K. C. Tseng

Bio: K. C. Tseng is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Buck converter & Voltage. The author has an hindex of 1, co-authored 1 publications receiving 438 citations.

Novel high-efficiency step-up converter

Abstract: As a result of the equivalent series resistor of the boost inductor, conventional boost converters are not able to provide high voltage gain. A high-efficiency high step-up converter is proposed, with low voltage stress on power switch, power diodes and output capacitors. The circuit topology of the proposed converter consists of an energy clamp circuit and a voltage boost cell. The boost converter functions as an active clamp circuit to suppress the voltage spike on power switch during the turn-off transient period. The boost converter output terminal and flyback converter output terminal are serially connected to increase the output voltage gain with the coupled inductor. By serially connecting the secondary windings of the boost inductor, a high voltage gain is achieved with less voltage stress on the power devices, such as power MOSFET and power diodes. The operational principle and steady-state analysis are described. A 35 W converter with simulation and experimental results is presented to demonstrate the performance. It shows that the efficiency of the proposed converter is very high (nearly 93%) with four times the voltage output.

An integrated of buck and half‐bridge high step‐down converter utilizing single‐stage driving design for high‐efficiency energy conversions

Abstract: In this paper, an integrated of buck and half‐bridge high step‐down converter utilizing single‐stage driving design for high‐efficiency energy conversion is proposed. The proposed converter has the ability to instantly and synchronously transfer energy from input to output within one conversion period. The proposed topology is capable of lowering the primary side voltage of the transformer, so the turns ratio could be reduced. The coupling rate is therefore better along with the leakage inductance. Furthermore, the duty cycle operated in an extreme situation is not necessary. As a combination of the advantages of high step‐down conversion, lower voltage stresses, and fewer amount of semiconductor elements, the feasibility of the proposed topology is verified by the implementation of a 300 W prototype. The proposed integrated topology utilizes the single‐stage energy transfer control algorithm to verify that the proposed experimental circuit has a full load efficiency of 92.4%, in the case of input voltage 380 V and output voltage 5 V, and the maximum efficiency, occurring at 100 W, is 94.55%.

An Integrated Buck and Half-Bridge High Step-Down Converter

Abstract: In this paper, an integrated buck and asymmetrical half-bridge (IBAHB) high step-down converter utilizing a single-stage driving design for highly efficient energy conversion is proposed. The proposed converter is able to instantly and synchronously transfer energy from input to output within one conversion period. The advantages of high step-down conversion, lower voltage stress and fewer semiconductor elements verify the feasibility of this proposed topology. The turns ratio of the transformer can be reduced to increase the coupling rate, which decreases the leakage inductance. The proposed integrated topology utilizes the single-stage energy transfer control algorithm to verify that the proposed experimental circuit has a full-load efficiency. This development will achieve the market’s demand for high-buck converters and other related products and the competitive advantage of growing with the trend.

A Novel Isolated High Step-Up Interleaved Converter for Renewable Energy Systems

Abstract: In this paper, an isolated high step-up interleaved converter for renewable energy systems is proposed. The input-parallel configuration introduced by two energy storage inductors, which can disperse the input current, reducing conduction losses and also improve the conversion efficiency. In order to improve the voltage gain and recover the energy stored in the leakage inductance, the auxiliary step-up structure is utilized in the proposed converter, that including an auxiliary inductor, an auxiliary capacitor, a voltage multiplier capacitor and two switches which serve to exchange the energy stored in auxiliary capacitors and inductors. On the secondary side, a voltage-doubler circuit is used to extend the voltage gain. Finally, a 48V-input, 400V-output and the rated power of 500 W prototype is implemented to verified the effectiveness of the proposed converter. The experimental results shows that the maximum efficiency is 95.97%, and the efficiency of full-load is 93.27%.

