An improved current-doubler rectifier with integrated magnetics

Recent literature on building energy performance simulation leans toward implementing uncertainty analysis (UA), instead of deterministic solutions, to handle ever-existing and pivotal uncertainties in building design decision-making process. Variations in weather temperature, degradation of building envelope material properties over time, and random behavior of occupants, among all, are the key sources of uncertainty in building energy consumption predictions. The UA couples to the sensitivity analysis (SA) to identify the most influential inputs on the uncertainties of the building energy consumption. This paper describes a newly-developed UA and SA predictive tool for building energy performance simulations. Energy performance simulations are based on a resistance-capacitance thermal model for the building. For a hypothetical residential building in College Station, Texas, USA, the present work describes and compares predicted probability distribution and sensitivity indexes produced by the UA-SA tool using a transient (dynamic) response analysis (TRA) and static response analysis (SRA). For brevity, the analysis considers uncertainty only for the exterior walls’ parameters including thickness, thermal conductivity, heat transfer coefficient, density, and heat capacity; i.e., a five-dimensional problem is solved. Compared to the TRA, predictions from the SRA underestimate the annual energy consumption up to 30%; however, SRA is significantly faster. Nonetheless, sensitivity indexes from the SRA and TRA closely match.

A new multiple-coupled inductor (MCI) is proposed for good cross regulation among low output voltages, high power density, and reduced converter volume. Moreover, a current doubler rectifier and a self-driven synchronous rectifier are presented to achieve high efficiency. The structure of the MCI is composed of four windings on a common core, and has the properties of a current doubler and good cross regulation. A dc-dc half-bridge converter using the proposed MCI is analyzed and designed for 40-W low output voltages (3.3, 4.5 V). This converter is very suitable for high current and low voltage applications. It is shown via experimental results that efficiency of over 90% and cross regulation of about 5% are achieved

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.

All parties favour the half-bridge current-doubling rectifier circuit due to its advantages: small output current pulsation, low switching voltage stress, and high anti-unbalance ability. Further integration of the secondary inductor and the transformer further reduces the size of the converter and dramatically improves the power density. This paper carefully analyzes the existing magnetic integration schemes. Combined with the characteristics of low-voltage and high-current DC converters, the secondary winding in this paper adopts the form of one turn to further reduce the loss so as to adapt to the secondary output of high current. The way the integrated magnetics are matrixed. The secondary side has a higher DC flux offset, and the magnetic core material adopts a magnetic powder core with high saturation magnetic density, which is equivalent to a distributed air gap, which significantly reduces the additional winding loss caused by the air gap diffusion magnetic flux cutting the winding. The winding loss, termination loss, core loss, and distribution parameters of single and matrix integrated magnetic components were compared and analyzed. Focus on optimization analysis. At the same time, it focuses on the influence of matrix on the DC bias and DC loss of the current-doubling rectifier core. At the same time, the leakage inductance and winding loss of the integrated magnetic components are comprehensively considered, and a compromise design is carried out further to improve the power density of the integrated magnetic components.

Discontinuous operation of a half-bridge PWM power converter with a current-doubler rectifier is analyzed in this paper. The converter is found to exhibit six different discontinuous conduction modes depending on the control methods (symmetrical or asymmetrical control) as well as whether discrete or integrated magnetics are used. The definition of each mode, boundary conditions among the different modes, and steady-state characteristics of the converter under each mode are presented. Simulation and experimental results are provided for verification of the analysis results.

This paper presents a new current-doubler rectifier for application on buck derived DC-DC converters, such as, push-pull, half-bridge, full-bridge, dual-bridge, NPC three-level, and others. This new proposal, named as Three-State Rectifier (TSR), is generated using the three- state switching cell. The proposed rectifier is similar to the Center Tapped Rectifier (CTR), and to the current-doubler rectifier named Interleaving Rectifier (IR). The new rectifier circuit is an alternative to substitute the previous rectifiers topologies, operating with rectifier diodes only, or with synchronized switches depending on the output voltage rating. Advantages of such a new proposal are: the current through the components of the converter are less pulsated which reflects in the conduction losses reduction and the current in the secondary winding of the transformer reaches maximum half of the output average current. The disadvantage of the proposed converter is that the sizes of the autotransformer and the inductor, both equals, are 20% higher than the sizes of the inductors of the IR rectifier. In order to verify the theoretical analysis and compare its performance with similar ones proposed in literature, experimental results consisting of relevant waveforms and curves from a full-bridge phase-shift control DC-DC converter with TSR rectifier and IR rectifier are presented, for a 1.5 kW output power prototype, an input voltage of 400 V and output voltage of 60 V.

