Turns Ratio Research Articles

A Novel Series 24-Pulse Rectifier Operating in Low Harmonic State Based on Auxiliary Passive Injection at DC Side

To reduce the current harmonics on the input side of a multi-pulse rectifier, this paper proposes a low harmonic current source series multi-pulse rectifier based on an auxiliary passive injection circuit at the DC side. The rectifier only needs to add an auxiliary passive injection circuit on the DC side of the series 12-pulse rectifier, which can change its AC input voltage from 12-step waves to 24-step waves. We analyzed the working mode of the rectifier, optimized the optimal turn ratio of the injection transformer from the perspective of minimizing the total harmonic distortion (THD) value of the input voltage on the AC side, and analyzed the diode open circuit fault in the auxiliary passive injection circuit. Test verification shows that, after using the passive harmonic injection circuit, the THD value of the input voltage of the AC side of the rectifier is reduced from 14.03% to 4.86%. The THD value of the input current is reduced from 5.30% to 2.16%. The input power factor has been increased from 98.86% to 99.83%, and the power quality has been improved.

A zero‐input‐current‐ripple high‐voltage‐gain DC‐DC converter with integrated Y‐source network

SummaryThis paper proposes a zero‐input‐current‐ripple (ZICR) high‐voltage‐gain dc‐dc converter with an integrated Y‐source network. It achieves zero input current ripple by introducing a parallel branch of an extra inductor, a coupled winding, and a capacitor at the input port. The voltage of the added inductor is opposite to that of the coupled winding. By adding the Y‐source coupled inductor, the boost capability of the converter is improved. The unique boost circuit structure makes that one winding in the three‐winding coupling inductance is step‐down type (the turns ratio n2 < 1) while the other winding is step‐up type (the turns ratio n1 > 1). In such a case, high voltage gain can be obtained under a lower turn ratio of the coupled inductor. The inherent passive clamping circuit clamps the spike voltage noises of the main switch to a low level and improves the efficiency. All the diodes have achieved ZCS (zero current switching) turn‐off. By comparing with several new converters, the advantages of this converter are proved. Finally, a 200‐W, 48‐ to 380‐V, 50‐kHz experimental prototype is built based on the theoretical research. At the rated power, the measured efficiencies with and without ZICR are 95.2% and 95.6%, respectively.

New Coupled-Inductor High-Gain DC/DC Converter With Bipolar Outputs

This paper presents a new bipolar step-up DC/DC converter with the capability of decreasing the input current ripple for renewable energy applications. Two power switches with the simultaneous operation are used in the proposed converter. The suggested topology can provide positive and negative output voltages in a quadratic form with the same and different voltage levels and common ground. The bipolar outputs of the presented topology can be varied independently using the duty cycle and tuning the turn ratio of the coupled inductor (CI). Moreover, the maximum voltage stress across the switching components is much lower than the output voltage. This topology operates under soft-switching conditions for the second switch and all diodes. The steady-state and the main operating equations of the converter are also derived. Finally, a 210 W prototype with 110 V, -110 V, and 220 V output voltages is implemented to justify the theoretical analysis and performance operation of the proposed converter.

Half‐bridge secondary series resonant converter control for full voltage range

SummaryThis paper proposes a full‐range regulation method for half‐bridge secondary series resonant converter. With the proposed method, the resonant converter can achieve full‐range regulation within a narrow frequency range regardless of the load level. Besides, the converter can be used for the battery charger systems and programmable power supply systems. The primary‐side transistors and the secondary‐side diodes are zero‐voltage switching turned on and zero‐current switching turned off, respectively. In‐depth analysis reveals the characteristics, that is, operation principle, voltage conversion ratio, component stresses, and ZVS condition of the half‐bridge secondary series resonant converter with the proposed method. Besides, the performance comparisons among the different methods are conducted to present the merits of the proposed method. Further, the performance comparisons between the half‐bridge secondary series resonant converter and primary series resonant converter with the proposed method are executed to show their superiority with different turns ratio range of the transformer, respectively. When the turns ratio is larger than 0.5 and smaller than 1, the performance of the half‐bridge primary series resonant converter is better; when the turns ratio is equal to 1, the two configurations feature the same performance; while when the turns ratio is larger than 1, the half‐bridge secondary series resonant converter is preferable. The experimental results validate the theoretical analysis.

