Abstracts

Shirin Askari

Fixed-Frequency Resonant Converters for CC-CV EV Battery Charging

Abstract:
Electric vehicles (EVs) are gaining prominence as eco-friendly alternatives to fossil fuel-based transportation, driven by their low emissions, reduced noise pollution, and cost-effective operation. A critical component of EVs is the battery charger, with resonant converters (RCs) being preferred due to their high efficiency, soft-switching capabilities, and low electromagnetic interference. Lithium-ion batteries, commonly used in EVs, require constant current-constant voltage (CC-CV) charging, necessitating a wide output voltage range. However, traditional variable frequency control (VFC) in RCs leads to a broad switching frequency range, causing deviations from the resonant frequency, increased circulating energy, and reduced efficiency. To address this, various techniques have been proposed, including hybrid control strategies, magnetic control, reconfigurable structures, phase-shift control, adjustable turns ratio transformers, and leveraging inherent RC characteristics. These methods, while effective in narrowing the frequency range, often introduce complexities such as increased component counts, intricate control schemes, or higher conduction losses. Novel fixed-frequency resonant battery chargers, combining LCC and LC resonant networks, offer a promising solution. They achieve intrinsic CC-CV charging with simplified control, reduced component count, and enhanced efficiency through zero-voltage switching (ZVS) and zero-current switching (ZCS), providing a robust and efficient charging solution for EV applications.

Piotr Bogusz

Switched reluctance machine as alternative drive for hybrid and electric vehicle

Abstract:
Switched reluctance machines (SRM) can be an alternative to permanent magnet machines (PMSM, BLDC) and induction machines (IM) in electric vehicle (EV) drive applications. The presentation includes non-classical control methods for this type of machine in both motoring and generating modes, aimed at improving the operational performance of the drive. These methods can be implemented in SRM drives virtually at no additional cost, as they do not require hardware modifications. The paper also presents a hardware-software solution designed to minimize current ripple drawn from the power supply, with the goal of reducing losses in the power source. SRM drives can also be used as a component of the vehicle’s onboard charger.

Karol Fatyga

DC-Link current pulsation compensation system based on a triple active bridge converter

Abstract:
The energy storage operating with a three-phase, four-wire converter is exposed to an AC current, pulsating with the doubled frequency of the grid. This current has negative influence on the electrochemical battery, and in order to reduce it, a solution is proposed, based on a triple-active bridge converter. A full design process is presented, starting with the modeling of the converter, building the laboratory bench, testing and analysis of the results. It is concluded, that the TAB converter can serve as a compensatory circuit for the DC-link current pulsation, with average pulsation reduction ratio of 98.3%.

Dave Figueroa

Control of Power Electronics Converters for Microgrids Applications

Abstract:
This presentation examines advanced control strategies for power electronic converters in microgrid applications. The first portion addresses the control challenges of Distributed Energy Resources (DERs) with LCL filter connections, focusing on a novel control approach that maintains system stability while satisfying operational constraints. The methodology incorporates filter dynamics into the model-based predictive control (MPC) control design to mitigate resonance issues while ensuring a secure operation for the converter. The second portion explores the development of an Interlinking Converter (IC) control system for hybrid AC/DC microgrids utilizing a Hybrid Distribution Transformer framework. This research presents a brief study of what is the state-of-the-art talking about ICs for hybrid microgrids and how the development of the hybrid distribution transformer (HDT) can be a promising solution to act as an IC.

Mikołaj Kądzielawski

Improved Modeling of Sigma-Delta-Based Measurement Dynamics

Abstract:

Growing demands for power quality and the dynamic performance of control algorithms in modern power electronics necessitate increasingly accurate modeling of controlled systems. Furthermore, the widespread adoption of measurements based on Sigma-Delta converters drives the need for a more in-depth analysis of their dynamic behavior. In this presentation, an existing solution found in the literature—utilizing a delay-based model—is analyzed both independently and within the current control loop of a buck converter. Based on the obtained results, the need for a more accurate model became evident. To address this, numerical fitting of the transfer function was employed. The proposed model was then compared with existing approaches, demonstrating improved performance.

Maciej Rudawski

Safe replacement of the electrochemical cells of a prosumer energy storage device in an emergency while maintaining its uninterrupted operation

Abstract:
This work presents a novel approach to prosumer energy storage employing a dedicated DC/DC converter based on a multi active bridge topology. The main research challenge addressed herein concerns the method of battery cell integration. In contrast to conventional energy storage systems where cells are connected in series or in parallel the proposed architecture assigns each individual cell to a separate port of the multi active bridge converter. This configuration enables the integration of battery cells with varying electrochemical characteristics, including differences in type, voltage profile, or degradation level, within a single storage unit. Furthermore, the system offers fault tolerance, allowing continued operation even after the failure of one or more cells. Unlike conventional solutions, defective cells can be hot-swapped and replaced with other cells of different characteristics without interrupting the storage system’s operation. The paper presents the proposed hardware implementation, outlines the associated control strategy, reviews existing state-of-the-art solutions in distributed energy storage, and discusses the results obtained from experimental validation.

Keywords: electrochemical energy storage, utility grid, multi active bridge

Bartłomiej Stefańczak

Analysis of the impact of four-wire AC/DC converters on load symmetry optimization and transformer efficiency in low-voltage distribution networks

Abstract:
The increase in the number of single-phase loads connected to low-voltage distribution networks, along with the large number of RES installations, increasingly leads to the phenomenon of load asymmetry and a situation in which the direction of current flow in all phases is not consistent. This leads to the formation of increased losses in transformers. The purpose of the presented speech is to present a method of load symmetrization, allowing to reduce losses to the rated level. The proposed solution uses a four-branch AC/DC converter with energy storage, which dynamically compensates for unequal phase loads. This makes it possible to reduce the zero-sequence components of the current and reduce additional losses in the transformer core and neutral conductor. The paper will present the sources of these phenomena and the effectiveness of the proposed method under conditions of actual grid operation.

Przemysław Trochimiuk

Resonant DC-DC converter with series-connected SiC MOSFETs

Abstract:
In the presentation, some issues related to the design and operation of the series resonant dual active bridge (SRDAB) converter intended for interfacing battery energy storage (BES) and connected to the medium voltage (MV) DC grid will be shown. To convert such a voltage level, the series-connection technique of low-voltage silicon carbide (SiC) MOSFETs was applied. During the standard battery charging/discharging cycle, the switching conditions of transistors change. Thus, special effort was put into providing effective and reliable voltage balancing in such a wide operating range. Finally, the built converter enabled bidirectional operation while interfacing a 1.5 kV MVDC grid with an 800 V battery.