• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1575-1585
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• 2017

This paper presents a synchronous generator with a distributed system of multiple parallel three-phase power cells. This generator can immediately output high DC. Each power cell comprises three-phase windings and a three-phase synchronous rectification bridge with a deadbeat control of load power feedforward, which can improve the characteristics of dynamic response and reflect the load variance in real time. Furthermore, each power cell works well independently and modularly using the method of automatic maximum current sharing. The simulation and experimental results for the distributed controller of multiple power cells demonstrate that the deadbeat control method can respond quickly and optimize the quality of the energy. Meanwhile, automatic maximum current sharing can realize the validity of current sharing among power cells.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.40-47
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• 2022

At present, the low-voltage, high-current type power supply is mainly used for effective sterilization in the ballast water treatment system. Research on PSFB converters without output capacitors has been ongoing. Such converters effectively treat ballast water without a separate disinfectant through electric pulses by applying a pulse-type power to the output electrode without an output capacitor. However, in the case of the pulse-type electrolysis treatment method, voltage overshoot can occur due to abrupt voltage fluctuations when the load changes, resulting in circuit reliability problems because of the output capacitorless system. Therefore, a new voltage control algorithm is required. In this paper, we will discuss voltage control for pulsed electrolysis topology without an output capacitor. The proposed voltage control method has been verified using Simulation and experiment. The usefulness of the proposed control method has been proven by the experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.57-66
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• 2012

When typical Z-source DC/AC inverter(ZSI) is operated in high voltage gain area, because of its high duty ratio, voltage and current stress in Z-network of typical ZSI are increased. This paper proposes a new switched trans ZSI(STZSI) with two switched trans cells which consist of one trans and two diodes. To confirm the operation performance of the proposed system, the PSIM simulation is performed for typical ZSI, switched inductor ZSI and the proposed STZSI. Voltage / current stress and transient state characteristics of each method are compared under the condition of DC input voltage 100[V] and output phase voltage 66[Vrms]. As a result, we confirmed that transient state of the proposed STZSI is short compared with the conventional ZSI because the high voltage gain is obtained using the same duty ratio, also a low duty ratio is required for the same output voltage. Finally, we could know the proposed system have low voltage and current stress in Z-network compared with the conventional ZSI.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.11
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• pp.37-44
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• 2003

A distortion suppression technology for employing multiple inputs in 3n＋1 type current mode Max circuit is proposed using the adjustment of transconductance. If the number of input blocks of the current mode Max circuit increases, the high frequency distortion in the output signal grows. In this paper, it has been disclosed that the distortion in the multiple input Max circuit is proportional to such accumulated parasitic capacitance, to the derivative of the output signal and also to tile inverse of transconductance of the common diode-connected transistor. The proposed idea is by employing as larger transconductance of the common diode-connected transistor as possible. The effectiveness of the proposed idea has been proved through the HSPICE simulation for the current mode Max circuits with various numbers of input signals.

• Journal of Power Electronics
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• v.1 no.2
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• pp.78-87
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• 2001

A new high-power step-up based on the two-module parallel-input (PISO) modular dual inductor-fed push-pull converter is proposed. The proposed converter is operated at a constant duty cycle and employs and auxiliary circuit to control the output voltage with a phase-shift between two modules. It shows a high efficiency due to the greatly reduced switch turn-off stress. It also shows a high and linear voltage conversion ratio, low current stress in the output capacitor, and fast control-to-output dynamics. The operation principles and the mathematical models of the proposed converter are presented. Features of the proposed converter are discussed in comparison with the two-module PISO modular dual inductor-fed push-pull converter. Also, experimental results from a 50kHz, 800W, 350 Vdc prototype with an input voltage range of 20-32 Vdc are provided to confirm the validity of the proposed converter. The new converter compares favorably with the conventional counterpart, and is considered well siuted to high-power step-up applications.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.262-266
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• 2011

A simulation study of a current-mode direct current (DC)-DC boost converter is presented in this paper. This converter, with a fully-integrated power module, is implemented by using bipolar complementary metal-oxide semiconductor (BiCMOS) technology. The current-sensing circuit has an op-amp to achieve high accuracy. With the sense metal-oxide semiconductor field-effect transistor (MOSFET) in the current sensor, the sensed inductor current with the internal ramp signal can be used for feedback control. In addition, BiCMOS technology is applied to the converter, for accurate current sensing and low power consumption. The DC-DC converter is designed with a standard 0.35 ${\mu}m$ BiCMOS process. The off-chip inductor-capacitor (LC) filter is operated with an inductance of 1 mH and a capacitance of 12.5 nF. Simulation results show the high performance of the current-sensing circuit and the validity of the BiCMOS converter. The output voltage is found to be 4.1 V with a ripple ratio of 1.5% at the duty ratio of 0.3. The sensing current is measured to be within 1 mA and follows to fit the order of the aspect ratio, between sensing and power FET.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.351-354
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• 2006

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[$V_{DC}$] and a PWM inverter with LC filter to convent the DC voltage to single phase 220[$V_{AC}$]. Expressly, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS 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 93-97[%]is obtained over the wide output voltage regulation ranges and load variations.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.7
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• pp.384-390
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• 1999

This paper describes a new ac-to-dc power converter using a multilevel converter. A conventional multilevel ac-to-dc converter has large output dc filter capacitors. When a short circuit happens in a load, the stored energy in the capacitors should be discharged through the load with a high short circuit current. The high current may cause considerable damage to the capacitors and the load. The output dc capacitors of the proposed converter do not discharge even under load short circuit condition. In the case of a load short circuit, the capacitors become a floating state immediately and remain in the state. Then the stored capacitor energy is supplied to the load again as soon as the short circuit has been cleared. Therefore, the rising time of the load voltage can be significantly reduced. This feature satisfies the requirement of a power supply for a load with frequent short circuits. The proposed converter has the characteristics of a simplified structure, a reduced cost, weight, and volume compared with conventional power supplies with frequent output short circuits. Experimental results are presented to verify the usefulness of the proposed converter.

• Journal of Power Electronics
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• v.9 no.2
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1207-1208
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• 2006

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, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS 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 93-97[%] is obtained over the wide output voltage regulation ranges and load variations.