Turns Ratio Research Articles

A 36 μW 2.8–3.4 dB Noise Figure Impedance Boosted and Noise Attenuated LNA for NB-IoT

This paper describes an ultra-low-power low-noise amplifier (LNA) targeting the 617-652 MHz narrowband-IoT (NB-IoT) frequency band. The design breaks the trade-off in practice between the input matching, minimum required DC current, and minimum NF by using a step-down transformer with an equivalent turns ratio of less than 1, resulting in input impedance boosting and noise attenuation of the main transistor. A local feedback loop is also employed to use the LNA current source transconductance to further attenuate the main transistor noise without additional power cost. The LNA power consumption scales efficiently with the required overall transconductance without being limited to the input matching condition, in practice, while enabling a sub-3dB minimum NF, making it a suitable option for a wide range of applications. A comparison between the proposed, conventional, and state-of-the-art low-power LNA structures is presented with both analytical and simulation models, while measurement results of a prototype designed in a 65 nm technology show a sub-3dB minimum noise figure (NF), −8.8 dBm IIP3, 15 dB gain, and a state-of-the-art FoM of 39.74 dB while consuming only 36 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> from a 0.55 V supply.

A Coupled Inductor Based Ćuk Microinverter for Single Phase Grid Connected PV Applications

A single phase, single stage, non-isolated microinverter scheme is proposed in this paper which can address the issues that are commonly associated with flyback derived microinverters, such as i) the appearance of high voltage turn OFF spikes across the high frequency switch, ii) the requirement of lossy snubbers to control these voltage spikes, iii) the necessity for high turns ratio of the transformer and iv) poor efficiency due to the involvement of a higher number of components. The proposed topology involves only one high frequency switch. A resonance capacitor is employed which not only controls the turn OFF voltage spikes across this power switch but also ensures zero voltage turn ON (ZVS) for this switch. A coupled inductor based Ćuk configuration is incorporated in this topology wherein the energy trapped in the transformer leakage inductance is fed back to the grid, thereby improving the overall efficiency. Implementation of a dedicated boundary conduction control (BCM) strategy effectively limits the value of overall system ohmic losses and thereby ensures performance with enhanced efficiency. The inverter operating principle, the process for deriving the reference current expression, and the optimum design strategy for the inverter parameters are discussed in detail. A 220 W laboratory prototype is fabricated to validate the efficacy of the proposed scheme.

A novel ultra-high step-up interleaved DC–DC converter based on the three-winding coupled inductor for distributed generation power system

Abstract In this paper, a non-isolated DC–DC converter with three-winding coupled inductors and switched capacitor cells is introduced. More output voltage is acquired without imposing any extreme duty cycle and high turns ratio. With the help of a two-phase interleaved technique, the input current ripple is reduced efficiently. The leakage inductance of coupled inductors causes the reverse recovery problem of circuit diodes to be solved and alleviates them. Leakage energy is also absorbed by switched capacitor cells. One of the advantages of this converter is the reduction of voltage stress of power switches, which leads to a reduction of conduction losses. In this way, low-voltage rated power switches can be used. Creating soft-switching conditions on power switches and high efficiency are also the prominent features of this structure. Laboratory and experimental results were produced and presented by making a prototype of 350 W–18 V/480 V. Their analysis indicates the effective performance of the proposed topology.

High Efficiency and High Voltage Conversion Ratio Bidirectional Isolated DC–DC Converter for Energy Storage Systems

In this paper, a novel high-efficiency bidirectional isolated DC–DC converter that can be applied to an energy storage system for battery charging and discharging is proposed. By integrating a coupled inductor and switched-capacitor voltage doubler, the proposed converter can achieve isolation and bidirectional power flow. The proposed topology comprises five switches and a common core coupled inductor that uses only a set of complementary pulse-width-modulated signals to control and achieve high voltage gain without requiring high turn ratios or excessive duty cycles. Moreover, the proposed topology can recover the leakage inductance energy to improve the conversion efficiency. The main switches exhibit zero-voltage switching, which reduces the switching losses. A 500-W bidirectional converter is used to verify the feasibility of the proposed bidirectional converter through theoretical analysis and experiments. The experimental results indicate that the highest efficiency of the proposed converter in the step-up and step-down modes is 97.59% and 96.5%, respectively.

Aerodynamic Performance and Neuromuscular Control in Patients with Unilateral Vocal Fold Paralysis.

