Zero-voltage Transition Research Articles

A New Zero Voltage Transition Non-Isolated Bidirectional DC-DC Converter

A New Zero Voltage Transition Non-Isolated Bidirectional DC-DC Converter

Design of a new modular‐isolated‐forward‐based active snubber cell for power switches

AbstractIn this paper, a new modular‐isolated‐forward‐based active snubber cell (SC) for power switches is designed. In the proposed new SC, the zero voltage transition (ZVT) technique is implemented with a forward converter although the current counterparts generally use a flyback converter. In the converter with the new SC, the main switch is turned on with ZVT (full zero voltage switching [ZVS]) and turned off with ZVS, the main diode is turned off with zero current switching (ZCS), the auxiliary switch is turned on with ZCS and turned off with ZVS, and the parasitic capacitor energies are recovered. In addition, thanks to the forward converter, it has been possible to minimize the transformer leakage inductance and greatly reduce the current values of devices in the new SC. The new cell is applied to a single‐phase, grid‐connected, T‐type three‐level inverter (T2‐3LI) as an example. A detailed steady‐state analysis of this inverter was made, and the theoretical analysis was confirmed with measurement results taken from a prototype with 100 kHz and 3.3 kW values. Compared to its hard switching (HS) equivalent, in the converter with soft switching (SS) cell, the total circuit loss was reduced from about 248 W to 86 W, thus achieving an increase in the total efficiency from 92.5% to 97.4%.

Harris Hawks Optimization Algorithm for reducing THD using ZVT-ZCT-based QRCC: A comparative approach

This study proposes a novel solution to address harmonic issues in a Renewable Energy Resource System (RES) connected to the grid, using a Voltage Source Inverter (VSI) controlled by a QRCC based on Zero Voltage Transition and Zero Current Transition (ZVT-ZCT). We enhance system performance by integrating Harris Hawks Optimization (HHO) with the VSI. Key outcomes include evaluating the system's effectiveness in terms of voltage drop, current drop, real power, active power, and total harmonic distortion (THD). Notably, settling times for various converters are highlighted: 0.01 s for SEPIC, 0.008 s for CUK, 0.005 s for ZETA, and an impressive 0.0001 s for the Cascade converter. Under different operational conditions, open-loop operation yields a THD of 18.45%, reduced to 7.843% in closed-loop with PI controller. Optimization techniques further improve the system, achieving a low THD of 0.0549%. We emphasize the significance of MPPT-based INC-IR for cascade converters, resulting in a minimal switching loss of 0.38W, showcasing the system's efficiency in energy conversion.

Proposal of an applicable ZVT Quadratic Boost Converter Topology in Renewable Energies.

In this paper, a new active snubber cell is proposed to contrive a new quadratic Boost pulse width modulated (PWM) converter. This snubber cell provides zero voltage transition (ZVT) for the main switch of a converter. A New ZVT–PWM Quadratic Boost converter equipped with the proposed snubber cell provides most the desirable features of ZVT converters presented previously, and overcomes most the drawbacks of these converters providing a large voltage step-up. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, the main devices do not have any additional voltage and current stresses. In this study, a detailed analysis of the new converter is presented, and this theoretical analysis is verified exactly by simulation and a prototype converter.

A Novel High-Frequency Inverter With ZVT in a Wide Range of Duty Cycles and PFs

This paper presents a wide-range zero-voltage-transition (ZVT) high-frequency single-phase inverter. The proposed inverter consists of a full-bridge inverter and two auxiliary switches that are magnetically coupled to the output filter inductor via an additional winding. The auxiliary circuit provides zero-voltage switching (ZVS) for the full-bridge converter switches, while the auxiliary switches are turned on and off with zero current switching (ZCS). A combination of unipolar and bipolar modulation is used as the modulation technique to ensure soft-switching over a wide range of duty cycles and power factors. The proposed auxiliary circuit has a simple structure and does not require floating gate drives for the auxiliary switches. A 1.5 kW-400 kHz prototype has been developed to verify the theoretical analysis, demonstrating a significant increase in efficiency for both unity and non-unity power factors.

