Coupled Inductor Techniques Research Articles

Interleaved ZVS DC‐DC converter with ultrahigh step‐down and flexible gain

AbstractThis paper proposes a novel non‐isolated ultrahigh step‐down interleaved DC‐DC converter with an extremely extended duty cycle based on the series capacitor and coupled‐inductor techniques. The proposed converter utilizes a three‐winding coupled inductor (TWCI) to enhance the step‐down conversion ratio. In contrast to conventional coupled inductor‐based step‐down converters, its voltage gain improves as the turn ratio approaches unity. Consequently, coupled inductors have significantly lower winding losses. Furthermore, there is no extra constraint on the turn ratio of the TWCI. It results in a highly flexible voltage gain and more design freedom. Other advantages of the employed series capacitor and coupled inductor techniques can be listed as, zero voltage switching (ZVS) condition for all switches, significant reduction of the total switching device power (SDP) and recovery of the energy of leakage inductors. They all reduce power losses and costs. Steady‐state analysis, derivation of voltage gain and design considerations are discussed in detail. Finally, a 200 W, 400‐to‐12 V experimental prototype is implemented to verify the effectiveness and feasibility of the proposed converter.

An ultra‐high voltage gain interleaved converter based on three‐winding coupled inductor with reduced input current ripple for renewable energy applications

AbstractThis article proposes an interleaved high step‐up DC–DC converter topology designed for renewable energy applications, featuring an ultra‐high voltage conversion ratio. The converter employs an interleaved structure, resulting in a low peak‐to‐peak ripple in the input source current, which is particularly advantageous for solar PV sources. To enhance the output voltage, the topology utilizes voltage multiplier cells (VMC) and coupled inductor techniques. Two coupled inductors with three windings are integrated into the proposed topology, with the secondary and tertiary windings combined with VMC. This combination effectively reduces the maximum voltage stress across power switches, enabling the use of low‐rated and cost‐effective power switches for implementation. The article offers comprehensive operation modes and steady‐state analyses to demonstrate the converter's performance. A comparison is made between the suggested structure and other similar converter topologies. To validate the mathematical analysis, a 200‐W prototype is constructed, operating at a frequency of 25 kHz and achieving a voltage conversion range of 20 to 409 V. The experimental results are presented to support the findings.

A High Step-Up, High Efficiency, and Low Switch Voltage Stress Coupled-Inductor DC–DC Converter With Switched-Capacitor and Coupled-Inductor Techniques

This article proposed a high step-up, high efficiency, and low switch voltage stress coupled-inductor (CL) dc–dc converter with switched-capacitor (SC) and CL techniques. The design method of the converter is to replace the single switch in the single-switch dc–dc converter with an SC and then combine the CL. Compared to other typical dc–dc converters, the improved topology power switch has lower voltage stress, low diode current stress, fewer devices in total, and common grounding, and all diodes are capable of ZVZCT. The operation mode and steady-state analysis of the proposed converter are given. The device stress derivation, the theoretical efficiency analysis, and the comparison with other dc–dc converters are carried out. Finally, experiments on a 200-W dc–dc converter are carried out to verify the reliability of the converter.

An Ultrahigh Step-Down DC–DC Converter Based on Switched-Capacitor and Coupled Inductor Techniques

In this article, high step-down dc–dc converters are widely employed in data center applications. Due to the higher step-down conversion ratio in the new generation 48 V voltage regulator module, a conventional buck converter is not suitable for such applications. To conquer this problem, a novel dc–dc converter is proposed in this article to achieve an ultrahigh step-down voltage conversion ratio for data centers. The nonisolated topology can be optimally designed to integrate both the switched-capacitor and coupled inductor techniques, which allows zero-voltage-switching (ZVS) of all active switches to be achieved and improves high efficiency. In addition, the converter presents the advantages of lower voltage stress, ultrahigh voltage gain, common ground, and simple control strategy. A comprehensive analysis of the steady-state analysis, derivation of voltage gain, voltage stress, and ZVS condition is presented in detail. Finally, a 30 W, 48-to-1 V experimental prototype is built and tested, which validates the ultrahigh step-down voltage gain and soft-switching characteristic of the proposed converter. The maximum efficiency of the prototype is 89.1% and the efficiency is 81.4% in full-load condition.

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.

