Hybrid Topology Research Articles

Increasing the activity of DNAzyme based on the telomeric sequence: 2’-OMe-RNA and LNA modifications

Abstract2’-OMe-RNA analogues and LNA point modifications of DNA oligonucleotides were applied for the modulation of the G-quadruplex topology and enhancement of peroxidase activity of the resulting DNAzymes. The effect of the 2’-OMe-RNA analogue was studied for full length modified oligonucleotides with various sequences. In the case of LNA-point modification, we have chosen a telomeric DNA sequence and investigated various numbers of modifications. Our main goal was to prove that the application of these modifications can influence the activity of DNAzyme, especially those, which normally form poor DNAzymes. As an example, we have chosen the telomeric HT22 sequence which is known to form DNAzyme characterized by low activity. In all cases, the DNAzymes formed by a telomeric sequence with the application of the 2’-OMe-RNA analogue as well as LNA-point modification, showed significantly higher peroxidase activity. We were also able to shift the formation of hybrid or antiparallel topology to parallel topology. These results are important for the development of probes for biological applications as well as for the design of probes based on DNA sequences that normally form DNAzymes with low activity. This paper also provides information on how the application of nucleotide analogues can transform the topology of G-quadruplexes.

Innovative and Highly Integrated Modular Electric Drivetrain

A highly integrated electric drivetrain module with 157 kW peak power is presented, which incorporates novel technologies in the field of electric machines, power electronics and transmissions: 1. High-speed electric machine with six phases and injection mould polymer-bonded magnets; 2. High-ratio dual-speed transmission with double planetary gear set (Ravigneaux gear set); 3. Gallium nitride (GaN) power electronics with winding reconfiguration feature.The combination of these components in one single housing makes the drive module flexible to integrate and to combine with conventional or alternative propulsion technologies, thus allowing various hybrid and electric drivetrain topologies. All technologies are selected in accordance with mass production potential and can therefore have a high impact on the automotive market in the future. Currently, the drive module is under development; the first models will be assembled in winter 2019. The integration into a demonstrator vehicle in 2020 will prove the potential of many new technologies and the suitability for the automotive market.

Very High Step-Up Converter with Switched Capacitor and Coupled Inductor

To increase the voltage gain of power electronic circuits, numerous converters have been designed by researchers. In particular, step-up converters are used in various circuits and systems due to their reliability. Mostly, in some studies, researchers proposed to use coupled inductors and switched capacitors. Therefore, in this study, we aim to use new-generation E-HEMT switches by using a hybrid topology which includes both a switched capacitor and a coupled inductor to deliver ultra-high voltage to the output. The proposed switched capacitor-based hybrid converter (SCBHC) is modeled in Simulink and PowerSim to verify the analytical voltage gain derivations. The proposed SCBHC is compared with a traditional boost converter, a switched capacitor-based topology and two different coupled inductor-based schemes in terms of gain performance for different duty cycles, switching frequencies and turn ratios. With this combined design, we obtain approximately 300–400% more voltage gain than a traditional boost converter. The proposed SCBHC provides a considerable gain and a wide output voltage range with lower turn ratios compared with other topologies.

Highly Efficient Fault-Tolerant Modular Embedded Thyristor Directed Converter for HVDC Applications

Modular multilevel converter containing half-bridge submodules (SMs) is the most preferred topology for high voltage dc (HVDC) applications. However, the inability to block/limit dc fault current and large number of capacitors requirement are some of its limitations. Recently, hybrid topologies utilizing thyristors for such applications have gained significant interest as they offer lower on-state voltage drop, higher reliability, and power handling capability. In this article, the modular embedded thyristor directed converter (METDC) is proposed, which uses series-connected thyristors as the high voltage switches and chain-links comprising of IGBT based half and full-bridge SMs. A control technique is proposed for force-commutation of thyristors by using full-bridge SMs for lagging loads, while they are naturally commutated for leading loads. The METDC offers wide operating range besides being fault tolerant. The results obtained from the METDC-HVDC model developed in PSCAD substantiate its ability to provide independent active and reactive power control required for HVDC application. The fault studies carried out validate the dc fault tolerant capability of METDC. The results obtained from the various ac fault/unbalanced case studies substantiate the efficacy of proposed controller to force-commutate the thyristors even during contingencies. Loss computation validates the ability of converter to provide higher efficiency.