Unilateral vocal fold paralysis (UVFP) causes glottal incompetence and poor vocal efficiency. The influence of laryngeal neuromuscular control on aerodynamics in UVFP remains unclear. This study investigated the relationship between laryngeal muscle activities using quantitative laryngeal electromyography (LEMG) and aerodynamics in UVFP. This prospective study recruited patients with UVFP, and the diagnosis was confirmed with videolaryngostroboscopy and LEMG. The patient received aerodynamic assessment and LEMG of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex and the cricothyroid (CT) muscle. The relationship between quantitative LEMG and aerodynamic parameters was analyzed. A total of 134 UVFP patients without concurrent CT muscle involvement were enrolled. Compared with the normal side, the peak turn frequency of the lesioned side was lower in the TA-LCA (p &lt; 0.001) and CT (p = 0.048) muscles. Stepwise linear regression revealed that the turn ratio of TA-LCA muscles was a robust factor in the decrease in peak expiratory airflow (β = -0.34, p = 0.036), mean airflow during voicing (β = -0.28, p = 0.014), and aerodynamic power (β = -0.42, p = 0.019), and an increase in aerodynamic efficiency (β = 27.91, p = 0.012). In addition, the turn ratio of CT muscles was a potent factor in inducing an increase in aerodynamic resistance (β = 14.93, p = 0.029). UVFP without CT involvement still showed suppression of CT muscles on the lesioned side, suggesting that neurological impairment of the TA-LCA complex could cause asymmetrical compensation of CT muscles, further impeding aerodynamics. The residual function of TA-LCA muscle complexes facilitates less air leakage and power dissipation, enhancing aerodynamic efficiency. On the other hand, the symmetrical compensation of the CT muscles improves aerodynamic resistance.

Research on the DC-Side Passive Harmonic Reduction Methods of the Ultramultiphase Parallel-Connected Multipulse Rectifier

The interphase reactor (IPR) is one of the most important components of the passive harmonic reduction circuit (HRC), and the optimum turns ratio design of the IPR is of great significance to ensure the effect of the passive HRC. In combination with the pulse number multiplication methods, the configuration of the multipulse rectifiers (MPRs) with single/dual/triple-passive HRCs are constructed, respectively. The general optimum turns ratio design method for the IPRs is proposed, which contains most of the realizable combinations of the HRCs. The relationship between the turns ratio of the IPR and the phase number of the bridge rectifier in the main circuit is established, the influence of the turns ratio selection on the power quality of the MPRs is presented. In addition, this article takes <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> equal to five as an example to verify the effectiveness of the proposed general optimum turns ratio design method of IPR. The power quality of the MPRs with different HRCs or phase number are compared. All the research can provide a useful guideline and theoretical foundation for the MPR selection and the HRC design under the specific occasions.

General Injection Transformer Turn Ratio Design Method and Hybrid Harmonic Reduction Methods for Series-Connected Multipulse Rectifiers

To simplify the complex calculation process of the optimal injection transformer turn ratio, a minimum error energy method is proposed in this article. According to the structure of multipulse rectifiers, the injection waveform when the rectifier without harmonics is analyzed, and the relationship between the input voltage and the injection voltage is studied. According to the relationship, the minimum error energy method is researched. To prove the accuracy of the minimum error energy method and improve the harmonic suppression ability of multipulse rectifiers, an improvable hybrid harmonic suppression method is proposed. Based on the structure of the proposed hybrid method, the optimal injection transformer turn ratio is calculated, respectively, by the minimum THD of input voltages and the minimum error energy method. The results show that the proposed minimum error energy method accurately solves the optimal turn ratio of the injection transformer with reduced computation. The proposed harmonic reduction method effectively suppresses the harmonics of the input side, which is suitable for high-power quality requirements.

Equivalent-Circuit Modeling of Lossless and Lossy Bi-Periodic Scatterers by an Eigenstate Approach

The use of an eigenstate-based equivalent-circuit topology is proposed for the analysis and modeling of lossless and lossy bi-periodic scatterers. It significantly simplifies the design of this kind of surfaces, since it reduces the number of elements with respect to other general equivalent circuits. It contains at most only two admittances and one complex turns ratio. The real parts of these admittances can be assured to be nonnegative, an interesting aspect in the modeling of lossy surfaces such as those present in absorbers. Moreover, due to the capability of decomposition into the eigenexcitations of the structure, the circuit provides an important physical insight. Different cases of scatterers have been analyzed: symmetric and asymmetric, and lossy and lossless. In all these cases, modeling of the circuit admittances has been successfully achieved with a few positive and frequency-independent RLC elements. In the case of structures with symmetries, the turns ratio directly reflects the physical orientation of the scatterer eigenexcitations. Furthermore, in the case of lossy scatterers without symmetries, the resulting equivalent circuit reveals that their eigenexcitations are not linear polarizations, but elliptic polarizations whose properties are described by a complex turns ratio.

