High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

With the requirements for reducing emissions and improving fuel economy, automotive companies are developing electric, hybrid electric, and plug-in hybrid electric vehicles. Power electronics is an enabling technology for the development of these environmentally friendlier vehicles and implementing the advanced electrical architectures to meet the demands for increased electric loads. In this paper, a brief review of the current trends and future vehicle strategies and the function of power electronic subsystems are described. The requirements of power electronic components and electric motor drives for the successful development of these vehicles are also presented.

Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles

Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics.

Energy Storage Systems for Transport and Grid Applications

The issues of global warming and depletion of fossil fuels have paved opportunities to electric vehicle (EV). Moreover, the rapid development of power electronics technologies has even realized high energy-efficient vehicles. EV could be the alternative to decrease the global green house gases emission as the energy consumption in the world transportation is high. However, EV faces huge challenges in battery cost since one-third of the EV cost lies on battery. This paper reviews state-of-the-art of the energy sources, storage devices, power converters, low-level control energy management strategies and high supervisor control algorithms used in EV. The comparison on advantages and disadvantages of vehicle technology is highlighted. In addition, the standards and patterns of drive cycles for EV are also outlined. The advancement of power electronics and power processors has enabled sophisticated controls (low-level and high supervisory algorithms) to be implemented in EV to achieve optimum performance as well as the realization of fast-charging stations. The rapid growth of EV has led to the integration of alternative resources to the utility grid and hence smart grid control plays an important role in managing the demand. The awareness of environmental issue and fuel crisis has brought up the sales of EV worldwide.

A review of energy sources and energy management system in electric vehicles

The fuel efficiency and performance of novel vehicles with electric propulsion capability are largely limited by the performance of the energy storage system (ESS). This paper reviews state-of-the-art ESSs in automotive applications. Battery technology options are considered in detail, with emphasis on methods of battery monitoring, managing, protecting, and balancing. Furthermore, other ESS candidates such as ultracapacitors, flywheels and fuel cells are also discussed. Finally, hybrid power sources are considered as a method of combining two or more energy storage devices to create a superior power source.

Energy Storage Systems for Automotive Applications

This paper deals with the multi-input DC-DC converter with high power efficiency. A novel full-bridge type zero voltage switching (ZVS) multi-input DC-DC converter is proposed, in which the circulation current induced by the currents through the other windings of its transformer is interrupted by the additional switches. The prototype two-input DC-DC converter is made and examined. As a result, the high power efficiency of 93% is obtained at the rated power of 500W in the two-input operation.

A novel multi-input DC-DC converter with high power efficiency

We have already reported the novel digital control method "static model reference" which is the improved smart digital reference of output voltage for its digitally controlled dc-dc converter The circuit mechanism and the static characteristics have been cleared This paper presents dynamic characteristics of the digitally controlled dc-dc converter with static model reference Moreover, a new algorithm of the output current balance operation is proposed and dynamic characteristics of the multi-phase performance are clarified As a result, the superior dynamic characteristics are obtained and it is clarified in the simulation that the undershoot of the output voltage in step change of the load from 100 Omega to 25 Omega is suppressed enough within 5% and the transient time is very short within 007 ms Also, the undershoot is suppressed within 05% and the transient time is within 004 ms when the input voltage is step-changed from 20 V to 16 V Furthermore, the good dynamic balance of the load current is confirmed

Dynamic Characteristics of Switching DC-DC Power Converter with Static Model Reference

This paper deals with the analysis of the output characteristics of the new digitally controlled dc-dc converter with auxiliary switches, which are used to prevent the extremely lowering of the switching frequency caused by the decrease of the load current and/or the increase of the input voltage. This dc-dc converter with auxiliary switches has two major operation modes; that is, the frequency control and on-time control modes. Taking account of the forward voltage drops and loss resistances of the main switches, auxiliary switches and diodes, and the winding series resistances of the trans­former, the detailed circuit operation and the output characteristics are analysed. As a result of analysis, it is clarified that the superior regulation characteris­tics of the output voltage is obtained, and that the power efficiency of the digitally controlled dc-dc converter with auxiliary switches is improved in the relatively light load region, compared with that of the conventional one with analog control circuit.

Characteristics of the new digitally controlled series resonant dc-dc converter using frequency and on-time control modes

It is often required in the robot and battery charging systems that the primary side of the input power source and secondary side of the load should be isolated by the transformer and that the output voltage should be regulated in the primary side. This paper presents a novel output voltage regulation strategy in the primary side of flyback converters. Also, the nonlinear control is useful to perform the high degree of output voltage regulation when the input voltage and the load change largely. The insights of the nonlinear control and over-voltage/current protection method are obtained analytically.

A novel output voltage regulation strategy for primary side of flyback converter

This paper describes the principles and characteristics of a novel bidirectional superposed dual active bridge DC-DC converter with synchronous rectifier, which has a mechanism formed from two bridge-type converters that are linked through superposition in additive polarity in series. Conventionally, for an isolated dual active bridge DC-DC converter, the rated voltage of its switching elements is decided according to the DC power source voltage and load current. Therefore, as the voltage and current specifications of a DC-DC converter become higher, physical size becomes larger, conduction and switching losses increase and power efficiency reduces. To solve this problem, the authors devised the proposed DC-DC converter capable of lowering the rated voltage of switching elements, by means of sharing DC power source voltage and load current between two converters. Further, the capacity of the high frequency transformer becomes small, making the DC-DC converter more efficient and smaller. We designed and constructed a lkW DC-DC converter prototype, and conducted performance evaluation testing. As a result, a conversion efficiency of 98.2% at a rated output of lkW was obtained. A detailed analysis of power flow was also carried out, to identify the characteristics of the converter developed.

Hirofumi Matsuo

Papers

A novel multi-input DC-DC converter with high power efficiency

Dynamic Characteristics of Switching DC-DC Power Converter with Static Model Reference

Characteristics of the new digitally controlled series resonant dc-dc converter using frequency and on-time control modes

A novel output voltage regulation strategy for primary side of flyback converter

An analysis of bidirectional superposed dual active bridge DC-DC converter with synchronous rectifier