• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.267-269
• /
• 2006

In this paper, a new single phase voltage sag/swell compensator using direct power conversion is introduced. A new compensator consists of input/output filter, series transformer and direct ac-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc-link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy to compensate voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method commonly required in the direct power conversion. Simulation results are shown to demonstrate the advantages of the new compensator and PWM strategy.

• Journal of Power Electronics
• /
• v.13 no.1
• /
• pp.113-121
• /
• 2013

This paper introduces a simple core loss calculation method for output filter inductor in pulse width modulation (PWM) DC-AC inverter. Amorphous C-core (AMCC-320) is used to analyze the core loss. In order to measure core loss of the output filter inductor and validate the proposed method, a single-phase half-bridge inverter and a calorimeter are used. By changing switching frequency and modulation index (MI) of the inverter, core loss of the AMCC-320 is measured with the lab-made calorimeter and the results are compared with calculated core loss. The proposed method can be easily extended to other core loss calculation of various converters.

• Journal of Power Electronics
• /
• v.18 no.4
• /
• pp.1015-1026
• /
• 2018

A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.3
• /
• pp.224-230
• /
• 2016

In this study, a single-power-conversion series-resonant ac-dc converter with high efficiency and high power factor is proposed. The proposed ac-dc converter consists of single-ended primary-inductor converter with an active-clamp circuit and a voltage doubler with series-resonant circuit. The active-clamp circuit clamps the surge voltage and provides zero-voltage switching of the main switch. The series-resonant circuit consists of leakage inductance $L_{lk}$ of the transformer and resonant capacitors $ C_{r1}$ and $ C_{r2}$. This circuit also provides zero-current switching of output diodes $D_1$ and $D_2$. Thus, the switching loss of switches and reverse-recovery loss of output diodes are considerably reduced. The proposed ac-dc converter also achieves high power factor using the proposed control algorithm without the addition of a power factor correction circuit and a dc-link electrolytic capacitor. A detailed theoretical analysis and the experimental results for a 1kW prototype are discussed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.6
• /
• pp.488-495
• /
• 2009

This paper proposes a new AC/DC RPPB(Resonant Piezo-Powered Boost) converter for energy harvesting using a piezoelectric device which converts mechanical vibration energy to electrical energy. The AC/DC RPPB converter can operate with only the harvested energy without an additional power conversion circuit for switching circuit and transfer energy to a load of which the voltage is higher than piezoelectric voltage. With the review of published topologies of the converter for energy harvesting, the operation principle of the AC/DC RPPB converter, and the results of PSPICE simulation and experiment are presented to prove the feasibility of the new converter for the energy harvesting.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.328-329
• /
• 2020

The AC/DC converter, which connects the AC grid to the DC grid in the microgrid, is a critical component in power sharing and stable operation. Sometimes the AC/DC converters are connected in parallel to increase the transmission and reception capacity. When connected in parallel, circulating current is generated due to line impedance difference or sensor error. As a result of circulating current, there is deterioration and loss in particular PCS(Power Conversion System). In this paper, we propose droop control with novel adaptive virtual impedance for reducing circulating current. Feasibility of proposed algorithm is verified by PowerSIM simulation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.1
• /
• pp.16-21
• /
• 2012

The growth in IT industry has brought a corresponding rise in the number of connected digital devices in the distribution network. These digital loads lead to AC to DC conversion losses in order to supply power to them. The more the renewable energies and plug-in electrical vehicles penetrated our lives, the more the electrical losses are caused by AC to DC conversion process. Hence, this paper suggests the methodology for evaluating the amount of power supplied according to the ratio of DC power supply and performs an economic analysis of DC distribution system considering grid parity. In here, the cost of carbon emission reduced by renewable energy is also concerned.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.902-904
• /
• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.3114-3116
• /
• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%] of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2462-2464
• /
• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a Practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.