Single Active Bridge Converter Research Articles

Single-Phase AC-DC-AC Multilevel Five-Leg Converter Based on a High-Frequency Transformer

This paper investigates a single-phase ac-dc-ac multilevel five-leg converter based on a high-frequency transformer. The system consists of a three-leg module with a full-bridge module connected to the shared part of the system. In the proposed configuration, the dc link of the three-leg module is supplied by the full-bridge module through a single active bridge converter. This feature improves the power quality and efficiency of the structure and simplifies the design of the control strategy compared to the conventional solution that uses floating capacitors. The proposed system is composed of a shunt unit and a series unit. The first one is responsible for compensating reactive power and harmonic currents, while the second one provides load voltage compensation against voltage sags and harmonics in the grid voltage. In addition, the proposed converter operates with low dc-link voltages in applications with the same input and output frequency, such as unified power quality conditioner. The model of the system, a space-vector pulse-width modulation and the overall control scheme are addressed. Simulations and experimental results are presented to confirm the feasibility of the proposed converter and the correctness of the design methodology.

Analyzing the Effectiveness of Single Active Bridge DC-DC Converter under Transient and Load Variation

Over the last couple of years, the use of DC-DC converters is being widely used in several applications. The need for a reliable and robust converter for application is very important because of the social impact that it can have on the losses in high-power electronics applications and output efficiency. This paper gives a comprehensive review of single-active-bridge (SAB) converters. The detail modelling and performance evaluation of SAB topology with PI controllers are also presented in this article. The performance of SAB topology is analyzed under transient and load variations. Due to the nonlinear behavior of SAB topology, the traditional PI controllers have not minimized transient disturbances. The major problem with the usage of conventional controllers and traditional configurations for the SAB converter are the ripples, which are generated in output voltage and current. These ripples severely affect the performance of the SAB converter. An effort has been made to analyze and contribute to the importance of a robust controller to mitigate the converter dynamics. This article also gives an in-depth dynamic analysis of SAB converters, which were controlled using PI controllers and failed to perform satisfactorily under non-linearities.

An Overall Analysis of the Static Characteristics of the Single Active Bridge Converter

The dual active bridge (DAB) converter has been extensively analyzed and used in recent years for applications where bidirectional power flow is required. The unidirectional version of the DAB, which replaces the active output bridge with a diode bridge, has been called the single active bridge (SAB). The static behavior of the SAB differs markedly from similar DC/DC converters and can provide interesting advantages in certain applications. This paper presents a thorough study of the static behavior of the single active bridge (SAB) converter in different conduction modes. This study focuses on the description of the conduction modes, marking the main differences compared to similar DC/DC converters. Moreover, the SAB can be designed to operate in conduction mode for a given power level with different performance. A design guide is proposed, and the performance of different designs are compared, quantifying current stresses in the semiconductors. Finally, the main contribution of this paper is the identification of the similarities and differences between the SAB and the buck, forward, and phase-shifted full-bridge converters. It should be noted that the position of the inductor, either before or after the output rectifier bridge, modifies the voltage withstood by the output diodes and depends on the conduction mode, the voltage conversion ratio of the converter, and consequently, its main operation and performance. Moreover, the operation of the SAB is similar to a current source in all conduction modes, and it is not usual in similar converters. This peculiar behavior can be useful in certain applications. The theoretical study, the different designs, and the predicted operation of the SAB in different conduction modes have been validated using simulation and experimental results.