A Soft-Switching Bridgeless Buck-Boost Power Factor Correction Converter With Simple Auxiliary Circuit and Low Input Current THD

In this paper, a new bridgeless (BL) buck-boost power factor correction (PFC) converter using pulse width modulation (PWM) control is presented. The introduced structure operates in discontinuous conduction mode (DCM) to achieve the sinusoidal form of the input current inherently. The proposed converter utilizes a simple zero voltage transition (ZVT) circuit in which the auxiliary switch is turned ON and OFF under zero current switching (ZCS) condition, and the main switches turn ON and OFF under zero voltage switching (ZVS). Moreover, all diodes are turned OFF under ZCS condition, and the reverse recovery problem is solved. By reducing the number of semiconductor elements in the current flow path, conduction loss is minimized. Also, the proposed structure utilizes only one magnetic element. The above-mentioned advantages along with a low total harmonic distortion (THD) and high efficiency are the main benefits of the proposed structure compared to previous topologies. In addition, unlike the BL-buck converter, the input current dead angle is omitted without adding any extra components. Finally, a 500 W-100 kHz prototype at 90-265 Vrms input and 96 V output is implemented to verify the theoretical analysis and it illustrates the efficiency of 97.35 % and the input current THD is about 2.7 % at 220Vrms input voltage.

Design and Implementation of a Flyback-Assisted Wide-Range Fully Soft-Switched T-Type Inverter

A novel soft-switched three-level T-type inverter (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> I) is proposed in this paper. The proposed inverter provides turning-on by zero voltage transition (ZVT) and turning-off by zero voltage switching (ZVS) for main switches without any voltage or current stresses. The switching energies are transferred to the snubber capacitors, so the turning-off process of the main switches is improved by these snubber capacitors. Besides, the auxiliary switches are turned on by zero current switching (ZCS) and turned off by ZVS. Furthermore, all snubber diodes are operated by soft switching (SS), and the proposed SS snubber cell decreases the electromagnetic interference (EMI) noises. The novel snubber cell has a simple structure, ease of application, common-ground switches, and low-cost features. The theoretical analysis of the inverter is clarified, and the operating modes for steady-state analysis are presented in detail. The experimental results rated 1 kW output power and 100 kHz switching frequency are provided to justify the theoretical analysis. The proposed unique snubber cell can be easily implemented in other three-level inverters (3LIs), and the practice is demonstrated in the paper.

A Family of Zero-Voltage-Transition Magnetic Coupling Bidirectional DC/DC Converters

In this paper, a family of zero-voltage-transition (ZVT) magnetic coupling bidirectional DC/DC converters (BDCs) is proposed. The coupling inductor has two functions: to serve as a filter; and to provide the auxiliary current. In addition, the phase-shifting control method is used to reduce the conduction loss of the auxiliary circuit. The auxiliary switches are all working under zero-current-switching (ZCS) conditions; thus, all the switches have no switching loss. Furthermore, compared with the traditional ZVT implementation method based on the coupled inductor, this topology avoids the input source current notch and has a smaller ripple. Finally, a prototype of 800 W BDC is built to verify the feasibility of the proposed topology.

Ripple Steering Interleaved Boost PFC Converter Analysis, Simulation, and Experimentation

A zero-voltage-transition (ZVT)-based ripple steering interleaved boost converter is proposed in this paper for power factor correction. The ZVT auxiliary circuit enables soft-switching, reducing the current input ripple and the stress on the main circuit device. The proposed converter achieves better performance in terms of THD and power factor with fewer elements, reducing size and cost. A non-linear current control strategy is employed to suppress harmonics in the supply current. The theoretical study and design are validated through simulations and laboratory tests. Automatic current sharing characteristic is an added advantage when interleaved boost converters are employed. In this work, the devices in the semiconductor power are soft switched and consequently, the losing switches are eliminated, thereby making the across the switchers there is stress voltage which is very less. The results show that the converter achieves ZVT operation, reducing switching losses and improving efficiency. The measured supply current THD is 3.029%, and the switching frequency hardly affects the soft switching performance. The converter proposed reduces the stress on the devices and significantly lowers the switching loss when compared to hard switching. The proposed ZVT-based IBC accomplishes soft switching operation and lessens the number of power devices, improving power factor and efficiency.

