Conventional Dual Active Bridge Converter Research Articles

Loss Balance and Transient DC-Bias Suppression Strategies in Three-Level DAB Converters Modulated With Five DoFs

In the three-level (3 L) neutral-point-clamped (NPC) dual-active-bridge (DAB) converter, both sides of the converter can adapt to higher DC bus voltage, and more control degrees of freedom (DoFs) are provided compared to the conventional DAB converter. In the PWM generating technique with 5 DoFs, loss imbalance may develop in inner switches and outer switches because the leading or lagging arm is introduced, affecting system reliability. In addition, the transient DC-bias issue may also arise in the 3L-NPC-DAB converter modulated with 5 DoFs, leading to the transformer saturation. In this paper, two strategies are proposed to suppress the loss imbalance and the transient DC-bias in the current stress and magnetizing branches. It is also general and applicable for SPS, DPS, and TPS modulations. Furthermore, the loss balance strategy and DC-bias suppression strategy are applied in the PWM generation technique simultaneously without additional components. With the proposed solutions, the loss imbalances of inner switches and outer switches are suppressed and DC-bias in the integral of voltages on both sides of the 3L-NPC-DAB converter is abolished. The effectiveness of the proposed strategies is validated by a series of experiments conducted under varying situations.

A Dual-Transformer-Based Hybrid Dual Active Bridge Converter for Plug-in Electric Vehicle Charging to Cope With Wide Load Voltages

A dual-transformer-based hybrid dual active bridge (DAB) converter for plug-in electric vehicle charging to cope with wide load voltages is introduced in this article. The control degrees of freedom are extended by splitting the leg and transformer of the conventional DAB converter (CDABC) in two parts. Based on the numerical analysis, the full-domain four-variable closed-form optimal trajectories targeting at the minimum root mean square value of the leakage inductor current is attainted, and the unified-segmental control strategy is proposed to handle the working modes shifting without the current inrush. As a result, the conduction losses and switching losses can be significantly reduced in boost mode compared to CDABC. The discussed converter and control strategy are verified by a 1.0-kW prototype.

Practical Evaluation of Loss Reduction in Isolated Series Resonant Converter with Fixed Frequency Modulation

Nowadays, power converters with reduced cost, compact size and high efficiency are evolving to overcome the emergent challenges of renewable energy integrations. In this context, there is an increased demand for well-designed power converters in renewable energy applications to reduce energy utilization and handle a variety of loads. This paper proposes a center-tapped bridge cascaded series-resonant LC dual active bridge (DAB) converter for DC-DC conversion. The low part count of the proposed converter enables a high-power density design with reduced cost. The proposed converter offers reduced conduction losses as the reverse current is eliminated by adopting current blocking characteristics. Reverse current blocking also enables zero voltage switching (ZVS) and zero current switching (ZCS) over a wide operating range. Therefore, using a simple fixed frequency modulation (FFM) scheme offers a wide operating range compared to a conventional DAB converter. A thorough comparison of the proposed converter and a conventional DAB converter is provided based on conduction losses and switching losses to illustrate the performance improvement. Lastly, the effectiveness of the proposed converter is validated through simulation and experimental results.

An Enhanced Dual Active Bridge Converter With Full Domain ZVS by Utilizing a Simple Segment Control for Wide Voltage Range Applications

A dual-transformer-based enhanced dual active bridge (DAB) dc–dc converter for wide voltage range applications is introduced in this article. A power leg and transformer of the conventional DAB converter (CDABC) are split in two parts, leading to an expansion of the control freedom. Its wide voltage operating range does not rely on the small leakage inductor design and high transformer turns ratio. The root mean square value of the leakage inductor current is optimized with the ensuring of full domain zero voltage switching. The conduction losses and switching losses can be significantly reduced in buck mode compared to the CDABC. A simple segment control strategy with four control degrees of freedom is employed to avoid inrush from mode switching. The analysis and control processes are simplified, and the control loop is a simple closed voltage loop without the need for look-up table checking. The discussed converter and control strategy are verified by a 1.0 kW prototype.