Conformational rearrangements of G-quadruplex topology promoted by Cu(II) 12-MCCu(II)PyrAcHA-4 metallacrown

Cu(II) 12-MCCu(II)PyrAcHA-4 metallacrown was studied by several spectroscopic techniques as an interacting ligand with G-quadruplex DNA structures. Investigations were performed on oligonucleotides bearing human telomeric and protooncogenic c-myc sequences in buffered solution mimicking ionic conditions in cellular environment. The planar square-based Cu(II) 12-MC-4 metallacrown interacts with GQ via an end-stacking mode with 1:1 stoichiometry. Circular dichroism (CD) titration revealed capability of this metallacrown to induce transformation of the GQ hybrid topology into the parallel form. Thermal melting experiment indicated higher thermal stability of both antiparallel (ΔTm = +15 °C) and parallel (ΔTm = ≥27 °C) G-quadruplexes in the presence of Cu (II) 12-MC-4. Indirect GQ FID assay let to determine high binding affinity of the Cu(II) 12-MC-4 to antiparallel 22Htel/Na+ GQ (KMC = 3.9 (±0.4) x 106 M−1). Comparing with lower binding constants previously reported for Ln (III) 15-MC-5 and Sm (III) 12-MC-4, one can conclude that the square planar geometry and the positive charge of metallacrown play an important role in MC/GQ interactions.

Design and Analysis of Heterogeneous Hybrid topology for VLAN configuration

Design and Analysis of Heterogeneous Hybrid topology for VLAN configuration

A New PV-SOFC based Hybrid topology using PI Controller for the Regulation of Voltage and Frequency Profile in an Autonomous Microgrid

This paper proposes a new, reliable and efficient microgrid structure which incorporates PV arrays and SOFC interconnected via Voltage Source Inverter (VSI) as an alternative to reduce the detrimental impact of energy generation on atmosphere using fossil fuels. Inorder to meet the growing energy demands, the excessive usage of nonrenewable energy resources disregarding the environmental impacts resulted in major environmental problems. As a result the spotlight is turned towards promotion of energy production from renewable energy sources like solar, wind, tidal, geothermal etc. Taking into consideration the aforesaid concept, this paper proposes a hybrid microgrid consisting of PV-SOFC with VSI based PI controller working in an islanding mode so that voltage and frequency is maintained in their acceptable limits and the output demonstrated using Matlab/Simulink shows the efficacy of the controller in providing efficient energy which gives the lowest environmental impacts

A Reconfigurable Passive RF-to-DC Converter for Wireless IoT Applications

In this brief, we present a reconfigurable rectifier, which makes it feasible to harvest energy with net-zero energy consumption, i.e., without draining power from battery, in a wide input power range. The proposed topology can operate with low input power signals and can be fine-tuned for a specific operating frequency in a wide frequency range from several MHz to GHz in remotely powered systems. A prototype is fabricated in 0.35- $ {\mu }\text{m}$ standard CMOS process and occupies 0.019 mm2. Although the proposed rectifier supports four different rectifier topologies, on silicon it only occupies the footprint of a single rectifier. At 13.56 MHz with 2.2 mW input power, the four-switch rectifier topology yields 82% power conversion efficiency (PCE), while the hybrid topology (diodes + switches) provides 81% PCE at 11.2 mW input power. The rectifier operates with input power as low as 1.1 mW, at which level the PCE is still reasonable at 65.2%. This allows a wireless device at low power level to operate at extended read range. This reconfigurable rectifier is especially suitable for Internet of Things mobile application, where the power of the incoming signal changes by the distance between the power source and the device.

High Gain Quasi-Mutually Coupled Active Impedance Source Converter Utilizing Reduced Components Count

High voltage gain using a mutually coupled inductor network is quite popular in recent years for Z source converters. To achieve high gain, reduced number of components used is a prime challenge to improve efficiency and reduce the cost and size. In the coupled inductor network, the energy stored is twofold, hence, the effective number of components is reduced. Moreover, the boosting factor is also governed by the number of turns which again helps in reducing the number of components. In general, coupled inductor network is based on two winding transformers. However, to increase the effective number of turns, an autotransformer principle may be used where turns ratio is increased by one as compared to two winding transformers. Therefore, in this article, a coupled inductor network is proposed which is based on the autotransformer concept. The proposed converter is called as quasi-mutually coupled active impedance source converter. The proposed converter has a continuous input current which is helpful in reducing the current stress on the source. The operation, steady-state analysis and its comparison with the existing topology are discussed. Moreover, the developed topology is extended for hybrid topology. Furthermore, the converter is validated using experiment to prove its feasibility.

