary motor control of all subjects were improved from their intervention phase to their baseline phase. During the follow phase which the intervention was removed, the ability that was enhanced during the prior phases was still either maintained or only reduced slightly. Conclusion : The Vojta therapy used on children diagnosed with spastic diplegia was effective on both GMFM and SVMC. In other words, the therapy was effective on coordination. However, this study is difficult to be generalized due to the insufficient number of subject. In further studies, it will be necessary to increase the number of trials with a control group in order to generalize the effectiveness of Vojta therapy.

• 전기학회논문지
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• 제62권7호
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• pp.950-955
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• 2013

This paper proposes a new low-cost current detection method to implement vector-controlled inverter of 3-phase induction motor or permanent-magnet synchronous motor using 2 shunt resistors instead of expensive Hall current sensors. The proposed method can detect perfect phase currents without current-immeasurable area in all operating conditions of motor. This method uses 2 shunt resistors in Hall current sensor positions conventionally used to detect phase currents. Therefore, it requires accurate analog differential amplifiers to detect voltages across shunt resistors at high electric potential to ground. We show the good solutions which are implemented by voltage-divider resistors networks and the instrumentation amplifiers using several Op Amps at cheap price. Computer simulations and experiments were performed to confirm the effectiveness of proposed method. These results show that proposed method can perfectly detect phase currents without current-immeasurable area in all operating conditions of motor.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.761-768
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• 2017

This paper deals with the performance analysis of three phase induction motor considering its stator side faults and operating thermal limits. The speed control of induction motor using three phase boost converter operated by a MOSFET switch and a PI controller is demonstrated and presented in this article. IGBTs switches are used for inverter drive mechanism. The experimental result of speed control of induction motor using voltage control technique clearly shows better accuracy than conventional methods of speed control. A three phase 1HP 415V 0.78 kW 4 Pole induction motor is designed using motor solver software. Based on the parameters used in the software thermal analysis of induction motor is done and torque variation with conductor area, efficiency, output curve, losses in different parts of motor has been obtained. Also different types of faults namely under voltage, over voltage, stator imbalanced voltage, turn to turn, locked rotor bar, wrong alignment of rotor bar with respect to stator are studied and fault analysis is performed. Hence comparison is made based upon the results obtained before and after faults.