An active power filter based on a three-level neutral point clamped T-type converter with LCL input filter is presented in the paper. The main goal of the paper is the analysis of a control system that ensures independent control of a current in each phase. The presented control method of the filter allows reactive power compensation and/or a higher harmonics reduction to be achieved in each phase independently, with the possibility of control tan (φ) coefficient. This allows the power flow between the phases to be minimalized and reduces the RMS values of filter currents without the need to balance grid currents. The analysis presents the possibility of an operation in different modes, which was verified by experimental results. The results have been obtained in a 20 A_RMS laboratory system described in the paper. The results reveal relatively low power losses, which are a feature of the selected three-level T-type topology. Additionally, that topology, when compared to a two-level one, ensures the reduction in current ripples with the same parameters of passive components.

The paper presents a shunt hybrid active power filter for 1 kV mining applications in configuration with a single-tuned passive filter. The focus is on the method of controlling the filter, with particular emphasis on the influence of network voltage distortion and time delays in control on the effectiveness of harmonic reduction, which is one of the most important aspect of power quality. The low-power loss configuration of a hybrid filter with SiC transistors is shown, as well as the control algorithm which limits the influence of voltage distortion. Theoretical considerations are verified by results obtained from simulations and tests of the hybrid active power filter prototype.

The paper presents a Dual Active Bridge (DAB) converter operating as an interface between the LiFePo4 battery and the fuel cell/hydrogen generator. The hydrogen tank can increase the stored energy of the battery system. Among the main requirements for a converter is the need to transfer power of up to 10 kW and operate with widely changing voltages on both sides of the converter. The design of the power electronic part and passive components of the converter is deeply discussed. Next, the influence of the wide voltage range on the operation of the converter is depicted, including its impact on power losses and current values. Different topological modifications for power loss reduction are presented and experimentally verified. Finally, a simple modification of the control system, giving the possibility of increasing efficiency, is briefly presented.

The paper shows the construction and operation of the High-Voltage High-Frequency Coaxial Cable Energy Transfer System dedicated to a three-phase 500 V mining grid with an ungrounded neutral point. The correct operation of the model was verified through simulation and experiments. This paper focuses on the overall system efficiency and the power loss analysis of its components. Based on these measurements, it is concluded that the presented system is suitable for mining applications, where high energy conversion efficiency is essential due to the difficulty of dissipating heat to the environment.

The paper presents the possibilities offered by the ePEDlab platform supporting teaching of electrical drive. A case of using this open educational resources for self-study or distance education is presented. The paper focuses on the power quality aspects in electrical drives. The teaching process based on interactive lectures, computer simulation exercises and experimental exercises is described in the paper. The ePEDlab platform presents interactive lectures divided into two courses (for users with different level of knowledge). The courses present idea of operation, block schemes, description of control methods, features, power electronic converters and aspects of power quality in electrical drives. The paper presents examples of interactive lectures focused on power quality aspects and operation of DC and AC drives. Then prepared simulation models, used during self-study process for this aspects are showed. These models ensure a rich form of results presentation, can be parametrized during exercise realization and are tightly connected with the experimental part of the course. Last part of the paper presents possibility of experimental verification of the theory with aspects of distance measurement of the drive operation. The summary indicates the possibility of using remote access to teaching materials, including the experimental part, used during lockdown.

The paper concerns Forced Dynamics Control (FDC) of the squirrel-cage induction motor based on Direct Torque Control (DTC) method. Combination of these methods gives very good dynamic response and precise tracking of the reference speed. Principles of DTC and FDC methods are described, and simulations and laboratory tests results of the proposed combination are presented in the paper.