Triple Active Bridge Converter Research Articles

A decentralized coordinated control scheme for the DC network with a multiport converter

For complex networks with multiple subgrids formed by solid-state transformers, existing studies primarily focus on coordination within the networks in islanded mode, overlooking cooperation in grid-connected mode. To address this gap, this paper proposes a coordinated control scheme for the triple active bridge (TAB) converter in the grid-connected DC network. By establishing a droop relationship between the input power and the voltage difference, the TAB converter facilitates coordination between the utility grid and the DC network. The energy exchange with the utility grid is not only regulated by the TAB converter but also adjusted according to the utility grid state. So, the proposed scheme effectively facilitates coordination between the higher- and lower-level networks, strengthening system stability. Besides, the proposed scheme employs a unified control structure, which has power sharing and voltage regulation capabilities in grid-connected mode, as well as operating in islanded mode. This control structure enables the TAB converter to seamlessly transition across different operation modes, avoiding mode switching process and reducing the control complexity. Moreover, the proposed scheme is decentralized which negates the necessity for communication links, bolstering the system reliability. Lastly, the feasibility of the proposed scheme is analyzed in theory and validated by the hardware-in-loop tests.

Triple active bridge converter in nanogrid applications: A direct interface for photovoltaic modules and storage

Triple active bridge converter in nanogrid applications: A direct interface for photovoltaic modules and storage

Simplified control of TAB converter for scalable multibattery charging system

SummaryThe integration of distributed energy resources (DERs) into DC microgrids has become commonplace in many applications, including electric vehicle (EV) systems that use batteries, fuel cells, and supercapacitors as energy storage systems. To make a sustainable charging system for electric vehicles, DERs can be used in conjunction with the grid. In many cases, charging systems based on isolated DC‐DC converters, such as the dual active bridge (DAB) converter, with various controls, are typically used. However, integrating multiple DERs at the common input DC link can result in a loss of isolation in the DAB converter and also leads to problems with circulating current. To maintain isolation, multiple DAB converters can be used, but this increases the system's size. Alternatively, the multiport isolated DC‐DC converter can address such issues but introduces complexities such as cross‐coupling between power flow. This paper proposes a hardware decoupling control methodology for a triple active bridge (TAB) based isolated DC‐DC converter, with power routing features for simultaneously charging two EV's battery stack. Through hardware decoupling control, appropriate passive components are designed and selected to connect with the individual H‐bridges of the TAB for power decoupling. The paper discusses the cross‐coupling issue in the TAB and describes a methodology derived from mathematical expressions for achieving power decoupling. For validation of the control, a 5 kW system is modeled in MATLAB Simulink, and the results demonstrate how the proposed approach overcomes cross‐coupling issues. Further, a 500 W hardware prototype has been developed to validate the proposed approach.

A Unified Modeling Approach for Steady State and ZVS Analysis of a Triple Active Bridge Converter

A Unified Modeling Approach for Steady State and ZVS Analysis of a Triple Active Bridge Converter

Simplified Power Decoupling Control of Triple Active Bridge Converter in Polar Coordinate System for EV Application

Simplified Power Decoupling Control of Triple Active Bridge Converter in Polar Coordinate System for EV Application

Streamlined QPS Control with Magnetizing Current Injection for All-ZVS Operation in Decoupled-Type Triple Active Bridge Converters

Streamlined QPS Control with Magnetizing Current Injection for All-ZVS Operation in Decoupled-Type Triple Active Bridge Converters

Streamlined QPS Control with Magnetizing Current Injection for All-ZVS Operation in Decoupled-Type Triple Active Bridge Converters

Streamlined QPS Control with Magnetizing Current Injection for All-ZVS Operation in Decoupled-Type Triple Active Bridge Converters

A Simplified All-ZVS Strategy for High-Frequency Triple Active Bridge Converters With Designed Magnetizing Inductance

A Simplified All-ZVS Strategy for High-Frequency Triple Active Bridge Converters With Designed Magnetizing Inductance