Mitigation of Interturn Short Circuit Fault Based on Axial Split Phase Permanent Magnet Synchronous Machine

In order to solve the problem that three-phase PMSM cannot operate under interturn short circuit (ITSC) fault, an ITSC fault mitigation scheme based on three-phase axial split phase permanent magnet synchronous machine (ASP-PMSM) is proposed in this paper. The ASP-PMSM has inherently superior fault isolation capability among phases, high inductance and low copper loss induced by ITSC current, which greatly reduces the fault severity and difficulty of fault mitigation from machine structure. The inherently low fault severity of ASP-PMSM leaves space for postfault torque production. Therefore, it does not need the phase current to be totally injected to d-axis. As a result, the operation of three-phase PMSM under ideal ITSC fault can be realized while maintaining more than half of rated torque. In order to find out the most serious fault condition for different winding types, the influence of the number of parallel strands and the SC turn ratio on the severity of ITSC fault is investigated by theoretical analysis (TA) and finite element analysis (FEA) for the first time. And the effectiveness of the fault mitigation for the ASP-PMSM with different number of parallel strands is investigated by FEA. Finally, a three-phase prototype of ASP-PMSM is served as an example to verify the validity of analysis above. The ITSC current and temperature at different SC turn ratio and operating conditions are tested. The test results are consistent with that of TA and FEA. It is verified that the proposed fault mitigation scheme can realize the postfault operation of three-phase PMSM.

Ultrahigh Step-Up Quadratic Boost Converter Using Coupled Inductors With Low Voltage Stress on the Switches

In this article, a new ultrahigh step-up dc–dc converter is proposed. The circuit is composed of a quadratic boost converter (QBC), two coupled inductors (CIs), and a voltage multiplier cell. The distinguishing features of this converter are low voltage stress on the main power switches, continuity of the input current, common ground between load and source, and ultrahigh voltage gain. Among all the compared converters, voltage gain of the converter in the entire duty cycle and the CIs turn ratio range is higher and unique of its kind. A prototype is also prepared in order to experimentally validate feasibility and effectiveness of the proposed converter. This prototype is rated at 250 W and 600 V output power and voltage, respectively. In the experiments, the output voltage is controlled on its rated value of 600 V, while the input voltage varies from 15 to 30 V, meaning that the maximum experimental voltage gain is equal to 40.

A Modeling Approach for the VIRT and Other Coupled Electronic and Magnetic Systems

Recently, a new class of magnetic component has emerged in which the electronics that connect to these components are fundamental to defining the conductive loops that comprise them. In these “coupled electronic and magnetic systems” (CEMSs), a clear partition cannot be made between the electrical and magnetic domains and this prevents the application of established modeling techniques for deriving their circuit representation. One such CEMS is the variable inverter/rectifier transformer (VIRT), which enables a transformer with fractional effective turns and a variable effective turns ratio. Previous investigations into the VIRT have invoked simplifying assumptions to synthesize a circuit representation, omitting the full details of operation such as the possibility and implications of ac currents induced on conductors that encircle the VIRT. Other fractional-turn transformers have simply assumed a circuit representation without undertaking modeling. In this work, a modeling approach is proposed which enables the circuit representation of a CEMS to be extracted directly from first principles. Two case studies are explored and the derived models are shown to match well with experiment. The proposed approach is suitable both for assessing the finer details of the VIRT, and other fractional-turn transformers, and as a framework for deriving and understanding new CEMS implementations.

