• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.2
• /
• pp.229-234
• /
• 2008

An AC-DC transfer standard(TS) is used for the AC voltage standard in the range of 2 mV to 1000 V below 1 MHz. Micro-potentiometer(${\mu}Pot$) is used to evaluate the ac-dc transfer difference(ADD) of the TS below 200 mV range. The ADD of the TS were changed by the loading effect caused from the input impedance change of the TS depend on frequency. An input impedance evaluation technique of the TS using ${\mu}Pot$ has been developed.

• Journal of Sensor Science and Technology
• /
• v.14 no.5
• /
• pp.350-356
• /
• 2005

We have developed a dual-channel type automatic measurement system to evaluate AC-DC current transfer difference of the thermal current converter(TCC) which is primary standard of AC current. The output drift effect of the TCC is minimized by measuring simultaneously the output voltages of two TCCs using voltmeter. Furthermore, the offset voltage of the voltmeter is cancelled nearly out by taking the average values of two outputs of TCCs measured with the forward-reverse directions using dual channel scanner. The uncertainties of the automatic system were 7 to $86{\mu}A/A$ for 3 mA to 10 A at 40 Hz to 20 kHz, which were evaluated by the comparisons between adjacent range of TCCs and inter-comparison with national measurement institute of Germany(PTB). The capability for ac-dc transfer difference measurement was improved by one order compared with that for the manual ac-dc measurement system.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.1
• /
• pp.9-13
• /
• 1996

The high precision of electrical power and energy measurements with wide range of frequency and power factor can be achieved by using the thermo-electrical power comparators. The paper describes the development of a precision power measuring system by using a ac/dc power comparator for measurement of power. Based on a thermal principle, the instrument performs ac-dc transfer for ac power measurements in the range of currents from 0 to 5 $A_{ms}$ , voltages from 0 to 240 $V_{ms}$ , power factors from 0 to 1 and frequencies from 0 to 1000 Hz. Two thermal converters with two heater are used in the functional element of the comparators. The ac-dc transfer accuracy is better than 20 ppm at unity power factor and better than 50 ppm at 0.5 power factor. (author). 8 refs., 5 figs., 3 tabs.

• Proceedings of the KIEE Conference
• /
• 1995.07b
• /
• pp.676-678
• /
• 1995

The Paper describes a dc/nc power comparator for measurement of power. Based on a thermal principle, the instrument performs ac-dc transfer and absolute power and energy measurements in the range of currents from 0 to 5 A, voltages from 60 to 240 V, power factors from 0 to 1 and frequencies from 50 to 1000 Hz. The ac-dc transfer accuracy is better than 20 ppm at unity power factor and better than 50 ppm at 0.5 power factor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.10
• /
• pp.15-20
• /
• 2013

In this paper, wireless power transfer system using the magnetic resonance was designed and applied to LED lighting for implementation of wireless lighting. This lighting was made by the converted DC driving type and the direct AC driving type. In the former, transferred AC power was rectified into DC and regulated to the specified voltage value, which leads to produce the loss at the rectifying and regulating circuit. In the latter, wireless-transferred AC power was directly applied to LED, which get rid of the loss derived from the additional circuit. For the efficiency-comparison between the former and the latter, the power at each stage was measured when the same optical output radiated from LED lighting part. The result revealed that the direct AC driving type had 18% higher efficiency than the DC driving type and confirmed that LED lighting using magnetic resonance wireless power transfer system can be efficient by direct AC power supply. And the direct AC driving type had the simple circuit structure and the simple LED lighting formation, so this can leads to various application.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.3
• /
• pp.276-282
• /
• 2014

In a single-phase grid-connected power system consisting of a dc-dc converter and a dc-ac converter, the current drawn from renewable energy sources has a tendency to be pulsated and contains double-fundamental frequency ripple components, which results in several drawback such as a power harvesting loss and a shortening of the energy source's life. This paper presents a new double-fundamental current reduction-scheme with a fast dc-link voltage loop for two-stage dc-dc-ac grid connected systems. In the frequency domain, an adequate control design is performed based on the small-signal transfer function of a two-stage dc-dc-ac converter. To verify the effectiveness of proposed control algorithm, a 1 kW hardware prototype has been built and experimental results are presented.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.1
• /
• pp.111-119
• /
• 2022

This paper is about power transfer between heterogeneous systems in zero-energy buildings. Currently, electricity used in buildings, from renewable energy generation power in buildings, consists of alternating current networks. In order to use electricity, alternating current must be converted to direct current, which typically results in a loss of 10%. In order to solve this problem, research is needed to reduce power loss as much as possible by implementing both a DC network and an AC network in a zero-energy building. Therefore, in this paper, an inter-link converter capable of bidirectional power transfer between DC and AC networks applied to zero-energy buildings is developed. The structure of the inter-link converter to be developed was proposed and its feasibility was verified through simulations and experiments.

• 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.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.2
• /
• pp.141-149
• /
• 2021

In the field of electric vehicles and AGVs, wireless power transfer (WPT) charging systems have been developed recently because of its convenience, reliability, and positive environmental impact due to cable and cord elimination. In this study, we propose a WPT charging system using a single stage AC-DC converter that can be reduced in size and weight and thus can ensure convenience. The proposed single-stage AC-DC converter can control a wide output voltage (36-54 VDC) within coupling ranges by using the variable link voltage applied to the WPT resonant circuit through phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype that can operate with an air gap range of 40-50 mm is fabricated and validated through experimental results and analysis.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.2
• /
• pp.107-113
• /
• 2012

This paper proposes a PDS(Power Transfer Display separation) method for AC-PDP. The proposed PDS method can transfer power and perform an energy recovery by a power conversion circuit operates differently depending on the time. As a result, it uses less of components than conventional PDP power supply and sustain circuit use. Moreover, the manufacturing process can be streamlined. Therefore, the proposed method is suitable for low cost PDP module. To confirm the operation, validity and features of the proposed PDS method, experimental results from a prototype for 42-in diagonal PDP are presented.