Open-Circuit Fault Diagnosis and Tolerant Method of Multiport Triple Active-Bridge DC-DC Converter

The triple active-bridge (TAB) DC-DC converter, as a representative multiport converter, is widely used in DC distribution system. The open-circuit fault (OCF) of TAB seriously threatens the system safety operation. In this article, an OCF diagnosis and tolerant method is proposed for TAB converter to reduce the impact of OCF. The fault mode of TAB converter is first analyzed. Based on the analysis, an fault diagnosis method using the average value of bridge arm midpoint voltage and inductance current is proposed. To eliminate the DC bias and over-current caused by OCF, the symmetrical topology is constructed by modulation reconfiguration, and corresponding fault-tolerant operation strategies are proposed for OCF at different locations. When the OCF occurs on the bipolar DC bus side, the fault bus is cut off, while ensuring the power transmission between the monopolar bus and the critical load. When the OCF occurs on the critical load side, the bipolar DC bus could still supply its power. Based on the above strategy, the power transmission capability under OCF is guaranteed and the reliability of TAB converter is improved. Finally, the OCF diagnosis and fault-tolerant operation methods are verified through comparative numerical simulation and experimental results.

Topology of Wind Power DC Collection Converter Based on Double Bus Structure and Its Power Balancing Control Strategy

Wind power collection technology is the key to grid-connected wind power generation. Compared with AC wind integration, DC wind power collection is more advantageous. Using a triple active bridge (TAB) converter as a submodule, this paper proposes a wind power DC converter topology and its control strategy for medium-voltage dc (MVDC) grid connection. The converter adopts a double bus structure, with the MVDC bus connected to the grid and the low-voltage dc (LVDC) bus handling the mismatched power. It has independent maximum power point tracking (MPPT) control, power balancing, and autonomous voltage balancing on the output side. The converter system is simulated and verified on the MATLAB/SIMULINK software platform. The simulation results show the effectiveness of the control strategy and the ability of the converter to operate stably under multiple conditions.

Improved reliability of Electric Vehicle (EV) charging by using multiport triple active bridge (TAB) converter

Improved reliability of Electric Vehicle (EV) charging by using multiport triple active bridge (TAB) converter

Multidimensional Ripple Correlation Technique for Optimal Operation of Triple-Active-Bridge Converters

The paper presents a multidimensional ripple correlation search technique of optimal operating points of triple active bridge (TAB) converters. Such converters present multiple modulation parameters that should be exploited to achieve high operation efficiency. On the other hand, the several degrees of freedom available make the identification of optimal parameters a challenging task, not easily tackled analytically or in closed form. A model-free on-line search method based on the ripple correlation technique is then proposed in this paper. The proposed method finds the optimum modulation parameters of TAB converters utilizing a three-dimensional ripple correlation control. The key property of the proposed solution is the adoption of orthogonal perturbation signals, where the orthogonality is simply obtained using different injection frequencies. The multidimensional correlation technique originally shown herein can be applied to other generic optimization problems. The proposed search is verified through a hardware-in-the-loop validation setup and an experimental prototype rated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5kW$</tex-math></inline-formula> .

Dynamic Performance Enhancement of a Triple Active Bridge With Power Decoupling-Based Configurable Model Predictive Control

The multiport active bridge (MAB) converter has been recently proposed aiming to increase the power density and the availability of electrical power distribution systems. However, the dynamic performance of proportional-integral (PI) controller for MAB voltage control is characterized by a relatively slow response and large overshoot. To address this issue, a power decoupling based configurable control (PDC-MPC) strategy inspired by the model predictive control (MPC) was developed. The proposed control strategy can achieve good transient performance and high control flexibility with good precision to comply to DC voltage regulations. In this paper, the PDC-MPC was investigated and implemented in a triple active bridge (TAB) converter with multi-winding high frequency transformers. The operating principle of the PDC-MPC is divided into two phases: prediction of the DC current through a binary search and decoupling of the desired power of each isolated virtual branch to its phase shift angles under the single phase shift (SPS) modulation strategy. Steady-state and dynamic performances of the proposed PDC-MPC for TAB converters were analysed using modified cost function and predictive models. Simulation and experiments were conducted to validate the theoretical analyses.