Double‐input triple‐output non‐isolated DC–DC converter based on coupled inductor with high step‐up output voltages

SummaryThis paper introduces a new non‐isolated double‐input triple‐output (DITO) high voltage gain DC–DC converter with a wide range of applications, including hybrid voltage source systems, solar home appliances, DC‐bus power distribution systems, and electrical vehicles (EVs). The proposed DITO converter interfaces two hybrid voltage sources to supply three different output loads with varying voltage and power levels. Compared to conventional converters of the same type, the proposed DITO converter offers several advantages, including operation for all duty cycles, integration of hybrid energy sources to transfer power to multiple loads, high voltage conversion ratio for all three‐output ports, a higher ratio of total voltage gain to total components number, common grounded input and output DC ports, simultaneous DC voltage regulation of three‐output ports by tuning separate controlling parameters of duty cycles, an additional turns ratio of coupled inductors to increase the voltage gain of output ports, and medium voltage stress on switches. The proposed DITO converter utilizes a new single‐switch single‐coupled‐inductor DC–DC structure, which is analyzed and verified through a prototype implementation for 25 and 30 V input voltages and 210, 330, and 400 V output voltages with a total power of 480 W. The experimental results confirm the simulation results and theoretical analysis.

Coupled Inductor-Based Current-Fed Ultra-High Step-Up DC-DC Converter Featuring Low Input Current Ripple

A DC-DC converter with ultra-high voltage gain is presented in this article. The current-fed structure of the proposed converter provides outstanding performance for sensitive source applications due to its continuous input current with minimal ripple. Using two double-winding coupled inductors in the suggested structure provides more degree of freedom arising from the turn ratios. Simultaneous operation of the two switches causes a simple operation and a simple control system in addition to the need for a single switch gate pulse. Operation of the converter in continuous and discontinuous conduction modes is analyzed as well as design considerations of the active and passive components. The converter is compared with some recent introduced converters, and a 200 W laboratory prototype of the converter is implemented, and experimental results confirming the converter performance are given.

Unified strategy for cooperative optimization of pedestrian control patterns and signal timing plans at intersections

Pedestrian traffic management and control at intersections is crucial for ensuring traffic safety and efficiency while promoting green transportation development. Numerous studies have been conducted on optimizing signal timing of various pedestrian control patterns, such as exclusive pedestrian phases (EPPs) and leading pedestrian intervals (LPIs). However, cooperative optimization of these patterns and the corresponding signal timing is lacking. Hence, this study proposes a unified strategy for the cooperative optimization of pedestrian control patterns and signal timing plans to improve the efficiency and safety of pedestrian–vehicle mixed traffic flow. The existing control patterns, such as EPPs, LPIs, and two-way crossing (TWC), are unified. The safety and efficiency costs are monetized, and the minimization of average costs per traffic participant is taken as the optimization objective. Additionally, decision variables for diagonal crossing at intersections and pedestrian–vehicle priority are introduced to achieve cooperative optimization of the pedestrian control patterns and signal timing plans. The proposed model parameters were calibrated and validated using a real-world case study, and the applicable boundaries of different pedestrian control patterns under different pedestrian and vehicle flow scenarios were identified based on cost difference analysis. The results indicate that the vehicle turn ratio, average vehicle carrying rate, and unit cost ratio dynamically change the applicable boundaries. On average, the proposed method reduced the cost by 2.62% compared with separately optimized EPPs, LPIs, and TWC across various scenarios.

An isolated high step‐down DC–DC converter with dual coupled inductors for ultracapacitor charger applications

SummaryIn this paper, an isolated high efficiency, high step‐down DC–DC converter for ultracapacitor charger applications is presented. In the proposed converter, by utilizing the structure of asymmetrical half‐bridge that combined the current‐doubler synchronous rectifier and the technique of coupled inductors to achieve high step‐down. The step‐down conversion ratio of the proposed converter can be increased by decreasing the turns ratios of transformer and coupled inductors. In contrast to the conventional full‐bridge or half‐bridge converter, the proposed converter can operate in a high step‐down situation; the extreme low duty and turns ratios are not necessary. The theoretical results are verified by experimental results, in the case of 380 V input voltage and 14.6 V output voltage with rated power 1 kW. In addition, the 250F ultracapacitor charged by prototype of the proposed converter from 0 to 14.6 V in 1 min verified its feasibility.

