Unidirectional Ports Research Articles

A novel multi-input medium-gain DC-DC boost converter with soft-switching performance

This paper proposes a new non-isolated dual-input zero-voltage switching (ZVS) dc-dc boost converter with medium voltage gain. Two input ports of the converter are current-fed and suitable for a unidirectional dc power source, and a chargeable dc energy storage. The proposed converter basic circuit composed of three cascaded power switches, which at their connection points join to the converter three inductors and a switched capacitor voltage multiplier (VM) cell is accompanied. Using this VM cell the converter voltage gain achieves two times of that in the conventional boost converter and also half voltage stress across the power switches. Through the converter two input inductors powers from a unidirectional source (like PV) and a chargeable battery source can be accepted. Taking a triangular resonant current at the switching frequency, the converter third inductor aids to reach ZVS for the power switches. The converter power switches turn-on with ZVS and the power diodes stop conducting with ZCS in all operation conditions. As a result, low switching power losses, reduced reverse recovery issue, and high efficiency are accessible especially for higher input and output powers. The converter power switches are switched in PWM manner with two individual duty ratios, allowing to regulate the output voltage and control the extracted power from the input unidirectional port. The proposed circuit has been analyzed in detail to find its different operating modes, determine its capacitor currents, estimate its power losses components and design its control system. Behavior of the proposed system is also examined by a low-power laboratory prototype tested under four different practical operation conditions. The proposed converter benefits from simple and compact structure, current-fed input ports, low number of power switches and magnetic elements, low voltage stress across the power switches, medium voltage gain and high efficiency.

A novel non-isolated high gain multiport DC-DC converter for integrating fuel cell/solar PV and battery energy storage system

ABSTRACT This paper presents a novel non-isolated capacitor-assisted quasi-Z-source (CA-QZS) multiport DC-DC boost converter, which operates as a dual-input single-output high gain boost converter. It consists of a bidirectional port for the smooth operation of the energy storage system, and a unidirectional port for the solar/fuel cell to deliver power to the battery and the load. The availability of common ground between input and output ports, high voltage conversion ratio, and continuous current of the unidirectional port are the main features of this novel design, making it suitable for a wider range of applications. A typical switching strategy is followed to regulate the output voltage as well as control input power from the sources. As a battery-incorporated system, the converter’s performance is determined by its selection between three operating modes. Therefore, the CA-QZS converter offers a viable interface for the management of battery energy storage systems. A comparative study is performed with other multi-port converters to highlight the advantages. It is observed that the voltage conversion ratio of 10, can be achieved at a low duty ratio of 0.3. To evaluate the effectiveness of the proposed topology, a prototype is developed with a nominal output power rating of 200W and an output voltage of 200 V.

New multi‐operational multi‐port DC–DC converter with bidirectional capability

AbstractA new triple‐input DC–DC converter with bidirectional ability is proposed in this paper. This converter is an interface between two unidirectional ports, one bidirectional port for the battery, and a DC link. This makes the proposed converter suitable for hybrid energy systems (HES). The load power can be provided by each input source separately or simultaneously. Also, the battery can be charged by input sources as well as with the energy returned from the output. These features provide a high degree of flexibility for the proposed converter. Boost and buck‐boost operation and low‐voltage stress on semiconductors are other advantages of the proposed converter. The performance of the converter in continuous conduction mode (CCM) is given along with the governing mathematical equations. The experimental results on a laboratory prototype confirm the theoretical calculations.

Integrated DC/DC Converter Topology Study for Fuel Cell Hybrid Vehicles with Two Energy Sources

Conventional hybrid vehicles with two energy sources require two separate on-board DC/DC converters to connect the battery and the fuel cell, which have the disadvantages of large size, high cost, high losses and few applicable operating conditions. To address this situation, this paper proposes an optimized on-board integrated DC/DC converter with a non-isolated multi-port scheme that integrates a unidirectional port for the fuel cell and a bidirectional port for the battery and load. This can achieve a combined energy supply and recovery with a single integrated converter, effectively overcoming the above disadvantages. The optimized converter topology is relatively simple, and the magnetic losses of the transformer are removed. Furthermore, the switched capacitor is introduced as a voltage doubling unit to achieve high-gain output, so the fuel cell and battery voltage demand levels are reduced under the same load conditions. In addition, it has superior performance in system energy management for hybrid vehicles, which can distribute power and switch operating states by controlling the on/off of switching devices to make it suitable for five driving conditions. This paper discusses in detail the operating principles of the converter and analyzes its steady-state performance under five operating modes, derives its dynamic model, and proposes a proportional-integral control scheme. Finally, the simulation model of the topology is built by Matlab/Simulink software to verify the converter operation in each driving state, and the simulation experimental results verify the applicability of the proposed integrated DC/DC converter topology.