Review of Nonisolated High-Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications

Abstract: The photovoltaic (PV) grid-connected power system in the residential applications is becoming a fast growing segment in the PV market due to the shortage of the fossil fuel energy and the great environmental pollution. A new research trend in the residential generation system is to employ the PV parallel-connected configuration rather than the series-connected configuration to satisfy the safety requirements and to make full use of the PV generated power. How to achieve high-step-up, low-cost, and high-efficiency dc/dc conversion is the major consideration due to the low PV output voltage with the parallel-connected structure. The limitations of the conventional boost converters in these applications are analyzed. Then, most of the topologies with high-step-up, low-cost, and high-efficiency performance are covered and classified into several categories. The advantages and disadvantages of these converters are discussed. Furthermore, a general conceptual circuit for high-step-up, low-cost, and high-efficiency dc/dc conversion is proposed to derive the next-generation topologies for the PV grid-connected power system. Finally, the major challenges of high-step-up, low-cost, and high-efficiency dc/dc converters are summarized. This paper would like to make a clear picture on the general law and framework for the next-generation nonisolated high-step-up dc/dc converters.

Transformerless DC–DC Converters With High Step-Up Voltage Gain

Abstract: Conventional dc-dc boost converters are unable to provide high step-up voltage gains due to the effect of power switches, rectifier diodes, and the equivalent series resistance of inductors and capacitors. This paper proposes transformerless dc-dc converters to achieve high step-up voltage gain without an extremely high duty ratio. In the proposed converters, two inductors with the same level of inductance are charged in parallel during the switch-on period and are discharged in series during the switch-off period. The structures of the proposed converters are very simple. Only one power stage is used. Moreover, the steady-state analyses of voltage gains and boundary operating conditions are discussed in detail. Finally, a prototype circuit is implemented in the laboratory to verify the performance.

High step-up converter with coupled-inductor

Abstract: In this study, a high step-up converter with a coupled-inductor is investigated. In the proposed strategy, a coupled inductor with a lower-voltage-rated switch is used for raising the voltage gain (whether the switch is turned on or turned off). Moreover, a passive regenerative snubber is utilized for absorbing the energy of stray inductance so that the switch duty cycle can be operated under a wide range, and the related voltage gain is higher than other coupled-inductor-based converters. In addition, all devices in this scheme also have voltage-clamped properties and their voltage stresses are relatively smaller than the output voltage. Thus, it can select low-voltage low-conduction-loss devices, and there are no reverse-recovery currents within the diodes in this circuit. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage drift problem of the power source under the load variations. As a result, the proposed converter topology can promote the voltage gain of a conventional boost converter with a single inductor, and deal with the problem of the leakage inductor and demagnetization of transformer for a coupled-inductor-based converter. Some experimental results via examples of a proton exchange membrane fuel cell (PEMFC) power source and a traditional battery are given to demonstrate the effectiveness of the proposed power conversion strategy.

Design and Analysis of a Grid-Connected Photovoltaic Power System

Abstract: A grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented in this paper. For a typical PV array, the output voltage is relatively low, and a high voltage gain is obligatory to realize the grid-connected function. The proposed PV system employs a ZVT-interleaved boost converter with winding-coupled inductors and active-clamp circuits as the first power-processing stage, which can boost a low voltage of the PV array up to a high dc-bus voltage. Accordingly, an accurate steady-state model is obtained and verified by the simulation and experimental results, and a full-bridge inverter with bidirectional power flow is used as the second power-processing stage, which can stabilize the dc-bus voltage and shape the output current. Two compensation units are added to perform in the system control loops to achieve the low total harmonic distortion and fast dynamic response of the output current. Furthermore, a simple maximum-power-point-tracking method based on power balance is applied in the PV system to reduce the system complexity and cost with a high performance. At last, a 2-kW prototype has been built and tested to verify the theoretical analysis of the paper.

Survey on non-isolated high-voltage step-up dc–dc topologies based on the boost converter

Abstract: The major consideration in dc-dc conversion is often associated with high efficiency, reduced stresses involving semiconductors, low cost, simplicity and robustness of the involved topologies. In the last few years, high-step-up non-isolated dc-dc converters have become quite popular because of its wide applicability, especially considering that dc-ac converters must be typically supplied with high dc voltages. The conventional non-isolated boost converter is the most popular topology for this purpose, although the conversion efficiency is limited at high duty cycle values. In order to overcome such limitation and improve the conversion ratio, derived topologies can be found in numerous publications as possible solutions for the aforementioned applications. Within this context, this work intends to classify and review some of the most important non-isolated boost-based dc-dc converters. While many structures exist, they can be basically classified as converters with and without wide conversion ratio. Some of the main advantages and drawbacks regarding the existing approaches are also discussed. Finally, a proper comparison is established among the most significant converters regarding the voltage stress across the semiconductor elements, number of components and static gain.