An interleaved non‐isolated high gain soft switching DC–DC converter with small input current ripple

AbstractThis article suggests a non‐isolated high step‐up interleaved DC–DC topology for renewable energy applications. Two three‐winding coupled‐inductors along with two voltage multiplier cells are used to enhance the voltage gain significantly. One interesting aspect of this new topology is that high duty cycles are not required to achieve high voltage gains; this is done by adjusting the turn ratio of the coupled inductors. Moreover, the presented interleaved converter enjoys not only having less current stress due to the interleaving structure, but also showing 16% increase in voltage gain compared to the best similar boost topologies. Additional elements are designed for the purpose of soft switching and gain increase, which have little effect on the cost, weight and size of the proposed converter. Interestingly, the voltage stresses both on the switching devices and passive elements are much less than the output voltage. Furthermore, the coupled inductor's leakage inductance energy is recovered by employing a passive clamp circuit to minimize stresses across the semiconductors; therefore, efficiency is improved. The suggested converter is analyzed in the steady state, and a 400 W experimental setup was implemented; the outcomes verify the practicality of the proposed boost converter in accordance with the analysis.

An Ultra High Step-Up Dual-Input Single-Output DC–DC Converter Based on Coupled Inductor

This article introduces a new coupled inductor based dual-input ultra-high step-up dc–dc converter with a high voltage conversion ratio, low voltage stress across semiconductor components, and high efficiency features. The coupled inductor and voltage multiplier circuit (VMC) techniques have been utilized to enhance the voltage gain. The blocking voltages of power switches are clamped by VMC at low values and can be controlled via the turn ratio of the coupled inductors that decreases the voltage rate of power switches and converter's cost. The presented dual-input structure can transfer power to the load from two independent voltage sources. Besides, the inputs and output ports are common ground, which can reduce the electromagnetic interference influences. Operation modes delineation, steady-state analysis, and comparison section are provided for describing the proposed structure performance. Finally, to confirm the effectiveness of the presented topology, experimental waveforms with a 200 W output power at 50 kHz switching frequency are presented.

Hybrid Resonant Switched-Capacitor Converter for 48–3.4 V Direct Conversion

As the power required by modern data center processors increases, the power architecture must be adapted; for example, 48 V distribution voltage allows to reduce copper losses by a factor 16 with respect to the use of traditional 12 V power architecture. In order to generate the required processor core voltage, a two-stage approach is usually preferred, where the intermediate bus voltage is generated using an unregulated resonant dc–dc converter as, for instance, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter. Compared to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLCs</i> , hybrid resonant switched-capacitor converters (ReSCCs) make it possible to achieve large voltage conversion ratios without the need of high turns ratio transformers. In this letter, a novel hybrid ReSCC that performs a 48–3.4 V direct conversion is presented. A prototype of the proposed converter has been implemented, capable of providing a continuous output power of 440 W with a maximum efficiency of 96.3% at 30 A load current.

A Single Switch High Step-Up DC-DC Converter Based on Tri-Winding Coupled Inductor for Renewable Energy Applications

This article introduces a novel nonisolated single-switch high step-up DC-DC converter using a tri-winding coupled inductor (TWCL) for renewable energy applications such as PV systems. Also, the voltage multiplier cell (VMC) is used to attain a high voltage gain. The used VMC acts as a passive clamp circuit and reduces the voltage stress across the power switch. So, a low voltage-rated power switch can be used in the presented converter. The suggested topology uses only one power switch with low on-state resistance (RDS-ON), which leads to a simple control circuit and decreases the conduction losses. Highefficiency, operating with low duty cycle, low peak voltage over semiconductor elements, low turns ratio, the number of the coupled inductor, and high voltage conversion ratio are the significant benefits of the recommended DC-DC converter. To show the achievement of the presented structure, operational mode principles, steady-state, efficiency calculations, and comparison results are provided. Finally, a 120 W experimental prototype with 200 V output voltage and 50 kHz switching frequency is built to prove the usefulness of the suggested high step-up converter. The efficiency is measured 92.11% at rated power.

Design and fabrication of an interleaved high step‐up DC–DC converter with soft‐switching capability to implement in renewable energy systems

AbstractThis paper presents a soft‐switching non‐isolated interleaved high step‐up topology to implement in renewable energy systems. By using low number of power electronic devices and incorporation with the coupled inductors (CIs) and built‐in transformer (BIT), simultaneously, mixed with a voltage multiplier cell (VMC), an ultra‐large gain can be obtained. In addition, the interlevead structure in the input side causes to diminish the input current ripple. Moreover, the automatic current sharing is another characteristic of the proposed converter. The voltage stresses across power semiconductors are decreased by increasing the turns ratio of the implemented CIs and BIT and also reverse recovery losses are attenuated which improves the efficiency. Furthermore, zero‐current‐switching (ZCS) condition for diodes is achieved at turn off instant, due to the leakage inductances of the magnetic means. Also, power MOSFETs are switched with zero‐voltage‐switching (ZVS) performance by adding active clamp. A 600‐W experimental prototype with 24‐V input to 400‐V output voltage at a switching frequency of 100 kHz is built and tested to examine the merits of the proposed topology