Toroidal seawater conductivity sensors and instrumentation for anti-submarine warfare

This paper describes the development of toroid-based seawater conductivity sensors and instrumentation for 0 to 60 mS/cm conductivity range and 50 bar hydrostatic pressure operational capability which is equivalent to 500 metres of ocean depth. Double core toroidal transformer concept was used and investigated for Mn-Zn and Fe based nanocrystalline cores, turns ratio and temperature dependence. Different excitation and sense coil turn numbers were fabricated by keeping the turn’s ratio 1:2, 1:4, 1:6 and 1:8. Optimum frequency of Mn-Zn based conductivity sensors with lower and higher turn numbers were observed for turn ratio 1:8 and 1:4 respectively at 120 kHz and obtained voltage responses of 952 and 1567 mV. Fe based Nano crystalline core with turn ratio 1:8 shows an optimum frequency of 70 kHz and giving a voltage difference of 830 mV. Two dimensional polynomials of order 2 were presented for temperature dependence of conductivity for Mn-Zn core based sensors. Sensor responses of Fe based nanocrystalline core sensors in ‘lower turn number’ configuration with same turn ratio is presented and observed linear temperature dependence compared to Mn-Zn based sensors. The mechanical design and frequency of operation of developed conductivity sensors gives inherent immunity to ASW band of frequency interference. The efficacy of conductivity sensor with measuring electronics and commercial standard sensors profiling was proved experimentally compared up to 500 metres in sea profiling and obtained a root mean square error of 0.42 for profile data.

Analysis and Evaluation of 99% Efficient Step-up/down Converter based on Partial Power Processing

A step-up/and down converter based on partial power processing is proposed in this paper. With the same state equations, the step-up and step-down modes have the same small signal modelling. Therefore, a unified control strategy can be designed for both operating modes, achieving the auto-switching between two operating modes without requiring any additional control. The effect of the transformer's turn ratio on the current and voltage stresses is then analysed. The component stresses are reduced due to the decoupling of transformer. Moreover, the component stress factor method is implemented to evaluate the proposed step-up/down partial power converter. Compared with conventional step-up or step-down partial power converters, the proposed converter has the least component stress factor for a high voltage electrolysis system. In order to validate the proposed topology and modulation strategy, a 400 V prototype is implemented and experimentally evaluated. Measurement results confirm the high efficiency in the overall voltage range, and the maximum efficiency exceeds 99.5%.

Structure of the Contact Layers of Steel and Their Deterioration in Dry Sliding Against Steel Under High-Density Electric Currents at Different Turn Ratios of a Supply Transformer

Structure of the Contact Layers of Steel and Their Deterioration in Dry Sliding Against Steel Under High-Density Electric Currents at Different Turn Ratios of a Supply Transformer

A non‐isolated single‐switch ultra‐high step‐up DC–DC converter with coupled inductor and low‐voltage stress on switch

AbstractThis paper presents a non‐isolated single‐switch ultra‐high step‐up (UHSU) DC–DC converter with a three‐winding coupled inductor (CI) which is utilized to achieve ultra‐high voltage gain with a small amount of duty cycle leading to low conduction losses of the power switch and higher efficiency. The voltage gain of the suggested UHSU converter is adjusted by two methods: the duty cycle of the power switch and the three‐winding CI turn ratio, therefore enhancing the design flexibility of the suggested converter. Due to the utilization of the passive clamp circuit in the structure of the proposed converter, it is possible to select a power switch with low voltage rated and small ON‐state resistance, further enhancing the converter efficiency. The operation modes are discussed in detail and to clarify the salient features of the proposed converter, a comparison with other configurations is provided. Finally, to accredit the performance of the proposed converter, a 150‐W laboratory archetype with an input and output voltage of 20 and 300 V, respectively, at 50 kHz switching frequency is fabricated.