Renewable electricity options, such as fuel cells, solar photovoltaic, and batteries, are being integrated, which has made DC micro-grids famous. For DC micro-grid systems, a multi input interleaved non-isolated dc-dc converter is suggested by the use of coupled inductor techniques. Since it compensates for mismatches in photovoltaic devices and allows for separate and continuous power flow from these sources. The proposed converter has the benefits of high gain, a low ripple in the output voltage, minimal stress voltage across the power semiconductor devices, a low ripple in inductor current, high power density, and high efficiency. Soft-switching techniques are used to realize that the reverse recovery issue of the diodes is moderated, the leakage energy is reused, and no new scheme is appropriated. To reduce conduction losses, minimum voltage rating MOSFETs with a low ON-resistance can be utilized. The converter can supply the required power from the load in the absence of one or two resources. Furthermore, due to the high gain of boosting voltage, the converter works in an Adaptive Neuro-Fuzzy Inference System (ANFIS). The operation principle, steady-state analysis of the proposed converter, is given and simulated utilizing MATLAB/Simulink simulation software.

This paper describes a new method for evaluating the steady state and dynamic responses of a dc separately excited motor fed by load dependent chopper using time-ratio control (TRC). The proposed method takes into account the effect of commutation time and armature reaction. The area of armature current versus time characteristics during commutation interval is approximated by a trapezoid rather than a rectangle as in the constant current method. This method is applicable to both continuous and discontinuous current modes of operation. The results of this method are compared with those obtained from a digital computer by numerically solving the simultaneous differential equations valid for different intervals of chopper cycle, the constant current method and by experimental set up. The results show a close agreement with the exact solution by digital computer and experimental values.

This paper proposes a variable frequency zero-voltage-switching (ZVS) digital controlled boost-flyback converter (BFC) to achieve high efficiency and high step-up conversion. With no auxiliary switch introduced, ZVS of the MOSFETs can be achieved and reverse-recovery of diode eliminated naturally by operating the converter in boundary-conduction-mode. With the proposed control, both soft-switching and high efficiency are achieved in a wide load range. To achieve higher step-up ratio, lower voltage and current ripple in both input and output and lower current stress of the switches, a two-channel interleaved parallel-input/series-output BFC is presented. The operation principle and control strategy is analyzed in detail and verified with a 230W 30V to 380V prototype.

Developing dielectric capacitors with both a high power density and a high energy density for application in power electronics has been a long-standing challenge. Glass-ceramics offer the potential of retaining the high relative permittivity of ceramics and at the same time of exhibiting the high dielectric breakdown strength and fast charge/discharge rate of glasses, thus producing concurrently high power and energy densities in a single material. In this work, glass-ceramics are fabricated to achieve simultaneously high power and energy densities, high efficiency, and thermal stability by tuning the glass crystallization process via a suitable nucleating agent and a high oxygen partial pressure. Under the same practical charge-discharge test conditions, the as-prepared glass-ceramics combine the high energy density of ceramics and ultrafast discharge rate of glasses, producing the highest power density among glass- and ceramic-based dielectric materials. This work demonstrates the significant potential of achieving both high power and energy densities in glass-ceramics by optimizing the glass crystallization process.