Novel Quadratic High Gain Boost Converter With Adaptive Soft-Switching Scheme and Reduced Conduction Loss

In this article, an improved soft-switching quadratic boost converter is proposed. Instead of inserting an additional active clamp or auxiliary zero-voltage transition circuit at the switching node, the proposed topology connects the high-voltage switching node to the input diode node by replacing one of the input diodes with a low-rated switch. The proposed topology can attain soft-switching condition for all the switches and input diode turns- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> under zero-current switching (ZCS). The operation of input-side switch not only aids zero-voltage switching (ZVS) turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> for the main switch but also helps in reducing the conduction loss. Also, the input-side switch operates under ZCS turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and ZVS turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> , making it a loss economical solution. An adaptive timing scheme for driving the input switch is proposed, which can ensure soft-switching condition under varying gain and load range. The detailed operational modes, analysis, and design considerations of the proposed topology are presented. A 250 W hardware prototype is built to validate the performance of the proposed converter operating at 100 kHz switching frequency. Results with adaptive soft-switching scheme shows that the converter is modulated to achieve its best efficiency condition under various system conditions. A peak efficiency of 96.1% at 155 W and efficiencies above 95.75% over a wide load range are achieved using all Si devices.

An Interleaved Soft Switched High Step-Up Boost Converter With High Power Density for Renewable Energy Applications

In this article, a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or ac grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. To provide soft-switching condition in the wide range of output power, a new zero-voltage transition auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements, and only one auxiliary gate-driver. These merits provide very high efficiency at both full-load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the interleaved converter prototype with 400-V output voltage at 400 W and 100 kHz switching frequency are provided. The full load efficiency of 98% was achieved and the power density was observed 1.9 W/Cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

ZVT High Step-Up Boost Converter With Wide Input Voltage and Wide Output Power for Renewable Energy Applications

In this article, a high-efficiency, high step-up dc–dc converter is introduced by utilizing a new soft-switching circuit based on the zero-voltage transition (ZVT) technique. Soft-switching performance is independent of the output load and input voltage. The simple auxiliary circuit benefits from a low number of components. The resonant circuit comprises merely one switch and one small capacitor, and in comparison to the existing ZVT high step-up converters, no extra auxiliary diode and resonant inductor are used to provide soft switching. The proposed auxiliary circuit can be applied to coupled inductor (CI)-based step-up topologies, because of exploiting the leakage inductance of the CI cell in the resonant network. Providing soft-switching performance for all the semiconductor elements alleviates the reverse recovery and switching losses, which considerably enhances the efficiency. The proposed topology is a competitive structure in terms of efficiency, voltage gain ratio, and the number of components due to the mentioned features. The theoretical results are validated on a 200-W laboratory prototype with a 400-V output voltage.

Resonance Network Structuring Method for Zero-Voltage-Transition Transformerless Inverters

In this article, the soft-switching technique is an important way to achieve high frequency and high conversion efficiency for transformerless grid-connected inverters (TLIs) with distributed photovoltaic generation. Meanwhile, new technical standards require TLIs to have a wider power factor operation range to support grid voltage, which means that there are positive power regions and negative power regions in a grid period. In order to fulfill soft-switching for high-frequency working switches during all power regions, a pair of zero-voltage-transition (ZVT) resonant cells with different capacitor connections are first derived in this article, and two equivalent two-quadrant resonance networks are originated by using the pair of ZVT resonant cells alternatively. Furthermore, defined connection points of the obtained two-quadrant resonance networks in TLIs are explored, and a guideline to invent new ZVT-TLIs is summarized. As a result, two families of ZVT-TLIs with full power factor range (ZVT-TLIs-FPF) are obtained. In order further to verify the correctness of the proposed guideline, the obtained ZVT-HERIC-FPF is taken as an example to analyze its operation principle. Finally, experimental results from a 1 kW prototype at 100 kHz are provided to verify the effectiveness of the proposed structuring method.

