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120Hz 맥동전류를 갖는 LED 조명용 LLC 공진 컨버터 제어기법
권민준(Min-Jun Kwon),이우철(Woo-Cheol Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.12
LED(Light Emitting Diode) lighting is a light source used in various fields because of its high efficiency. In order to operate the LED, a driver consisting of a PFC(Power Factor Corrector) converter and a DC-DC converter to keep the constant current in the LED is required. DC link capacitors in LED driver can have 120Hz voltage ripple during rectification. This voltage ripple can also affect the DC-DC converter and cause 120Hz current ripple on the LED output current. LED current ripple affects power quality and system performance. Therefore, research is needed to reduce current ripple. This paper is a study on the control technique of LLC resonant converter for LED driver with 120Hz ripple current. The direct forward compensation method using the ripple current is explained base on the LLC resonant converter which is widely used as the LED power supply. The validity of the analysis and compensation method was investigated by simulation and experiment.
권민준(Min-Jun Kwon),이우철(Woo-Cheol Lee) 대한전기학회 2018 전기학회논문지 Vol.67 No.3
LLC resonant converter is popular with industrial fields because it can be achieved high efficiency by zero voltage switching (ZVS). As interest grew, analysis of characteristics in LLC resonant converter have been actively studied. Generally, characteristic of LLC resonant converter is analyzed based on first harmonic approximation(FHA). The FHA analysis represents the characteristics of LLC resonant converter by obtaining the series resonant operation. FHA analysis of LLC resonant converter in load condition is correct. but it is not correct in no load condition. This paper proposed analysis of characteristics considering the parasitic components to overcome the limitation of FHA and analyze no-load characteristics. The validity of the proposed method has been investigated by simulation and experimental results.
권민준(Min-Jun Kwon),김태훈(Tae-Hun Kim),이우철(Woo-Cheol Lee) 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.4
The LED is attracting attention in lighting market as advantages such as long life and low power consumption. As a LED has a limitation on the brightness per cell, multiple LEDs are used. Therefore, the multi-path consisting of several LEDs is used variously depending on the application. There are parallel and serial connections in multiple output LED. The brightness and quality of LED module are affected by current, and parallel configuration has a disadvantage of current matching. However, the parallel connection has a advantage that remaining LEDs are turned on , even though some LEDs are out of order. The serial configuration has a advantage of accurate current matching. However, the serial configuration has a disadvantage that whole LEDs are turned off, even though one LED is out of order. This paper proposes a multi-path LED driver circuit including the protection circuit. The proposed circuit has the advantages of the serial connection, and overcomes the disadvantages of the serial connection with the protection circuit. To verify the performance of the proposed circuit, simulation and experimental results were carried out.
플라즈마 전원장치용 LLCC 공진컨버터의 이득 특성 분석
권민준(Min-Jun Kwon),김태훈(Tae-Hun Kim),이우철(Woo-Cheol Lee) 대한전기학회 2016 전기학회논문지 Vol.65 No.12
The plasma process is applied to various industrial fields such as high-tech IT industry, textiles and medical. Therefore, there is increasing interest in the plasma power supply, and demand for power devices of high efficiency and high power density is increased. Plasma power supply for process must solve the arc problem, when the plasma is unstable. The output capacitor is closely related to the arc problem. If the output capacitor is smaller, the damage from the arc problem is reduced. However, the small value of the output capacitor affects the operating characteristics of the power supply. In this paper, a LLC resonant converter is adopted, because it can achieve high efficiency and power density in the plasma DC power supply. However, due to the small value of the output capacitor, the converter is operated as a LLCC resonant converter. Therefore, a gain characteristic of LLCC resonant converter is analyzed by using the FHA (First Harmonic Approximation) in plasma power supply. Simulation and experimental results are presented to verify the characteristic analysis of LLCC Resonant Converter.