Stacked Buck Converter: Current Ripple Elimination Effect and Transient Response

The Weinberg converter is a suitable choice for the battery discharge regulator of a geostationary satellite due to its high efficiency, continuous input and output current, and soft switching of switches and diodes. Nevertheless, this converter has high output current ripple during the commutation period of its output diodes. Therefore, the output RMS current and output voltage ripple are high, which may directly affect the lifetime and total capacitance of bus capacitors and hence, the lifetime and volume of the geostationary satellite. Thus, reducing the output current ripple is important to the design of the geostationary satellite. An improved Weinberg converter with an additional inductor and capacitor is proposed in this paper to reduce the output current and voltage ripple. It features soft switching of all switches, no reverse recovery problems of the diodes, and reduced magnetizing offset current in the coupled inductor. The proposed converter is verified with experimental results from a 750W, 100kHz, 36-50Vdc prototype.

In order to improve the performance of traditional phase-shifted full-bridge converters and reduce the output current ripple, an improved zero voltage and zero current switching phase-shifted full-bridge PWM converter is proposed in this article. By adding a simple auxiliary circuit, the leading-leg switches realize zero voltage switching and the lagging-leg switches realize zero current switching. The primary current is reset during the freewheeling period, so the efficiency of the converter is improved. What is more, the improved converter can effectively reduce the output current ripple. The added auxiliary circuit does not include any lossy components or saturable reactors. The improved phase-shifted full-bridge converter has many advantages, including simple circuit topology, easy implementation of soft switching, high efficiency, and low output current ripple. The operational principle and analysis of the proposed converter are presented in this article. An 800 W experimental prototype is built for experimental verification.

This paper presents a current‐doubler rectifier with low output current ripple and high step‐down voltage ratio. In the proposed rectifier, two extra inductors are introduced to extend the duty ratio of the switches, which in turn reduces the peak current through the isolation transformer as well as the output current ripple; two extra diodes are used to provide discharge paths for the two extra inductors. To highlight the merits of the proposed rectifier, its performance indexes, such as voltage gain function, secondary winding peak current of the isolation transformer, and output current ripple, are analyzed and compared with the conventional current‐doubler rectifier. In this paper, a zero‐voltage‐switching phase‐shift full‐bridge converter with the proposed rectifier with an input voltage of 400 V, output voltage of 12 V, and full load power of 500 W has been implemented and verified, and experimental results have shown that 90% conversion efficiency could be achieved at full load. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Electrolyzers are widely used in renewable energy hydrogen production, and the performance of electrolyzers is directly related to dc–dc converters. To realize the high-efficiency operation of the electrolyzer, new challenges, such as a high step-down ratio and low output current ripple, are put forward for the dc–dc converter. In this article, we propose a novel type of dc–dc converter for hydrogen production. The topology is simple and has the advantages of higher step-down gain and low switching stress. In addition, the scheme can achieve ultralow output current ripple without active devices. Finally, the topology connects the electrolyzer hydrogen production load in the experiment to verify the scheme's effectiveness.

The interleaved converter has may advantages such as low power losses and small output current ripple. The output current ripple of interleaved converter is the key parameter for the filter inductor design and the overall converter optimization. In this paper, the output current ripple behavior of interleaved Buck converter is analyzed, both in CCM and DCM. Further, a simplified numerical method for the output current ripple calculation of the Buck converter in DCM is presented. The proposed method provides a straightforward calculation procedure which is easy to be programmed. Simulation and experimental results validate the effectiveness of the analysis and the calculation method.

A single-stage TRIAC (TRIode for alternating current switch) dimmable LED (light emitting diode) driver using a buck converter fed through a capacitor input rectifier provides many advantages such as small-scale implementation, low output current ripple, and stable dimming operation. This circuit topology, however, has a serious issue: A large inrush current to the smoothing capacitor. To solve this issue, this paper focuses on a bleeder circuit in the TRIAC dimmable LED driver. This paper presents the mechanism of the large inrush current issue and its relationship to a conventional bleeder circuit. Moreover, this paper proposes a turn-off delay controlled bleeder circuit. The proposed bleeder circuit is analyzed by using its discrete-time state-space model in order to set proper circuit parameters for inrush current reduction. Experimental results demonstrate the inrush current reduction by the proposed method, which leads to a 37% reduction of maximum input current, as well as proper dimming operation and low output current ripple. The proposed method achieves further small-scale implementation, which enhances the advantages of the intended main circuit topology.

The interleaving technique is required for LLC resonant converters to achieve high power levels, handle higher input/output currents, and reduce output current ripple. However, the high system efficiency and the low output current ripple for the multi-phase LLC resonant converter cannot be achieved at the same time at low and medium power levels. Most methods try to keep the multi-phase LLC resonant converter in load-sharing mode regardless of the power level, which will result in low system efficiency at low and medium power levels. In this paper, an output current ripple and efficiency optimal control method with finite load distribution schemes is proposed for the multi-phase LLC resonant converter to balance the efficiency and output current ripple. The optimal control method improves the efficiency as much as possible while keeping output current ripple low. According to the calculation of output current ripple and efficiency, the optimal load distribution scheme is selected. The pulse-frequency modulation (PFM) and phase-shift modulation (PSM) hybrid control is applied to regulate the load of each phase. An analysis is provided, and a 540-W three-phase interleaved LLC resonant converter is built to verify the superiority.