RETRACTED: Control of Bidirectional DC-DC Converter for Micro-Energy Grid’s DC Feeders' Power Flow Application

Referred to by: Retraction notice to ‘Control of Bidirectional DC-DC Converter for Micro-Energy Grid’s DC Feeders' Power Flow Application' IJRED 11(2), 533-546International Journal of Renewable Energy Development, 12(6). https://doi.org/10.14710/ijred.2023.57139

A Novel Interleaved Parallel Bidirectional Dual-Active-Bridge DC–DC Converter With Coupled Inductor for More-Electric Aircraft

Although conventional dual-active-bridge (DAB) dc–dc converters have been applied in more-electric aircraft, the maximum transmission power of conventional DAB converters is still limited by its structure. In order to increase the maximum transmission power, this article proposes a novel interleaved parallel bidirectional DAB converter. Two bidirectional buck/boost converters are applied in low-voltage side of the proposed converter. So the voltage of transformer primary side would not be limited by the voltage of low-voltage bus and can be controlled by the duty cycle according to the modulation strategies. In this article, three phase-shift control methods are used for the proposed topology. From the analysis of operation modes and power characteristics of the proposed topology, compared with the single phase-shift (SPS), the extended phase shift can reduce the reactive power and current stress. The pulsewidth modulation (PWM) plus single phase-shift (PWMSPS) can achieve more than twice of the maximum transmission power of conventional DAB converter. Finally, test results verify the theoretical analysis and the validity of the proposed converter.

Split-Capacitor Dual-Active-Bridge Converter

In this article, a split-capacitor (SC) dual-active-bridge (DAB) converter is proposed. In the proposed converter, dc-link capacitors in both the input and output are split, and primary and secondary windings of the transformer are connected to midpoints of the input and output dc links, respectively. Although the switch current stress of the proposed converter is twice that of conventional DAB converter, its switch voltage stress is reduced to half. Therefore, the proposed converter has higher conduction loss than the conventional DAB converter, however, the switching loss can be reduced, which implies that the proposed converter is beneficial and can achieve higher efficiency than the conventional DAB converter as switching frequency increases. In addition, owing to the SC structure, no dc-blocking capacitors are required and the proposed converter can be readily connected to neutral-point-clamped or half-bridge-type converters without increasing the number of dc-link capacitors. To verify the performances of the proposed converter, 3-kW prototypes are built, tested, and compared.

Realization of High-Efficiency Dual-Active-Bridge Converter With Reconfigurable Multilevel Modulation Scheme

Efficiency optimization of dual-active-bridge (DAB) converters involves the minimization of both conduction and switching losses. However, it is challenging to achieve these two objectives simultaneously due to their conflicting nature, i.e., circulating current is required to realize zero-voltage switching (ZVS) but the presence of an excessive amount of the circulating current is the main cause of conduction loss and low efficiency. This dilemma has been common to conventional DAB converter topologies and modulation schemes which cannot provide sufficient degrees of freedom (DoFs) to the design of their operation modes. This paper is an illustration of the merits of utilizing reconfigurability of the operation mode as a new DoF in designing the operation of DAB converters to minimize both conduction and switching losses. The proposed DAB converter is designed to switch between two operation modes. For 25%-100% of the rated output power, a new modulation scheme based on the four-level ac voltages is proposed to achieve zero circulating current, zero backflow power, and full-range ZVS. Below 25% of the rated output power, the new modulation scheme transitions smoothly to the enhanced dual-phase-shift (EDPS) modulation scheme that continues to achieve zero backflow power and full-range ZVS while the incurred circulating current is moderated by operating the ac voltages at half-amplitude. The experimental results obtained from a 2-kW prototype show that, in comparison to conventional modulation schemes, the proposed modulation scheme is capable of maintaining the highest efficiency over the full output power range and greatly improves the reliability of switches due to full-range ZVS operation.

FRS-DAB Converter for Elimination of Circulation Power Flow at Input and Output Ends

Dual active bridge (DAB) converter is the most suitable converter to transfer high power with bidirectional power flow capability and isolation. However, it has the drawbacks of circulation power flow (CPF) and limited range of zero voltage switching (ZVS). To overcome these drawbacks, several modulation strategies have been proposed; however, the CPF can be eliminated either at input or output voltage ends. In order to eliminate the CPF at both input and output sides, a novel front and rear end switch DAB (FRS-DAB) bidirectional dc–dc converter has been proposed in this paper. It has the advantages of lower current stress, extension of ZVS range, higher power transfer capacity, and improved efficiency compared to the conventional DAB converter. The paper presents the detailed operating modes and analysis of power flow control for the proposed FRS-DAB converter. The operation and analytical results of the proposed converter have been verified through the experimental results using an FPGA Spartan 3AN processor.