A 48–80-V Input 2-MHz Adaptive ZVT-Assisted Bus Converter With Light-Load Efficiency Improvement

This article presents a dc–dc bus converter with a new soft-switching scheme. Adaptive zero-voltage transition (AZVT) is proposed to enable ZVS turn-on of the power FET via a ZVT auxiliary branch for removing the switching loss of the converter. In AZVT, the current of the auxiliary branch is discontinuous and its peak value is controlled to decrease with the load current. This feature not only minimizes the conduction loss of the auxiliary branch but also significantly improves the light-load power efficiency of the converter. In addition, a high-voltage flipped current sensor (HVFCS) is developed to enable fast and accurate auxiliary inductor current sensing for supporting proper AZVT control in the MHz range. The proposed converter was validated using three 100-V e-mode GaN FETs together with the proposed AZVT controller and gate drivers implemented in a 0.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> , 120-V CMOS process. The proposed AZVT converter supports a wide input range from 48 to 80 V, operates at 2 MHz, and provides the power efficiency improvements up to 14.5% and 8.7% over the hard-switching operation at the input voltages of 48 and 80 V, respectively. Compared with the state-of-the-art designs, the proposed converter not only obtains >90% power efficiency over a load range of 6–60 W but also improves light-load efficiency by over 5% with more than two times higher switching frequency.

A new zero voltage transition interleaved flyback converter

The paper introduced a new zero voltage transition (ZVT) interleaved flyback converter which has two similar flyback converters. Two flyback converters are in parallel connection and auxiliary circuit in this converter provides ZVT condition for all of the main switches and also provides zero current switching and zero voltage zero current switching (ZVZCS) conditions for the auxiliary switch. Also, ZCS conditions are created for diodes turning off, so reverse recovery problem is solved. The auxiliary circuit in the suggested converter is modular, and by adding parallel branches to the flyback circuit, this circuit can provide soft switching conditions for all switches without significantly change. A complete analysis of the converter is provided and its operating intervals are explained. A 180 W laboratory prototype of the converter is made to approve the theoretical calculations. The experimental results show 7.7% increase in efficiency.

A novel zero voltage transition boost converter and artificial neural network‐based estimation of converter efficiency

AbstractIn this paper, a novel zero voltage transition (ZVT) boost converter is proposed, and the overall efficiency of the converter is predicted with an artificial neural network (ANN) model. In the proposed converter, the main switch is turned on by ZVT and turned off by zero voltage switching (ZVS). Also, the other semiconductor elements operate by soft switching (SS). Besides, the proposed snubber cell has the bidirectional direct power transfer feature. The theoretical analyzes of the converter are verified by an prototype having 50 VDC input voltage, 100 VDC output voltage, 250 W output power, and 100 kHz switching frequency. The overall efficiency of the converter in hard switching (HS) condition is increased from 87.2% to 95.4% thanks to proposed snubber cell. Moreover, the efficiency of converter at HS operation is estimated with ANN. For this estimation, 110 efficiency values are obtained based on the different switching frequency and the output power values. When the actual efficiency measurements and the estimation results obtained with the ANN model are compared, it is seen that the results overlap and is obtained very close result to the truth by ANN. Thus, owing to the ANN model, the semiconductor power elements will not need to be operated at high frequencies and overheating, and the damaging to the elements will be prevented. Finally, the efficiency curve measurement of the converter takes long time in the experimental study when it takes highly short time as a few minutes in the estimation with ANN.

