Wide ZVS Research Articles

Modulated-Coupled-Inductor-Based ISOP Phase-Shifted Full-Bridge Converter With Wide ZVS Range and Reduced Duty-Cycle Loss

Modulated-Coupled-Inductor-Based ISOP Phase-Shifted Full-Bridge Converter With Wide ZVS Range and Reduced Duty-Cycle Loss

Closed-Form Continuous Asymmetrical Hybrid Modulation, Ensuring Wide ZVS Range and Seamless Transients for DAB Converters

Closed-Form Continuous Asymmetrical Hybrid Modulation, Ensuring Wide ZVS Range and Seamless Transients for DAB Converters

Harmonic Current Control for Wide ZVS Operation of Single-Stage WPT Resonant Converters

Harmonic Current Control for Wide ZVS Operation of Single-Stage WPT Resonant Converters

Offset Current Modulation Technique for Wide ZVS Range in Dual Active Bridge (DAB) DC-DC Converter

Offset Current Modulation Technique for Wide ZVS Range in Dual Active Bridge (DAB) DC-DC Converter

LLCC Resonant Converter With Wide ZVS Range and Low Voltage and Current Stress

LLCC Resonant Converter With Wide ZVS Range and Low Voltage and Current Stress

Ripple-Free Bidirectional DC–DC Converter With Wide ZVS Range for Battery Charging/Discharging System

A ripple-free bidirectional dc-dc converter (BDC) with wide soft-switching range is proposed for battery charging/discharging application in this paper. On battery side, the current ripple can maintain zero by two-phase interleaving technology in spite of the battery voltage and transfer power variation. Through series connection, high voltage conversion ratio and reduced voltage stresses of switches can be achieved effectively. The built-in transformer technology allows for a small magnetic component size, due to its inherent saturation avoidance. With the proposed control law, the control variables can be decoupled. The duty cycle is fixed by battery side voltage while the transfer power can be regulated monotonously by phase-shift angle. Theoretical derivation illustrates that soft switching can be obtained in all switches by adopting proper parameter design. Furthermore, comparative analysis shows the proposed converter is suitable for battery charging/discharging applications. The experimental verification proves the merits of the proposed converter by a 40-60V/400V 1 kW prototype.

A Mode-Switching-Based Phase Shift Control for Optimized Efficiency and Wide ZVS Operations in Wireless Power Transfer Systems

This paper proposes a mode-switching based phase shift control (MS-PSC) for wireless power transfer (WPT) systems, which is able to achieve power regulation, load matching, and wide ZVS operations simultaneously without using additional dc-dc converters. Based on the mode transitions between the full-bridge, mixed-bridge, and half-bridge modes of both the inverter and the rectifier, the MS-PSC method guarantees a wide-range ZVS with minimized circulation of reactive power. Therefore, the system efficiency is improved over a wider power range compared to the conventional triple-phase-shift (TPS) control and the existing hybrid modulation control. The principles of different operating modes are analysed. Then, the implementation of the proposed MS-PSC method and the mode selection strategy are presented. Finally, the effectiveness of the proposed MS-PSC method is validated in a WPT prototype. Experimental results show that the proposed MS-PSC method can achieve a high overall efficiency in a wide power range. Compared with the conventional TPS control, the MS-PSC method further optimizes the efficiency in 10%-63% of the rated power, with efficiency improvements ranging from 1.5% to 6%. As a result, the system efficiency remains at 93.5%-96.1% in the power range of 1-10 kW, with the transformer coupling coefficient k=0.19.

Design of a 7.5 kW Dual Active Bridge Converter in 650 V GaN Technology for Charging Applications

High-voltage GaN switches offer low conduction and commutation losses compared with their Si counterparts, enabling the development of high-efficiency switching-mode DC–DC converters with increased switching frequency, faster dynamics, and more compact dimensions. Nonetheless, the potential of GaN switches can be fully exploited only by means of accurate simulations, optimal switch driving, suitable converter topology, accurate component selection, PCB layout optimization, and fast digital converter control. This paper describes the detailed design, simulation, and implementation of an air-cooled, 7.5 kW, dual active bridge converter exploiting commercial 650 V GaN switches, a compact planar transformer, and low ESL/ESR metal film capacitors. The isolated bidirectional converter operates at a 200 kHz switching frequency, with an output voltage range of 200–500 V at nominal 400 V input voltage, and a maximum output current of 28 A, with a wide full-power ZVS region. The overall efficiency at full power is 98.2%. This converter was developed in particular for battery charging applications, when bidirectional power flow is required.

