Dual active bridge (DAB) converters play a crucial role in high-power applications such as electric vehicles, renewable energy systems, and grid-tied converters due to their ability to provide bidirectional power transfer, high efficiency, and galvanic isolation. However, the pursuit of higher power density in these converters often necessitates increased operating frequencies, creating challenges in magnetic component design due to semiconductor thermal limitations. Traditional approaches, such as detailed thermal modeling and experimental methods, are time-intensive and impractical during the initial design stages. This paper presents a rapid analytical method to establish feasible operating frequencies and inductance ranges for DAB converters based on semiconductor thermal constraints, utilizing readily available device datasheet parameters and application-specific data. The proposed method omits complex thermal models and experimental procedures, streamlining the early-stage design process for magnetic components while maintaining thermal compliance. A real-time hardware-in-the-loop model was developed to validate the proposed method across power levels from 10 kW to 30 kW, demonstrating safe operation within thermal limits. The findings underscore the potential of this method to provide timely, practical guidance for magnetic designers, reducing iteration cycles and associated costs while setting the stage for further optimization and control refinement in DAB converter systems.

Harmonic pollution imposed by non-linear loads has become one of the main power quality challenges. In addition, reactive power absorption related to non-linear loads may result in serious power quality issues like voltage drop or voltage instability. Among different passive and active power filters (APFs), shunt active power filter (SAPF) is used a lot since it can compensate both complete harmonic and reactive components as well as high flexibility without any resonance. However, harmonic detection, hardware, and control design play vital role in the performance of the SAPF. From hardware point of view, design of the DC-link capacitor and series inductor are two main challenges. In this paper, a comprehensive design procedure is presented to design the suitable passive elements. In addition, high performance control design is also considered. Several simulation and experimental results are provided to verify the proper design and controller performance.

Inductive wireless power transfer has become one of the most important emerging technologies in electric-vehicle applications. Important parameters in such technology are the variable coupling coefficient and equivalent load resistance that depend on the relative position of the coils and the load power, respectively. These parameter values are needed to optimize the system performance. This work proposes a novel method to accurately estimate the values of coupling coefficient and load resistance dynamically without any receiver side measurements. The method is based on measuring the system input impedance seen from the transmitter side. A set of perturbation voltages with different frequencies are injected into the system, and the magnitude of the impedance obtained from measured voltage and current responses is then utilized to estimate the parameter values. The proposed method does not require communication between the transmitter and receiver subsystems, and therefore, the technique is well suited for applications in which the dynamics of the charged object are unknown. The effectiveness of the method is validated by experimental results.

Stability issues have emerged in the grid interfaces of power electronics when the grid impedance is high or multiple devices are connected in parallel. Impedance-based stability criterion has demonstrated high applicability in the stability assessment, as the analysis can be performed based on the terminal impedances of the grid and the converter. Typically, impedance measurements are required to obtain the terminal impedances. However, extracting the stability margins and predicting the system dynamics from the measured impedances typically requires complex methods, such as transfer function fitting. This work proposes an extension to the impedance-based stability criterion, where the critical system damping and the critical resonant mode are extracted from the impedance data. An impedance-based sensitivity function is constructed from the terminal impedances, and the system damping factor is calculated from the sensitivity function. A second-order transfer function is constructed from the obtained damping factor and resonant frequency, which captures the critical resonant mode of the system. The method is validated in experimental stability analysis of a 2.7 kW grid-connected three-phase inverter, where the method accurately predicts the resonant dynamics of the system when the stability margins are low.

The impedance of a Li-ion battery is an important parameter for the battery state-of-health (SOH) estimation. The dependency of the battery impedance to the SOH can be monitored by fitting an equivalent-circuit-model (ECM) to the impedance data and observe the changes in the ECM parameters. The ECM is typically fitted by the complex-nonlinear-least-squares (CNLS) algorithm which requires accurately chosen initial conditions for the parameters to guarantee the consistent performance of the algorithm. In order to use the ECM parameters for SOH estimation in practical applications, the impedance measurements should be fast and simple to implement to the battery system. This paper demonstrates the utilization of practical and fast pseudo-random-sequence (PRS) impedance measurements to the SOH analysis of a nickel manganese cobalt Li-ion battery by observing the variations in the ECM parameters. The measured impedances are fitted to the ECM by using the CNLS with adaptively obtained initial conditions. It is shown that the ECM parameters are changing as the battery capacity degrades. In addition, it is observed that some parameters are able to indicate a drastic reduction in the battery capacity and SOH.

The amount of grid-connected three-phased inverters is increasing rapidly. In a weak grid, the non-ideal grid impedance decreases the control performance and can even compromise the system stability through load effect. The stability assessment of the inverter-grid interface has been assessed extensively through state-space and impedance-based methods. The current work presents stability analysis method based on the load-affected loop gain of the innermost control loop, which includes the effect of phase-locked loop and grid impedance. The stability analysis is carried out by assessing modeled and measured loop gains using the Nyquist criterion, step responses, and system closed-loop poles. The stability issues originating from grid impedance or too high phase-locked loop bandwidth are accurately predicted by examining the innermost control loop.

As the amount of renewable energy increases rapidly, power systems will face novel challenges to maintain power quality. Power quality issues, which usually arise from the grid connection through power-electronic devices, can be reduced by proper control strategies. Grid-connected devices are conventionally optimized into a single operating point, but real performance is affected by the interfaced grid conditions. As the grid conditions change over time, the control performance varies, as does the quality of the power produced. To tackle this issue, the adaptive grid-voltage feedforward is introduced to the control system. The adaptive method, applying a perturb-and-observe algorithm, improves the produced power quality in real time by taking the control system characteristics and the grid conditions into account. The results show the improved power quality in various grid conditions when comparing the adaptive grid-voltage feedforward and the conventional implementations.

The impedance of a Li-ion battery is an important parameter for the battery's state-of-charge (SOC) and state-of-health (SOH) estimation. Battery impedance is typically modeled by an equivalent-circuit-model (ECM) in which the variations in the specific model parameters can be used for estimating the SOC and the SOH. However, the fact that the battery impedance is highly non-linear complicates the parameterization of the model. The model is traditionally obtained by a complex non-linear least-squares fitting algorithm which comes with high complexity. This paper proposes a novel approach to extract all the ECM parameters of the battery impedance obtained with online-capable pseudo-random-sequence (PRS) measurements. Although the algorithm has low complexity, it still captures the desired variations in the ECM parameters as a function of SOC. The algorithm is validated for the impedance data from a lithium-iron-phosphate cell.