In this paper, a novel three-level converter with an integrated magnetic self-driven current-doubler-rectifier (CDR) is proposed. The proposed converter can reduce the current ripple of filter inductors, then split the main transformer into two transformers, and then replace the filter inductors with excitations, at last integrated these two transformers into one core. Compared to traditional ZVS CDR TL-HB converter, the proposed converter have several advantages, the current ripple of filter inductors is smaller, the windings of main transformer can be directly used to drive synchronous rectifiers, and the problem of poor clamped diode reliability in traditional ZVS CDR TL-HB converter is avoided. This paper presents the principle of the converter, discussed in detail the main switches to realize ZVS range and self-driven for SR. A 28V/100A prototype is built in lab to verify the theoretical analysis.

This paper shows the simulation results of the effects of phase difference on the output ripple voltage of a low voltage power supply circuit. The circuit uses a rectifier circuit which adds the squares of two out-of-phase sine waves. The circuit focuses on the constraint of rectifying a low voltage input AC source while analyzing the ripple voltage in the output and is designed in such a way that the phase difference can be determined by varying only discrete values of a resistor and capacitor. The simulation is operated with a 100mV input sine wave with an output of 1.622 V DC is obtained. The ripple voltage varies from 732 μV to 434 μV for a phase difference ranging from 97.33° to 82.34° with its minimum ripple at 90°.

This paper presents a unified analysis of half-bridge converters with current-doubler rectifier using an averaged circuit model. The model is applicable for both symmetrical and asymmetrical control. Different approaches to integrating the transformer with the inductors are discussed and their equivalent circuit models for use with the averaged converter model are developed. In addition, an inductor loop formed by the transformer and the two filter inductors is identified, and its effects on converter operation and control design are discussed. Numerical simulation and experimental results from a prototype converter are also reported.

In this paper, a novel nonisolated interleaved high step-up DC-DC converter is proposed based on the coupled inductor and voltage multiplier cell (VMC) methods. Due to the interleaved structure, its input current ripple is low. The low input current ripple and also high power efficiency make the proposed converter suitable for renewable energy applications like photovoltaic (PV) and fuel cell (FC) power generation systems. The windings of the coupled inductors are combined with VMCs to further increase the output voltage with a low power switch’s duty cycle. This combination also leads to obtaining a flexible voltage gain that can be adjusted by coupled inductors’ turns ratio and power switches’ duty cycle. The voltage peaks over semiconductors are much lower than the output voltage. Therefore, low-rated semiconductors can be used for the implementation of the proposed converter, which can reduce the cost and volume. Generally, high voltage gain, low voltage, current stress of power switches, low input current ripple, high efficiency, common ground between the input and output ports, and a low number of elements are the main benefits of the suggested structure. The operation principle, steady-state analysis, and comparison with other converters are presented to show the advantages of the suggested converter. Also, a prototype is built, and the experimental results are presented to prove the theoretical analysis. This prototype is implemented with 200 W rated power, 25 V∼400 V voltage conversion, and 50 kHz switching frequency. Additionally, the efficiency is measured at 95.3% at the rated power.

Concrete is a heterogeneous material exhibiting quasi-brittle behaviour. While homogenization of concrete is commonly accepted in general engineering applications, a detailed description of the material heterogeneity using a mesoscale model becomes desirable and even necessary for problems where drastic spatial and time variation of the stress and strain is involved, for example in the analysis of local damages under impact, shock or blast load. A mesoscale model can also assist in an investigation into the underlying mechanisms affecting the bulk material behaviour under various stress conditions. Extending from existing mesoscale model studies, where use is often made of specialized codes with limited capability in the material description and numerical solutions, this paper presents a mesoscale computational model developed under a general-purpose finite element environment. The aim is to facilitate the utilization of sophisticated material descriptions (e.g., pressure and rate dependency) and advanced numerical solvers to suit a broad range of applications, including high impulsive dynamic analysis. The whole procedure encompasses a module for the generation of concrete mesoscale structure; a process for the generation of the FE mesh, considering two alternative schemes for the interface transition zone (ITZ); and the nonlinear analysis of the mesoscale FE model with an explicit time integration approach. The development of the model and various associated computational considerations are discussed in this paper (Part 1). Further numerical studies using the mesoscale model for both quasistatic and dynamic loadings will be presented in the companion paper (Part 2).