• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.266-268
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• 2005

A new synchronous switch controlled transient current build-up zero voltage switching (TCB-ZVS) forward converter is proposed. The proposed converter is suitable for the low-voltage and high-current applications. The features of the proposed converter are low conduction loss of magnetizing current, no additional circuit for the ZVS operation, high efficiency, high power density and low EMI noise throughout all load conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.140-149
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• 2017

This study proposes a new type of active-clamp forward-flyback converter with two transformers that operate in forward and flyback modes during on and off times, respectively, instead of not using an output inductor. The main switch can be turned on with zero-voltage switching (ZVS) using the leakage inductance of the transformer and the output capacitor of the main switch. The leakage inductance should be increased to ZVS. However, the ringing between the leakage inductance of the transformer and the parasitic output capacitance of the secondary side rectifier switches results in a serious voltage spike. A forward-flyback converter employing auxiliary inductor and auxiliary diode is proposed to overcome the problem. The operational principles are analyzed in detail and validated through experiments with a 385 V-to-53 V/37 A prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.60-66
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• 2005

This paper presents the single-stage TSFC(Two-Switch Forward Converter). Recently, due to growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as ICE 61000-3-2 and IEEE 519, There is a need to reduce the harmonic contests of AC line currents of power supplies. This research proposed the single-stage two switch forward circuit for low voltage and high current output. The principle of operation, feature and design considerations is illustrated and verified through the experiment with a 200[W](5[V], 40[A]) 100[kHz] MOSFET based experimental circuit.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.592-597
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• 2005

The push pull forward converter is suitable in a low output voltage, a high output current applications with wide input voltage ranges. All magnetic components including output inductor, transformer and input filter can be integrated into single EI/EE core. The integrated push pull forward converter is considered through the comparison of efficiency according to the circuit parameters. The Nicera company's 5M FEE18/8/10C and NC-2H FEI32/8/20 cores are used for the transformer. The integrated push pull forward converter ratings are of $36\~72V$ input and 3.3V/30A output. In case that NC-2H FEI32/8/20 core used in the converter, the efficiency is measured up to $83.5\%$ at the switching frequency 200 kHz and the 11A load. The efficiencies of $76.4\%$ at a full load and $82.95\%$ at a half load are measured.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.235-238
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• 2003

This paper presents an ZVT(Zero Voltage Transition) Forward Converter using Primary Auxiliary Circuit operation. An auxiliary resonant circuit was added to the basic forward converter, implementing the fVT technique for the main switch. The switch employed by the auxiliary circuit operates under Zero-Current-Switching(ZCS) condition. The complete operating principle, simulation and experimental results are presented

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1309_1310
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• 2009

The topology of active clamp forward converter provides ZVS characteristic and also the stress of voltage and current is smaller than that of the conventional forward converters. The benefits of this technique include a higher efficiency at a high switching frequency, lower EMI/RFI. In this paper, the active clamp forward converter is designed for operation in wide range voltage and has 19.5V/120W ratings with efficiency more than 90%.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.226-228
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• 2005

This paper presents the single-stage High Power Factor TTFC(Two-Transistor Forward Converter). Recently, due to growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as ICE 61000-3-2 and IEEE 519, There is a need to reduce the harmonic contests of AC line currents of power supplies. This research proposed the single-stage two switch forward circuit for low voltage and high current output.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.36-39
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• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. All the magnetic components (output inductor, transformer, input filter) can be integrated into a single core. The integrated magnetics can reduce the number of the magnetic components. Developed the push pull forward converter rating are of 36 $\~$72V input and 3.3V/30A output. In this converter, the efficiency was measured by $76.4\%$ at full load and 82.95$\%$ at full load. The maximum efficiency is up to 83.$\%$ at 200kHz switching frequency, l1A output.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.2
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• pp.112-120
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• 1997

The clamp mode (CM) forward zero voltage switching multi resonant converter (ZVS-MPC) with self-driven synchronous rectifier is studied. The loss at the synchronous rectification stage of the converter is analyzed using MOSFET piecewise linear model and is compared with the loss at the conventional schottky diode rectification stage of th econverter. From the results of the analysis, it is known that the use fo MOSFETs as a synchronous rectifier reduces the loss at the rectification stage overthe whole load range comparing the use of schottky diodes as a conventional rectifier in the converter. In order to verify the validit of the analysis, we have built a 33W(3.3V/10A) CM forward ZVS-MRC with self-driven synchronous rectifier, in which switching frequency is 1MHz, and tested. FRom the experimental results, it is known that the synchronous rectification achieved about 1W improvement in the loss at the rectification stage and about 3% in the efficiency at the converter as compared with the conventional schottky diode rectification.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.965_966
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• 2009

In this paper, a new soft-switching Two-switch Forward converter topology has been proposed. Compared with conventional two-switch forward converter, the proposed converter employs an auxiliary switch and a clamp capacitor to instead of two reset diodes, not only its duty cycle can exceed 0.5 to achieve wide range input voltage, but also soft switching can be achieved for all switches. Especially, voltage stress across main switches can be clamped at $1/2V_{in}$, voltage stress across auxiliary switch can be clamped at $V_{in}$. In addition, due to clamp capacitor series with the transformer, duty ratio can be extended with equation $V_o=\frac{V_{in}(1-D}D{N}$. Therefore, as a kind of better cost-effective approach, it is very attractive for high input, wide range and high efficiency application.