• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.256-264
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• 2018

This paper proposes a three-bridge LLC resonant converter with auxiliary switches for a wide output voltage control range. This converter can be controlled in two ways to achieve a wide controllable output voltage control range of $V_o$ to $3V_o$. The first control mechanism is achieved through the pulse width modulation (PM) of the auxiliary switches and primary switching devices, while the second control mechanism is achieved through the frequency modulation (FM) of the primary switching devices that are configured to operate in the full-bridge switching mode when the auxiliary switches are turned off. The feasibility of using the proposed converter is verified by the results of an experiment with a 2kW prototype.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.89-96
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• 2004

High-linearity voltage-controlled current sources (VCCSs) circuits for wide voltage-controlled oscillator and automatic gain control are proposed. The VCCS consists of emitter follower for voltage input, two common-base amplifier which their emitter connected for current output, and current mirror which connected the two amplifier for large output current. The VCCS used only five transistors and a resistor without an extra bias circuit. Simulation results show that the VCCS has current output range from 0㎃ to 300㎃ over the control voltage range from 1V to 4.8V at supply voltage 5V. The linearity error of output current has less than 1.4% over the current range from 0A to 300㎃.

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.274-279
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• 2009

In this paper, a wide dynamic range active pixel sensor(APS) with output voltage feedback structure has been designed by a 2-poly 4-metal 0.35 $\mu$m standard CMOS technology. We presented a novel APS with output voltage feedback, which exhibits a wide dynamic range. The dynamic range increases at the cost of an additional diode and an additional MOSFET. The output voltage feedback structure enables the control of the output voltage level by itself, as incident light power varies. It is confirmed that the light level which the output voltage level of proposed APS is saturated is about 120,000 lux, which is higher than that of a conventional 3-transistor APS.

• Journal of Power Electronics
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• v.9 no.3
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• pp.396-402
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• 2009

A DC/DC converter generally needs to work under high switching frequency when used as an adjustable power supply to reduce the size of magnetic elements such as inductors, transformers and capacitors, but with the rising of the switch frequency, the switch losses will increase and the efficiency will reduce. Recently, to solve these problems, research is actively being done on a soft switching method that can be applied under high frequency and on a PWM converter that can be applied under low frequency such as a multi-level topology. In this paper a novel DC-DC conversion method for reducing the ripple of output voltage is proposed. In the proposed converter, buck converters are connected in series to generate the output voltage. By using this method, the ripple of output voltage can be reduced compared to a conventional buck converter. Particularly when output voltage is low, the number of acting switching elements is less and the result of ripple reduction is more obvious. It is expected that the converter proposed in this paper could be very useful in the case of wide-range output voltage.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1619-1626
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• 2018

The output power of most facilities for renewable energy generation is unstable due to external environmental conditions. In distributed power systems with two or more sources, a stable output can be achieved with the complementary power supply among the different input sources. In this paper, a double-input DC-DC converter with a wide-input-voltage-range is proposed for renewable energy generation. This converter has the following advantages: the circuit is simple, and the input voltage range is wide and the fault tolerance is excellent. The operation modes and the steady-state analysis are examined. Finally, experimental results are illustrated to verify the correctness of the analysis and the feasibility of the proposed converter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.143-145
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• 2015

One of the many problems besetting the converter designer is being able to design a switching power supply that can operate in the range of very wide input voltage. Specially, in an emergency diesel generator system, the AVR(Automatic Voltage Regulator) is a regulator which regulates the output voltage of the generator at a nominal constant voltage level. In addition, the AVR must be operated in very wide input voltage. Therefore, a power supply for the AVR must be operated at the very wide input voltage range. In this paper, a quasi-resonant flyback power supply with very wide input voltage range is proposed. Also, the performance of the proposed power supply is demonstrated through experiments.

• Journal of Power Electronics
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• v.9 no.5
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• pp.736-747
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• 2009

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.434-435
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• 2018

In this paper, a single-phase single-stage three-level AC/DC converter with a wide controllable output voltage is presented. It integrates a PFC converter and a three level DC/DC converter into one. The proposed converter operates at a fixed frequency and provides a wide controllable output voltage ($200V_{dc}-430V_{dc}$) with high efficiencies over a wide load range. In addition, the input boost inductors operate in a discontinuous mode to improve the input power factor. Moreover, all the switching devices operate with ZVS, and the converter's THD is small especially at full load. The feasibility of the proposed converter is verified with experimental results of a 1.5kW prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.517-526
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• 2017

In this paper, we propose an LLC resonant converter that operates over a wide controllable output voltage ($50V_{DC}$ to $800V_{DC}$) and shows high efficiency characteristics under all load conditions and output voltages. Two 3.3kW prototypes are designed for an experimental comparison between the variable frequency control (control scheme 1) and the variable input voltage($V_{IN}$) control (control scheme 2) mechanisms. The experimental results show that the variable input control mechanism demonstrates high efficiency under all loads and output voltages.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.302-305
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• 2021

Selection of the optimal inductance for power factor improvement of a buck AC/DC light-emitting diode (LED) driver with wide input voltage range is described in this study. The power factor change based on the slope compensation is obtained for various normalized output current (NOC) values using discrete-time domain analysis. The possibility of implementing constant slope compensation is described using power factor curves for various NOC values. NOC = 0.5 is chosen for the value of inductance with consideration for the simple implementation and reduction of inductor size. Experimental results of the inductance corresponding to NOC = 0.5 are presented.