Isolated multiport converters can host loads and sources at different power and voltage levels to their ports by a single topology, giving potential merits in terms of power density and efficiency. However, the higher the number of ports, the higher the number of degrees of freedom in the modulation patterns. This high number of modulation variables complicates the optimization problem, making closed-form solutions impractical. This article avoids the analytic solution to the optimization problem by proposing a data-driven solution. The presented approach is based on an artificial neural network (ANN) trained to minimize the rms value of the currents flowing through the switches and the transformer windings of a triple active bridge (TAB) converter. This minimization is achieved by determining suitable values of the duty-cycles for modulating the converter switches. The proposed ANN-based modulation is validated considering an experimental TAB prototype rated $5 \,\mathrm{k}\mathrm{W}$ .

This paper proposes and analyzes a two-stage dc-dc isolated converter for electric vehicle charging applications, where high efficiency over a wide range of battery voltages is required. The proposed conversion circuit comprises a first two-output isolation stage with CLLC resonant structure and a second two-input buck regulator. The transformer of the first stage is designed such that its two output voltages correspond, ideally, to the minimum and maximum expected voltage to be supplied to the battery. Then, the second stage combines the voltages provided by the previous isolation stage to regulate the output voltage of the whole converter. The first stage is always operated at resonance, with the only function of providing isolation and fixed conversion ratios with minimum losses, whereas the second stage allows output voltage regulation over a wide range of battery voltages. Overall, it is shown that the solution features high conversion efficiency over a wide range of output voltages. This paper comprehensively describes the solution, including modeling, analyses, design considerations for the main circuit components (e.g., magnetics, switches), and modulation choices. Experimental results are reported considering a converter module prototype rated $10 \mathrm{kW}$ , input voltage $800 \mathrm{V}$ , and output range $250 \mathrm{V}$ to $500 \mathrm{V}$ , employing silicon-carbide and gallium-nitride semiconductors.

The paper presents a multidimensional ripple correlation search technique of optimal operating points of triple active bridge (TAB) converters. Such converters present multiple modulation parameters that should be exploited to achieve high operation efficiency. On the other hand, the several degrees of freedom available make the identification of optimal parameters a challenging task, not easily tackled analytically or in closed form. A model-free on-line search method based on the ripple correlation technique is then proposed in this paper. The proposed method finds the optimum modulation parameters of TAB converters utilizing a three-dimensional ripple correlation control. The key property of the proposed solution is the adoption of orthogonal perturbation signals, where the orthogonality is simply obtained using different injection frequencies. The multidimensional correlation technique originally shown herein can be applied to other generic optimization problems. The proposed search is verified through a hardware-in-the-loop validation setup and an experimental prototype rated $5kW$ .

Active balancing techniques have become increasingly popular for mitigating voltage mismatches in series-connected lithium-ion (Li-ion) batteries. These techniques outperform passive balancing in enhancing battery capacity as the battery ages, leading to an increased lifetime, especially in the electric transportation sector, where residual capacitance plays a crucial role in determining battery lifespan. This study proposes a circuit configuration that utilizes a multiport active half-bridge converter for active cell balancing. The proposed method offers a high degree of flexibility owing to multiple operating modes and a relatively straightforward circuit configuration. Based on the state of charge of each cell, bidirectional power flow can be controlled between two or more arbitrary cells or between the entire battery string and a group of batteries. The proposed approach has been experimentally validated in a battery pack of seven Li-ion cells.

State-of-the-art PWM AC/DC converters often suffer from high switching losses due to hard-switching and thus are limited in their efficiency and power density. In this paper, the concept of the integrated Triangular Current Mode (iTCM) operation is introduced, which enables soft-switching over the entire AC mains period and can overcome the limitation of PWM, resulting in a higher system performance. Thereby, an LC-circuit is added to the well-known full-bridge-based PWM AC/DC converter, which internally superimposes a high triangular current to the AC mains current in order to reverse the current direction in the semiconductors in each switching cycle and by this enabling soft-switching operation of all devices. In this paper, the iTCM concept is presented in detail and its performance is compared to the standard PWM and TCM approaches. Furthermore, the proposed iTCM concept is applied to a 10 kV SiC-MOSFET-based bidirectional 25kW single-phase AC/DC converter operated from the 6:6 kV medium-voltage AC grid. In this case, compared to PWM, the iTCM concept allows to increase the switching frequency by almost a factor of five while the total semiconductor losses are reduced by more than 40%.

This paper proposes and analyzes a two-stage isolated dc-dc converter for electric vehicle charging applications, where high efficiency over a wide range of battery voltages is required. It employs a first pre-regulation stage and a second half-bridge LLC stage, integrated with the first. The second stage is always operated at resonance, ensuring high efficiency. The first pre-regulation stage is responsible for the desired input-to-output voltage conversion ratio and the zero-voltage switching operation of all the switches. This allows low conversion losses even with voltages that may vary over a wide range. The paper presents the conversion structure, the converter analysis, the design of the magnetic elements, and demonstrates the converter operation considering an experimental prototype interfacing a $\boldsymbol{750} \mathbf {V}$ dc-link with an output bus with nominal voltage range $\boldsymbol{250} \mathbf {V}$-$\boldsymbol{500} \mathbf {V}$. The implemented module is rated $\boldsymbol{5} \mathbf{kW}$ and achieves a peak efficiency of $\boldsymbol{98.0\%}$ at $\boldsymbol{3} \mathbf{kW}$ output power.