New Dual-Source High-Gain ZVS DC-DC Converter for Integrating Renewable Power Source and Battery Storage

A new soft-switching high-gain two-source dc-dc boost converter is proposed here. The proposed converter provides two bidirectional and unidirectional input ports, handling the energies of a battery storage and a renewable power source, respectively, to supply a resistive load through a switched-capacitor (SC) voltage multiplier. As a result, three power switches, four power diodes, two inductors and four capacitors are used in the converter structure. The ZVS of all power switches is realized without any auxiliary circuit and in whole power ranges of the converter input sources and the output load. The converter power MOSFETs are switched in PWM manner with two individual duty ratios, allowing to regulate the output voltage and control the power coming from the input unidirectional port. Depending on the converter duty ratios, its basic operation principle is analyzed in two different operation cases. The behavior of the proposed converter is analytically investigated, and a low-power laboratory prototype is built to evaluate the converter performance in different operation conditions. The proposed converter benefits from simple and compact structure, minimum number of power switches and magnetic elements, reduced voltage stress across the power semiconductor devices, high voltage gain and high efficiency.

Design, analysis and implementation of a new three‐port DC‐DC converter with bidirectional capability

The proposed converter here is a dual-input DC-DC converter with bidirectional power flow. One of the inputs is unidirectional, while the other is a bidirectional port for a battery. The proposed converter can combine two alternating sources with different characteristics. The demanded power of the load can be provided by each input source individually or simultaneously. What is more, the unidirectional port can charge the battery as well as power the output load. Due to the bidirectional capability, the energy returned from the output can be stored in the battery which is suitable for electric vehicle (EV) applications. Step-up capability, the low voltage stress on semiconductors, and the smaller number of passive elements are the other advantages of the converter. Depending on the battery usage status, four different operation scenarios are defined in the proposed converter. The converter operation is described in each scenario and the mathematical analysis is presented. Based on these, the experimental prototype is conducted to verify the characteristics and feasibilities of the converter.

A High Step Up Multi-Input DC/DC SEPIC-Based Converter with Coupled Inductor for Renewable Applications

To overcome low output voltage of renewable energy sources such as photovoltaic arrays and fuel cells, a high step up SEPIC-based multi-input converter with dual coupled inductor is proposed. A new structure is presented in this paper, as an improved structure. This converter is based on combination of modified quadratic buck-boost converter, Dickson switched capacitor (DSC), and voltage multiplier modules (VMM). The high voltage gain can be achieved by adjusting the duty cycle and turn ratio of coupled inductor of VMM. This structure inherits all the advantages of the SEPIC converter such as step-up/down capability without inverting the polarity of regulated output voltage and using a bidirectional input port (in which an energy storage system (ESS) can be connected), and several unidirectional input ports. The load power can be flexibly divided among various power sources. Due to the buck-boost characteristics of the presented converter, it is suitable to charge-discharge the ESS. A coupled inductor (CI) is used to couple energy from input to the output equipped with the VMM. The usage of the DSC technique also enables the converter to obtain an additional double voltage gain while reducing the voltage stress on switches. Simulation results verify the performance of the proposed converter and feasibility of the control strategy.

New Dual-Input Zero-Voltage Switching DC–DC Boost Converter for Low-Power Clean Energy Applications

This article introduces a new dual-input nonisolated zero-voltage switching (ZVS) dc–dc boost converter. The proposed converter hybridizes two bidirectional and unidirectional boost converters to harvest energy from a rechargeable energy storage element and a clean energy dc generator, respectively. Hence, the proposed circuit utilizes three power switches, one power diode, two inductors, and an output filtering capacitor. The ZVS of all the power switches and zero-current switching (ZCS) for the power diode are realized without any auxiliary circuit. The soft-switching performance is designed to be valid for the whole power ranges of the converter input sources and the output load. The converter power switches are switched in pulsewidth modulation manner with two individual duty ratios, allowing to regulate the converter output voltage and control the extracted power from the input unidirectional port through a simple and useful control system. Depending on the converter duty ratios, its basic operation principle is analyzed in two different operation cases. The proposed converter benefits from a simple and compact structure, minimum numbers of power switches and magnetic elements, and high efficiency. The behavior of the proposed converter is analytically investigated, and a low-power laboratory prototype is designed and fabricated to evaluate the converter performance in different operating conditions.