Soft-Switching Full-Bridge Topology with AC Distribution Solution in Power Converters’ Auxiliary Power Supplies

The auxiliary power supply in a power converter is a key topic in the optimization of the converter’s low-voltage electronic circuit performance. In this article, a low-voltage DC-AC soft-switching full-bridge topology, with an innovative, driven technique to achieve a zero-voltage transition, is presented and discussed. The full-bridge converter drives a high-frequency transformer (called the main transformer) that on the secondary side, distributes an AC voltage and current to the several electronic circuit’s supplies. Every power supply is composed of an HF transformer (called load transformer) that converts the AC secondary voltage of the main transformer to the voltage and current levels requested by the electronic circuit. In this paper, the operating conditions are first investigated by several simulation results. Furthermore, an actual DC-DC power converter is used as a workbench for an experimental investigation of the effectiveness of the proposed auxiliary DC-AC soft-switching topology, and the AC distribution approach, to realize the several points of load power supply requested. Finally, the advantages and drawbacks of this auxiliary power supply solution are critically discussed, providing guidelines for the power converter designer.

A 300 kHz, 63 kW/L ZVT DC–DC Converter for 800-V Fuel Cell Electric Vehicles

In this article, one of the very first 800-V fuel cell DC–DC converter (FDC) is developed for the next-generation fuel cell electric vehicles. The higher boost gain ratio and switching loss associated with increasing dc-link voltage, along with gradually increasing power density and efficiency demanded in the next-generation EV power converters, make the conventional boost converter not suitable for 800-V FDC. This article proposes a new design approach in which a zero voltage transition (ZVT) high step-up dual floating output boost converter (DFOBC) is introduced. Due to higher voltage gain, the operating duty cycle of DFOBC is reduced and lies in the vicinity of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> = 0.5, which reduces filter size. The ZVT cells greatly reduce switching losses at 300 kHz, which enables using only a single discrete SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> for the main switch of 25-kW module, contributing to volume and cost reduction. Moreover, the proposed converter successfully demonstrates the possibility of using planar core and printed circuit board (PCB) windings at 100-kW power level, which is rarely seen in previous works. Finally, a 25-kW prototype of the proposed ZVT DFOBC is built and test. The power density of 63 kW/L excluding heatsink is achieved. The peak and full-load efficiency are measured to be 99.0% and 97.7%, respectively.

A new interleaved ZVT high step-up converter with low input current ripple

ABSTRACT In this paper, an interleaved zero-voltage transition (ZVT) high step-up converter is presented. The proposed converter has the coupled inductors and the switched capacitor to increase the voltage gain, but the coupled inductors are not at the input, so the input current is continuous, which makes this converter suitable for photovoltaic systems. Since all switches, including main and auxiliary switches, are switched at zero-voltage condition, the efficiency of the converter is high. Therefore, the voltage stress on the switches has also decreased. The proposed converter has been thoroughly analysed and a prototype has been developed to prove theoretical analyses. The experimental results show an improvement of 4% in efficiency and 9 dB.µV in noise compared to hard switching counterpart.

A Universal ZVT Design for a Family of Multiphase Interleaved High Step-Up Converters With Minimized Voltage Stress and Wide Operating Range

Multiphase interleaved boost diode-capacitor (MIBD) converters, as the combination of multiphase interleaved input and voltage multiplier cells (VMCs), provide a preferred solution for both high voltage gain and high-efficiency application. This article proposes a universal zero-voltage transition (ZVT) circuit design method for a family of MIBD converters with different VMC structure and cell number. Compared with other soft-switching (SS) design methods, there is no extra voltage stress for all the semiconductor devices. An auxiliary circuit consisting of two low-voltage rating switches, two diodes, two capacitors, and one small inductor is integrated into the hard-switching (HS) two-phase interleaved boost diode-capacitor (TIBD) converters to provide zero-voltage switching (ZVS) turn-on and turn-off for the main switches and zero-current switching (ZCS) turn-off for all the diodes. Besides, the auxiliary switches turn on under ZCS. All the SS is accomplished within a wide duty cycle and power rating. From the comprehensive comparison, the constructed converters' performance exceeds that of ZVS converters published in the recent literature. Furthermore, the extendable high voltage gain, low input current ripple, low voltage stress, and simple parameter design characteristics of HS MIBD converters are also conserved. Finally, a 320-W laboratory prototype is implemented to validate the theoretical analysis.