Tapped-inductor Buck Research Articles

A New Tapped Inductor Buck Converter with Large Step-Down Voltage Conversion

This paper presents a new DC(DC converter with large step-down voltage conversion. The proposed converter is obtained by cascading an input circuit of a Quadratic Buck Converter (QBC) to a Tapped Inductor Buck Converter (TIBC). It uses only one active switch and provides a wider voltage conversion range than other well-known step-down converters. In the paper, the operation of the proposed converter is described. Circuit analysis is performed to derive the voltage gain and key current and voltage equations. The prototype circuit operating with the input voltage of 150 V, the output voltage of 5 V, the load current of 10 A and the switching frequency of 100 kHz is implemented. Experimental results show that the prototype converter exhibits good output voltage regulation and achieves the 30-to-1 voltage step-down operation with a maximum efficiency of 82%. In addition, measurement results confirm that the converter operation is consistent with the theoretical analysis.

Dynamic Modeling and Closed-Loop Control of a Tapped Inductor Buck Converter

Modern smart electronic and information technology (IT) devices require a low DC voltage for operation. The low supply voltage is typically provided by a dedicated DC−DC converter by stepping down the system’s bus voltage (e.g., 12 V). It is essential that the converter possesses a large voltage step-down gain and, at the same time, operates at high efficiency. A tapped inductor buck converter (TIBC) is a topology that has a potential to meet these requirements. It has a simple circuit structure and high efficiency similar to a buck converter, but can give a larger voltage step-down gain. This paper presents a dynamic modeling and closed-loop control of a TIBC. The state space averaging (SSA) method is adopted for the dynamic modeling to derive small-signal transfer functions of the converter. Based on the duty-cycle-to-output voltage transfer function, a closed-loop control is designed to keep the converter’s output voltage constant. To verify the design, a prototype TIBC with closed-loop control is implemented. Experimental results show that the prototype converter has good output voltage regulation and fast transient response when subject to a step load. The effect of the crossover frequency and phase margin on the converter’s transient response is also illustrated.

Small-Signal Modeling of Open-Loop PWM Tapped-Inductor Buck DC–DC Converter in CCM

A tapped-inductor buck dc-dc converter uses the tapped-inductor to further step-down the output voltage. This article presents a small-signal model of a tapped-inductor buck dc-dc converter by using the circuit averaging technique. The obtained nonlinear model is linearized to derive its linear large-signal, small-signal, and dc models. The small-signal model is then used to derive open-loop transfer functions namely, control-to-output voltage transfer function and the input-to-output voltage transfer function. MATLAB was used to obtain their respective Bode plots and later validated experimentally using a gain-phase network analyzer.

High efficiency wide input extreme output (WIEO) tapped inductor buck–boost converter for high power LED lighting

A power factor corrected single switch tapped-inductor buck–boost converter is proposed to achieve improved efficiency in extreme step-up and step-down conditions. This new and modified topology is having diode-tapped and switch-tapped configurations for step-down and step-up modes of operation, respectively. The proposed modified buck–boost converter is designed to operate in critical conduction mode (CrCM) to achieve quasi-resonant operation. Both the buck and boost functionalities of the buck–boost converter are analysed using state space analysis with closed loop stability under varying input and output conditions. Several advantages and necessity of tapped versions are discussed and implemented under wide input and extreme output (WIEO) conditions. Two different prototypes are developed at extreme buck and boost levels to establish the benefits of the proposed arrangements. The efficiency improvement of the proposed converter is compared with the conventional buck–boost converter. The achieved efficiency of diode-tapped buck mode and switch-tapped boost mode is found 95% and total harmonic distortion is observed only 4% at 230 V AC mains for a prototype of 150 W, which is much improved results as compared to the previous research work on the tapped-inductor converter.

