• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.221-223
• /
• 2003

This paper presents a new hybrid control method of asymmetrical/symmetrical half-bridge converter (AHBC/SHBC) with low voltage stress of the diodes. The proposed new control scheme is executed by using feedback of the input voltage and then can decide operation of the converter is divided into two ranges, which are asymmetrical control and symmetrical control, So the proposed control scheme has many advantages such as a low rated voltage of the secondary diodes, and low conduction loss according to the low voltage drop. The proposed control scheme is verified by simulated results.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.8
• /
• pp.416-422
• /
• 2006

With the increasing demand for renewable energy, distributed power included in fuel cells have been studied and developed as a future energy source. For this system, a power conversion circuit is necessary to interface the generated power to the utility. In many cases, a high step-up dc/dc converter is needed to boost low input voltage to high voltage output. Conventional methods using cascade dc/dc converters cause extra complexity and higher cost. The conventional topologies to get high output voltage use flyback dc/dc converters. They have the leakage components that cause stress and loss of energy that results in low efficiency. This paper presents a high boost converter with a voltage multiplier and a coupled inductor. The secondary voltage of the coupled inductor is rectified using a voltage multiplier and series-connected with the boost voltage of primary voltage of the coupled inductor. Therefore, high boost voltage is obtained with low duty cycle. Theoretical analysis and experimental results verify the proposed solutions using a 300W prototype.

• 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.

• Journal of Power Electronics
• /
• v.3 no.3
• /
• pp.159-166
• /
• 2003

The winding insulation of low-voltage induction motors in adjustable-speed drive system with voltage-fed Inverters is substantially stressed due to the uneven voltage distribution and excessive voltage stress (dv/dt), which result in the premature insulation breakdown In this paper, the detailed insulation test results of 26 low-voltage induction motors are presented. Six different types of insulation techniques are applied to 26 motors. The insulation characteristics are analyzed with partial discharge, discharge inception voltage, AC current, and dissipation factor tests Also, insulation breakdown tests by high voltage pulses are performed, and the corresponding breakdown voltages obtained.

• Journal of Power Electronics
• /
• v.15 no.1
• /
• pp.235-245
• /
• 2015

This paper proposes a reactive current assignment and control strategy for a doubly-fed induction generator (DFIG) based wind-turbine generation system under generic grid voltage sag or swell conditions. The system's active and reactive power constrains during grid faults are investigated with both the grid- and rotor-side convertors (GSC and RSC) maximum ampere limits considered. To meet the latest grid codes, especially the low- and high-voltage ride-through (LVRT and HVRT) requirements, an adaptive reactive current control scheme is investigated. In addition, a torque-oscillation suppression technique is designed to reduce the mechanism stress on turbine systems caused by intensive voltage variations. Simulation and experiment studies demonstrate the feasibility and effectiveness of the proposed control scheme to enhance the fault ride-through (FRT) capability of DFIG-based wind turbines during violent changes in grid voltage.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.117-120
• /
• 1988

A new current source inverter (CSl) with dc-side commutation and load-side energy recovery circuit is proposed with analysis and explanation of the circuit operation. Proposed inverter overcomes the most drawbacks of the conventional CSI's - high device voltage stress, low operating frequency range, large commutation capacitance, etc. - by employing simultaneous recovery and commutation concept. The new CSI employs only one commutation capacitor and it can be built with considerably low cost. The commutation energies are temporarily stored into a large dc capacitor and recovered to the load side, thus the device voltage stress is low and the efficiency is high in the proposed inverter. Computer simulation results are given at the steady state, and a guideline determining the commutation circuit is given.

• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.68-70
• /
• 2006

A new low-cost energy-recovery circuit (ERC) for a plasma display panel (PDP) is proposed. It has two auxiliary switches clamped on a half sustain voltage, and inductor currents are built up before the PDP is charged and -discharged. Therefore, it features a low cost, fully charged/discharged PDP, zero voltage switching (ZVS), low electromagnetic interference (EMI), low current stress, no severe voltage notch, and high energy-recovery capability.

• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.356-363
• /
• 2018

The combination of a buck converter and a forward converter can be considered to accomplish a high step-down non-isolated converter. To decrease the insufficient step-down ratio of a regular buck converter and to distribute switch voltage stress, a forward-integrated buck (FIB) converter is proposed in this paper. The proposed interleaved DC-DC converter provides an additional step-down gain with the help of a forward converter. In addition to its simple structure, the transformer flux reset problem is solved and an additional magnetic core reset winding is not required. The operational principle and an analysis of the proposed FIB converter are presented and verified by experimental results obtained with a 240 W, 150 V/24 V prototype.

• Proceedings of the IEEK Conference
• /
• 2002.06b
• /
• pp.17-20
• /
• 2002

This study has been investigated that traps generated inside of the oxide and at the oxide interfaces by the stress bias voltage. The traps are charged near the cathode with negative charge and charged near the anode with positive charge. The charge state of the traps can easily be changed by application of low voltages after the stress high voltage. These trap generation involve either electron impact ionization processes or high field generation processes. It determined to the relative traps locations inside the oxides ranges from 113.4A to 814A with capacitor areas of 10$^{-3}$ $\textrm{cm}^2$ The oxide charge state of traps generated by the stress high voltage contain either a positive or negative charge.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.520-522
• /
• 2008

A novel two-switch active clamp forward converter suitable for high input voltage applications is proposed. The main advantage of the proposed converter, compared to the conventional active forward converters, is that circuit complexity is reduced and the voltage stress of the main switches is effectively clamped to either the input voltage or the clamping capacitor voltage by two clamping diodes without limiting the maximum duty ratio. Also, the clamping circuit does not include additional active switches, so a low cost can be achieved without degrading the efficiency. Therefore, the proposed converter can feature high efficiency and low cost for high input voltage applications. The operational principles, features, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 200W, 375V input, and 12V output.