• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.502-504
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• 2008

A new output inductor less phase shift full bridge converter with current reduction technique for server power application is proposed in this paper. The proposed converter can reduce the current stress by using the auxiliary circuit. Since the auxiliary circuit causes the additional resonance between the leakage inductor and auxiliary capacitor before the powering period, the proposed converter has lower current stress even no output filter inductor. Small size and circulating energy can be also the merits of the proposed converter. The operational principles and analysis are presented. Experimental results demonstrate that the current stress can be reduced effectively by using the auxiliary circuit without large output filter inductor.

• Journal of Power Electronics
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• v.11 no.1
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• pp.10-15
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• 2011

In this paper, a new soft switching three phase inverter with a quasi-resonant dc-link is presented. The proposed inverter has a dc-link switch and an auxiliary switch. The inverter switches are turned on and off under zero voltage switching condition and all auxiliary circuit switches and diodes are also soft switched. The control utilizes PWM and the auxiliary switch does not require an isolated gate drive circuit. In this paper, the operation analysis and design considerations of the proposed soft switching inverter are discussed. The presented experimental results of a realized prototype confirm the theoretical analysis.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.56-61
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• 2018

In this paper, a new type of active snubber was proposed to lower the excessive rated voltage of the clamp capacitor which was a problem in the conventional circuit by applying auxiliary winding into the active snubber. A simplified equivalent circuit of the proposed snubber was derived by applying it to QR flyback converter, and the equivalent circuits for each switch state was shown under the steady-state condition. In addition, the maximum voltage of the clamp capacitor as well as the main switch was found by using the steady-state equations. In particular, it was found that the clamp capacitor voltage could be controlled by the auxiliary winding ratio. In order to verify the utility and practicality of the proposed converter with auxiliary winding type active snubber circuit, a prototype with an output voltage of 19V and a maximum load current of 6A was produced and the results were reported.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.11-116
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• 2000

A topology decreased switching loss and voltage stress by zero voltage switching is presented in this paper. Generally, Switching mode converting productes voltage stress and power losses due to excessive voltage and current. which affect to performance of power supply and reduce overall efficiency of equipments. Virtually, In flyback converter, transient peak voltage and current at switcher are generated by parasitic elements. To solve these problems, present ZVS flyback converter topology applied a auxiliary circuit. Incorporation of auxiliary circuit into a conventional flyback topology serves to reduce power losses and to minimize switching voltage stress. Snubber capacitor in auxiliary circuit serves ZVS state by control voltage variable time at turn on and off of main switch, then reduces voltage stress and power losses. The proposed converter has lossless switching in variable load condition with wide range. A detailed analysis of the circuit is presented and the operation procedure is illustrated. A (50W 100kHz prototype) ZVS flyback converter using a auxiliary circuit is built which shows an efficiency improvement as compared to a conventional hard switching flyback converter.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2512-2514
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• 1999

A new zero voltage and zero current switching(ZVZCS) full bridge DC-DC converter with transformer isolation is proposed for arc welding machines. The proposed DC-DC converter uses an auxiliary transformer to obtain ZCS for leading leg, which provides load current control capability even in short circuit condition. The auxiliary circuit also operates in ZVZCS mode. The power rating of the auxiliary transformer is about 10% of the main transformer. The operation is verified by experiments for 12[KW] prototype.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.209-212
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• 2003

This paper proposes a soft-transition control strategy for a three phase ZCS(Zero Current Switching) inverter circuit. Each phase leg of inverter circuit consists of an LC resonant tank, two main switches, and one auxiliary switches. This paper presents design consideration via a study example of a three phase prototype inverter for motor drives. A simple device tester with zero current switching capability is proposed to select eligible auxiliary switches. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 2.2kW 5kHz IGBT based experimental circuit.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.413-416
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• 2006

The power source of an AC-PDP fur sustainer circuit is operated in high-voltage and high frequency switching during the process required to achieve the gas discharge current to generate light in a PDP panel. Since PDP has the characteristics of a pure capacitive load, the displacement current that occurs during charge and discharge generates considerable reactive power. An auxiliary circuitry called Energy Recovery Circuit (ERC) reduces the capacitive displacement current. However, this auxiliary topology also bears high stress in its components. In this paper, a multilevel voltage wave shaping sustainer circuit with auxiliary ERC characteristics for an AC-PDP driver is proposed. A comparative analysis and experimental results are presented.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1099-1101
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• 2003

The diagnosis of power converter using auxiliary circuit connected to output terminal is proposed and verified by experimental results in this paper. On contrary to conventional diagnosis method, the proposed monitoring technique is possible to measure the state of power converter and unbalanced output caused by a misfiring of switch and unusual control signal. Conventional method gives a monitoring approaches for only a unusual operation of power converter. In this paper, three signals with auxiliary circuit are obtained and analyzed to see the state of electrolytic capacitor, power semiconductor switches and output voltage balance. 2kVA inverter is made and fisted to verify the proposed circuit.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.5-6
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• 2016

This paper introduces a high efficiency bidirectional resonant converter using an additional LC auxiliary circuit for dcdistribution applications. The LC auxiliary circuit operates as a variable inductor and the additional LC circuit helps to increase the effective magnetizing inductance, thereby reducing the turn-off and primary circulating current. A 5 kW bidirectional converter for dc-distribution system is implemented to verify the validity of the proposed method. The experimental results show the high efficiency characteristics of the proposed converter over the wide range of load in both direction of power flow. The maximum efficiency of the proposed system was 98.1 % at 3 kW.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.149-158
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• 2006

A soft-switching scheme for the PWM boost converter, ZCT (Zero current transition : ZCT) boost converter Is newly proposed to obtain the desirable features of both the conventional BWM boost and resonant converters such as easy of control, reduced switching losses and stresses, an4 low EMI. In order to achieve the soft-switching action, the proposed scheme employs an auxiliary circuit, which is added to the conventional boost converter and used to achieve soft-switching for both the main switch and the output diode while not incurring any additional losses due to auxiliary circuit itself. The basic operations, in this paper, we discussed and design guidelines are presented. Through a 100kHz, 60-W prototype, the usefulness of the proposed scheme is verified.