• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.4
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• pp.76-85
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• 2008

In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.528-532
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• 2004

Novel single-stage power factor correction AC/DC converter with low DC link voltage using new magnetic feedback technique is proposed in this paper. The Proposed converter has high power factor, tight output voltage regulation and low link capacitor voltage less than 450V for all the load range through the universal input line. This converter has also no dead-zone in the input current, which is seen in the conventional converter using the previous magnetic feedback technique. In this paper, the analysis of operations and features of the proposed converter is provided, and the experimental results of 90W-prototype shows the low harmonic distortions satisfied with EN 61000-3-2 Class D, high power factor and low link voltage less than 450V.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.1
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• pp.36-41
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• 2012

This paper presents torque control of DC motor using the velocity profile based acceleration/deceleration controller for automatic guided vehicles (AGVs). This technique has some advantage; to reduce the damage of motors and to extend the life time of motors. First, we generate velocity profiles for three cases and design the state feedback controller using the generated velocity profile as a reference. The state feedback controller has servo system for solving regulation problem. For the verification, we apply the proposed method to control a cart position and shows some simulation result.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.74-80
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• 2003

In this paper, a robust two-degree-of-freedom(TDF) the speed control system using $H_{\infty}$ optimization method and real genetic algorithm is proposed for the robust stability and the robust performance in dc servo motor system. This control system composed of feedback and feedforward controller. The feedback(FB) controller with $H_{\infty}$ optimization method is designed for real genetic algorithm that is model matching problem using mixed sensitivity function. The feedforward(FF) controller with $H_{\infty}$optimization method is minimized the error between transfer function of the optimal model and the overall transfer function. The proposed robust two-degree-of-freedom speed control system is simulated to the dc servo motor. By the simulation, feedback controller can obtain the robust stability property and feedforward controller can obtain the robust performance property under modelling error. The performance of the dc servo motor is analyzed by the experiment setting. The validity of the proposed method is verified through being compared with pid(proportional integrated differential)control system design method for the dc servo motor.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.182-184
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• 2007

본 논문에서는 2단 AC/DC 컨버터와 단일단 AC/DC 컨버터가 가지고 있는 단점들을 개선 할 수 있는 새로운 준 단일 전력단 컨버터를 제안한다. DC/DC 단으로는 동적 특성이 좋은 LLC 컨버터를 채용하여 별도의 제어기 없이 고정 주파수 및 고정 Duty(50%) 발생기에 의해 Open Loop로 구동 시킴으로써 저가격화 및 고효율화를 획득 할 수 있다. 또한 역률개선단은 Boost 컨버터를 채용하고 간단한 제어기 1개를 사용하여 역률 개선과 동시에 DC/DC 단의 최종출력을 제어한다. 기존 2단 PFC 컨버터와는 다르게 PFC 링크전압을 Feedback 하지 않고 DC/DC 단의 최종 출력을 Feedback 하여 제어한다. 제안된 회로의 우수성 검증을 위해 600W급 시작품을 이용한 실험 결과를 제시한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1177-1182
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• 2018

We designed a 500W zero voltage switching DC / DC converter operating at 100Mhz with phase shift topology using UCC3895 driver. The dead time of the UCC3895 driver is designed so that the leading and lagging leg of the full bridge can be driven separately. So, the dead time can be given between the two legs separately. The dead time, which is an asymmetrical relationship between the two legs, enables the implementation of zero voltage switching. This paper proposed a negative feedback circuit design method for stable output voltage. The maximum efficiency of the prototype was 95.5% at $500{\Omega}$ load.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.257-260
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• 1997

In this paper, the double inverted pendulum having a single actuator is built and the controller for the system is proposed. The lower link is hinged on the plate to free for rotation in the x-z plane. The upper link is connected to the lower link through a DC motor. The double inverted pendulum built can be kept upright posture by controlling the position of the upper link even though the proposed inverted pendulum has no actuator in lower hinge. The algorithm to control the inverted pendulum is consisted of a state feedback controller within a linearizable range and a fuzzy logic controller coupled with a feedback linearization control for the rest of the range. Concept of the virtual work is employed to drive the linearlized model for the state feedback controller. The feedback linearization controller drives a DC motor with the modified reference joint angle from the fuzzy controller which adjusts a upright posture of a proposed pendulum system. Finally, the experiments are conducted to show the validity of the proposed controller.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.270-275
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• 1998

A new single phase power factor correction rectifier/regulator with dc linked energy feedback circuit is proposed, which is capable of achieving the zero voltage switching (ZVS) of a boost rectifier stage without any auxiliary switch. The performance of the proposed rectifier/regulator is demonstrated through a 200W, 90 KHz prototype. This proposed rectifier/regulator with dc linked energy feedback circuit is particularly suited for distributed power system applications

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.522-529
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• 2014

This study proposes an isolation amplifier circuit for the sensing and feedback of inverter DC-link voltage, which is inevitable for the precise control of inverter output voltage. The isolation amplifier consists of a pulse-width modulator and a pulse transformer with dual secondary windings. The accuracy of the proposed circuit depends on the precise matching of filter parameters in dual secondary circuits. The influences of parameter inaccuracy on the amplifier performances are analyzed. A modified circuit is proposed to reduce the dependency on filter parameters. The validity of the proposed method is verified through simulation and experiment.

• 전기의세계
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• v.30 no.8
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• pp.501-508
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• 1981

A novel and simple method of designing the current feedback loop for the velocity controller of an armature controlled dc servo motor is presented. Instead of constructing the usual tight current feedback loop, a loose current feedback loop is suggested in this paper. More specifically, the armature current is not limited to a fixed constant value, but instead the upper bound value is allowed to be variable along with the present motor speed. The control system designed in this manner shows that the motor under control is robust to a wide range of loading conditions and yields a more rapid transient characteristics which is verified experimentally by applying the method in the design of the controller for an Industrial robot.