• Journal of Power Electronics
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• v.17 no.4
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• pp.983-990
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• 2017

This paper proposes a model predictive control based on the discrete Lyapunov function to improve the performance of power electronic converters. The proposed control technique, based on the finite control set model predictive control (FCS-MPC), defines a cost function for the control law which is determined under the Lyapunov stability theorem with a control error compensation. The steady state and dynamic performance of the proposed control strategy has been tested under a single phase AC/DC voltage source rectifier (S-VSR). Experimental results demonstrate that the proposed control strategy not only offers global stability and good robustness but also leads to a high quality sinusoidal current with a reasonably low total harmonic distortion (THD) and a fast dynamic response under linear loads.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.359-359
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• 2000

Generally, level control in the steam generator of a nuclear power plant is difficulty process control, because the low power operating can lead nonminimum phase characteristics(swell and shrink phenomenon) and flow measurement are unreliable and nonlinear characteristics. This paper presents a framework for solving this problem based on the constrained linear model predictive control and introduces the design of method for the level of the controller in the entire operating power of the steam generator, and compares with conventional PI controller.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.413-414
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• 2014

This paper proposed an optimized design of a dual active bridge converter for a low-voltage charger. The dual active bridge converter among various bi-directional DC/DC converters is a high-efficiency isolated bi-directional converter. In the general design, when the battery voltage is high, the ZVS region is reduced. In contrast, when the battery voltage is low, the efficiency is low due to high conduction loss. In order to increase the ZVS region and the power conversion efficiency, depending on the battery voltage, variable switching frequency method is applied. At the same duty, the same power is obtained regardless of the battery voltage using the variable switching frequency method. The proposed method was applied to a 5kW prototype converter, and the experimental results were analyzed and verified.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1060-1061
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• 2015

This paper presents the control method of MPPT (Maximum Power Point Tracking) using back-to- back converter. The windturbine system use PMSG(ermanent Magnet Synchronous Generator) system considering low maintenance costs and driving performance at low wind. This paper use the adaptive sliding mode control to the torque control. Proposed method was analyzed mathematically.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.117-125
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• 2016

In this paper, the inverter switch losses of BLDC motor for three types of PWM methods and power devices were analyzed. When the BLDC motor is driven at low currents, the inverter switch losses for MOSFET are low because MOSFET operates like resistance. However, the inverter switch losses for IGBT are higher than MOSFET due to its large turn-off losses. Moreover, synchronous rectification switching method is adaptable because MOSFET has 2-channel. So, MOSFET can be driven with more low impedance and losses. For low power inverter with MOSFET, the power losses of unified PWM are lower than that of unipolar and bipolar PWM. Proposed method and losses analysis results are verified by examination and simulation using Matlab/Simulink.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1018-1019
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• 2015

Recently, standby power reduction techniques of AC/DC adaptor were developed, consuming power almost arrived to 300mW level. The standby power losses are composed of the input filter loss 11.8mW, the control IC for AC/DC adaptor 18mW, the switching loss 9.53mW and the feedback loss 123mW. And there are the standby power reduction techniques. In this paper, in order to reduce the standby power of SMPS more, the loss due to a voltage difference between input and output is reduced by the control circuit which is composed of the low voltage driving circuit and voltage regulator. The low voltage driving circuit operates on the low voltage of input and off the high voltage. The low voltage driving IC was produced by the $1.0{\mu}m$, high voltage DMOS process.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.140-144
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• 2003

A sensor network consists of many low-cost, low-power, and multi-functional sensor nodes. One of most important issues in of sensor networks is to increase network lifetime, and there have been researches on the problem. In this paper, we propose a routing mechanism to prolong network lifetime, in which each node adjusts its transmission power to send data to its neighbors. We model the energy efficient routing with power control and present an algorithm to obtain the optimal flow solution for maximum network lifetime. Then, we derive an upper bound on the network lifetime for specific network topologies.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.37-42
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• 2016

While datacenter operation cost increases with electricity price rise, many researchers study low-power processor based supercomputers to reduce power consumption of datacenters. Reliability of low-power processors for supercomputers can be of concern since the reliability of many low-power processors are assessed based on mobile use conditions. This paper assessed the reliability of low-power processor packages based on supercomputer use conditions. Temperature cycling was determined as a critical failure cause of low-power processor packages through literature surveys and failure mode, effect and criticality analysis. The package temperature was measured at multiple processor load conditions to examine the relationship between processor load and package temperature. A physics-of-failure reliability model associated with temperature cycling predicted the expected lifetime of low-power processors to be less than 3 years. Recommendations to improve the lifetime of low-power processors were presented based on the experimental results.

• Journal of Power Electronics
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• v.10 no.4
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• pp.382-387
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• 2010

This paper presents a novel design method for determining the PID gains of a speed controller for a servo system compensating variations in bandwidth at a low speed. The variations in bandwidth of a speed controller are measured at a low speed and the relationship between the bandwidth and the damping ratio are verified by determining the location of the closed loop pole. The proposed algorithm uses the z-transform of a plant and speed controller and applies the time-varying sampling method for determining the PID gains of the speed controller at low speed. The magnitude and the phase condition are considered for finding a suitable control gain. The usefulness and effectiveness of the proposed method is demonstrated through experimental results such as low speed control and robust disturbance responses.

• Biomedical Science Letters
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• v.13 no.3
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• pp.223-230
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• 2007

Low power laser and neuromuscular electrical stimulation have been utilized in many clinical applications for the treatment of musculoskeletal lesion. This study was to investigate the effects of low power He-Ne IR laser and neuromuscular electrical stimulation on the change of the serum biochemical components in experimentally induced muscle injured rats. The twenty Sprague-Dawley male rats were randomly assigned to the 4 groups: the normal group (n=5), the control group (n=5), the low power laser irradiation group (LLI) (n=5) and the neuromuscular electrical stimulation group (NMES) (n=5). The experimentally induced muscle injury was induced by the subcutaneous injection of a 0.1 ml Freund's Complete Adjuvant into the right hind paw and calf muscles in control, LLI and NMES groups. The LLI group was irradiated with He-Ne IR laser for 5 minutes every day during 10 days. Also, the NMES group was electrically stimulated 15 minutes every day during 10 days. The normal and control groups were not received with any therapeutic intervention. The authors performed tests which were the concentration of the serum biochemical components to detect the effects of therapeutic interventions. The results were as follows: 1. The level of the aspartate aminotransferase (AST) was significantly decreased in the LLI and NMES groups compare to the control group. 2. The level of the serum lactate dehydrogenase (LDH) was significantly decreased in the LLI and NMES groups compare to the control group. 3. The level of the serum creatine kinase (CK) was significantly decreased in the LLI and NMES groups compare to the control group. From the results, we could come to the conclusion that low power laser and neuromuscular electrical stimulation could be accelerating healing processes of skeletal muscle injury and further clinical work will be required.