A Hybrid 7-Level Inverter Using Low-Voltage Devices and Operation With Single DC-Link

This paper proposes a new 7-level inverter topology for induction motor drives. It is a hybrid topology formed by cascading a 5-level active neutral-point-clamped inverter with a 3-level T-type converter. It is obtained using low-voltage semiconductor devices with voltage blocking capability of Vdc/3 and Vdc/6. The topology uses three floating capacitors per phase, which are balanced within a pulsewidth modulation (PWM) switching duration using switching-state redundancies for each pole-voltage level. Topology forms two stacks at the front-end, which requires individual symmetrical dc source. The analysis of switching loss and conduction loss is performed and compared with some of the existing 7-level multi-level inverters reported in various literatures to show the advantages of the proposed topology. Furthermore, the single dc source operation with two stacked capacitors and closed-loop control of neutral-point voltage using symmetrical six-phase induction motor is proposed. The voltage-control algorithms for floating capacitors and dc-link stacked capacitors are proposed, which are independent of load power factor and modulation index. Open-loop V / f and closed-loop rotor field oriented control are performed, and various results at steady and transient states are presented to validate the aforementioned claims.

Design of MIMO Antenna Isolation Structure Based on a Hybrid Topology Optimization Method

A hybrid topology optimization (HTO) method is utilized to optimize the isolation structure of a multiple-input multiple-output (MIMO) antenna. The HTO method, in which the scalar isotropic material with penalization (SIMP) and the level set method (LSM) are integrated, is based on the gradient optimization method with fast convergence speed. It combines the advantages of strong topology-searching ability of SIMP and smooth structure boundary of LSM. The proposed HTO method is adopted to optimize the isolation structure for good impedance matching, high isolation and high polarization purity of the MIMO antenna simultaneously. By setting the optimization structure as a symmetric one, the number of optimization variables is reduced by half. The optimization is validated by the full-wave simulation and the measurement. At the expected frequency of 5.8 GHz, the measured mutual coupling between the MIMO antenna elements with a center-to-center distance of $0.25\lambda _{0}$ is reduced by more than 24 dB, and the cross-polarization ratio reaches more than 27 dB. Furthermore, the reason for the isolation improvement is analyzed as well.

Hybrid Topology of a Diode-Rectifier-Based HVDC System for Offshore Wind Farms

This paper proposes a hybrid converter for the high-voltage direct-current (HVDC) transmission of offshore wind farms. The proposed converter consists of a diode rectifier and a paralleled auxiliary modular multilevel converter (MMC). The auxiliary converter is a low-power bidirectional ac/dc converter with a high conversion ratio. During the startup procedure of a wind farm, the auxiliary converter actively sets up the ac voltage of the collection grid and supplies the necessary startup power to the wind turbines. In addition, the auxiliary converter provides the reactive power and partly compensates harmonic currents to the wind farm collection system, so that the hybrid topology can overcome the disadvantages of a diode-rectifier-based HVDC system. After the startup sequence, power delivery is shifted from the auxiliary converter to the diode rectifier by controlling the ac voltages. Compared with HVDC systems based on full-power MMCs, the proposed system significantly decreases the number of submodules, resulting in lower volume, weight, and cost. The effectiveness of the proposed system is verified by the simulation results of a 160-MW offshore wind power system and the experiment results of a 300 W system.

