• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.362-371
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• 2018

This work proposes FPGA implementation of Carrier Disposition PWM for closed loop seven level diode clamped multilevel inverter in speed control of induction motor. VLSI architecture for carrier Disposition have been introduced through which PWM signals are fed to the neutral point seven level diode clamped multilevel using which the speed of the induction motor is controlled. This proposed VLSI architecture makes the power circuit to work better with reduced stresses across the switches and a very low voltage and current total harmonic distortion (THD). The output voltages, currents, torque & speed characteristics for seven level neutral point diode clamped multilevel inverter for AC drive was studied. It has observed the proposed scheme introduces less distortion and harmonics. The results were validated using real time results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.927-929
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• 2003

The rib in synchronous reluctance motor(SynRM), which has segment type rotor, is mechanical weak Point. To make up for the weak point, a web has inserted in the flux barrier. However, the inductance in the q-axis is increased and then the motor performance has been decreased because of the inserted web. This paper presents a model, which has permanent magnets on the both side of the web, to decrease the inductance in the q-axis. The finite element method is applied to analyze the characteristics.

• 항공우주기술
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• 제7권1호
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• pp.170-176
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• 2008

고체모터 추력제어를 위한 플렉시블 셀 개념 설계를 수행하였다. 개념 설계를 통해 플렉시블 씰의 구동 점 위치, 플렉시블 씰의 형상, 고무 및 보강재 소재를 결정하였으며, 연소가스로부터 플렉시블 씰을 보호하기 위한 적절한 열 차폐 시스템을 선정하였다. 플렉시블 씰의 회전 중심은 노즐 후방에 위치하며, 단면 형상은 원뿔형 으로 설계하였다. 노즐의 구동 토크를 만족하기 위해 고무의 전단 계수는 약 0.6MPa 이하가 되도록 개발 하였으며, 전단 응력은 2.5MPa 이상이다.

• Journal of Power Electronics
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• 제18권3호
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• pp.714-722
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• 2018

This paper presents a wide-range speed control scheme of brushless DC (BLDC) motors based on a hall sensor with separated low- and normal-speed controllers. However, the use of the hall sensor signal is insufficient to detect motor speed in the low-speed region because of low sensor resolution and time delay. In the proposed method, a micro-stepping current control method according to the torque angle variation is presented. In this mode, the motor current frequency and rotating angle are determined by the reference speed without the actual speed fed by the hall sensor. The detected torque angle is used to adjust the current value in a limited band to control the current value in accordance with the load. The torque angle is detected exactly at the changing point of the hall sensor signal. The rotor can follow the rotating flux with the variable torque angle. In a normal speed range, the conventional vector control scheme is used to control the motor current with a PI speed controller using the hall sensor. The torque characteristics are analyzed on the basis of the back EMF and current shape. To adopt the vector control scheme, the continuous rotor position is estimated by the measured speed and hall sensor position. At the mode changing point between low and normal speed range, the proper initial current command and reference rotor position are calculated. The calculated current command can reduce the torque ripple during transient mode. The proposed method is simple but effective in extending the speed control range of a conventional BLDC motor with hall sensor without the need for a high-resolution encoder. The effectiveness of the proposed method is verified by various experiments on a practical BLDC motor.

• Physical Therapy Rehabilitation Science
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• 제9권4호
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• pp.318-323
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• 2020

Objective: Reacquisition of motor functions following stroke depends on interhemispheric neural connections. The intervention highlighted in the present case is an insight for augmenting motor recovery by stimulating the lesioned area and adjacent areas governing the motor behaviour of an individual. The purpose of this study was to determine the changes in the motor and cognitive outcomes through multi target stimulation of cortical areas by application of multichannel transcranial direct current stimulation (M-tDCS) in a stroke survivor. Design: A case report. Methods: The patient was a participant of a trial registered with the clinical trial registry of India (CTRI/2020/01/022998). The patient was intervened with M-tDCS over the left primary motor cortex i.e. C3 point and left dorsolateral prefrontal cortex i.e. F3 point with 0.5-2 mA intensity for the period of 20 minutes. SaeboFlex-assisted task-oriented training, functional electrical stimulation over the lower extremity (LE) to elicit dorsiflexion at the ankle and eversion of the foot, and conventional physiotherapy rehabilitation including a tailored exercise program were performed. Outcome assessment was done using the Fugl-Meyer assessment scale (FMA) for the upper and lower extremity (UE and LE), Montreal Cognitive Assessment (MOCA), Wisconsin Gait Scale (WGS) and the Stroke Specific Quality of Life (SSQOL) measures. Assessment was taken at Day 0, 15 and 30 post intervention. Results: Improvement was observed in all the outcome measures i.e FMA (UE and LE), MOCA, SSQOL and WGS across the span of 4 weeks. Conclusions: M-tDCS induced improvement in motor functions of the UE and LE, gait parameters and cognitive functions of the patient.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.157-164
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• 2000

This study is about predicting the interior pressure level of the korean high speed train using ray acoustic method. The motor car and the motor and passenger cabin are investigated under the environment of passing open countryside and inside tunnel of 350 km/hr. Calculated sound levels are compared with the proposed sound levels and suggestions about the transmission Joss values of isolating panels inside motor car and the guide lines of allowed sound power limit of motor equipments are provided. Results of TPI car show calculated interior sound level is below the proposed values for both cases of open countryside running and inside tunnel. Since ray acoustic method calculated only air borne noise component, real sound level of the motor car may be higher than prediction. Passenger cabins of TMI, TM5 show higher sound level than the proposed values, so window method was carried out to find the contribution of each panel components and point out the remedy of transmission path. Reduction of sound power of motor equipments should be condisered at the same time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.26-29
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• 2001

In this paper, a brief overview of problems related to the electromagnetic, mechanical design criteria is reported. Also, we described the results about the comparisons between BLDC motor and induction motor for Turbo Compressor considering motor cost, efficiency and reliability. As a result, we select an induction motor for 12.5RT Turbo compressor for the application of small building's all-conditioning system. Finally, a prototype induction motor was manufactured and tested under compressor set. The test results were successfully met the mechanical, thermal and electromagnetic point of view.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.60-71
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• 2012

This paper proposes a new design and implementation of multi-protocol IED for networked control system of multi-induction motor in industrial fields. The experimental multi-induction motor based multi-protocol IED of Modbus/LonTalks/TCP/IP module is designed and fabricated. This article addresses issues in architecture of LonWorks/Ethernet sever, embedded processors architecture for converting Modbus protocol to LonTalks protocol, integrating preconfigured software, and Internet technologies. It is also verified that the multi-induction motor control and monitoring system using LonWorks/Ethernet server have available, interoperable, reliable performance characteristics from the experimental results, especially, the seamless integration of TCP/IP networks with control networks allows access to any control point from anywhere. Thus, the results provide available technical data for remote distributed motor control system of industrial field or building microgrid with LonWorks BAS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.94-96
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• 1993

At an operating point of the induction motor, there are many sets of stator frequency and voltage. This paper presents an algorithm to determine the stator frequency and voltage which maximizes the power factor without any informations of motor parameters. Improvement of efficiency us also expected due to high-power-factor operation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.207-210
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• 1995

In this paper, two representative schemes for vector control of induction motor without speed sensor are studied. First, the two sensorless systems which are implemented by voltage and current source are presented with new ideas and interpretations. Then a linear model around an operating point is proposed. Finally, the stability improvement of these systems are studied and evaluated by computing the trajectories of poles and zeros.