This paper presents an analysis and design of a unidirectional resonant switched capacitor (URSC) step-up converter for OLED lamp driving. The URSC converter includes a very small inductor in series with the switched capacitor to improve the switching behavior. Also, the URSC converter presents the advantages of high power density, higher efficiency compared to other SC converters, low output voltage and current ripples and low EMI noise, which make it adequate for driving OLED lamps. URSC is designed to operate in closed loop with constant current VI control technique. By working the resonant inductor as a VI, the OLED current can be regulated and dimmed because of resonant frequency change. Simulation and experimental results of the VI inductor, which are in a good agreement, and the results of a URSC step-up converter design example for a 21.8 W OLED lamps array supplied from 48Vdc are presented, where a maximum 91.5% efficiency is obtained.

Consistent growth of emission free electric vehicles (EV) in the transportation sector directs the environment more towards the cleaner and greener society. The existence and successive development in the phenomena of EV relies equally on the development of charging infrastructure. This proposed research integrates the operative differences of various converter configurations suitable for EV charging under diverse working conditions. Analysis and the assessment of these power converters are portrayed with respect to the power output, active and passive components and other reliable factors respectively.In addition, evaluations of the converters are presented with their topological design and supporting architecture for EV charging stations. Multidevice interleaved bidirectional converter is observed as the most appropriate interfacing converter for the EVs on account of its low output voltage and current ripples. This article explicitly addresses the characteristics and categories of power converter for EVs powertrain and the ideas are validated through the real time PSACAD/EMTDC simulation tool.

This paper presents a design and simulation of a controller circuit for Power Factor Correction applied to BLDC Motor Control. To achieve accurate and dynamic performance from a BLDC motor, it is usually fed from a Voltage Source Inverter (VSI). Such drives have to deal with problems in power quality and poor power factor at AC mains input as they include a diode bridge rectifier. To overcome such problems and provide faster dynamic performance a power factor correction One Cycle Controlled Cuk converter is proposed to feed the Voltage Source Inverter based BLDC motors. The Cuk PFC converter inherits many advantages like low output current and voltage ripple, near unity power factor with simple control. The One Cycle technique provides excellent power source disturbance rejection, fast dynamic response, automatic switching error correction and robust performance.

This brief proposes a thorough methodology for the steady-state characterization of input and output current ripples in discontinuous conduction mode (DCM) interleaved power converters, under inductance mismatch. The proposal analyzes total ripple for any number of phases, any inductance ratio and operating point. Furthermore, calculation of amplitude, rms value and harmonic content of total input and output current ripples is presented. Experimental tests on a 5-phase boost converter are conducted under different conditions to verify the presented method.

This paper presents a merged-two-stage hybrid-switched-capacitor converter featuring the Linearly Extendable Group Operated Point-of-Load (LEGO-PoL) architecture with coupled inductor-enabled vertical power delivery for ultra-high-current microprocessors. By merging a switched-capacitor stage with a multiphase buck converter stage, the proposed converter achieves reduced device stress, minimized magnetics size, and soft charging. A systematic way of designing coupled inductors in multiphase buck converters, based on an inductance dual model which links the geometry of the magnetic core to a lumped circuit model, is introduced. Coupled inductors in the multiphase buck stage reduce the steady-state per-phase current ripple and improve the transient performance of the system. By delivering power vertically from the motherboard to microprocessors, a high current and power density prototype is designed to minimize the parasitic resistance and enable fast transient with low output current ripple. A 48 V to 1.5 V LEGO-PoL converter rated to deliver 750 A of output current with 100 A/cm2 current area density and 1125 W with 1725 W/in3 power density is designed and simulated with customized four-phase coupled inductors.

This work has adopted the concept of asymmetric inductor magnetization to develop a new quadratic converter with the advantages like a wide range quadratic voltage gain and low source current ripple. In addition, the proposed high quadratic converter has achieved reduced voltage stress due to the presence of switched capacitor cell at the output side. Initially, the operation of the converter and steady-state analysis, including efficiency calculations, are explained. In addition, the design and selection of converter components are presented along with a small-signal analysis. Further, a comprehensive comparison with recent high quadratic gain converters is presented. The comparison is made with regard to the total component count, voltage conversion ratio, effectiveness index, electric stress, current ripple, switching device power (SDP) rating, and input current ripple factor. Furthermore, the 150 W laboratory prototype is used to verify the performance of the proposed converter in terms of operation, dynamic response, and efficiency, and the corresponding experimental findings are reported. The wide range voltage gain, low current ripple, and low electric stress features of the proposed converter highlight its superiority in fuel cell electric vehicle applications.

In order to meet the high current quality and low leakage current requirements in high power rating photovoltaic applications, an improved carrier-based modulation (ICBM) for parallel converters is presented in this article. Different from existing methods which are based on phase-shifted pulsewidth modulation, a proper zero-sequence modulation wave is injected into the three-phase modulation waves to achieve a low total current ripple based on the root mean square value analysis of the output current ripple. Aside from this, the initial phase shift angles for the carriers in each converter are modified to minimize the excitation source of leakage current, while the quality of total output current is not affected. Furthermore, the proposed ICBM is extended to parallel multilevel converters according to the vector shift principle. By using the proposed ICBM, total current ripple reduction and leakage current attenuation in parallel converters can be achieved simultaneously. Experimental results validated the correctness and effectiveness of the proposed method.

This work proposes a new interleaved converter to supply Power LEDs. As an interleaved scheme, the converter provides a very low output current ripple, which makes it suitable for this application. The low inductor values used in the device allow the ability of attaining PWM dimming of the Power LEDs at high frequencies (20 kHz and higher). The main operation concept is explained, and a full design process is shown. An experimental setup, for a full diming range assembly of 10 Power LEDs has been built and tested, and experimental results are shown and discussed. Conclusions and limitations of the proposed converter are also commented.