• Journal of Power Electronics
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• 제19권6호
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• pp.1582-1590
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• 2019

A new method for reducing the common-mode current generated by the voltage variations in a two-inverter air conditioner system by applying a synchronized pulse-width modulation (PWM) strategy is proposed. The PWM signals of the master-mode inverter are generated based on the reference voltage, while those of the slave-mode inverter are output in the opposite direction when the master-mode inverter changes its switching state. However, the slave-mode control results in a mismatch between the reference voltage and the actual output voltage that is modified by synchronized control operation. The proposed method is capable of reducing and controlling this voltage error by performing signal selection in the vector space of the slave-mode inverter, which mitigates the distortion of the phase current. The efficacy of this method in reducing conducted emissions has been validated both theoretically and experimentally.

• 한국소프트웨어감정평가학회 논문지
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• 제16권2호
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• pp.109-115
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• 2020

본 논문에서는 어댑터나 배터리에 의해 단일전원을 공급받는 IT기기에서, 저렴한 buck 소자를 이용해 마이너스 전압을 발생할 때 발생하는 문제점을 분석하였다. 원인 분석을 위해 buck 소자의 동작원리와 inverter 회로의 원리를 살펴보고, buck 소자를 이용해 inverter 회로를 구성했을 떄의 회로적 특성을 분석하였다. 분석 결과 buck 소자를 이용한 inverter회로는 초기에 큰 기동전류가 필요함을 확인하였으며, 특히 전원을 공급하는 회로에서 기동전류에 미치지 못하는 전류용량일 경우 래치 업 현상과 유사한 상태에 빠질 수 있음을 확인하였다. 분석결과를 확인하기위해 실험회로를 구성하고 입력전류를 확인한 결과, 공급전류가 충분한 경우 과전류가 흐르면서 기동됨을 확인하고, 공급전류가 충분치 않은 경우에는 회로가 기동하지 못해 래치 업 현상이 발생해 회로 전체가 위험상태에 도달함을 확인하였다.

• Journal of Power Electronics
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• 제12권1호
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• pp.172-180
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• 2012

Z-source inverters (ZSI) are used to realize both DC voltage boost and DC-AC inversion in single stage with a reduced number of power switching devices. A traditional MPPT control algorithm provides a shoot-through interval which should be inserted in the switching waveforms of the inverter to output the maximum power to the Z-network. At this instant, the voltage across the Z-source capacitor is equal to the output voltage of a PV array at the maximum power point (MPP). The control of the Z-source capacitor voltage beyond the MPP voltage of a PV array is not facilitated in traditional MPPT algorithms. This paper presents a unified MPPT control algorithm to simultaneously achieve MPPT as well as Z-source capacitor voltage control. Development and implementation of the proposed algorithm and a comparison with traditional results are discussed. The effectiveness of the proposed unified MPPT control strategy is implemented in Matlab/Simulink software and verified by experimental results.

• 전기학회논문지
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• 제65권10호
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• pp.1682-1687
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• 2016

Approximately 520thousand elevators are operating now in Korea, about 40% ~ 60% of the elevator power is generated. In this paper, by using the method of adding regeneration power of the elevator to the grid-tied photo voltaic inverter, PV generation that was dependant on the solar radiation was significantly improved. In order to confirm this, the regeneration power of the elevator has been simulated in 12% of the rating load, and measured the regeneration power of the elevator in the actual condition to assess the differences of it. The 5[kW] hybrid grid-tied photo voltaic invertor has been fabricated to conduct an experiment for the confirmation of the proposing method. The effectiveness of the proposing method has been reassured with the result of experiment that include the transfer interface part of the regeneration power of the elevator.

• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.417-420
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• 2008

Solar electric systems have very little impact on environment, making them one of the cleanest power-generating technologies available. While they are operating, PV systems produce no air pollution, hazardous waste, or noise, and they require no transportable fuels. In PV system design, the selection and proper installation of appropriately-sized components directly affect system reliability, lifetime, and initial cost. In this research, we have studied the PWM(Pulse Width Modulation) signals. I proposed an efficient photovoltaic power interface circuit incorporated with a DC-DC converter and a sine-pwm control method full-bridge inverter. In grid-connected solar power systems, the DC-DC converter operates at high switching frequency to make the output current a sine wave, whereas the full-bridge inverter operates at low switching frequency which is determined by the ac frequency. Thus, it can reduce the switching losses incurred by the full-bridge inverter. Full-bridge converter is controlled by using microprocessor control method, and its operation is verified through computer aided simulations.

• Journal of information and communication convergence engineering
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• 제14권2호
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• pp.122-128
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• 2016

In the future, hybrid power management systems using fuel cells (FCs) and batteries will be used as the driving power systems of ships. These systems consist of an FC, a converter, an inverter, and a battery. In general, an FC provides steady-state energy; a battery provides the dynamic energy in the start state of a ship for enabling a smooth operation, and provides or absorbs the peak or dynamic power when the load varies and the FC cannot respond immediately. The FC voltage range is very wide and depends on the load; Therefore, the FC cannot directly connect to the inverter. In this paper, we propose a power management strategy and design process involving a unidirectional converter, a bidirectional converter, and an inverter, considering the ship's operating conditions and the power conditions of the FC and the battery. The presented experimental results were verified through a simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.370-371
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• 2006

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy Production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as ell as the analysis of energy saving effect. his paper presents he present state analysis of inverter DSM program and propose he improvement for activation of inverter DSM program.

• 전기학회논문지
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• 제58권8호
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• pp.1551-1558
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• 2009

This paper proposes a new power conditioning system for the fuel cell power generation, which consists of a LLC resonant DC-DC converter and 3-phase inverter. The LLC resonant converter boosts the fuel cell voltage of 26-48V up to 400V, using the hard-switching boost converter and the high-frequency ZVS half-bridge converter. The operation of proposed power conditioning system was verified through simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was verified through experimental works with a laboratory prototype, which was built with 1.2kW PEM fuel-cell stack, 1kW LLC resonant converter, and 3kW PWM inverter. The proposed system can be utilized to commercialize a real interconnection system for the fuel-cell power generation.

• 전기학회논문지
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• 제56권12호
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• pp.2150-2156
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• 2007

According as level of industry develops day after day, electricity load system of industry requires high level control, effectiveness and high efficiency. Among supply and control unit of suitable power supply in these load characteristic, inverter systems of constant current regulate is used widely control of lighting and electric heating system. But, problems that power factor deterioration and fast response of control, efficiency, harmonics and etc are still remain. Therefore, in this paper proposed an inverter systems with constant current regulation and power factor correction (PFC) circuit for lighting and beaconing of aerodromes. The effectiveness of the proposed system confirmed through experimental results of 10[kW] power supply system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.521-523
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• 2001

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of Inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as well as the analysis of energy saving effect. This paper presents the cost-effectiveness analysis for DSM program evaluation and case study to analyze inverter DSM program.