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The use of multiple transmitters (Txs) has been an attractive solution for enabling free-positioning wireless power transfer (WPT) in a large area. One of the key challenges in such multi-Tx WPT systems is the cross-coupling between Tx coils. This letter proposes a compact self-decoupled Tx coil solution for multi-Tx WPT systems. The measured cross-coupling between Tx coils has been reduced by 95% compared with conventional coil designs. In addition, an integration method for a compensation inductor with the main Tx coil is proposed. Therefore, the coil design proposed in this letter facilitates creation of fully modular and scalable Tx coils for multi-Tx WPT systems. The proposed designs are experimentally verified in a laboratory prototype. [ABSTRACT FROM AUTHOR]

Forward converter with active clamp is a suitable topology for a low output voltage and high output current dc-dc power supply module. The topology can be used in a resonant transition manner to obtain a low voltage over the main switch at turn-on instant. A low voltage can be obtained by adjusting the magnitude of the magnetizing current of the transformer and the delay between the two primary side switches. An increased magnetizing current, however, increases conduction losses in the primary side of the converter and may consume the advantage gained in the switching losses. The converter can also be easily used for self-driven synchronous rectification. However, pursue for low switching losses for the primary side switch may deteriorate performance of the self-driven synchronous rectifiers, particularly at high loads. This paper presents a study of the applicability and advantage of the use of the resonant transition in Forward with active clamp and self-driven synchronous rectifiers. The emphasis is on the comparison of the achieved efficiency with different voltage levels over the primary switch prior to turning on. Measurement results show that, at low loads, a reduced voltage level improves the efficiency but, on the other hand, at high loads the advantage is not so significant, or it may be totally lost, mainly due to the increased losses of the self-driven synchronous rectifiers. The paper includes discussion on the effect of the magnetizing inductance on the efficiency of the converter and the optimal voltage level at which the primary switch should be turned on. Measurement results from a 3.4-V 30-A prototype converter are included. Index Terms--Forward converter, magnetizing inductance, self-driven synchronous rectifiers.

This article proposes a novel approach for operating hybrid fuel cell and battery power systems in marine vessels. The target of the approach is to reduce energy losses in drivetrain devices. In the proposed approach, the dc bus voltage of the hybrid power system is adjusted according to fuel cell operating points, which enables operation in freewheel mode, and thus significantly reducing power conversion losses. Feasibility of the proposed approach is verified using a real-time hardware-in-loop simulation setup consisting of prevalidated virtual models and real industrial power converter controllers. The results presented in the work illustrate that the variable dc approach enables significant improvements in drivetrain efficiencies, and thus providing significant savings for vessel operators. Additionally, variable dc approach is shown to eliminate high-frequency current ripple at the fuel cell terminals, which can further improve the efficiency and the lifetime of the fuel cells. [ABSTRACT FROM AUTHOR]

This study presents the performance comparison of two scenarios to obtain high voltage gain. A high step-up converter (HSU) and a cascaded boost converter are chosen for this study. For analytical analysis, a loss model for both converters is developed on MATLAB. Gallium nitride- based prototypes of HSU and cascade boost converter provided the validation of the analytical analysis. Based on the theoretical evaluation and practical tests, efficiencies of both converters are expressed in terms of their voltage gain to find the optimal point of operation. Results showed that the cascaded boost converter is more efficient than the HSU converter at higher voltage gain values. However, the HSU converter has a higher energy density and lower switch voltage stress than those of the cascaded boost converter. [ABSTRACT FROM AUTHOR]

A new implementation of an iron-loss model for laminated magnetic cores in the MATLAB/Simulink environment is proposed in this paper. The model is based on numerically solving a one-dimensional diffusion problem for the eddy currents in the core lamination and applying an accurate hysteresis model as the constitutive law. An excess loss model is also considered. The model is identified merely based on the catalog data provided by the core material manufacturer. The implementation is validated with analytical and finite-element models and experimentally in the case of a toroidal inductor supplied from a GaN FET full-bridge inverter with 5–500 kHz switching frequencies and a deadtime of 300 ns. Despite the simple identification, a good correspondence is observed between the simulated and measured iron losses, the average difference being 3.3% over the wide switching frequency range. It is shown that accounting for the skin effect in the laminations is significant, in order to correctly model the iron losses at different switching frequencies. Some differences between the measured and simulated results at high switching frequencies are also discussed. The model is concluded to be applicable for designing and analyzing laminated magnetic cores in combination with power-electronics circuits. The Simulink models are openly available. [ABSTRACT FROM AUTHOR]