An Analysis-Supported Design of a Single Active Bridge (SAB) Converter

Currently, due to its various applications, the high-performance isolated dc-dc converter is in demand. In applications where unidirectional power transfer is required, the single active bridge (SAB) is the most suitable one due to its simplicity and ease of control. The general schematic of the SAB converter consists of an active bridge and a passive bridge, which are connected through a high-frequency transformer thus isolated. The paper summarizes the behavior of this converter in its three operation modes, namely the continuous, discontinuous, and boundary modes. Later, the features of this converter, such as its input-to-output and external characteristics are discussed. Input-to-output characteristics include the variation of converter output power, voltage, and current with an input control variable i.e., phase-shift angle, whereas the external characteristic is the variation of the output voltage as a function of output current. In this discussion, the behavior of this converter in its extreme operating conditions is also examined. The features of the characteristics are elucidated with the help of suitable plots obtained in the MATLAB environment. Afterward, the specifications of a SAB converter are given and, based on the results of the analysis, a detailed design of its electrical elements is carried out. To validate the features and the design procedures presented in this paper, a prototype is developed. An element-wise loss estimation is also carried out and the efficiency of the converter has been found to be approximately equal to 93%. Lastly, the test was executed on this prototype, confirming the theoretical findings concerning this converter.

Analysis and Output Power Control of Unidirectional Secondary-Resonant Single-Active-Half-Bridge DC-DC Converter

Development of high-frequency-isolated DC-DC converters is underway for charging and discharging electric vehicle batteries. As a charger, a Single Active Bridge (SAB) converter, which is composed of a primary full-bridge converter, a high-frequency transformer, and a secondary full-bridge diode rectifier circuit, has been proposed as a unidirectional high frequency isolated DC-DC converter. In this paper, as a simple circuit configuration, a Secondary-Resonant Single-Active-Half-Bridge (SR-SAHB) converter, in which the primary and secondary circuits of the SAB converter are both half-bridge circuits, and a resonant capacitor connected in parallel to each secondary diode, is created. Due to the partial resonance on the secondary side, power transmission with unity transformer turn ratio and unity voltage conversion ratio can be realized, and a high total input power factor of the transformer can be achieved. As a result, the maximum voltage and current of the switching devices and the transformer voltage can be reduced. Moreover, soft switching in all commutations can be realized. The operation waveform is analyzed, and output power control is derived using the variable frequency control method. The effectiveness of the proposed SR-SAHB has been verified by experimental results using a 2.4 kW 20 kHz, 265 V laboratory prototype.

Analysis of Unidirectional Secondary Resonant Single Active Bridge DC–DC Converter

A compact and highly efficient unidirectional DC–DC converter is required as a battery charger for electrical vehicles, which will rapidly become widespread in the near future. The single active bridge (SAB) converter is proposed as a simple and high-frequency isolated unidirectional converter, which is comprised of an active H-bridge converter in the primary side, an isolated high frequency transformer, and a rectifying secondary diode bridge output circuit. This paper presents a novel, unidirectional, high-frequency isolated DC–DC converter called a Secondary Resonant Single Active Bridge (SR–SAB) DC–DC converter. The circuit topology of the SR–SAB converter is a resonant capacitor connected to each diode in parallel in order to construct the series resonant circuit in the secondary circuit. As a result, the SR–SAB converter achieves a higher total power factor at the high frequency transformer and a unity voltage conversion ratio under the unity transformer turns ratio. Small and nonsignificant overshoot values of current and voltage waveforms are observed. Soft-switching commutations of the primary H-bridge circuit and the soft recovery of secondary diode bridge are achieved. The operating philosophy and design method of the proposed converter are presented. Output power control using transformer frequency variation is proposed. The effectiveness of the SR–SAB converter was verified by experiments using a 1 kW, 48 VDC, and 20 kHz laboratory prototype.

System efficiency of a DC/DC converter‐based wind farm

AbstractIn this paper, three DC/DC converter topologies are evaluated from an energy efficiency point of view regarding their suitability for the application in a DC wind farm grid. The three investigated topologies are the fullbridge (FB) converter, the single active bridge (SAB) converter and the series parallel resonant (LCC) converter. The energy efficiency of the three converter topologies is evaluated for different control strategies. It is found that the LCC and FB converters have the lowest losses of the three topologies. It is also shown that the wide range of operation creates problems for all three converters. The SAB converter has the largest increase in losses caused by the wide range of operation. The FB converter also has an increase in losses for this variable operating range, whereas the LCC converter has large stresses for the input and output filters. By considering some further factors, such as the contribution to the energy production cost, the design and the control of the converters, the FB converter is found to be a suitable choice for wind farm application. Copyright © 2007 John Wiley & Sons, Ltd.