Intelligent Fuzzy Based High Gain Non-Isolated Converter for DC Micro-Grids

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

A topology of coupled inductor DC–DC converter with large conversion ratio and reduced voltage stress on semiconductors

This study presents a high boost DC–DC converter, integrates voltage multiplier cell, voltage lift capacitor, and coupled-inductor techniques to achieve a high-voltage gain. The proposed topology has the capability of extension without utilising any additional winding for a very large voltage conversion ratio. With utilising a passive clamp circuit and without requiring higher duty cycle values, the suggested converter obtains a large conversion ratio, low conduction losses, and reduced voltage stress of semiconductors with a steady value for the whole range of duty cycle. The converter operation principle is discussed and its steady-state operation is analysed in detail. Also, theoretic efficiency calculation and design guidelines of the topology are explained. Then, the proposed DC–DC converter is compared with similar configurations to indicate its advantages. Eventually, the validity of theoretic analysis is verified using experimental measurement results of the implemented prototype with a power rating of 226 W.

Partly isolated three‐port DC–DC converter based on impedance network

This study proposed a novel partly isolated three port converter (PITPC) based on a quasi-Z source converter for photovoltaic applications. Compared with the conventional quasi-Z source converter, the proposed DC–DC converter has dual input sources and uses the switched capacitors and coupled inductor techniques, helping the converter to gain a high voltage. To achieve the power flow control, the proposed converter uses only three power switches with low voltage stress and it is developed for hybridising photovoltaic panels, rechargeable batteries and isolated loads. For this purpose, the proposed PITPC can be easily reconfigured into dual-input single-output, single-input dual-output and single-input single-output modes; so it can even operate when the photovoltaic panel fails to provide energy to the load. Moreover, the study thoroughly discusses various converter operating modes and provides explanations and necessary relationships for circuit operations. The study also explains the control strategy as well as the pulse width modulation waveforms for the proposed converter. Simulation results from MATLAB/Simulink examine the proposed topology performance. The experimental results confirm the advantages claimed for the proposed converter; the results also show a well-distributed efficiency curve and a peak of 96.3%.

Design, analysis and experimental verification of a high voltage gain and high‐efficiency DC–DC converter for photovoltaic applications

With the rapid development of photovoltaic systems, high step-up dc–dc converters draw significant attention, which shows the design challenges for simple topology, high efficiency, reduce voltage stress, and long lifespan. This study proposes a new high voltage gain converter that utilises the primary boost conversion cell and integrates with both switched-capacitor and coupled-inductor techniques. The proposed topology is modular and extendable for ultra-high step-up voltage gain. The leakage energy is recycled by a clamp circuit to minimise the switch voltage stress and power loss. One distinctive feature is that the voltage stress on the diodes and switch becomes low as well as constant against the variation of the duty cycle. Furthermore, the coupled inductor alleviates the diodes reverse recovery losses. The steady-state analyses, operation principles, and design guidelines are presented comprehensively. A prototype circuit is constructed to test the maximum power point tracking operation with voltage conversion from 30 to 380 V at 300 W. Experimental results substantiate the theoretical analysis and claimed advantages. The proposed converter demonstrates maximum power point tracking capability and high conversion efficiency over a wide range of power. The prototype shows the weighted efficiency of 96.3% according to the EU standard.

Comprehensive Conception of High Step-Up DC–DC Converters With Coupled Inductor and Voltage Multipliers Techniques

Due to the plethora of non-isolated high gain step-up dc-dc converters presented in the literature, it has become important to comprehensively review and classify them, as well as to derive methods to generalize the usage of the commonly employed techniques. Motivated by this need, this paper not only proposes a new family of high gain step up dc-dc converter, but a generalized methodology to derive them from any classical dc-dc topology by applying a coupled inductor and voltage multiplier cells. For illustrating the methodology, high gain dc-dc converters based on the basic topologies (Buck, Boost, and Buck-Boost) are developed and analyzed. These converters are compared in terms of voltage gain, coupled inductor size, voltage stresses, total device rating, switching frequency effect in power loss, and output power regulation. Moreover, in order to verify the proposal, two practical experimentations are accomplished. Firstly, a prototype able to operate as any of the three basic topologies with different gain cells is developed for comparing theoretical, simulated, and experimental static gain results. Secondly, well-designed prototypes concerning to the Buck-, Boost-, and Buck-Boost-based converters are assembled for efficiency evaluation.