Space Vector Modulation for SiC and Si Hybrid ANPC Converter in Medium-Voltage High-Speed Drive System

Medium-voltage high-speed drive is promising in applications, such as the centrifugal compressors and electrified transportation. However, it raises lots of design challenges for the converters, which drive the motors. A SiC and Si hybrid ANPC converter is developed to address these challenges. In this article, the essence of this hybrid structure is investigated to clearly show the derivation process of the hybrid active neutral-point-clamped (ANPC) converter and inspire future research on these hybrid topologies. A dedicated space vector modulation (SVM) scheme is proposed for the hybrid ANPC converter, which enables the three-phase hybrid ANPC converter operating with SiC mosfet s in high frequency and Si IGBTs in fundamental frequency. A neutral point (NP) voltage balancing scheme is added to the SVM scheme to balance the NP voltage imbalance under low-frequency modulation index. All these efforts make the hybrid ANPC converter become a high power density and fairly low-cost solution. A 400 Hz fundamental frequency, 3.6 kHz switching frequency, medium-voltage high-speed drive system is assumed and tested by the scaled-down experimental results. The effectiveness of the proposed SVM and NP voltage balancing method have both been verified.

A 48-V:16-V, 180-W Resonant Switched-Capacitor Converter With High-Q Merged Multiphase LC Resonator

Hybrid-resonant switched-capacitor (SC) converters have gained traction as a way to increase efficiency and power density in high conversion ratio dc–dc applications. However, there is still room to improve passive component utilization and performance by exploiting resonant behavior and the unique circuit networks in hybrid topologies. This article explores a nominally 3:1 step-down resonant SC dc–dc converter that uses a high- $Q$ multiphase $LC$ resonator. The resonator combines flying capacitors and inductor(s) into a single component, leveraging advantages of each to improve the performance (efficiency and power density) of the overall structure. A hardware prototype is presented that achieves over 97% efficiency at >100 W in a 48-V:16-V step-down configuration. The prototype is used to highlight an interesting direction for future research in intermediate-bus converters for data center applications.

Passive hybrid energy storage system based on lithium-ion capacitor for an electric motorcycle

Abstract This paper presents the multiple energy storage system usability for an electric motorcycle focused on passive hybrid topology. The studied hybridization is based on a passive parallel topology connecting lithium manganese nickel 18650-type cells and lithium-ion-capacitor to supply the motorcycle powertrain. The passive hybrid energy storage system design is fully addressed based on an extension of Ns/Np battery pack sizing maps to passive hybrid topology using lithium-ion-batteries and lithium-ion-capacitors. The improved sizing method is able to size simultaneously an integrated energy storage system made from two different cells chemistries. The proposed design optimizes the common voltage range and distribute the current according to the intrinsic cells characteristics. Relationship between dimensions are established to plot as a traditional two-dimensional map a four-dimension sizing problem. The benefits and performance improvements obtained by the Ns/Np hybrid design for a case study involving an electric motorcycle are presented and discussed based on root-mean-square and mean value of the current cell, standard deviation of the C-rate and instantaneous current peaks variation coefficient. The proposed configuration could reduce the stress on the battery cells by 42% on standard deviation and 36% on variation coefficient with a decrease of 9% in average current while reducing the root-mean square value by 15% on a specific motorbike race simulation.

A Hybrid Modular DC/DC Converter for HVDC Applications

Recently, remarkable progress has been made in the voltage-source-converter-based high-voltage direct current (HVdc) transmissions. For the upcoming need to interconnect multiple dc transmission lines with different voltage levels, high-voltage and large power dc/dc converters are necessary. This article investigates a nonisolated bidirectional dc/dc converter that is composed by cascaded half-bridge submodules, series-connected diodes, and mechanical disconnectors. This hybrid topology presents very attractive features, such as low cost, high efficiency, and light weight. Operation principle, parameter design, and dedicated control strategies are developed. Simulation of a 150-MW, 200 kV/300 kV dc/dc converter has been performed to verify its performance and evaluate the efficiency. Moreover, a downscaled three-phase prototype rated at 500 V/300 V 4.5 kW has been built and tested. The experimental results further confirm the effectiveness of the proposed dc/dc converter.