Application of Triple Active Bridge Converter for Future Grid and Integrated Energy System

Abstract: Renewable energy systems and electric vehicles (EVs) are receiving much attention in industrial and scholarly communities owing to their roles in reducing pollutant emissions. Integrated energy systems (IES), which connect different types of renewable energies and storages, have become common in many applications, such as the grid-connected photovoltaic (PV) and battery systems, fuel cells and battery/super capacitor in EVs. The advantages of all energy sources are maximized by utilizing connection and control strategies. Because many storage systems and household loads are mainly direct current (DC) types, the DC grid has considerable potential for increasing the efficiency of distribution grids in the future. In IES and future DC grid systems, the triple active bridge (TAB) converter is an isolated bidirectional DC-DC converter that has many advantages as a core circuit. In this paper reviews the characteristics of the TAB converter in current applications and suggests nextgeneration applications. First, the characteristics and operation modes of the TAB converter are introduced. An overview of all current applications of the TAB converter is then presented. The advantages and challenges of the TAB converter in each application are discussed. Thereafter, the potential future applications of the TAB converter with an adaptable power transmission design are presented.

Power Flow Control for Decoupled Load Performance of Current-Fed Triple Active Bridge Converter

This paper presents a phase-shift control method for a converter containing a multi-winding transformer. The control strategy is developed from a power flow analysis of the converter and uses the derived power flow equations to supply constant power at a load port while the second load port experiences large load changes. This control method prevents the constant load port from experiencing transient behavior caused by magnetic coupling with the other load port. The approach is demonstrated with an experiment using a controller within a control hardware-in-the-loop set-up and then a full experimental setup within a lower power test bed. By using control to mitigate the effects of mutual flux within a multi-winding transformer, the load ports of the converter are effectively decoupled. The analytical procedure described in this paper can also be applied to other converter topologies containing multi-winding transformers to achieve similar decoupled load performance, as demonstrated in the triple active bridge converter test bed.

Phase-Duty Modulated Loop Decoupling and Design Optimization for a Triple Active Bridge Converter for Light Electric Vehicle Charging

This article presents a comprehensive generalized harmonics approximation based modeling and design of a triple active bridge (TAB) dc–dc converter topology aimed to facilitate simultaneous—main and auxiliary—battery charging solutions for light electric vehicle charging applications. A three-loop control scheme, incorporating the duty and phase control parameters, is proposed in this article to address the issue of inherent coupling of two output bridges and their control loops (as observed in conventional phase modulation-based voltage control techniques), along with an objective to enhance the operational efficiency of the system, in affiliation with a real-time power flow optimization algorithm. Adhering to the objective of achieving minimized losses, the optimization algorithm provides insightful design limitations in terms of selecting the required leakage inductances to ensure desired power flow at the output bridges. Furthermore, to validate the effectiveness of the proposed three-loop control, a detailed set of simulation and experimental results are presented at various steady state and dynamic load change conditions. A detailed analytical loss model of the TAB topology is also presented along with a comparative study elucidating the effectiveness of the proposed three-loop control over the conventional control schemes. The analyses portray a peak efficiency of 96.24% at the rated load of 300 W, which is 2.94% and 4.97% higher than the decoupled and the conventional phase shift control schemes, respectively.

An SOC Based Adaptive Energy Management System for Hybrid Energy Storage System Integration to DC Grid

In this paper, an efficient adaptive energy management strategy (EMS) is presented for a hybrid energy storage system (HESS) application to compensate power fluctuation. The HESS consists of a battery and super-capacitor, which are integrated into the DC grid using a modified triple active bridge converter (m-TAB). The conventional EMS uses a low pass filter (LPF) to distribute high and low-frequency components of power. However, the time constant of the LPF is fixed throughout the process, which discharges the battery at the same rate even near the low state of charge (SOC) region. This increases the degradation rate of the battery. The proposed EMS employs an adaptive time constant LPF-based power allocation method to distribute the total power between the energy storage devices. The adaptive feature of the EMS changes the power distribution ratio dynamically to increase the utilization of the super-capacitor and battery operation time, thereby enhancing the life cycle. The proposed EMS is simulated in MATLAB/SIMULINK platform with the m-TAB converter, and the results are compared with the conventional EMS to prove its superiority. The system is also tested on an experimental prototype of 500 W for different test cases, and the outcomes are presented to support the proposed EMS.