A High Conversion Ratio and High-Efficiency Bidirectional DC–DC Converter With Reduced Voltage Stress

A dc-dc converter is proposed to achieve a high voltage conversion ratio for bidirectional power flow applications. The nonisolated topology is optimally designed to integrate both the switched capacitor and coupled inductor techniques for high efficiency. The windings of the coupled inductor are stacked at the low voltage source, which transfers any leakage energy of the coupled inductor directly into the output port and simplifies the clamping circuit. The optimal design keeps the voltage stress on the main switches low for the entire duty cycle operation. Thus, the converter demonstrates the advantage of wide-voltage gain based on common ground and low and steady voltage stress in both buck and boost modes of its operation. Furthermore, the converter can realize zero-voltage switching through the synchronous rectifiers without requiring extra hardware circuitry to enhance conversion efficiency. The operation principle, including the steady-state analysis, dynamic modeling, controller design, efficiency analysis, and optimization, are discussed in detail and verified by the experimental test. The prototype substantiates the theoretical analysis and soft-switching operation. The converter exhibits the capability for load and line regulation and demonstrates a peak efficiency of 96.38% in the boost mode and 95.61% in the buck mode of operation.

A New Coupled Inductor Nonisolated High Step-Up Quasi Z-Source DC–DC Converter

In this article, a new nonisolated high step-up quasi Z-source (QZS) dc–dc converter with coupled inductor techniques is presented, which is suitable for renewable applications. The main advantages of the proposed topology are continuous input current, common ground between load and input dc source, low normalized voltage stress on the semiconductors (switch/diodes), and low total voltage stress on devices compared to the conventional QZS converter. However, increasing the turns ratio value of the coupled inductor windings not only limit the duty cycle but also leads to decrease the voltage stress on switch/diodes and increase the output voltage level. The operating performance of the proposed converter, theoretical analysis and comparison between the proposed converter and other published works (i.e., QZS converters) are provided. Finally, one prototype at 500 W is built and tested, which shows experimental results and theoretical analysis verify each other well.

An Interleaved High Step-Up Converter With Coupled Inductor and Built-In Transformer Voltage Multiplier Cell Techniques

This paper presents an interleaved converter that benefits the coupled inductor and built-in transformer voltage multiplier cell (VMC). Compared with the other converters with only a built-in transformer or only a coupled inductor, the combination of these techniques gives an extra degree of freedom to increase the voltage gain. The VMC is composed of the windings of the built-in transformer and coupled inductors, capacitors, and diodes. The voltage stress of MOSFETs is clamped at low values and can be controlled via the turns ratio of the built-in transformer and coupled inductor that increases the design flexibility. Moreover, the energy of the leakage inductances, is recycled to the clamp capacitors which avoids high voltage spikes across MOSFETs. In addition, the current falling rate of the diodes is controlled by the leakage inductances, and the reverse current recovery problem is alleviated. Meanwhile, due to the interleaved structure of the proposed converter, the input current ripple is minimized and the current stress of the power devices is decreased. All of these factors improve the efficiency of the proposed converter in high-current and high-voltage applications. The principle operation and steady-state analysis is given to explore the advantages of the proposed converter. Finally, a 1.3-kW prototype with 50–600 V voltage conversion is built to demonstrate the effectiveness of the proposed converter.

Implementation of high step‐up DC‐DC converter using voltage‐lift and coupled inductor techniques

SummaryA high step‐up DC‐DC converter using the voltage‐lift and coupled inductor techniques is presented in this paper. Only a single switch is utilized for this converter. The voltage‐lift and coupled inductor techniques are integrated to achieve high voltage gain for the proposed converter. The leakage energy of the coupled inductor is recycled for improving the conversion efficiency. In addition, the operating principles and steady‐state analyses are illustrated for continuous conduction mode. The boundary condition is analyzed in detail. To demonstrate the performance for the proposed converter, a prototype circuit is built in the laboratory.

Input‐parallel output‐series DC–DC converter for non‐isolated high step‐up applications

A high voltage conversion ratio interleaved boost converter is proposed with connecting input in parallel and output in series. By introducing coupled-inductor and diode-capacitor techniques, the converter can further extend the voltage gain. Because of the interleaved structure, the input current ripple can be reduced significantly, alleviating the electromagnetic interference problem. The test results of a 200 W prototype are provided and high efficiency above 93.5% is achieved.