Single Conversion Stage Three Port High Gain Converter for PV Integration with DC Microgrid

A high gain three port converter with a unidirectional port for photovoltaic (PV) side and two bidirectional ports one each for the battery and the DC bus for PV integration to DC microgrid is presented. High gain is achieved by a coupled inductor with switched capacitor, whereas single stage conversion is used between the ports to achieve high efficiency. The proposed converter is modelled in PLECS/MATLAB and the simulated results for various operational modes are validated using a 500 W prototype. For main operating mode, i.e., single input single output (SISO), the efficiency is calculated to be as high as 96 %. Similarly, owing to the reduced number of components, the losses are reduced considerably for different operation modes.

Non-Isolated High-Gain Triple Port DC–DC Buck-Boost Converter With Positive Output Voltage for Photovoltaic Applications

The solar PV based power generation systems are growing faster due to the depletion of fossil fuels and environmental concerns. Combining PV panels and energy buffers such as battery through multi-port converter is one of the viable solutions to deal with the intermittency of PV power. The goal of this paper is to design and analyze the proposed triple port DC-DC buck-boost converter for high step-up/step-down applications. It has two unidirectional ports (port-1 and port-3) and one bi-directional port (port-2) for harnessing photovoltaic energy and charging the battery. At port-1, the combined structure of buck and buck-boost converter is used with a particular arrangement of switches and inductors. The step-up/step-down voltage conversion ratio is higher than the conventional buck-boost converter, and the polarity of the output voltage is maintained positive. The battery is added at the bi-directional port, for the storage of energy through the bi-directional boost converter. The switches operate synchronously for most of the modes making the control strategy simple. The characteristics and modes of operation along with a switching strategy, are elaborated. Experimental results are presented which validate the agreement with the developed theoretical expectation.

Modular Switched Multiported SRAM-Based Memories

Multiported RAMs are essential for high-performance parallel computation systems. VLIW and vector processors, CGRAs, DSPs, CMPs, and other processing systems often rely upon multiported memories for parallel access. Although memories with a large number of read and write ports are important, their high implementation cost means that they are used sparingly. As a result, FPGA vendors only provide dual-ported block RAMs (BRAMs) to handle the majority of usage patterns. Furthermore, recent attempts to create FPGA-based multiported memories suffer from low storage utilization. Whereas most approaches provide simple unidirectional ports with a fixed read or write, others propose true bidirectional ports where each port dynamically switches read and write. True RAM ports are useful for systems with transceivers and provide high RAM flexibility; however, this flexibility incurs high BRAM consumption. In this article, a novel, modular, and BRAM-based switched multiported RAM architecture is proposed. In addition to unidirectional ports with fixed read/write, this switched architecture allows a group of write ports to switch with another group of read ports dynamically, hence altering the number of active ports. The proposed switched-ports architecture is less flexible than a true-multiported RAM where each port is switched individually. Nevertheless, switched memories can dramatically reduce BRAM consumption compared to true ports for systems with alternating port requirements. Previous live-value-table (LVT) and XOR approaches are merged and optimized into a generalized and modular structure that we call an invalidation-based live-value-table (I-LVT). Like a regular LVT, the I-LVT determines the correct bank to read from, but it differs in how updates to the table are made; the LVT approach requires multiple write ports, often leading to an area-intensive register-based implementation, whereas the XOR approach suffers from excessive storage overhead since wider memories are required to accommodate the XOR-ed data. Two specific I-LVT implementations are proposed and evaluated: binary and thermometer coding. The I-LVT approach is especially suitable for deep memories because the table is implemented only in SRAM cells. The I-LVT method gives higher performance while occupying fewer BRAMs than earlier approaches: for several configurations, BRAM usage is reduced by greater than 44% and clock speed is improved by greater than 76%. The I-LVT can be used with fixed ports, true ports, or the proposed switched ports architectures. Formal proofs for the suggested methods, resources consumption analysis, usage guidelines, and analytic comparison to other methods are provided. A fully parameterized Verilog implementation is released as an open source library. The library has been extensively tested using Altera’s EDA tools.

Heterogeneous NoC Router Architecture

We introduce a novel heterogeneous NoC router architecture, supporting different link bandwidths and different number of virtual channels (VCs) per unidirectional port. The NoC router is based on shared-buffer architecture and has the advantages of ingress and egress bandwidth decoupling, and better performance as compared with input-buffer router architecture. We present the challenges facing the design of such heterogeneous NoC router, and describe how this router architecture addresses them. We introduce and formally prove a novel approach that reduces the number of required middle shared-buffers without affecting the performance of the router. In comparison with an optimal input-buffer homogeneous router, our NoC router improves saturation throughput by 6-47 percent for standard traffic patterns. The router achieves significant run-time improvement for NoC-based CMP running PARSEC benchmarks. It offers better scalability, area, and power reduction of 15-60 percent, for NoC based CMPs of size 4 × 4 up to 16 × 16, as compared with optimal input-buffer homogeneous and heterogeneous routers.

