• Proceedings of the Korean Institute of Communication Sciences Conference
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• 한국통신학회 1984년도 추계학술발표회논문집
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• pp.70-73
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• 1984

By generalizing the concept of nonlinear switching filter, a transmission scheme for the PRS system is constructed. A hardware implementation of the transmission system is presented and its relations with the conventional system are measured. Our system provides the same speed as the traditional PRS system for a bandlimited channel, but has smaller ISI, Timing-jitter and maximum overshoot. Hence this technique improves speed-tolerance and power of the PRS system.

• Proceedings of the KIPE Conference
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.412-413
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• 2019

This paper deals with the comparisons of gain design of current controller with the first order lag characteristics. Usually the current controller for motor drives and PCSs has the first order lag characteristics to avoid the current overshoot. This paper suggests a new inductor current controller for the PCSs and also compares with other two current controllers. The simulation results show that the proposed design method also gives the first order lag characteristics and can be used as an alternative current controller for PCSs.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제2권2호
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• pp.231-239
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• 1998

In this paper, we designed a current controlling servo system for speed control of a PMSM. In existing auto-tuning methods for PI controller parameters, the output response is delayed and the overshoot is generated. By solving these existing problems in this paper, a new PI auto-tuning method is applied to the speed controller for fast-response and reduced overshoot. PMSM servo systems offer a great advantage in unmanned factories where a great number of servo motors are employed, because of its easy maintenance characteristics and controllability. The implemented servo system is composed of absolute position detecting circuits of a rotor, a new auto-tuning PI control algorithm, a speed controller by using DSP, and power driving section. The proposed servo system is verified for it's practical availability by considering experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제53권1호
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• pp.47-54
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• 2004

A new high voltage DC power supply is proposed. The proposed power supply is constructed with several power converters connected in series. It is easy to obtain high DC voltage for the same structure of each power converter. The output DC power of the proposed power supply can be disconnected from the load within several hundred microseconds at the instant of a load short-circuit fault. The rising time of the output DC voltage is also as small as several hundred microseconds, and there is no overshoot of the voltage because all of the output filter capacitors keep undischarged state even in load short-circuit condition. Therefore, the proposed scheme is suitable for the protection of frequent output short-circuit and fast on/off switching of output DC voltage. The proposed power supply has improved features such as simple structure, high power factor, and reduced size and volume compared with the conventional schemes. The operating principle is described and the validity of the proposed scheme is proved through simulations and experiments.

• Proceedings of the KIEE Conference
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.135-137
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• 1992

A new algorithm for self-tuning digital controller is proposed. The system to be controlled is identified on line in auto-regressive-moving-average(ARMA) form via recursive least mean square method. The control law is obtained from the minimization of an objective function. The proposed objective function is similar to that of Generalized Minimum Variance(GMV) method but modified to lessen the overshoot and to avoid numerical divergence problem. This algorithm is applied to the power system stabilization and the comparison of the proposed method with a conventional power system stabilizer(PSS) is presented.

• Journal of the Korean Society for Precision Engineering
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• 제20권12호
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• pp.89-95
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• 2003

A PID controller integrated with a velocity feedback is designed for fluid power elevator model system in this study. In this case, for outside disturbance load a hydraulic cylinder and a pressure control valve are used. In this method overshoot is reduced and settling time becomes also shorter than the values achieved from the PID controller system only In conclusion a PID controller integrated with a velocity feedback is considered a suitable control method for fluid power elevator system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제29권2호
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• pp.79-83
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• 2016

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If thhe distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• Journal of Power Electronics
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• 제14권3호
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• pp.421-431
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• 2014

A DSP-based self-adaptive proportional-integral (PI) controller to control a DC-DC converter is proposed in this paper. The full-bridge topology is adopted here to obtain higher power output capability and higher conversion efficiency. The converter adopts the zero-voltage-switching (ZVS) technique to reduce the conduction losses. A parallel secondary active clamp circuit is added to deal with the voltage overshoot and ringing effect on the transformer's secondary side. A self-adaptive PI controller is proposed to replace the traditional PI controller. Moreover, the designed converter adopts the constant-current and constant-voltage (CC-CV) output control strategy. The secondary active clamp mechanism is discussed in detail. The effectiveness of the proposed converter was experimentally verified by an IGBT-based 10kW prototype.

• Proceedings of the KIEE Conference
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.850-852
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• 1993

A buck-boost zero current switched(ZCS) series resonant AC to DC converter for the DC output voltage regulation together with high power factor is proposed. A dynamic model for this AC to DC converter is developed and an analysis for the internal operational characteristics is explored. With the proposed control technique, the unity power factor and the DC output voltage regulation without a current overshoot can be obtained.

• Journal of Power Electronics
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• 제17권5호
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• pp.1363-1371
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• 2017

In this paper, an improved Direct Power Control (DPC) algorithm is presented for grid connected three phase PWM rectifiers. The new DPC approach is based on two main tasks. First the optimization of the look-up table, which is well-known in conventional DPC, is outlined for selecting the optimum converter output voltage vectors. Secondly a very simple and effective method is used to directly calculate their duty cycles from the power errors. Therefore, the measured active and reactive powers are made to track their references using hysteresis controllers. Then two vectors are selected and applied during one control cycle to minimize both the active and reactive power ripples. The main advantages of this method are that there is no need of linear current controllers, coordinates transformations or modulators. In addition, the control strategy is able to operate at constant switching frequencies to ease the design of the power converter and the AC harmonic filter. The control exhibits a good steady state performance and improves the dynamic response without any overshoot in the line current. Theoretical principles of the proposed method are discussed. Both simulation and experimental results are presented to verify the performance and effectiveness of this control scheme.