• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1108-1112
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• 2005

Recently, the fuel charge is accounted for very high in the navigation cost. Therefore Shipowner is tried to find method for reducing oil consumption. ERCS(Energy Reduced Cooling System) is one of the method. The ERCS algorithm operates to decrease a power consumption of main sea water cooling pump through inverter control. We have developed ERCS controller with algorithm. The ERCS controller consists of CPU board, Digital I/O board, A/D board, D/A board and LCD/SW board. We tested with dummy signal to confirm the algorithm working correctly and achieved the good results. Before soon we will test under real condition in the ship and expect to get the result as forecasted.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.164-171
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• 2006

In this paper, the fault tolerant system for BLDC motor has been proposed to maintain control performance under an open switch fault of inverter. The fault identification is proposed to two methods, which are using the difference between reference and actual current, and adding voltage sensors across lower legs of inverter. The reconfiguration scheme is achieved by the four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. The proposed fault tolerant system quickly recovers control performance by short fault detecting time and reconfiguration of system topology. Therefore, continuous free operation of the BLDC motor drive system after faults is available. The superior performance of the proposed fault tolerant system is proved by simulation.

• Journal of IKEEE
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• v.24 no.3
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• pp.877-882
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• 2020

This paper presents performance comparison study of current control methods for grid connected inverter (GCI) system. Different current control methods have been developed for GCI systems and each controller has its own advantages and limitations. Steady state and transient dynamic performance of the GCI current controllers are compared in this paper. The performance of the proposed command feedforward control (CFFC) and disturbance rejection control (DRC) is analyzed before and after application to all GCI current controllers. The proposed CFFC and DRC control algorithms is analyzed in a frequency domain and the simulation and experiment models of each GCI current control methods are developed for verification of the performance.

• Journal of Power Electronics
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• v.15 no.1
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.308-310
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• 1996

Recently, as a result of the progress in power electronics and microelectronics, the inverter technology is quickly developing. Also, by using the fast microprocessor and small-sized switching devices, such as IPM, the Inverter becomes more compact and cheap. This paper proposes an inexpensive and small-sized vector controller for induction motors using 87C196MC and IPM. The proposed inverter contributes further space-saving, and high performance features to motor drives system.

• Solar Energy
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• v.13 no.2_3
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• pp.140-150
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• 1993

This paper describes technical details of Separate Excitation Inverter(SEI) application for the photovoltaic system. Depending on the output characteristics of solar cell modules, optimum control for the maximum electricity generation of photovoltaic system could be determined. New control mechanism of Separate Excitation Inverter for the Photovoltaic-Diesel Hybrid Generator was tested and examined. Results of this paper describe that maximum out of solar cell array could be obtained at two points. Therefore the two point control method was applied and verified between, the theory and the experiment.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1578-1586
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• 2016

A power quality improvement scheme for grid connected inverters, even in the presence of the disturbances in grid voltages due to harmonic distortions and three-phase imbalance, is presented for distributed generation (DG) power systems. The control objective is to force the inverter currents to follow their references with robustness even under external disturbances in grid voltages. The proposed scheme is realized by a disturbance observer (DOB) based current control scheme. Since the uncertainty in a system can be effectively canceled out using an estimated disturbance by the DOB, the resultant system behaves like a closed-loop system consisting of a disturbance-free nominal model. For experimental verification, a 2 kVA laboratory prototype of a grid connected inverter has been built using a digital signal processor (DSP) TMS320F28335. Through comparative simulations and experimental results under grid disturbances such as harmonic distortion and imbalance, the effectiveness of the proposed DOB based current control scheme is demonstrated.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.2
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• pp.179-186
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• 2007

This paper presents new ignition method and ignition recognition logic for a microturbine. New ignition method is designed by constant speed control of a microturbine with pre-determined time during a ignition period. It make more accurate air-fuel ratio as well as give enough time to ignition system to have full performance under cold temperature. And ignition recognition logic is designed by observing output current change of inverter by generating output torque of a microturbine in the instant of ignition. For filtering a output torque current of inverter with high frequency, we applied a moving average method. So far, ignition recognition is usually implemented by measuring of exhausted gas temperature(EGT) of microturbine. The proposed logic can give more accurate judgement of ignition as well as keep a good working of starting system under out of order a temperature measuring system and biased initial value of EGT sensor. Finally, the two proposed logics are proved by field operating a microturbine under various conditions.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1601-1608
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• 2015

This paper presents a PQ control strategy for micro grid inverters with axial voltage regulators. The inverter works in the voltage-controlled mode and can help improve the terminal power quality. The inverter has two axial voltage regulators. The 1st regulator involves the output voltage amplitude and output impedance, while the 2nd regulator controls the output frequency. The inverter system is equivalent to a controllable voltage source with a controllable inner output impedance. The basic PQ control for micro grid inverters is easy to accomplish. The output active and reactive powers can be decoupled well by controlling the two axial voltages. The 1st axial voltage regulator controls the reactive power, while the 2nd regulator controls the active power. The paper analyses the axial voltage regulation mechanism, and evaluates the PQ decoupling effect mathematically. The effectiveness of the proposed control strategy is validated by simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.51-57
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• 1998

This paper proposed a novel SIT high frequency resonant inverter having drive signal phase shift control function. Phasor control type inverters using SIT can realize a power conversion on the high switching frequency with low switching loss. Especially, the high output power can be abstained by connecting the output voltage of two unit inverters In serIes. The stability of system using protection circuit for over current and the automatic follow-up control with load variation by PLL is presented. This inverter produce approximately sinusoidal waveform at a high frequency, switching frequency ranging from 180[kHz] to 220[kHz], and is applied to the 2[kW] induction heating. The operating characteristics of this inverter circuit are discussed from a theoretical point of view and compared with experimental results. results.