• Journal of Power Electronics
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• v.17 no.1
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• pp.31-40
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• 2017

A novel voltage-fed single-stage power factor correction (PFC) full-bridge converter based on asymmetric phase-shifted control for battery chargers is proposed in this paper. The attractive feature of the proposed converter is that it can operate in a wide output voltage range without an output low-frequency ripple, which is indispensable in battery charger applications. Meanwhile, the converter can maintain a high power factor and a controllable dc bus voltage over a wide output voltage range. In this paper, the realization of PFC and the operation principle of asymmetric phase-shifted control are given. A small-signal analysis of the proposed single-stage power factor correction (PFC) full-bridge converter is performed. Experimental results obtained from a 1kW experimental prototype are given to validate the feasibility of the proposed converter. The PF is higher than 0.97 over the entire output voltage range with the proposed control strategy.

• Journal of Power Electronics
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• v.15 no.1
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• pp.78-85
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• 2015

This paper presents a new structure of single-stage flyback power factor correction (PFC) converter with a controllable coupled negative magnetic feedback (NMF) winding. NMF winding is used to reduce the bulk capacitor voltage at high line voltages and light loads. However, it would cause line current distortion at zero crossing condition. In the proposed circuit, a series winding is used with NMF inductor to eliminate the NMF inductor at low line voltages. As a result, the dead angle of the input current, near zero voltage crossing, is eliminated and the power factor is increased. The presented experimental results of the proposed PFC converter confirm the integrity of the new idea and the theoretical analysis.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.986-989
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• 2002

This paper proposes a new single stage power factor correction (PFC) full bridge converter which operates at continuous conduction mode(CCM). The proposed single stage PFC consists of typical zero voltage switching(ZVS) full bridge DC/DC converter, two transformer auxiliary windings, and two small inductors, and two diodes. Neither additional active switch nor any control circuit are added for PFC resulting in very low cost. The proposed converter provides input power factor correction with CCM control and tight output voltage regulation. All switching devices are operated under ZVS with minimum voltage stress. Operation principle and analysis are explained and verified with computer simulation and experimental results on a 1.2kW, 100kHz prototype.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1101-1107
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• 2013

A light emitting diodes(LED) lighting has been increasingly used due to its low power consumption, long life time, high efficiency, and environment friendly characteristics. Also various power converters has been applied to drive these LED lighting. Among many power converters, a LLC resonant converter could be applied for LED lighting because of its high efficiency and high power density. Furthermore, the function of power factor correction(PFC) might be added. In this paper, 1-stage asymmetrical LLC resonant converter is proposed. The proposed converter performs both input-current harmonics reduction and PFC using the discontinuous conduction mode(DCM). The proposed 1-stage LLC resonant converter approach has the lower voltage stress across switching devices and achieve the zero voltage switching(ZVS) in switching devices. To verify the performance of the proposed converter, simulation and experimental results from a 300[W] prototype are provided.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.163-167
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• 2000

This paper presents the digital control of single-phase power factor correction(PFC) converter which has the variable gain according to the condition of inner control loop error. Generally the gain of inner current control loop in single-stage PFC converter has a constant magnitude. This has a bad influence on the power factor because current loop doesn't operate smoothly in the condition that input voltage is low In particular a digital controller has more time delay than an analog controller and degrades This drops the phase margin of the total digital PFC system,. It causes the problem that the gain of current control loop isn't increased enough. In addition the oscillation happens in the peak value of the input voltage open loop PFC system gain changes according to ac input voltage. These aspects make the design of the digital PFC controller difficult The digital PFC controller presented in this paper has a variable gain of current control loop according to input voltage. The 1kW converter was used to verify the efficiency of the digital PFC controller.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.1-8
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• 2014

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

• Journal of Power Electronics
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• v.16 no.3
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• pp.872-882
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• 2016

A novel pseudo-continuous conduction mode (PCCM) voltage-fed single-stage power factor correction (PFC) full-bridge battery charger is proposed in this paper. By connecting a freewheeling transistor in parallel with an input inductor, the PFC cell can operate in the PCCM with a constant duty ratio. Thus, the dc/dc stage can be designed using this constant duty ratio and the restriction on the duty ratio of the PFC cell is eliminated. As a result, the input current distortion is less and the dc bus voltage becomes controllable over the wide output power range of the battery charger. Moreover, the operation principle of the dc/dc stage is designed to be similar to that of a conventional phase-shifted full-bridge converter. Therefore, it is easy to implement. In this paper, the operation of the new converter is explained, and the design considerations of the controller and key parameters are presented. Simulation and experimental results obtained from a 1 kW prototype are given to confirm the operation of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.52-59
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• 2010

The conventional CCFL (Cold Cathode Fluorescent Lamp) inverter used in the backlight unit for LCD-TV, composed of the three power stage, can degrade the whole power conversion efficiency. In this paper, a novel scheme to drive the CCFL, composed only of the two power stage without using a dc/dc power stage, is proposed to enhance the whole power conversion efficiency. By adopting the proposed "4-in-1 Transformer", the current balance and the simultaneous ignition among the four CCFL lamp are assured with the one inverter circuit. The proposed scheme features the simple circuit structure, which can save the volume and the cost in the LCD backlight unit. Design considerations are discussed and design procedures are derived. Experimental results of the proposed scheme for 40" LCD-TV are presented to confirm the theoretical analysis.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.547-550
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• 2004

An interleaved single-stage power-factor-correction (PFC) AC/DC converter is presented in this paper. The proposed converter is combined by two single-stage AC/DC converters based on flyback converter Each PFC stage operates in discontinuous conduction mode (DCM). By exploiting the interleaving technique, the input ripple current and output ripple voltage are reduced. The proposed converter complied with EN/1EC61000-3-2 harmonic regulations achieves high efficiency and low cost. The performance of the proposed converter was evaluated on a 180W $(90W\times2,\;24V,\;7.5A)$ experimental prototype.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.235-238
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• 2001

A novel single-stage power factor corrected (PFC) drive for switched reluctance motor (SRM) is presented to achieve sinusoidal, near unity power factor input current. The proposed PFC SRM drive has no additional active switch. And a single-stage approach, which combines a DC link capacitor used as dc source and a drive used for driving the motor into one power stage, has a simple structure and low cost. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.