Ming-Hui Chen

Bio: Ming-Hui Chen is an academic researcher from National Taiwan University of Science and Technology. The author has contributed to research in topics: Ćuk converter & Flyback converter. The author has an hindex of 5, co-authored 10 publications receiving 269 citations.

Cascade Cockcroft–Walton Voltage Multiplier Applied to Transformerless High Step-Up DC–DC Converter

Abstract: This paper proposes a high step-up dc-dc converter based on the Cockcroft-Walton (CW) voltage multiplier without a step-up transformer. Providing continuous input current with low ripple, high voltage ratio, and low voltage stress on the switches, diodes, and capacitors, the proposed converter is quite suitable for applying to low-input-level dc generation systems. Moreover, based on the n-stage CW voltage multiplier, the proposed converter can provide a suitable dc source for an n + 1-level multilevel inverter. In this paper, the proposed control strategy employs two independent frequencies, one of which operates at high frequency to minimize the size of the inductor while the other one operates at relatively low frequency according to the desired output voltage ripple. A 200-W laboratory prototype is built for test, and both simulation and experimental results demonstrate the validity of the proposed converter.

A Novel Active Interphase Transformer Scheme to Achieve Three-Phase Line Current Balance for 24-Pulse Converter

Abstract: A new active interphase transformer (IPT) scheme to achieve three-phase line current balance for a 24-pulse converter is proposed in this paper. The proposed active IPT scheme consists of three IPT and a current-controlled inverter with required rating only 1.16% of system power rating. A current injection method for an active IPT is also proposed in this paper. The balance of three-phase current and high power quality can be achieved by injecting compensation current into the secondary winding of the active IPT. Moreover, the proposed scheme can operate in flexible load configurations, by which separated loads can be connected to the separated outputs of the converter independently. The operation criteria for flexible load arrangements are analyzed to obtain better performance. System simulation is conducted and a 6-kW laboratory prototype is built both for evaluation and test. Both simulation and experimental results demonstrate the validity of the proposed scheme.

A novel single-phase ac to high voltage dc converter based on Cockcroft-Walton cascade rectifier

Abstract: This paper proposes a novel single-phase ac to high voltage dc converter based on Cockcroft-Walton cascade rectifier with only adding one bi-directional switch and one boost inductor This paper also derives a new method of circuit representation for Cockcroft-Walton cascade rectifier, which simplifies the equivalent circuit and is convenient for simulation Compared with conventional Cockcroft-Walton rectifier, the proposed converter provides half-wave symmetric and low-distorted line current, adjustable power factor at the ac source, and regulated dc output voltage Unit power factor is achieved by the average-current method and the dc output voltage is regulated by a PI compensator Moreover, this paper employs a digital signal processor to implement a digital controller for operating the proposed converter and a prototype with 500w rating is implemented for test Both simulation and experimental results demonstrate the validity of the proposed converter

High power factor transformerless single-stage single-phase ac to high-voltage dc converter with voltage multiplier

Abstract: This study proposes a transformerless single-stage single-phase ac to high-voltage dc converter based on Cockcroft–Walton (CW) voltage-multiplier circuit with only adding one bi-directional switch and one boost inductor. This study also derives a new method of circuit representation for CW voltage multiplier, which simplifies the equivalent circuit and is convenient for simulation. Compared with conventional CW voltage multiplier, the proposed converter provides half-wave symmetry and low-distorted line current, improved power factor at the ac source and a regulated dc output voltage for wide load range. In addition, a current-fed analysis approach is used to derive a general expression of the output voltage ripple as function of the load to facilitate the design of the system parameters. A commercial average-current-control continuous conduction mode power factor correction integrated circuit (IC) is used to implement the control strategy of the proposed converter that does not need the multiplier and sensing of the input ac voltage; this strategy simplifies the design and reduces the control circuit components. A 500 W prototype is built for testing. Both simulation and experimental results demonstrate the validity of the proposed converter.

Transformerless high step-up DC-DC converter with Cockcroft-Walton voltage multiplier

Abstract: This paper proposes a high step-up dc-dc converter based on Cockcroft-Walton (CW) voltage multiplier without step-up transformer. Providing high step-up rate, the proposed converter is quite suitable for applying to low-input level dc generation systems. The proposed converter improves the impractical operation of the conventional boost dc-dc converter at high duty ratio due to non-ideal characteristics of the circuit components, such as the equivalent series resistance of the inductor. For easy design, a commercial average-current-control continuous conduction mode (CCM) integrated circuit (ICE1PCS01) and a complex programmable logic device (CPLD) LC4256V are used to implement the control strategy of the proposed converter. A modified switching function, which is built in CPLD, controls the switches to generate an alternating source to the CW voltage multiplier. Under CCM operation, the output voltage ripple of the proposed converter can be limited by the flexibly adjustable frequency. A 200W laboratory prototype is built for test and the experimental results demonstrate the validity of the proposed converter.

Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

Abstract: DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

Nonisolated High Step-Up DC–DC Converters Adopting Switched-Capacitor Cell

Abstract: In a photovoltaic (PV)- or fuel-cell-based grid-connected power system, a high step-up dc-dc converter is required to boost the low voltage of a PV or fuel cell to a relatively high bus voltage for the downstream dc-ac grid-connected inverter. To integrate the advantages of the high voltage gain of a switched-capacitor (SC) converter and excellent output regulation of a switching-mode dc-dc converter, a method of combining the two types of converters is proposed in this paper. The basic idea is that when the switch is turned on, the inductor is charged, and the capacitors are connected in series to supply the load, and when the switch is turned off, the inductor releases energy to charge multiple capacitors in parallel, whose voltages are controlled by a pulsewidth modulation technique. Thus, a high voltage gain of the dc-dc converter can be obtained with good regulation. Based on this principle, a series of new topologies are derived, and the operating principles and voltage gains of the proposed converters are analyzed. Finally, the design of the proposed converter is given, and the experiment results are provided to verify the theoretical analysis.

A DC–DC Converter With High Voltage Gain and Two Input Boost Stages

Abstract: A family of nonisolated high-voltage-gain dc–dc power electronic converters is proposed. The suggested topologies can be used as multiport converters and draw continuous current from two input sources. They can also draw continuous current from a single source in an interleaved manner. This versatility makes them appealing in renewable applications such as solar farms. The proposed converters can easily achieve a gain of 20 while benefiting from a continuous input current. Such a converter can individually link a PV panel to a 400-V dc bus. The design and component selection procedures are presented. A 400-W prototype of the proposed converter with $V_{\text{in}} = 20$ and $V_{\text{out}} = 400$ V has been developed to validate the analytical results.

Cascade Cockcroft–Walton Voltage Multiplier Applied to Transformerless High Step-Up DC–DC Converter

Abstract: This paper proposes a high step-up dc-dc converter based on the Cockcroft-Walton (CW) voltage multiplier without a step-up transformer. Providing continuous input current with low ripple, high voltage ratio, and low voltage stress on the switches, diodes, and capacitors, the proposed converter is quite suitable for applying to low-input-level dc generation systems. Moreover, based on the n-stage CW voltage multiplier, the proposed converter can provide a suitable dc source for an n + 1-level multilevel inverter. In this paper, the proposed control strategy employs two independent frequencies, one of which operates at high frequency to minimize the size of the inductor while the other one operates at relatively low frequency according to the desired output voltage ripple. A 200-W laboratory prototype is built for test, and both simulation and experimental results demonstrate the validity of the proposed converter.