Reactive power minimization of dual active bridge DC/DC converter with triple phase shift control using neural network

Reactive power flow increases dual active bridge (DAB) converter RMS current leading to an increase in conduction losses especially in high power applications. This paper proposes a new optimized triple phase shift (TPS) switching algorithm that minimizes the total reactive power of the converter. The algorithm iteratively searches for TPS control variables that satisfy the desired active power flow while selecting the operating mode with minimum reactive power consumption. This is valid for the whole range of converter operation. The iterative algorithm is run offline for the entire active power range (-1pu to 1pu) and the resulting data is used to train an open loop artificial neural network controller to reduce computational time and memory allocation necessary to store the data generated. To validate the accuracy of the proposed controller, a 500-MW 300kV/100kV DAB model is simulated in Matlab/Simulink, as a potential application for DAB in DC grids

Insights into dynamic tuning of magnetic-resonant wireless power transfer receivers based on switch-mode gyrators

Magnetic-resonant wireless power transfer (WPT) has become a reliable contactless source of power for a wide range of applications. WPT spans different power levels ranging from low-power implantable devices up to high-power electric vehicles (EV) battery charging. The transmission range and efficiency of WPT have been reasonably enhanced by resonating the transmitter and receiver coils at a common frequency. Nevertheless, matching between resonance in the transmitter and receiver is quite cumbersome, particularly in single-transmitter multi-receiver systems. The resonance frequency in transmitter and receiver tank circuits has to be perfectly matched, otherwise power transfer capability is greatly degraded. This paper discusses the mistuning effect of parallel-compensated receivers, and thereof a novel dynamic frequency tuning method and related circuit topology and control is proposed and characterized in the system application. The proposed method is based on the concept of switch-mode gyrator emulating variable lossless inductors oriented to enable self-tunability in WPT receiversPeer ReviewedPostprint (published version

Design considerations for a high-power dual active bridge DC-DC converter with galvanically isolated transformer

Multi-megawatt scale isolated DC-DC converters are likely to become increasingly popular as means to interconnect the MVDC grids of different voltage levels. Threephase dual active bridge DC-DC (3DAB) converters operating with the zero-voltage switching (ZVS) is a promising candidate for the target multi-megawatt application. This paper presents a systematic approach of the design considerations for a 3DAB converter. Firstly, the use of snubber capacitors in medium voltage and medium frequency operating conditions is proposed. Snubber capacitor influence on turn-off current levels and ZVS operating range are introduced and analyzed. In addition, details of thermal management design are introduced. It is established through power loss analysis that the proposed design method reduces the semiconductor losses substantially at full load conditions. Finally, the proposed method has been validated from a 10kW simulation model using PLECS software package

Geometry optimization and characterization of three-phase medium frequency transformer for 10kVA isolated DC-DC converter

Three-phase Dual Active Bridge converter is advisable for the High-power DC-DC conversion system. In the ac link, galvanically isolated transformer operated at a medium frequency range provides stepping up or down of the secondary bridge voltage. This paper provides a magnetic design optimization of the medium frequency transformer for maximizing its efficiency when excited by a non-sinusoidal waveform. In this paper, a mathematical design of a 10kVA non-sinusoidal transformer had been developed and validated using two-dimensional (2D) transient finite element analysis (FEA). The set of selected design variables is defined in order to enhance the power density and efficiency of the targeted transformer and an optimization is carried out. Finally, a 10kVA transformer is prototyped and the results of core losses for nonsinusoidal excitation is confirmed experimentally

Power Device Loss Analysis of a High-Voltage High-Power Dual Active Bridge DC-DC Converter

The insulated-gate bipolar transistor (IGBT) offers low conduction loss and improved performance and, hence, is a potential candidate for high-current and high-voltage power electronic applications. This chapter presents the power loss estimation of IGBTs as employed in a high-voltage high-power dual active bridge (DAB) DC-DC converter. The mathematical models of the device currents are derived, and the power loss prediction is clearly explained using the mathematical models. There are many parameters to consider when selecting an appropriate power device for a given application. This chapter highlights the step-by-step procedure for selecting suitable IGBTs for a 20 kW, 540/125 V, 20 kHz DAB converter designed for aerospace energy storage systems. Experimental results are given to demonstrate the device performance at 540 V, 80 A operation of high-voltage IGBTs and 125 V, 300 A operation of low-voltage IGBTs and thus validate the selection procedure presented

System configuration, fault detection, location, isolation and restoration: a review on LVDC Microgrid protections

Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations， fault detection, location, isolation and restoration

Triple-Phase Shift Modulation for Dual Active Bridge based on Simplified Switching Loss Model

In this paper the dual active bridge (DAB) is analyzed and three modulation approaches are proposed and tested to improve the converter's efficiency. Zero-voltage switching maps are reported to show the most favorable operating conditions to reduce switching and conduction losses contributions. The results are validated considering an experimental DAB converter prototype. It is shown that accounting ZVS with the characterization of switching behavior of the devices allows significant improvements with respect to simply give a constraint on the instantaneous current switching values, at the reported operating conditions

Solar Photovoltaic and Thermal Energy Systems: Current Technology and Future Trends

Solar systems have become very competitive solutions for residential, commercial, and industrial applications for both standalone and grid connected operations. This paper presents an overview of the current status and future perspectives of solar energy (mainly photovoltaic) technology and the required conversion systems. The focus in the paper is put on the current technology, installations challenges, and future expectations. Various aspects related to the global solar market, the photovoltaic (PV) modules cost and technology, and the power electronics converter systems are addressed. Research trends and recommendations for each of the PV system sectors are also discussed.Junta de Andalucía P11-TIC-7070Ministerio de Ciencia e Innovación TEC2016-78430-

Design of a 7.5 kW Dual Active Bridge Converter in 650 V GaN Technology for Charging Applications

High-voltage GaN switches offer low conduction and commutation losses compared with their Si counterparts, enabling the development of high-efficiency switching-mode DC-DC converters with increased switching frequency, faster dynamics, and more compact dimensions. Nonetheless, the potential of GaN switches can be fully exploited only by means of accurate simulations, optimal switch driving, suitable converter topology, accurate component selection, PCB layout optimization, and fast digital converter control. This paper describes the detailed design, simulation, and implementation of an air-cooled, 7.5 kW, dual active bridge converter exploiting commercial 650 V GaN switches, a compact planar transformer, and low ESL/ESR metal film capacitors. The isolated bidirectional converter operates at a 200 kHz switching frequency, with an output voltage range of 200-500 V at nominal 400 V input voltage, and a maximum output current of 28 A, with a wide full-power ZVS region. The overall efficiency at full power is 98.2%. This converter was developed in particular for battery charging applications, when bidirectional power flow is required