Double Active Bridge Operated in Quasi Discontinuous Conduction Mode

The quasi discontinuous conduction mode (QDCM) of the double active bridge (DAB) is addressed in this paper. The DAB converter usually is operated turning on always two semiconductors per bridge, and this leads to a continuous inductor current: However, a similar operation to dc/dc converters can be implemented, for this, less than two switches are turned on, at certain time, in one of the bridges; this leads to the quasi-DCM. With this mode of operation, a natural soft-switching is performed during the whole range of operation, but also low current stress is performed compared to the square modulation, not only at low power range. The modulation is relatively simple compared to other techniques. The proposed technique is described, analyzed, numerically simulated, and experimentally tested

PI Controller Based New Soft-Switching Boost Converter With A Coupled Inductor

Novel full bridge DC-DC boost converters is mainly used in research applications, where the output voltage is measurably higher than the source voltage. In this project designing of a new topology of a non isolated boost converter with zero voltage switching control technique is discussed. To achieve ZVS condition the auxiliary circuit has a coupled inductor and a diode. The advantages of the ZVS are reverse recovery problem of MOSFET anti parallel body diodes are resolved and also the voltage and current stress on the switch components are reduced. This topology has a light weight and cost less. This technique will reduce the switching losses and improve the efficiency by ZVS technique, but it does not improve the turn-off switching losses by a ZCS technique. In this topology have two operational conditions depending on the situation of the duty cycle. The detailed operating analysis of the proposed converter and the design method of the main circuit are presented. To improve the effectiveness and feasibility of the proposed boost converter PI controller is used. Here microcontroller is used in the proposed topology

Peak Current Control and Feed-Forward Compensation for the DAB Converter

This paper presents a double band peak current control for the DAB converter that permits to avoid the risk of transformer saturation. Additionally, feed-forward compensation is employed to achieve a fast transient response under load variations. The proposal is described, analyzed, and numerically simulated

A modified particle swarm optimization algorithm to enhance MPPT in the PV array

Due to the growing demand for electrical power, the researchers are trying to fulfill this demand by considering different ways of renewable energy resource as existing energy resources failed to do so. The solar energy from the sun is freely available, and by using photovoltaic (PV) cell power can be generated. However, it depends on rays fall on the PV cell, climatic condition. Thus, to enhance the efficiency of the photovoltaic (PV) systems, maximum power point tracking (MPPT) of the solar arrays is needed.The output of solar arrays mainly depends on solar irradiance and temperature. The mismatch phenomenon takes place due to partial shade, and it causes to the power output, which brings the incorrect operation of traditional MPP tracker. In this shaded condition, PV array exhibits multiple extreme points. In general, under this scenario, the MPPT approaches fail to judge the MPP, and it leads to low efficiency. The conventional approaches of PSO based algorithms can able to track the MPP under shading condition. However, the optimization process leads to issues in tracking speed. Thus, there a need for an efficient MPPT system which can track MPPT effectively in shaded condition? Hence, the proposed manuscript presents a modified Particle Swarm Optimization (PSO) algorithm is introduced to enhance the tracking speed as well as performance. The outcomes of the proposed system are compared with the traditional PSO system and are found that the tracking speed of MPP, accuracy, and efficiency is improved

Solid State Transformer with Integrated Input Stage

In this paper, a solid state transformer (SST) with integrated stages is addressed. The SST has been originally proposed for traction applications, after as an option to face the new requirements of the distributed generation but also suggested in many applications. There are different topologies, from one to three stages; certainly each one with their advantages and limitations. Some challenges for this type of systems are reducing the cost and increasing the efficiency.The components reduction is discussed in this paper, by integrating two stages of the SST; the ac/dc converter and the DAB converter share one leg. The proposed scheme is described and numerically simulated

Analytical Treatment of the Power Transfer Relationships for a Coupled, Current-Fed, Multi-Port Dual Active Bridge Converter

Existing research has demonstrated that mutual inductors within the load ports of a Dual Active Bridge (DAB)-based converter enable fault tolerant operation. Similar research efforts with the DAB converter have also proven that incorporating a multi-winding transformer in the design can result in an interconnection of multiple DC buses with isolation and reduced switching losses. Therefore, a current-fed, multi-port DAB converter is proposed with the intention of capturing the benefits of both features. The performance of the proposed converter is evaluated against the traditional multi-port DAB. In particular, the potentially non-ideal square waveforms at load port voltages are mathematically described. The converter characteristic equations are then verified with PLECS simulations. Finally, the effects of inductor size on port voltages and power transfer are explored. The results of the analyses provide the conditions in which simplification to power flow equations for voltage-fed multi-port converters is applicable

Power Balancing Control for Grid Energy Storage System in Photovoltaic Applications — Real Time Digital Simulation Implementation

Abstract: A grid energy storage system for photo voltaic (PV) applications contains three different power sources i.e., PV array, battery storage system and the grid. It is advisable to isolate these three different sources to ensure the equipment safety. The configuration proposed in this paper provides complete isolation between the three sources. A Power Balancing Control (PBC) method for this configuration is proposed to operate the system in three different modes of operation. Control of a dual active bridge (DAB)-based battery charger which provides a galvanic isolation between batteries and other sources is explained briefly. Various modes of operation of a grid energy storage system are also presented in this paper. Hardware-In-the-Loop (HIL) simulation is carried out to check the performance of the system and the PBC algorithm. A power circuit (comprised of the inverter, dual active bridge based battery charger, grid, PV cell, batteries, contactors, and switches) is simulated and the controller hardware and user interface panel are connected as HIL with the simulated power circuit through Real Time Digital Simulator (RTDS). HIL simulation results are presented to explain the control operation, steady-state performance in different modes of operation and the dynamic response of the system

Current-Fed Isolated DC/DC Converter for Future Aerospace Microgrids

High-performance power conversion equipment is currently gaining an increasing interest for aircraft applications. In particular, isolated bidirectional dc/dc converters are often proposed for modern aircraft distribution systems. A current-fed isolated dc/dc converter, named active-clamp active-bridge topology, is identified as the most promising for the proposed application, interfacing a 270-V dc network with a 28-V dc network. A comparison between the selected topology and the well-known dual-active-bridge topology has been carried out and an experimental prototype has been manufactured for the selected conversion architecture. Simulation and experimental results are provided in order to validate the tradeoff and the design of the proposed converter