A Multi-Inverter High-Power Wireless Power Transfer System With Wide ZVS Operation Range

Conventional high-power wireless power transfer (WPT) systems that are required to deliver power over a wide operating range suffer from issues like hard switching, poor current sharing, and unwanted cross-coupling issues. This article proposes a new resonant inductor integrated-transformer-based multi-inverter to improve the WPT power rating without compromising performance. Viable modulation schemes of the proposed system are analyzed, and a hybrid modulation scheme is proposed for wide-range power regulation. To further investigate the feasibility of the proposed system, the power transfer capacity, current sharing among multiple inverters, and the soft switching regions are studied. A 14-kW <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> – <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> WPT experimental system with three parallel inverters is built, which achieves 93.5% efficiency, demonstrating the high performance of the proposed system. This article is accompanied by a video demonstrating these experiments.

Variable Saturation Inductor-Based Full Bridge Converter With Wide ZVS Range and Reduced Duty Cycle Loss

A phase-shifted full-bridge (PSFB) converter is widely used in various applications due to its soft-switching characteristics. However, one of the recognized shortcomings of the PSFB converter is that it cannot simultaneously have a wide soft switching range and a small secondary-side duty cycle loss. The shortcoming hinders the high frequency and high efficiency of the converter. In this article, the change of the energy demand of the converter on the external series inductor with input voltage and load is analyzed. On this basis, a variable saturation inductor with controllable energy is proposed to meet the energy demand and solve the problem of core heating. The controllable change characteristics of the inductor energy are studied directly instead of the controllable change of the inductance value. By adjusting the inductor energy, the PSFB can not only achieve soft switching under light loads, but also reduce duty cycle loss under heavy loads. Theoretical analysis and experimental verification are carried out on the soft switching and duty cycle loss of the converter. Since the transformer ratio can be increased due to thesmaller duty cycle loss. The efficiency of the converter can be further improved.

Comprehensive Optimization Modulation Scheme of Low Current Level and Wide ZVS Range for Dual Active Bridge Converter With Dead-Zone Control

Due to the contradiction between

Analysis of novel phase-shifted full-bridge converters with wide ZVS range reduced filter requirement

Analysis of novel phase-shifted full-bridge converters with wide ZVS range reduced filter requirement

An Si MOSFET-Based High-Power Wireless EV Charger With a Wide ZVS Operating Range

This article proposes a new digitized modulation scheme suitable for a high-power wireless electric vehicle charger employing an integrated boost multilevel converter (IBMC) as its primary-side converter. Using the proposed modulation scheme, an IBMC can generate a boosted square-wave-shaped ac voltage with a controllable amplitude, enabling it to regulate the power efficiently over a wide load and/or coupling range while achieving zero voltage switching for all switches. This article focuses on the steady-state operating principles of the proposed digitized modulation scheme. Key practical considerations, such as capacitor voltage balancing and semiconductor device selection, are highlighted. To verify the benefits of the proposed modulation scheme, an SAE J2954 WPT2/Z2 compliant wireless EV charger prototype that uses an IBMC as the primary converter is designed and built. 200 V Si MOSFETs are employed in the 12 submodules (SMs) that compose the IBMC. The secondary side employs a passive rectifier, and the power flow is controlled using only the IBMC. This system maintains an efficiency between 90% and 93% when regulating power transfer at 7.7 kW under a 220% variation in coupling factor (i.e., 0.14–0.31) and a 150% variation in battery voltage (i.e., 280–420 V).

Secondary Side Cascaded Winding-Coupled Bidirectional Converter With Wide ZVS Range and High Conversion Gain

In this article, a secondary side cascaded bidirectional dc-dc converter (SSC-BDC) is proposed with the winding-coupled structure for the bidirectional operations of power flow, which features high voltage gain, full range of soft switching, low current ripple in low voltage side, and extended duty cycle range. Derived from a current-fed dual active bridge converter, the interleaved buck/boost circuit in the primary side is cascaded with the secondary side of full-bridge circuit through the winding coupled inductor to achieve high voltage gain. The differential voltage is designed to generate the bias current to realize soft switching of the eight power switches within a wide range of load variation. Meanwhile, pulse width modulation (PWM) plus phase-shift modulation is used to eliminate backflow power and increase conversion efficiency. The operation principle, steady-state analysis, and comparison result are presented in detail. Finally, a 1-kW experimental prototype is constructed to verify the feasibility of the SSC-BDC, and the correctness of the theoretical analyses is validated by experimental results.