An Interleaved Series-Capacitor Tapped Buck Converter for High Step-Down DC/DC Application

High step-down dc/dc converters are widely utilized in telecom and modern industrial applications. Due to the high step-down ratio, conventional Buck converter cannot provide satisfactory performance. To solve this problem, quite a few new topologies have been proposed to improve the performance of high step-down dc/dc converters, such as series-capacitor Buck (SC-Buck) converter, 3-level Buck converters, tapped inductor Buck converters, and LLC resonant converters. In this paper, the twice step-down benefit of SC-Buck converter and the zero-voltage switching benefit of series-capacitor tapped Buck (SC-TaB) converter are combined together to propose a new topology: interleaved series-capacitor tapped Buck (ISC-TaB) converter. To analyze the performance of the proposed ISC-TaB converter, the operation principles are discussed and the voltage conversion ratio is derived. In addition, to guide the design procedure and optimization, the current waveforms and voltage waveforms of the proposed ISC-TaB are derived. In order to verify the performance of the proposed ISC-TaB, hardware prototype of the proposed ISC-TaB converter and conventional two-phase series-capacitor tapped Buck converter (2ph-TaB) are designed and tested. The application is targeted at telecom with 48-V input and 3.3 V/20 A output. The test results are compared between these two converters. A peak efficiency of 95.6% is achieved on the proposed ISC-TaB and the efficiency of the ISC-TaB over all load range is at least 1% higher than that of 2ph-TaB.

An Expandable Two-Phase Interleaved Ultrahigh Step-Down Converter With Automatic Current Balance

In the high step-down voltage applications, the dc–dc converter with a high step-down voltage conversion ratio is usually used. Recently, a high step-down converter, named ultrahigh step-down converter, has been presented. As compared with the nonisolated tapped-inductor buck converter, the ultrahigh step-down converter has not only a higher voltage step-down gain but also a lower voltage spike. On the other hand, in the high-current applications, a multiple phase structure is preferable. Therefore, in this paper, a novel expandable two-phase interleaved ultrahigh step-down converter with automatic current balance is presented, which is derived from the existing single-phase ultrahigh step-down converter. There are four main advantages of the proposed converter. First, the step-down voltage gain is improved. Therefore, the turns ratio of each phase can be decreased. Second, due to the charge balance of the energy-transferring capacitor, the proposed two-phase ultrahigh step-down converter possesses an automatic current balance. Third, as compared with a single-phase ultrahigh step-down converter, the output current ripple can be reduced. Fourth, the phase number of the proposed converter can be expanded. Finally, the basic operating principle of the proposed converter is analyzed, and a prototype is constructed to verify its effectiveness by some experimental results.

Performance comparison between tapped-inductor buck converter and ultrahigh step-down converter

ABSTRACTIn this study, a detailed performance comparison between the tapped-inductor buck converter and the ultrahigh step-down converter is presented. The items used to compare include the voltage gain, DC magnetising inductance current, component voltage stress, coupled inductor size, output current ripple and efficiency. Moreover, the advantages and disadvantages are discussed herein. The experimental results with the same specifications are shown to compare.

Analysis and design of a high‐step‐down ratio resonant converter

In this study, a high-step-down ratio resonant converter is presented, which integrates one coupled inductor and one resonant energy-transferring capacitor with small capacitance. The resonant energy-transferring capacitor resonates with the leakage inductance of the coupled inductor. Furthermore, the energy-transferring capacitor is connected between the input voltage and the coupled inductor. Therefore, a high-step-down voltage gain can be achieved, which is lower than those of the traditional synchronously-rectified buck converter and the tapped-inductor buck converter. Moreover, the modulated switching frequency span is low; thus, it is easy to design the output filter. In addition, since the small value of the resonant energy-transferring capacitor is used, the power density can be upgraded. Finally, some analyses and experimental results are given to verify the feasibility and effectiveness.

