• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.785-792
• /
• 2019

In parallel operation of multiple power converter modules, equal power distribution among modules shall be made to improve the reliability of the system. In this paper, a novel droop method is proposed to present improved current distribution characteristics. In the proposed method, if the current in each module become greater than the current set-point value, the output voltage set-point is raised to improve the current distribution characteristics. Meanwhile, when the output voltage is to be managed within the tolerance range, the range of the usable control IC reference value ($v_{ref}$) will be reduced if the output voltage setting is always raised. Thus, in case the output voltage set-point among modules is reversed, the downward adjustment is introduced. The proposed method was experimentally validated with a 17.5V/500mA prototype of two boost converters operating in parallel.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.4
• /
• pp.21-28
• /
• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.6
• /
• pp.117-125
• /
• 2007

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system. It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system. Therefor, this paper, consists of an isolated DC-DC converter to boost the fuel cell voltage 380[VDC] and a PWM inverter with LC filter to convent the DC voltage to single-phase 220[VAC]. Expressly, The fuel cell system which it proposes DC-DC the efficient converter used PWM the phase transient control law and it depended to portion resonance ZVS switching, loss peek voltage and electric current of realization under make schedule, switching frequency anger and the switch reduction. And mind benevolence it sprouted 2 in stop circuit and it added and a direct current voltage and the electric current where the ingredient is reduced in load side ripple stable under make whom it will be able to supply. Besides the efficiency of 92[%]is obtained over the wide output voltage regulation ranges and load variations. Also, under make over together the result leads simulation and test, the propriety confirmation.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.4
• /
• pp.403-411
• /
• 2013

This paper proposes an isolated bidirectional three-phase push-pull dc-dc converter for high power application such as eco-friendly vehicles, renewable energy systems, energy storage systems, and solid-state transformers. The proposed converter achieves ZVS turn-on of all switches and volume of passive components is small by an effect of three-phase interleaving. The proposed converter has identical switching pattern for both boost and buck mode, and therefore can provide seamless characteristic at the mode transition. A 3kW prototype of the proposed converter has been built and tested to verify the validity of the proposed operation.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.335-336
• /
• 2016

This paper introduces a bidirectional full-bridge converter with new active damp structure. The proposed active damp circuit can damp the oscillating voltage across the rectifier diodes with a smaller voltage stress of the damping capacitor and eliminate the circulating current. In addition, the proposed converter can achieve additional advantages such as nearly ZCS switching for leading-leg switches and no recovery current for rectifier-bridge by the suitable design of the damp capacitor to resonate with leakage inductor. Since the ZVS is achieved for both leading-leg and lagging-leg switches by the magnetizing current of the transformer, it can be achieved regardless of the load variation. A 3.3 kW prototype converter is implemented for vehicle-to-grid (V2G) application and the advantages of the proposed converter are verified by the experiments. The maximum efficiencies of 98.2% and 97.6% have been achieved for the buck mode and boost mode operation, respectively.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.5
• /
• pp.431-439
• /
• 2014

The two-phase interleaved bidirectional DC-DC converter (TIBDC) is a very attractive solution to problems related to battery energy storage systems. However, the hard-switching TIBDC increases the switching loss and electromagnetic interference noise when the switching frequency increases. Hence, a soft-switching technique is required to overcome these disadvantages. In this study, a novel TIBDC with zero-voltage transition (TIBDC-ZVT) is proposed. Soft switching in the boost and buck main switches is achieved through a resonant cell that consists of a single resonant inductor and four auxiliary switches. Given its single resonant inductor, the proposed TIBDC-ZVT has a reduced size and can easily be implemented. The validity of the proposed TIBDC-ZVT is verified through experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.4
• /
• pp.322-329
• /
• 2012

This paper proposes a non-isolated bidirectional soft-switching converter with high voltage for high step-up/down and high power applications. Compared to the conventional boost converter the proposed converter can achieve approximately doubled voltage gain using the same duty cycle. The voltage ratings of the switch and diode are reduced to half, which result in the use of devices with lower $R_{DS(ON)}$ and on drop leading to reduced conduction losses. Also, voltage ratings of the passive components are reduced, and therefore the total energy volume is reduced to half. Further, the switch is turned on with ZVS in the CCM operation which results in negligible surge caused leading to reduced switching losses. The validity of the proposed converter is proved through a 10kW prototype.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.46-48
• /
• 2008

A concern about micro grid connection system is elevated. The reason is that carbon dioxide emission is regionally restricted to prevent the drain of fossil fuel, high oil prices and global warming. The existing photovoltaic DC-DC converter is operated by the full-bridge method. However, the configuration is complicated because a phase shift method is required to raise an efficiency. A photovoltaic DC-DC converter connected with second layered half-bridge converter and boost converter is proposed in this paper. This proposed DC-DC converter is easy to control and has an advantage of reducing the size. Finally, the validity of the proposed converter is verified by the experimentation.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.259-261
• /
• 2008

The electronic products such as laptop PC, cellular phone, robots and etc. need the DC power source. Recently, the secondary battery is frequently used as the portable DC power source and it needs forming process. In this paper, we proposed the bidirectional converter that the battery can be charged with high power factor and the discharged energy is regenerated into AC power source. In the charging mode, the converter acts as the boost rectifier. And the AC input current is controlled in phase with the AC input voltage. As a result, the power factor is improved nearly to unity. In the discharging mode, the DC power of battery wasted in resistor is regenerated to the AC bus line. Finally, the validity of the proposed bidirectional converter is verified by computer simulations and experimentation.

• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.88-90
• /
• 2012

A study on an integrated single stage AC/DC converter is presented in this paper. The input current can be controlled by the auxiliary winding($L_{aux}$), auxiliary primary winding($N_3$), and the boost inductor($L_B$) which are designed to operate in discontinuous conduction mode(DCM) to reduced the total harmonic distortion(THD) of input current. The auxiliary primary winding($N_3$) is critically selected in order to compress the input capacitor voltage($V_{in}$) as well as to reduce the current stress of the switch(Q). Low total harmonic distortion(THD), low input voltage($V_{in}$) in universal input voltage($V_{AC}$), low current stress at the switching device and high efficiency are the main consideration keys in this design to achieve high performance system with low cost of single stage AC/DC converter. A 30W single stage AC/DC prototype converter is under study.