A Novel High Step-up DC/DC Converter Based on Integrating Coupled Inductor and Switched-Capacitor Techniques for Renewable Energy Applications

In this paper, a novel high step-up dc/dc converter is presented for renewable energy applications. The suggested structure consists of a coupled inductor and two voltage multiplier cells, in order to obtain high step-up voltage gain. In addition, two capacitors are charged during the switch-off period, using the energy stored in the coupled inductor which increases the voltage transfer gain. The energy stored in the leakage inductance is recycled with the use of a passive clamp circuit. The voltage stress on the main power switch is also reduced in the proposed topology. Therefore, a main power switch with low resistance $R_{{\rm DS} ({\rm ON})}$ can be used to reduce the conduction losses. The operation principle and the steady-state analyses are discussed thoroughly. To verify the performance of the presented converter, a 300-W laboratory prototype circuit is implemented. The results validate the theoretical analyses and the practicability of the presented high step-up converter.

Development of Serial-Connected High Step-Up DC-DC Converter with Single Switch

In this paper, a novel high step-up DC-DC converter has been designed for fuel cell applications. The proposed high step-up converter can be used for various portable energy storage components such as fuel cells which are used for hybrid electric vehicles (HEV), and light electric vehicles (LEV).The proposed converter is integrated by boost circuit, voltage lift capacitor, and coupled-inductor techniques to achieve high step-up voltage and has several advantages. First, the circuit is controlled by one single pulse width modulation (PWM). Second, the converter consists of active clamp circuit to recycle the leakage inductance and send to output capacitor so that the voltage spike on active switch is suppressed and efficiency is also improved. Third, by using the winding of secondary boost circuit, and voltage lift capacitor techniques, the high voltage gain can be achieved without more than 50% duty ratio, and the slope compensation circuit can also be simplified.Finally, a 1k W prototype converter is implemented, to verify the performance of the proposed converter with input voltage 48V, output voltage 400V, and output power 1k W is also achieved. The highest efficiency is 92.96% at 400W, and the full-load efficiency is up to 90.48%.

Single-Stage Asymmetrical Half-Bridge Regulator With Ripple Reduction Technique

This paper presents a novel single-stage asymmetrical half-bridge regulator with input current ripple reduction technique. Most of the researched ripple reduction rectifiers cascade a boost-type converter integrates with the system. It is found that the asymmetrical half-bridge resonant converter, when the duty cycles are greater than 50%, can simplify the front end of the boost-type converter to a novel single-stage converter. In order to reduce the converter size and weight and to achieve better low-ripple input current, integrated magnetic and coupled inductor techniques are used in the proposed regulator. The operation principle and steady state analysis of the proposed regulator are discussed in detail. The prototype is built to demonstrate the system performance and effectiveness.

Single-Stage Autotransformer-Based VRM With Input Current Shaper

This paper presents a novel single-stage autotransformer-based voltage regulator module (VRM) with input current shaper. The proposed VRMs with autotransformer achieve possible reductions in switch rms current ratings and filter capacitance. This in turn leads to an increase in power density. The proposed topology can extend the converter duty cycle greater than 50% which the transient performance and overall efficiency may benefit from this. Most of the researched ripple reduction methods cascade a boost-type converter with the VRM system. It is found that the push pull converter, when the duty cycles of the switches are greater than 50%, can simplify the front end of the boost-type converter to a novel single-stage VRM. In order to reduce the VRM size and weight and to achieve near ripple-free input current, coupled inductor techniques are used in the proposed VRM. A prototype is built to illustrate the theoretical prediction.

Single-stage resonant converter with power factor correction

A novel single-stage resonant converter with power factor correction is presented. Most of the researched power factor corrected rectifiers cascade a boost-type converter with the system. It is found that the half-bridge resonant converter, when the duty cycles are greater than 50%, can simplify the front end of the boost-type converter to a novel single-stage converter. To reduce the converter size and weight and to achieve ripple-free input current, coupled inductor techniques are used in the proposed converter. The operation principle and system steady analysis of the adopted converter are discussed in detail. A prototype has been built to demonstrate the system performance.