Bidirectional Operation of High Step-Down Converter

In this paper, a high step-down bidirectional converter, utilizing one coupled inductor and two energy-transferring capacitors, is presented. In the step-down mode, the capacitor is connected between input voltage and coupled inductor, which plays a role to step down the input voltage. Therefore, the corresponding voltage conversion ratio is much lower than that of the traditional buck converter and also can be lower than that of the tapped-inductor buck converter. Moreover, the output voltage varies with the duty cycle linearly, making control easier. In the step-up mode, one capacitor is first charged by the coupled inductor, and then releases the energy along with the coupled inductor and the other capacitor connected in series. Therefore, a higher voltage gain can be obtained. Furthermore, the leakage inductance energy can be recycled. Therefore, the switching losses can be reduced and the efficiency can be improved. In this study, the operating principles and experimental results are provided to verify the effectiveness and performance of the proposed converter.

High-Voltage Tapped-Inductor Buck Converter Utilizing an Autonomous High-Side Switch

A high-voltage tapped-inductor buck converter utilizing a novel autonomous high-voltage valve is presented in this paper. Its application as auxiliary power supply for high-power cascaded-converter submodules is discussed, followed by a presentation of the most challenging problems in designing a low-power high-voltage step-down converter. The TI-buck converter topology is analyzed, which together with the novel autonomous high-voltage valve overcomes most of the problems. Analytical expressions describing the operation as well as circuit simulations are presented. Finally, an experimental evaluation of a 3-kV 70-W prototype converter utilizing the proposed autonomous high-voltage valve with series-connected super-junction MOSFETs is presented.

Tapped-Inductor Buck HB-LED AC–DC Driver Operating in Boundary Conduction Mode for Replacing Incandescent Bulb Lamps

High-brightness light-emitting diodes (HB-LEDs) are recognized as being potential successors of incandescent bulb lamps due to their high luminous efficiency and long lifespan. To achieve these advantages, HB-LED ballast must be durable and efficient. Furthermore, for this specific application, ac-dc HB-LED ballast requires a high-step-down ratio, high power factor and low cost. This paper presents a tapped-inductor buck power factor corrector (PFC) operating in boundary conduction mode design for replacing incandescent bulb lamps. This low-cost solution presents a suitable high-step-down ratio without galvanic isolation in order to produce an output voltage of about 20 V from line voltage. In addition, the tapped-inductor buck PFC maintains high efficiency in comparison to other one stage solutions widely used to design low-cost ac-dc HB-LED drivers (e.g., flyback PFCs). Static analysis, input current distortion analysis, and an average small signal model of the tapped-inductor buck PFC have been implemented in this paper both to check the validity of the proposed solution and to provide a suitable design procedure of the ac-dc HB-LED driver. Finally, a 12-W experimental prototype was developed to validate the theoretical results presented.

Analysis and Design of a Tapped-Inductor Buck–Boost PFC Rectifier With Low Bus Voltage

This paper presents a single-phase power factor corrector based on a tapped-inductor buck-boost converter. This paper suggests simplified models of the power stage under current-mode control and derives small-signal transfer functions of both the current and voltage control loops. Design rules for implementation of the proposed power factor corrector (PFC) are also suggested. The proposed PFC features low dc bus voltage, arbitrary lower than the peak line voltage. The proposed PFC is suitable for applications in computers and communications, where dc isolation can be provided by the downstream dc/dc converters. Simulation and experimental results are also reported and stand in good agreement with theoretical expectations.

Tapped-Inductor Buck Converter for High-Step-Down DC–DC Conversion

The narrow duty cycle in the buck converter limits its application for high-step-down dc-dc conversion. With a simple structure, the tapped-inductor buck converter shows promise for extending the duty cycle. However, the leakage inductance causes a huge turn-off voltage spike across the top switch. Also, the gate drive for the top switch is not simple due to its floating source connection. This paper solves all these problems by modifying the tapped-inductor structure. A simple lossless clamp circuit can effectively clamp the switch turn-off voltage spike and totally recover the leakage energy. Experimental results for 12V-to-1.5V and 48V-to-6V dc-dc conversions show significant improvements in efficiency.