An integrated of buck and half‐bridge high step‐down converter utilizing single‐stage driving design for high‐efficiency energy conversions

AbstractIn this paper, an integrated of buck and half‐bridge high step‐down converter utilizing single‐stage driving design for high‐efficiency energy conversion is proposed. The proposed converter has the ability to instantly and synchronously transfer energy from input to output within one conversion period. The proposed topology is capable of lowering the primary side voltage of the transformer, so the turns ratio could be reduced. The coupling rate is therefore better along with the leakage inductance. Furthermore, the duty cycle operated in an extreme situation is not necessary. As a combination of the advantages of high step‐down conversion, lower voltage stresses, and fewer amount of semiconductor elements, the feasibility of the proposed topology is verified by the implementation of a 300 W prototype. The proposed integrated topology utilizes the single‐stage energy transfer control algorithm to verify that the proposed experimental circuit has a full load efficiency of 92.4%, in the case of input voltage 380 V and output voltage 5 V, and the maximum efficiency, occurring at 100 W, is 94.55%.

Simplified Closed-Form Optimized Trajectories Control for a Dual Active Bridge Converter With ZVS Implementation Over Whole Domain

A dual active bridge converter is widely used in electric vehicle charging systems and other fields for its excellent features. Despite the diversity of relevant studies on the triple-phase-shift (TPS) modulation, the existing investigations fail in the zero-voltage-switching (ZVS) implementation over the whole voltage and load domains, especially in the transition process between different modes. To address the current state of research, the magnetic current is introduced to bridge the ZVS gap between different modes in this article. A simpler method of the acceptable maximal magnetic inductance design in view of the current stress and the transformer's turns ratio is presented. Afterward, the evaluation method of system efficiency over the full voltage range is raised. Most critically, the simplified optimal control trajectories considering the impact of the magnetic current are proposed for the first time for the TPS modulation, eliminating the nonmonotonicity and leapfrogging of the control variables. Compared with the existing works, the method proposed in this article accomplishes ZVS over the whole domain, thereby reducing potential electromagnetic interference and enhancing the efficiency. Eventually, the proposed method is verified by a 1.0-kW prototype.

Transformer Based 25-Level T-Type MLI for Renewable Energy Integration

The primary challenge with cascaded H-bridge multilevel inverters (MLI) is the need of a large number of switching components and distinct dc-sources for integration of renewable energy to medium voltage grid. As a result, in these types of systems, component minimization is crucial. With the advent of transformer cascaded multilevel inverters (TCMIs), multiple dc sources in cascaded H-Bridge (CHBs) are no longer required for operation. According to the findings of this research, a novel transformer cascaded MLI with 25 levels and 12 switches can be implemented using a single dc source. The proposed MLI is comprised of two different rated isolated transformers. The proposed MLI topology offers the structural advantage of fewer semiconductor components, provides self-galvanic isolation, and generates uniform voltage levels for all turn's ratio. Furthermore, the MLI employs a switching mechanism known as nearest level control, which reduces device power loss and, hence, enhances the systems overall efficiency. To assess the performance of the proposed TCMLI, a laboratory prototype was built and simulations in the MATLAB/Simulink environment were run. In addition, a study of the systems power loss analysis has been presented. A comparison of the proposed topology to other recent topologies of a similar nature is also provided.

A High Step-Up DC–DC Converter With Switched-Capacitor and Coupled-Inductor Techniques

This article proposes a high step-up dc–dc converter with single switch, which combines a multiplier voltage cell, two winding coupled inductor, and switched capacitor. The converter attained high voltage gain by the boost cell consisting of two winding coupled inductor and switched capacitor. A passive clamp circuit consisting of diode and capacitor can reduce the voltage spike of switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> and recover leakage inductance energy. Therefore, the power switch with low <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state resistance can be used, which will reduce the conduction losses of the switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> . The main properties of the suggested converter are high voltage gain with low turn ratio <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> at reasonable duty cycle <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> , and high efficiency. The operation modes and steady-state analysis are presented. Moreover, the stress of the components, theoretical efficiency analysis, and comparison with other dc–dc converters are analyzed and presented, respectively. Finally, a 200 W prototype construct in the laboratory based on the design guidelines verifies the validity of the suggested converter.