A new soft‐switching high gain DC/DC converter with bipolar outputs

AbstractThis paper introduces a new single‐input multi‐output step‐up DC/DC converter with soft‐switching performance and low input current for renewable energy applications. The proposed topology uses a three‐winding coupled‐inductor (TWCI) and voltage multiplier circuits to achieve high voltage gains. The bipolar output voltages of the proposed converter can be varied independently by tuning the turns ratios of the TWCI. Due to the semi‐trans‐inverse specification of the suggested topology, high voltage gains can be obtained under a lower number of turns ratio in the magnetic device. Furthermore, a regenerative passive clamp technique mitigates the voltage stress on the single power switch. Additionally, the power dissipations are further reduced by considering a resonant tank in the circuit. In the converter, the parasitic leakage inductances of the TWCI windings help to provide the soft‐switching conditions for the switch and also to eliminate the reverse‐recovery loss for all converter diodes. The operating mode of the presented converter has been introduced and the steady state, along with the main operating equations have also been derived. Finally, the theoretical analysis is verified by a sample prototype 235 W at the input voltage 25 V and outputs of 200 V and −200 V.

A Two-Transistor Forward Converter With Variable Turn Ratio Using Dual Optocouplers to Automatically Adjust Crossover Frequency

In order to solve the problems existing in the two-transistor forward converter (TTFC) with variable turn ratio, that is, the circuit for detecting the input voltage is easy to be damaged, the utilization rate of the winding is low, and the dynamic response will decrease due to the change of the turn ratio. A circuit for indirectly detecting the input voltage, an efficient method for changing the turn ratio, and the dual-optocoupler feedback circuit (DOFC) are proposed. When the converter with DOFC is connected to 140Vdc and 280Vdc, the settling time (Ts) is 112μs and 104μs; while the converter with fixed feedback circuit is connected to 140Vdc, the Ts increases to 188μs. Compared with the conventional converter, when the proposed converter is connected to 140Vdc, the efficiency is increased by 0.8%; when it is connected to 280Vdc, the efficiency is increased by 2.8%. This is beneficial to its promotion in server, industry, aviation and other fields.

Ultrahigh Step-Up DC–DC Converter Based on Two Boosting Stages With Low Voltage Stress on Its Switches

This paper proposes an ultrahigh step-up DC-DC converter composed of two boosting stages, a coupled inductor and switched capacitors. Advance features of the converter consist of its high voltage gain, low voltage stress on its switches, continuity of its input current and existence of a common ground between the source and load. In addition, it needs an inductor and a coupled inductor with smaller sizes in comparison to the compared references which lead to its performance with higher efficiency. Among the compared converters, the proposed converter boosts voltage with higher voltage gain per different turns ratio of the coupled inductor. Analysis of the converter has been performed for its main switching states to validate its quality and quantity factors. A prototype is built in order to experiment its performance per different conditions and evaluate the analysis. The experiments are rated for input voltage, output voltage and output power equal to 25V, 400V and 150W respectively.

Design and implementation a novel single switch high gain DC-DC converter based on coupled inductor with low-ripple input current

A novel high-gain and high-efficiency direct current to direct current (DC-DC) converter is introduced in this paper. The presented converter is suitable for low-voltage renewable energy resources such as photovoltaic (PV) and fuel cell (FC). The existence of series inductance with the input source ensures continuous and low-ramp input current, which is important for extracting maximum power from resources. Using coupled inductor technology and an intermediate capacitor in the suggested converter leads to a high gain voltage. In the presented topology for recovering energy from the leakage inductor, reducing voltage stress on the power switch, and so decreasing overall converter losses, a passive clamp circuit is used. The suitable operation range of duty cycle in the converter, besides the leakage inductor, decreases the problem of reverse recovery in diodes. The low value of the leakage inductor and the low volume and cost of the proposed converter are due to the low turn ratio of the coupled inductor. Details of the operation principles of the proposed converter have been discussed in this paper. The presented simulation and laboratory prototype results verify the theoretical analysis and performance of the suggested topology.

