• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.3
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• pp.131-138
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• 1999

Generally, the digital controller has many advantages such as high precision, robustness to electrical noise, capability of flexible programming and fast response to the load variation. In this study, we have established proper mathematical equivalent model of Brushless DC (BLDC) motor and estimated the motor parameter by means of the back-emf measurement as being the step input to the controlled target BLDC motor. And the validity of proposed estimation method is confirmed by the test result of step response. As well, we have designed the reasonable digital controller as a consequence of the root locus method which is obtained from the open-loop transfer function of BLDC motor with hall sensor, and the determination of control gain for variable speed control. Here, revised Ziegler-Nichols tuning method is applied for the proper digital gain establishment, and the system stability is verified by the frequency domain analysis with Bode-plot and experimentation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.3
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• pp.111-115
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• 2012

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensor. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. In this paper, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, in stead of detecting the zero crossing point of the nonexcited motor back electromagnetic force for the average motor terminal to neutral voltage, the commutation signal are extracted directly from the specific average line to line voltage with low-pass filter, adder and comparators circuit. In contrast to conventional methods, the neutral voltage is not need; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. The effectiveness of the proposed method is verified through simulation results.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.57-60
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• 2015

Electric power in large devices is controlled by digital circuits, such as switching mode power supply. This kind of power circuits require accurate current sensor for power distribution. We studied characteristics of shunt resistor, which has many advantages for commercial application compared to Hall-effect current sensor. We applied ceramic package to the shunt resistor. Ceramic package has good thermal conductivity compared to plastic package, and this point is important for space requirement in Printed Circuit Board (PCB). Another advantage of the ceramic package is that surface mount technology (SMT) can be used for production. Our experimental results showed that the ceramic packaged resistor showed about 50% lower temperature than the plastic packaged one. Burning point and frequency characteristics are also discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.38-46
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• 2000

This study have established proper mathematical equivalent model of Brushless DC (BLDC) motor and estimated the motor parameter by means of the back-emf measurement as being the step input to the controlled target BLDC motor. And the validity of proposed estimation method is confirmed by the test result of step response. As well, we have designed the reasonable digital controller as a consequence of the root locus method which is obtained from the open-loop transfer function of BLDC motor with hall sensor, and the determination of control gain for variable speed control. Here, revised Ziegler-Nichols tuning method is applied for the proper digital gain establishment, and the system stability is verified by the frequency domain analysis with Bode-plot and experimentation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.155-159
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• 2002

Wire ropes are used in a myriad of various industrial applications such as elevator, mine hoist, construction machinery, lift, and suspension bridge. Especially, wire rope of crane is important component to container transfer. If it happens wire rope failures in operating, it may lead to safety accident, economic power loss by productivity decline, competitive power decline of container terminal and so on. To solve this problem, we developed wire rope fault detecting system as a portable instrument, and this system is consisted of 3 parts that fault detecting part using hall sensor, permanent magnets and analog unit, and digital signal processing part using data acquisition card, monitoring part using wavelet transform, denoising method. In this paper, a wire rope is scanned by this system after makes several broken parts on the surface of wire rope artificially. All detected signal has external noise or disturbance according to circumstances. So, we applied to discrete wavelet transform to extract a signal from noisy data that was used filter. In practical applications of denoising, it is shown that wavelet pursue it with little information loss and smooth signal display. It is verified that the detecting system by denoising has good efficiency for inspecting faults of wire ropes in service. As a result, by developing this system, container terminal could reduce expense because of extension of wire ropes exchange period and could competitive power. Also, this system is possible to apply in several fields like that elevator, lift and so on.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.92-94
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• 2004

This paper presents modeling of dynamic system for slot less air-cored PM linear synchronous motor using space vector PWM. The vector control requires Information about rotor position. And we can need to the Hall sensor for sampling current. In order to agree with this purpose, Digital Signal Processor(TMS320F2406A) developed for implementation of a speed Field Oriented Control.

• Proceedings of the KIEE Conference
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• summer
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• pp.857-859
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• 2004

This paper presents design of speed control system for slot less air-cored PM linear synchronous motor using space vector PWM. The vector control requires information about rotor position. And we can need to the Hall sensor for sampling current. In order to agree with this purpose, Digital Signal Processor(TMS320F2406A) developed for implementation of a speed Field Oriented Control.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1273-1275
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• 2005

This paper presents design of speed control system for slot less iron-cored PM linear synchronous motor using space vector PWM. the design must be considered by the useable limits of the DC link voltage and dynamic operating rage as well as the characteristics of design parameters in a point of system. Therefore, in this paper, the permissible operating range of manufactured motor by determination of rate speed and rate thrust according to switching scheme of DC link voltage are offered. The vector control requires information about rotor position. And we can need to the Hall sensor for sampling current. In order to agree with this purpose, Digital Signal Processor(TMS320F240x) developed for implementation of a speed Field Oriented Control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.579-584
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• 2008

A novel nondestructive testing (NDT) system, which is able to detect a crack with high speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. This paper proposes an improved signal processing circuits, which uses the multiple amplifying circuits and the crack indicating pulse output system of the previous scan-type magnetic camera. Hall sensors are arrayed linearly, and the wheel is rotated with static speed in the vertical direction to sensor array direction. Each Hall voltages are amplified, converted and immediately operated by using, amplifying circuits, analog-to-digital converters and $\mu$-processor, respectively. The operated results, ${\partial}V_H/{\partial}t$, are compared with a standard value, which indicates a crack existence. If the ${\partial}V_H/{\partial}t$ is larger than standard value, the pulse signal is output, and indicates the existence of crack. The effectiveness of the novel method was verified by examine using cracks on the wheel specimen model.

• Journal of Engineering Education Research
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• v.8 no.1
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• pp.5-19
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• 2005

This paper describes the design and fabrication of magnetic levitation kits for use in the hands on experiments of automatic control, digital control and microprocessor applications in the division of mechatronics in Samcheok university. The kits are developed inspired by MIT's design, but it is designed on the digital basis, whereas MIT's is designed on the analog basis. As a result, the kits can be monitored and controlled on the analog and digital control techniques. Furthermore, the cost of kit components is comparable or lower to that of MIT design. And the kits can be controlled with magnetic hall sensors and/or infrared sensors, which provides more versatile experience on the use of sensors and signal filtering to the students. The design is fabricated and tested by authors and will be provided to the students as lab projects. The kits will be intentionally presented with a device that is poorly instrumented and poorly compensated. And the students are expected to analyze sensor signal and controller performance, and then, perform compensator design and signal filtering.