Investigation of ZVS Criteria and Optimization of Switching Loss in a Triple Active Bridge Converter Using Penta-Phase-Shift Modulation

Triple active bridge (TAB) as an isolated multiport dc–dc converter is a promising solution for integrated energy management systems to maintain an efficient power flow between the ports. This article presents the design, modeling, and switching loss optimized phase-duty-controlled PWM modulation scheme of a TAB converter composed of three full-bridge modules and a high-frequency planar transformer. The work aims at the derivation and analysis of the zero-voltage switching (ZVS) conditions for a TAB, where the turn-on switching loss is mitigated along with attaining an improved EMI performance, comprising of reduced noise peaks. Moreover, an optimized five-variable control-based TAB PWM modulation technique is proposed in this article in order to achieve minimized switching loss and the overall system loss for a wide voltage gain and load range. The instantaneous switching currents, responsible for the switching losses at the devices, are derived from the transformer winding current expressions, formulated employing the generalized harmonic approximation (GHA) technique. The various loss minimization techniques and the theoretically obtained criteria for ZVS are experimentally verified using a laboratory-developed prototype of an 800-W TAB converter. With the implementation of the proposed optimal phase-duty control, the experimental results show a nonunity gain light-load efficiency increment up to 10% compared to the conventional phase-shift modulation alone.

A Multiport Partial Power Processing Converter With Energy Storage Integration for EV Stationary Charging

Battery storage system (BSS) integration in the fast charging station (FCS) is becoming popular to achieve higher charging rates with peak-demand shaping possibility. However, the additional conversion stage for integrating the BSS increases the system losses, size, and cost. The concept of a partial power processing converter (PPPC) can mitigate this effect. Compared to conventional used full power processing converter (FPPC), PPPC reduces the amount of transferred power from the BSS to the electric vehicle (EV) by the converter. As a consequence, the power losses generated by the converter are reduced, leading to lower sized converters and higher system efficiencies. This article proposes a dc/dc multiport converter that allows the integration of battery storage in FCS based on a partial power processing concept while maintaining the specific requirements in terms of isolation for FCS. The proposed three-port partial power processing converter (3P-PPPC) is derived from the commonly used triple active bridge (TAB) converter. The resulting design tradeoffs, the dynamic behavior, and limitations of the topology are investigated. Furthermore, the round-trip efficiency of the 3P-PPPC for integrating BSS in FCS is compared with conventional FPPC solutions, highlighting the superiority of the proposed topology. A prototype has been built to validate the 3P-PPPC.

Simulations of the Comparative Study of the Single-Phase Shift and the Dual-Phase Shift-Controlled Triple Active Bridge Converter

This paper presents a comparative study between the traditional phase shift (also referred to as the Single-Phase Shift (SPS)) and the Dual-Phase Shift (DPS) controlled Triple Active Bridge (TAB) converter. Being a multi-port DC-DC converter with flexible power flow control and characterized by high power density, the TAB converter is applicable in almost any situation where a DC-DC converter is needed. With the availability of multiple control schemes, this work highlights the advantages and disadvantages of the most employed control scheme used on the TAB converter, in comparison with the DPS control scheme that has so far been applied only on Dual-Active Bridge (DAB) converters. As an example, for a TAB converter with a 14 kW maximum power capacity, the work sees the comparison of the backflow power, the maximum possible current, the processed power at the different ports of the converter, the transformer voltage and current waveforms, and the Total Harmonic Distortion (THD). Based on the results obtained, we found that the DPS-controlled TAB converter was more efficient when applied to the TAB converter compared to the traditional phase shift control algorithm.