Magnetically Controlled Transformer With Variable Turns Ratio and Low Series Inductance: Analysis and Implementation Toward Its Application in SMPS

Magnetically Controlled Transformer With Variable Turns Ratio and Low Series Inductance: Analysis and Implementation Toward Its Application in SMPS

Pathophysiological Mechanisms Underlying Unilateral Vocal Fold Paralysis in Female Patients: An Ultrasonographic Study.

Laryngeal ultrasonography (LUS) has been suggested as an alternative diagnostic tool for unilateral vocal fold paralysis (UVFP). The present study applied LUS and quantitative laryngeal electromyography (LEMG) in female UVFP patients to investigate the pathophysiologic mechanisms of UVFP. In this cross-sectional study, vocal fold (VF) length parameters included resting and phonating VF length measured using B-mode LUS, and color Doppler vibrating length (CDVL) measured using the color Doppler mode. Forty female patients with UVFP were enrolled, among whom 11 and 29 were assigned to the thyroarytenoid (TA) muscle+cricothyroid (CT) muscle group (with CT involvement) and the TA (without CT involvement) group, respectively. In the TA group, the turn frequency in thyroarytenoid-lateral cricoarytenoid (TA-LCA) on the paralyzed side, as observed through LEMG, correlated with the VF length during the resting phase (R=0.368, P=0.050) and CDVL values (R=0.627, P=0.000) on the paralyzed side. In the TA+CT group, the turn ratio in the CT muscle correlated with the normalized phonatory vocal length change (nPLC; R=0.621, P=0.041) on the paralyzed side. CDVL and nPLC are two parameters that can be utilized to predict the turn frequencies of TA-LCA in UVFP cases without CT involvement, and the turn ratio of CT in cases of UVFP with CT involvement, respectively. The findings suggest that LUS, as a noninvasive tool, can serve as an alternative method for assessing the severity of laryngeal nerve injury and offer valuable insights into the pathophysiology of UVFP.

Multi-objective optimization of two-stage AC–DC power supply for reliability and efficiency using NSGA-II and meta-heuristic honey bee algorithms

This paper introduces a novel approach to simultaneously optimize the reliability and efficiency of a switching power supply (SPS) using the Non-dominated Sorting Genetic Algorithm (NSGA-II) and Honey Bee Algorithm (HBA). The proposed method uses a Markov model to evaluate the reliability of the converter and maximizes objective functions, including efficiency and reliability, using optimization algorithms to identify the optimum values of the converter parameters. The optimization algorithm determines the optimal values for converter parameters, such as switching frequency, transformer turn ratio, and DC-link voltage. It also fine-tunes circuit components, such as the power factor correction inductor, DC-link capacitor, and output filter components. A sensitivity analysis is carried out to assess the impact of various parameters on the multi-objective functions of the converter. The converter’s reliability and mean time to failure (MTTF) are evaluated using the Markov reliability model, considering all components’ short and open circuit faults. The failure rates of converter components are calculated using the MIL-HDBK-217 methodology. The results obtained from the NSGA-II and HBA are compared to identify the superior algorithm with the best-optimized parameters. Simulation results indicate that the proposed optimization technique enhances the converter’s reliability performance while maintaining its efficiency. Furthermore, this paper presents comprehensive analyses, comparisons, and experimental findings to demonstrate the converter’s fault-tolerant capability. The multi-objective optimization approach offers a practical and effective strategy for optimizing switching power supplies for efficiency and reliability

Design and analysis of quasi-resonant high-gain impedance source DC–DC converter for DC microgrid

ABSTRACT This paper presents a quasi-resonant, isolated, high-gain, Y-source, DC/DC converter for a DC microgrid. Here, quasi-resonance is obtained by the LC tank during the shoot through period, resulting in natural commutation at the turn-off instant of the MOSFETs. The LC tank is formed by an additional parallel capacitor and transformer leakage inductance. The high voltage gain is obtained by including an isolation transformer with lower turns ratio, coupled inductor and voltage doubler. Here, frequency is modulated to regulate the output voltage with ON period constant. This converter’s zero current switching feature allows it to operate at a higher switching frequency and thus enhances the power density and efficiency. This converter’s continuous input current feature is an added advantage. The proposed converter inherits all the benefits of traditional impedance source converters. Finally, a 250 W hardware prototype is developed, and its performance is tested in the laboratory.