Extended Range ZVS Active-Clamped Current-Fed Full-Bridge Isolated Dc/Dc Converter for Fuel Cell Applications: Analysis, Design and Experimental Results

Abstract

This paper presents analysis and design of zerovoltage switching (ZVS) active-clamped current-fed full-bridge isolated dc/dc converter for fuel cells applications. The designed converter maintains ZVS of all switches from full-load down to very light load condition over wide input voltage variation. Detailed operation, analysis, design, simulation and experimental results for the proposed design are presented. The additional auxiliary active clamping circuit absorbs the turn-off voltage spike limiting the peak voltage across the devices allowing the selection and use of low voltage devices with low on-state resistance. In addition, it also assists in achieving ZVS of semiconductor devices. The converter utilizes the energy stored in the transformer leakage inductance aided by its magnetizing inductance to maintain ZVS. ZVS range depends upon the design, in particular the ratio of leakage and magnetizing inductances of the transformer. Rectifier diodes operate with zero-current switching. An experimental converter prototype rated at 500W has been designed, built and tested in the laboratory to verify the analysis, design and performance for wide variations in input voltage and load.

Design and Performance of a Bidirectional Isolated DC–DC Converter for a Battery Energy Storage System

Abstract

This paper describes the design and performance of a 6-kW, full-bridge, bidirectional isolated dc-dc converter using a 20-kHz transformer for a 53.2-V, 2-kWh lithium-ion (Li-ion) battery energy storage system. The dc voltage at the high-voltage side is controlled from 305 to 355 V, as the battery voltage at the low-voltage side (LVS) varies from 50 to 59 V. The maximal efficiency of the dc-dc converter is measured to be 96.0% during battery charging, and 96.9% during battery discharging. Moreover, this paper analyzes the effect of unavoidable dc-bias currents on the magnetic-flux saturation of the transformer. Finally, it provides the dc-dc converter loss breakdown with more focus on the LVS converter.

Control of a two-port supercapacitor converter based on differential flatness principle for transportation applications

Abstract

This paper presents a new control strategy for dc-link stabilization in weak transportation networks that use supercapacitors as the energy storage unit. A two-port isolated converter based on a dual active bridge topology is presented, and a reduced-order mathematical model of the system is described for power plant control. Using a nonlinear control approach based on the flatness property, we propose a simple solution to dynamic and stabilization problems in the power electronics systems of transportation networks. The controller design parameters are independent of the operating point at which interactions between the dc main substation, loads and energy storage unit are taken into account by the controller. To validate the proposed method, a hardware system is modeled using digital estimation with a DS1103 dSPACE controller platform. We analyze a prototype small-scale network that uses a 1 kW six-pulse rectifier as a dc substation and a 250 F, 32 V supercapacitor bank as an energy storage substation. Finally, the utility of the control algorithm is validated using experimental results measured during motoring mode, ride-though, and braking mode drive cycles.

Analysis and Implementation of a Novel Bidirectional DC–DC Converter

Abstract

A novel bidirectional dc-dc converter is presented in this paper. The circuit configuration of the proposed converter is very simple. The proposed converter employs a coupled inductor with same winding turns in the primary and secondary sides. In step-up mode, the primary and secondary windings of the coupled inductor are operated in parallel charge and series discharge to achieve high step-up voltage gain. In step-down mode, the primary and secondary windings of the coupled inductor are operated in series charge and parallel discharge to achieve high step-down voltage gain. Thus, the proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional dc-dc boost/buck converter. Under same electric specifications for the proposed converter and the conventional bidirectional boost/buck converter, the average value of the switch current in the proposed converter is less than the conventional bidirectional boost/buck converter. The operating principle and steady-state analysis are discussed in detail. Finally, a 14/42-V prototype circuit is implemented to verify the performance for the automobile dual-battery system.

Analysis and Design of a Zero-Voltage-Switching and Zero-Current-Switching Interleaved Boost Converter

Abstract

A novel interleaved boost converter with zero-voltage switching (ZVS) and zero-current switching (ZCS) characteristics is proposed in this paper. By using the interleaved approach, this topology not only decreases the current stress of the main circuit device but also reduces the ripple of the input current and output voltage. Moreover, by establishing the common soft-switching module, the soft-switching interleaved converter can greatly reduce the size and cost. The main switches can achieve the characteristics of ZVS and ZCS simultaneously to reduce the switching loss and improve the efficiency with a wide range of load. This topology has two operational conditions depending on the situation of the duty cycle. A driving circuit is designed for the proposed topology to determine the two conditions automatically. The operational principle, theoretical analysis, and design method of the proposed converter are presented. Finally, simulations and experimental results are used to verify the feasibility and exactness of the proposed converter.