A Novel Topology for Controlling a Four Port DC-DC Boost Converter for a Hybrid PV/PV/Battery Power System

This paper proposes a four port three input-dc-dc boost converter for hybridising two photovoltaic systems and a storage medium. Three unidirectional ports are utilised to interface the converter with the two input sources and the output load. A bidirectional port interfaces the converter with the storage system. The two sources individually or simultaneously supply the load and charge the battery. The proposed technique employs only four independently controlled switches with different duty ratios. The regulated dc output can be obtained by controlling these four switches and tracking the maximum power of the two photovoltaic systems. Three different modes of operation of converter influenced by the state of battery are presented. The proposed system is validated and verified by simulation performed in MATLAB under various operating conditions. DOI: http://dx.doi.org/10.11591/telkomnika.v14i3.7854

A Verilog Piecewise-Linear Analog Behavior Model for Mixed-Signal Validation

Full chip mixed-signal validation requires simulating the entire design through a large number of test vectors, which makes fast, event-based Verilog models of analog circuits essential. We describe an extensible approach to creating these models that maps continuous signals into piecewise linear waveforms by creating analog events which contain a value and slope. By breaking analog circuits into sub-blocks with mostly unidirectional ports, we avoid explicit time integration, thus fitting well into an event-driven digital framework. The result is Verilog analog functional models that are pin-accurate, fast to simulate, and capture the key dynamics in analog circuits. A 250 Ms/s open-loop track and hold circuit, 2.5 V-1.8 V buck converter, and 1 GHz PLL models are demonstrated.

Composing Multi-Ported Memories on FPGAs

Multi-ported memories are challenging to implement on FPGAs since the block RAMs included in the fabric typically have only two ports. Hence we must construct memories requiring more than two ports, either out of logic elements or by combining multiple block RAMs. We present a thorough exploration and evaluation of the design space of FPGA-based soft multi-ported memories for conventional solutions, and also for the recently proposed Live Value Table (LVT) [LaForest and Steffan 2010] and XOR [LaForest et al. 2012] approaches to unidirectional port memories, reporting results for both Altera and Xilinx FPGAs. Additionally, we thoroughly evaluate and compare with a recent LVT-based approach to bidirectional port memories [Choi et al. 2012].

Pyramid loudspeakers with twin cross-phased midrange speakers

A truncated, open top, pyramid housing is provided containing a downwardly propagating woofer mounted near the base of the pyramid; a forwardly and slightly upwardly propagating tweeter mounted on the front side of the pyramid; and a pair of rearwardly propagating, crossed polarity, mid-range speakers mounted on opposed sides of the pyramid housing. The push-pull propagation between the opposed mid-range speakers, within a single housing, and similar cooperation between stereo loudspeaker pairs, provides a generally phase distortion free, wide dispersion sound circulation. A polarity switch is provided for establishing the desired cross-phase relationship. The nonparallel side configuration of the housing reduces internal resonance by preventing standing wave formation. The open top functions as an unidirectional port which also reduces internal resonance. The upward portion of each sound cycle is guided out of the speaker housing towards the ceiling by the funneling action of the slanted, tapered sides. The return wave, however, is not guided back into the port, thus reducing the feedback energy required to support internal resonance. The housing may be packed with acoustical material to increase its effective acoustical volume.

A new generalized inverter based on the active hybrid

AbstractThe building block for the new generalized immittance inverter is a 3‐port known as the active hybrid network. One of its ports is bidirectional, and matches a design admittance y0. The second port operates in the send, while the third port operates in the receive direction. The hybrid is constructed from an op‐amp and a 5‐port network composed of a few resistors and the design admittance y0. There are two versions of the hybrid: the voltage‐inverting (i.h.) and the noninverting hybrid (n.i.h.).The inverter consists of an i.h. and an n.i.h. connected at their unidirectional ports in a loop. The gyration admittances are actual driving‐point admittances in the circuit, namely the design admittances y0, y'0 of the two hybrids. Such an inverter, when terminated at its output port by a load admittance y, will give at its input port an input admittance yin = y0y'0/y.Expressions are derived for the y parameters of the inverter at higher frequencies, thus accounting for the finite bandwidth of the op‐amp.Two special cases are particularly treated, and experimental results are obtained for them. The first is the case of the resistive gyrator, for which y0 and y'0 are pure conductances. The second is the case of the capacitive gyrator, for which y0 and y'0 are pure capacitive susceptances. The capacitive gyrator is used to produce the supercapacitor, or f.d.n.r., and the results of measurements on a number of f.d.n.r. networks are given.