• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.6
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• pp.41-48
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• 1995

In field oriented control of Induction motors, speed sensor is required, which reduces the sturdiness of drive system and together with the expenditure of hardware for faultless transmission and processing of sensor signals it causes considerable expenses. These expensive sensors can be replaced by speed sensorless concept. And for good control, the knowledge of the rotor flux component or the rotor resistance are needs. Thus, this paper is based on a Extended Kalman Filter (EKF) that estimates the state variables that are required for the control by only measuring the line voltages and currents of the machine. the rotor time constant and speed estimated by the EKF show satisfactory agreement with the real values, with the simulation approaches.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.205-206
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• 2015

본 논문에서는 단일 전류 센서를 가진 IPMSM 구동 시스템의 고주파 신호 주입 센서리스 제어를 제안한다. 단일 전류 센서 시스템에서 3상 전류를 재구축하기 위해 DC link 전류를 검출한다. DC link 전류를 이용하여 3상 전류를 재구축하는 경우의 문제점은 1개 또는 2개의 유효벡터가 DC link 전류를 검출하는데 필요한 최소 시간보다 짧게 인가될 때 발생한다. 센서리스 제어시 이러한 경우가 발생하면, 재구축된 전류의 왜곡에 의해 제어 성능이 저하된다. 본 논문은 전압 벡터가 작은 경우, 전류 예측을 통하여 신뢰할 만한 3상 전류를 재구축하여 전류의 왜곡을 줄임으로써 센서리스 제어 성능을 향상시켰다. 시뮬레이션을 통하여 제안한 기법의 타당성을 검증하였다.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.391-399
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• 2021

The conformal array sensor has different sub-array depending on different beam steering directions. According to the method to effective the sensor, the performance of the conformal array sensor can be different, where the sub-array selects an effective sensor. Also, due to the figure of the conformal array sensor, the figure of the sub-array can be different each other, which results in different performance on directivity index, beam width and etc. In this paper, two methods to select sub-array which is the criteria for each sensors position vector and directive vector were proposed. For two sub-array selection methods, the performance of the directivity index, horizontal and vertical beam width were compared with the average and variance. In addition, this comparison was conducted when the number of sensors was fixed. When the number of sensors was not fixed, the directional vector method mainly results in high performance, but the performance of vertical beam width was lower or equal. When the number of sensors was fixed, the performance of two methods is similar, but the performance of variance was deteriorated.

• The Journal of the Acoustical Society of Korea
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• v.35 no.5
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• pp.395-402
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• 2016

In this paper, a wideband adaptive beamforming approach for an acoustic vector sensor linear array is presented. It is a very important issue to estimate the stable covariance matrix for adaptive beamforming. In the conventional wideband adaptive beamforming based on coherent signal-subspace (CSS) processing, the error of bearing estimates is resulted from the focusing matrix estimation and the large number of data snapshot is necessary. To alleviate the estimation error and snapshot deficiency in estimating covariance matrix, the steered covariance matrix method in the pressure sensor is extended to the vector sensor array, and the subarray technique is incorporated. By this technique, more accurate azimuth estimates and a stable covariance matrix can be obtained with a small number of data snapshot. Through simulation, the azimuth estimation performance of the proposed beamforming method and a wideband adaptive beamforming based on CSS processing are assessed.

• The Journal of the Acoustical Society of Korea
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• v.14 no.1E
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• pp.65-72
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• 1995

The effects of random errors in array weight and sensor positions on the performance of a Linearly constrained linear sensor array is analyzed in a weight vector space. It is observed that a nonorthogonality exists between an optimum weight vector and the steering vector of an interference direction du e to random errors. A novel approach to improving the nulling performance by compensating for the nonorthogonality is proposed. Computer simulation results are presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.562-567
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• 2000

This paper proposed a speed estimator using MRAC(Model Reference Adaptive Control) for sensorless vector control. It is robust for parameter variation and the estimated speed is used as feedback in a vector control system. Computer simulation is presented to confirm the theoretical analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.251-257
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• 2010

In this paper, we propose modified algorithm of motion vector detection for the pixel of image in the optical sensor. It is designed to reduce the amount of operation and have more accuracy in the motion detection than previous block matching algorithm. The proposed algorithm is implemented with Cyclone and fabricated using SEC 0.35um CMOS 1-poly-4-metal technology. The result of test with CARTESIAN ROBOT meets the desired performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.336-342
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• 2015

Fall-related injuries are the most common cause of accidental death for the elderly and the most frequent work-related injuries in construction sites. Due to the growing popularity of smartphones, there has been a number of research work related to the use of sensors embedded in the smartphone for fall detection. Falls can be detected easily by measuring the magnitude and direction of acceleration vectors. In general, the direction of the acceleration vector does not show the object movement, but the velocity vector directly indicates the tangential direction in which the object is moving. In this paper, we proposed a new method for computing the fall direction based on the characteristics of the velocity vector extracted from the accelerometer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.212-218
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• 2007

This paper presents a implementation of speed sensorless vector control of induction motor using MATLAB/SIMULINK and dSPACE DS1104. Proposed flux estimation algorithm, which utilize the combination of the voltage model based on stator equivalent model and the current model based on rotor equivalent model, enables stable estimation of rotor flux. Proposed rotor speed estimation algorithm utilizes the estimated flux. And the estimated rotor speed is used to speed control of induction motor. Overall system consists of speed controller, current controller, and flux controller using the most general PI controller. Speed sensorless vector control algorithm is implemented as block diagrams using MATLAB/SIMULINK. And realtime control is performed by dSPACE DS1104 control board and Real-Time-Interface(RTI).

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.477-478
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• 2015

2상 유도전동기용 벡터제어 인버터에서는 전류센서를 사용하여 a상 및 b상의 전류를 측정해야 한다. 그러나, 이 전류값을 마이크로컨트롤러의 A/D컨버터로 읽어 들이는 과정에서 전류 센서와 증폭회로로부터 발생하는 오프셋 오차와 변환이득 오차를 포함할 수 있다. 2상 유도전동기의 벡터제어 시스템이 이러한 오차들을 포함한다면 전동기의 출력토크에 리플이 발생한다. 본 논문에서는 이러한 전류측정 오차를 실시간으로 보상하여 전동기의 토크리플을 제거하는 방법을 제안하였으며, 이러한 방식을 360[W]급의 2상 유도전동기용 벡터제어 인버터에 적용하여 컴퓨터 시뮬레이션과 실험으로 유효성을 확인하였다.