Low-Cost Single-Switch Bidirectional Wireless Power Transceiver for Peer-to-Peer Charging

A single-switch bidirectional wireless power transceiver aiming at cost-effective and reliable peer-to-peer charging applications is proposed. The transceiver comprises a single-switch resonant power circuit, a frequency synchronization circuit, and a microcontroller. It can operate in either transmitter mode or receiver mode. As a transceiver, the required number of semiconductor devices is minimized, i.e., only single active switch is used. This makes it easy to implement and is relatively reliable and cost-effective. The bidirectional power flow and dc output regulation are achieved solely by adjusting the phase shift ratio of the control signal. To make the phase shift power control feasible and to secure wide operating range ZVS operation, a holistic design method is provided such that the ac voltage waveforms remain relatively constant and independent of the coupling and the phase shift ratio changes. The operating principles, steady-state and dynamic models, and design considerations are discussed. Simulation and experiments are performed on a prototype based on the design. The results validate the features of relatively constant ac voltage waveforms of the transceiver, the effectiveness of the time-domain model, the ZVS turn on and turn off operations over wide operating power range, phase shift regulated transmission power control, bidirectional power flow, and accurate output regulation.

Leakage Inductor Current Peak Optimization for Dual-Transformer Current-Fed Dual Active Bridge DC–DC Converter With Wide Input and Output Voltage Range

A current-fed dual active bridge dc-dc converter using dual transformers is proposed for the energy storage system and electric vehicles, which is suitable to be used in wide input and wide output voltage range bidirectional power flow applications. Optimized switching pattern and the coupling relationship among all the controlled variables have been explored in order to minimize the leakage inductor current peak and rms value in spite of the load and voltage conversion gain variation, which can reduce the current stress in switches and conduction loss. Furthermore, wide ZVS range can be achieved. The preferred optimized working modes and real-time closed-loop implementation by employing the proposed control strategy are given. The ZVS conditions for each switch are discussed in detail. The turns ratio design is also demonstrated. The effectiveness of the proposed method is verified by the experimental results of a 1-kW prototype.

A wide load range ZVS high voltage gain hybrid DC‐DC boost converter based on diode‐capacitor voltage multiplier circuit

A wide load range ZVS high voltage gain hybrid DC‐DC boost converter based on diode‐capacitor voltage multiplier circuit

Three-Level DC-DC Controlled-Source Circuit of Marine Electromagnetic Detection Transmitter

Nowadays, marine electromagnetic method is a geophysical method which can effectively explore natural gas hydrate (NGH) resources. This method acquires seafloor structure and distribution laws of mineral resources by transmitting high-power electromagnetic waves to the seafloor, and its detection depth relies on the intensity of transmitted electromagnetic waves. At present, marine electromagnetic transmitter is not proper for transmission of high-power electromagnetic waves, and therefore, a novel controlled-source circuit of soft switching three-level marine electromagnetic transmitter is proposed in this paper, one step-down winding is added at the secondary side of high-frequency transformer in series connection with a linear inductor, asymmetric phase-shift PWM control is used, and soft switching of controlled-source circuit within the overall power range is realized. A detailed analysis of the operation process and circuit characteristics is given, and finally, a prototype is designed. Experimental results indicate that this circuit is of wide ZVS range and high efficiency, and it meets requirements for deep-sea detection of high-voltage power supply transmitter.

Voltage-Fed Push-Pull PWM Converter Featuring Wide ZVS Range and Low Circulating Loss with Simple Auxiliary Circuit

Voltage-Fed Push-Pull PWM Converter Featuring Wide ZVS Range and Low Circulating Loss with Simple Auxiliary Circuit

Asymmetrical hybrid‐controlled half‐bridge LCC resonant converter with low conduction loss and wide ZVS operation range

An asymmetrical hybrid-controlled half-bridge LCC resonant converter which integrated a buck–boost converter and a half-bridge LCC resonant converter is proposed. It benefits with wide soft switching range, low conduction loss and high power density. By utilising an asymmetrical hybrid control strategy, its switching frequency and duty ratio can be adjusted simultaneously. The proposed LCC resonant converter maintains output voltage regulation and zero-voltage switching of switches in wide input voltage and load variation range. Experiment results of a 500 W prototype are provided to verify the theoretical analysis results.