Investigation of modified multilevel inverter topology for PV system

Multilevel inverters become an alternative for high power and medium voltage applications in recent years. Multilevel inverters(MLI) are basically classified as Diode Clamped Multilevel inverter, Flying Capacitor Multilevel inverter, Cascaded H Bridge Multilevel Inverter (CHBMLI). The CHBMLI topology which consists of a series of H bridge unit with separate dc sources is mostly prefered to generate higher voltage levels, as it requires fewer components compared to the other topologies. As the level increases, the switching device requirement will be more and the circuit becomes large with this topology. To overcome this and to produce high quality output, reduced switch count topologies are the main focus in recent research.The reduced switch count structures are based on bidirectional switches, modified form of the structures, polarity and level generation based structure, reduced switch structures and hybrid topology structure. This paper proposes a three phase Modified Multilevel Inverter (MMLI) topology with reduced switch count for nine level and the topology is analyzed using different Pulse Width Modulation (PWM) technique. The proposed MLI structure consists of an H bridge unit with voltage conversion cell for each phase. It requires 24 switches for a 3Ф nine level inverter with eight switches per phase compared to 48 switches in CHBMLI. The Total Harmonic Distortion (THD) level of this topology is examined with the PWM techniques for symmetric and asymmetric DC voltage sources. THD results of the proposed MLI are compared with other reduced switch topology structure. The comparison result indicates that the proposed topology shows better harmonic level and reduced switches compared to that structure. A prototype of the proposed topology is built and is tested to validate with the simulation results. Simulation and experimental results show that the proposed topology produces a minimum harmonic level with fewer components.

Two‐/three‐coil hybrid topology and coil design for WPT system charging electric bicycles

Wireless power transfer (WPT) for charging electric bicycles (EBs) can save people from tiresome plugging actions and avoid electrical shock hazards, especially in adverse weather. This study proposed a two-/three-coil hybrid topology to achieve constant current (CC) and constant voltage (CV) for charging EBs, simplifying control schemes. The system realises CC output with two-coil topology and operates in CV mode with three-coil topology by turning on a switch. Besides, an inductor array is used to compensate reactive power in CV mode when massive EBs are charged by one high-frequency inverter (HFI). The secondary side of the proposed topology is compact, and the number of components and HFI can be reduced. A coil design process based on double-D-type for the three-coil system is given, with the constraint of mutual inductances among three coils and limited size. To demonstrate the validity of the proposed methods, an experimental setup is built, and the performance of the two-/three-coil hybrid system indicates that the fluctuations of charging current and voltage are <0.64 and 2.12% in the whole charging profile. Moreover, the performance of two WPT chargers connected with one HFI hints that massive EBs can be charged with only one HFI.

A Novel Hybrid Multilevel PWM Technique for Power Rating Enhancement in Improved Hybrid Cascaded Diode Clamped Multilevel Inverter

In this article, an improved hybrid topology called cascaded diode clamped half bridge multi-level inverter is proposed upon a conventional cascaded H-bridge (CHB) multi-level inverter (MLI) which has the limitation to withhold a specific cell voltage due to the constraint on the device voltage stress. The proposed topology will ensure the enhancement of cell voltage capability double times, reduces the device stress, modularity in structure, and allows even power distribution. As a result, the user can now integrate two numbers of active dc sources to a cell. This ensures the efficiency of power enhancement in the applications like on/off grid-connected renewable energy system which require the power to be converted from dc to ac or vice versa. The proposed topology is compared extensively with the conventional CHB MLI at different loads. Hybrid pulse width modulation technique allows to operate the individual half bridge. The simulation and experimental results confirm the performance and efficiency of this proposed topology. A mathematical model of the proposed topology has been derived for the better feasibility of this topology extension to various other applications.

A Global Optimization Approach Based on Opinion Formation in Complex Networks

Population-based metaheuristic optimization techniques have numerous applications in science and engineering. In this paper, we introduce a novel population-based binary optimization method, built upon consensus formation in interacting multi-agent systems. Agents, each associated with an opinion vector, are linked together through a network structure. The agents influence each other by performing interactions, and as a result their opinions evolve. Opinion vectors hold solutions to the problem, and at the same time, store additional information on agents’ interaction experience. The agents communicate and work collectively to solve an optimization task. In this study, we consider a specific opinion update rule and various underlying interaction network topologies. Results of the experiments, conducted on a number of benchmark cost functions, show that a dynamical ring topology, designed for our specific purpose, leads to the best performance compared to other network topologies. We also compare the performance of the proposed optimization algorithm with classical and state-of-the-art population-based optimizers, namely, Genetic Algorithm, Binary Hybrid Topology Particle Swarm Optimization, Selectively Informed Particle Swarm Optimization, Binary Learning Differential Evolution, and Discrete Artificial Bee Colony. Comparisons based on experimental analysis reveal that the proposed consensus-based optimizer is the top-performer.