This paper reports a stator shape optimization design for reducing the cogging torque of single-phase brushless dc (BLDC) motors by adopting an asymmetric air-gap to make them self-starting. A time step 2-D finite-element analysis (FEA) was carried out to analyze the characteristics of the single-phase BLDC motor. The Kriging model combined with Latin hypercube sampling and a genetic algorithm were used to reduce the cogging torque and maintain the efficiency and torque. As an optimal design result, the cogging torque of the optimal model was reduced. Finally, the analysis and optimal design results were confirmed by FEA as well as by experimental results.

The aim of this work was to eliminate the backflow power present in an isolated three-port DC–DC converter. Backflow power (which is an inherent property of phase-shifted DC–DC converters) is the major contributor of circulating current the converter, which in turn is known to be the leading cause of system loss. The dual phase shift (DPS) control scheme (which alters the transformer voltage waveform at the different winding terminals) was used to reduce the backflow power. Mathematical relations for the backflow power present in the three-port converter were derived. And from this equation, an operating point in which the backflow power is zero was also obtained. This condition for zero backflow power was confirmed by simulations on PSIM. Added to this were simulation results that show other operating conditions in which zero backflow power could be obtained in the converter. In addition, equations for the power processed at the different ports of the converter were also presented, and 3D plots were made to illustrate the variation of the power and backflow power with respect to the phase shift ratios of the DPS control scheme. It was observed that the backflow power can be totally removed from the three-port converter when using this control scheme.

This paper proposes the influence analysis of silicon carbide (SiC) MOSFET’s parasitic output capacitance on a dual active bridge (DAB) converter. Power converters are required for DC grids and energy storage. Because SiC metal-oxide-semiconductor FETs (MOSFETs) have lower on-state resistance and faster reverse recovery time than Si MOSFETs, they can be controlled with lower losses and higher frequencies. MOSFETs have a parasitic capacitance. Because of the output parasitic capacitance, the switch voltage does not rise instantaneously during switching but has a delay. The output parasitic capacitance of the switch depends on its drain-to-source voltage, and this parasitic capacitance affects the output of the DAB converter by delaying the switch voltage. In this paper, in order to analyze the effect of the parasitic capacitance on the DAB converter output, the delay time was calculated through a formula, and this value was compared with a simulated value. In addition, the effect of the parasitic capacitance of the SiC MOSFET on the output of the DAB converter was presented by comparing the actual output voltage with the ideal output voltage and analyzing the effect of the output voltage according to the delay.

This study presents a novel structure proposal of a variable inductance high-frequency transformer for enhancement power level of a dual-active-bridge (DAB) converter. The DAB converter is a solid-state transformer (SST) that requires high efficiency, power density, flexibility, and stability. Variable inductance facilitates achieving and extending maximum power levels. The proposed method adjusts the inductance based on the core insertion conditions of the transformer used in the DAB converter without requiring an additional inductor. The method was verified by analyzing the variable inductance characteristics of the transformer based on core insertion conditions via finite element analysis (FEA) and simulation and experiments within the variable inductance range.

This paper presents a comparative study between the traditional phase shift (also referred to as the Single-Phase Shift (SPS)) and the Dual-Phase Shift (DPS) controlled Triple Active Bridge (TAB) converter. Being a multi-port DC-DC converter with flexible power flow control and characterized by high power density, the TAB converter is applicable in almost any situation where a DC-DC converter is needed. With the availability of multiple control schemes, this work highlights the advantages and disadvantages of the most employed control scheme used on the TAB converter, in comparison with the DPS control scheme that has so far been applied only on Dual-Active Bridge (DAB) converters. As an example, for a TAB converter with a 14 kW maximum power capacity, the work sees the comparison of the backflow power, the maximum possible current, the processed power at the different ports of the converter, the transformer voltage and current waveforms, and the Total Harmonic Distortion (THD). Based on the results obtained, we found that the DPS-controlled TAB converter was more efficient when applied to the TAB converter compared to the traditional phase shift control algorithm.

The installed capacity of photovoltaic (PV) systems has increased significantly over the past few decades, and related technologies have advanced significantly. The electrical characteristics of a PV system change nonlinearly based on irradiation and temperature, and the I–V characteristic curve, expressed in terms of the voltage and current, is used to verify these characteristics. The maximum power point tracking (MPPT) control method was applied to maximize the performance of the PV system. Voltage and current sensors are used to control the I–V characteristic curve and MPPT; however, current sensors have various disadvantages in terms of price and system configuration. Therefore, this study presents a method for calculating the current of a PV system using the charging characteristics of a capacitor. The method presented in this paper analyzes the I–V characteristic curve’s qualities through simulations and experiments under normal, shaded, and mismatched conditions of the PV module.