• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.1
• /
• pp.86-93
• /
• 2003

This paper describes that the resonant tank type DC-DC converter consist of reactor and capacitor resonant tank circuit for increased the output current. This circuit configuration is composed of the resonant tank circuit used resonant capacitor and reactor and the capacitor connected in switch are a common using by resonance capacitor and ZVS(Zero Voltage Switching) capacitor. Therefore, the proposed converter can reduce a switching losses, noise, and voltage stress at turn-on and turn-on and has an advantage which is able to operating safely in load short, because DC reactor is connected with resonance reactor in order to supply a fixed current with low ripple from DC power supply. The analysis of proposed circuit uses normalized parameters and characteristic estimation is generally described the proposed circuit with the characteristics of power and output voltage etc. Also, design is based on the characteristic estmations in each step. Hence, We conform a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.4
• /
• pp.510-516
• /
• 2013

This paper suggests a 3-phase series-resonant type high voltage capacitor charger for an EML pulsed power system. The operating principle on the charger is explained by an equivalent circuit. Additionally, we analyze the charging characteristic in one discontinuous conduction mode and three continuous conduction modes. The analysis shows that the resonant current per phase is two thirds of the 3-phase charger's average charging current and one third of the single-phase charger's average charging current with the same capacity. We suggest a design method of the 3-phase capacitor charger in each operational mode and present an example of 3.5 kW capacitor charger at ${\omega}_s=0.33{\omega}_r$. The 3.5 kW 3-phase capacitor charger prototype is assembled with a TI28335 controller and a 40 kJ, 7 kV capacitor. The design rules based on the analysis are verified by experiment.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.226-228
• /
• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.10
• /
• pp.93-100
• /
• 2013

Generally, the conventional battery charging system using an analog method has the large, heavy hardware and low efficiency. Also, it has the disadvantage that it is necessary to replace the control circuit on the basis of the characteristic curve of the specific battery cell. The proposed programmable digital LLC resonant charging system use high efficiency control system(CC-CV), and has characteristic a small hardware and advantage that a digital programming of the voltage, current, and battery capacity characteristics can be flexible. The system proposed the use of Half-bridge LLC resonant converter is possible to improve efficiency and reduce switching losses by using ZVS topology. Further, a constant voltage - constant current(CC-CV) control algorithm apply to the charger which using a buck converter. The performance of the proposed system is demonstrated through experiments.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.7
• /
• pp.524-538
• /
• 1989

A new bilateral series resonant inverter and its control method are proposed. The proposed inverter consists of zero current switched cycloconverter. Output voltage is regulated by modulating the average magnitude of resonant current sinusoidally. Cycloconverter synthesizes low frequency output voltage from high frequency resonant current pulses. In the proposed inverter, bidirectional power flow in possible and isolation transformer is miniaturized. The proposed control method is verified through simulation and experiment. The proposed inverter will satisfy the small size and low cost requirements of small Uninterruptible Power Supply (UPS) of less than 1 KVA suitable for micro-computers and electronic equipments used in office and home automation.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.3
• /
• pp.188-194
• /
• 2020

This paper presents a high-efficiency Switch Mode Line Transformer (SMLT) composed of load-shared dual modules, which is based on the AC/AC LLC resonant converter. Given that the conventional adaptor is usually composed of two power stages, namely, the PFC and DC/DC converters, its system size can be increased according to the output power. However, given that the proposed SMLT can separate the PFC converter from the adaptor, the size reduction of the system can be achieved. Meanwhile, the SMLT with a single module has the limit of the size reduction because of a high resonant current. Thus, it can be configured with dual or multiple modules to reduce the resonant current. Then, their load sharing can be guaranteed by only the proposed transformer structure without an extra current controller. The validity of the proposed converter is proven through a 850-W prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.4
• /
• pp.71-78
• /
• 2005

This paper proposes a novel multi-level energy recovery sustaining driver for AC PDP(Plasma Display Panel), which solves the problems of the conventional multi-level sustaining driver. While the conventional circuit improves the voltage md current stress of the switching elements in Weber circuit not only there are parasitic resonant currents between resonant inductors and parasitic capacitance and hard switching, but also the changing period between 0 and sustain voltage is too long. Comparing the proposed circuit with the conventional circuit, the number of components are reduced and the parasitic resonant currents in resonant inductors are eliminated Moreover the hard switching problem is solved by using CIM(Current Injection Method) and the operating frequency will be high as much as possible by removing Vs/2 sustain period. And the circuit operations of the proposed circuit are analyzed for each mode and the validity is verified by the simulations using PSpice program.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.1
• /
• pp.46-53
• /
• 2009

A new zero-current switching LLC resonant post-regulator for multi-output power system is proposed in this paper. A conventional LLC resonant converter employs extra non-isolated DC/DC converters to obtain tight-regulated multi-slave output voltages. Therefore, it has several serious problems such as a poor efficiency and high cost of production. The proposed post-regulator features low voltage and current stress across the output rectifier diodes and power switches. Moreover, the proposed post-regulator requires only one power switch instead of the bulky and expensive non-isolated DC/DC converter. Therefore, it features a simple structure and lower cost. Especially, since the proposed post-regulator can ensure the ZCS of all power switches, it has very desirable advantages such as more improved EMI characteristics and reduced switching losses. Finally, to confirm the operation, validity, and features of the proposed circuit, experimental results from a proposed zero-current LLC resonant post-regulator are presented.

• Journal of Power Electronics
• /
• v.14 no.1
• /
• pp.30-39
• /
• 2014

This paper studies a new three-level pulse-width modulation (PWM) resonant converter for high input voltage and high load current applications. In order to use high frequency power MOSFETs for high input voltage applications, a three-level DC converter with two clamped diodes and a flying capacitor is adopted in the proposed circuit. For high load current applications, the secondary sides of the proposed converter are connected in parallel to reduce the size of the magnetic core and copper windings and to decrease the current rating of the rectifier diodes. In order to share the load current and reduce the switch counts, three resonant converters with the same active switches are adopted in the proposed circuit. Two transformers with a series connection in the primary side and a parallel connection in the secondary side are adopted in each converter to balance the secondary side currents. To overcome the drawback of a wide range of switching frequencies in conventional series resonant converters, the duty cycle control is adopted in the proposed circuit to achieve zero current switching (ZCS) turn-off for the rectifier diodes and zero voltage switching (ZVS) turn-on for the active switches. Finally, experimental results are provided to verify the effectiveness of the proposed converter.

• Journal of Power Electronics
• /
• v.19 no.1
• /
• pp.201-210
• /
• 2019

This paper proposes a multimode hybrid control strategy that can achieve zero-voltage switching of primary switches and zero-current switching of secondary rectifier diodes in a wide input voltage range for full-bridge LLC resonant converters. When the input voltage is lower than the rated voltage, the converter operates in Mode 1 through the variable-frequency control strategy. When the input voltage is higher than the rated voltage, the converter operates in Mode 2 through the VF and phase-shift control strategy until the switching frequency reaches the upper limit. Then, the converter operates in Mode 3 through the constant-frequency and phase-shift control strategy. The secondary-side diode current will operate in the discontinuous current mode in Modes 1 and 3, whereas it will operate in the boundary current mode in Mode 2. The current RMS value and conduction loss can be reduced in Mode 2. A detailed theoretical analysis of the operation principle, the voltage gain characteristics, and the realization method is presented in this paper. Finally, a 500 W prototype with 100-200 V input voltage and 40 V output voltage is built to verify the feasibility of the multimode hybrid control strategy.