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Discusses activities of the IES society that addresses the needs of both students and young professionals.

The paper is a comprehensive laboratory comparison study of two galvanic isolated solution off-board battery chargers: (1) Si-based cost-effective case, and (2) SiC-bidirectional ready for vehicle to grid concept case. All circuits are modular, and in both cases the DC/DC converter can be replaced according to the end user requirements (the coupled transformer remains the same and is constructed based on 12xC100 cores to avoid additional choke). In the case of single active bridge, an active RCD snubber is proposed to protect against overvoltage above 1kV in the DC_2 circuit. The dual active bridge is equipped with soft-star modulation using a zero vector to reduce in-rush current in case of no-load operation, while the AC/DC grid connected converter remains bidirectional to assure the highest power quality at the point of common coupling. All tests were made with real second-used batteries, which improves environmental, economic and technical feasibility of such systems for prosumers. The total efficiency of both AC/DC/DC converters (>97% in SiC and >94% in Si versions) was investigated in the same laboratory conditions.

This paper presents an originally-developed system for design and optimization of AC-DC converters dedicated in particular to operation in distributed generation systems. The proposed procedure is based on a multi-objective discrete optimization and expert knowledge of electrical engineering, especially power electronics. The required accuracy of calculations is obtained by using the database with real components, while the parameters applied in calculations are based on parameters provided by the manufacturer. The paper presents the foundations and basic system properties, the design and optimization process, and selected optimization results, obtained with a fully functional prototype of the design and optimization system (DaOS).

This paper presents the design process of a 6-kVA quasi-Z-source inverter built with SiC power devices, in particular, employing SiC MOSFETs and SiC Schottky diodes. The main design target is to find the optimal parameters and a good agreement between the efficiency and power density of the converter. The performance of the system may be influenced not only by the switching frequency but also from the specific pulsewidth modulated (PWM) method or type of SiC MOSFET, and, therefore, various design cases are analyzed. At a final step, the 6 kVA/3 × 400 VAC inverter employing the 80 mΩ SiC MOSFETs and operating at 100 kHz with the minimum switching number method is chosen for investigation and a laboratory prototype is built. From experiments, the high performance of the designed system is confirmed. More specifically, it is shown that an efficiency above 95.6% (at 400 VDC, B = 1.9) and a power density higher than 2 kW/dm3 have been reached. Last but not least, the obtained results, which can be recognized as leading in the area of impedance source converters, show the great benefits gained by employing the new power semiconductor devices.

This paper presents a grid-connected 10 kVA AC/DC converter built with 25mΩ SiC MOSFETs. The converter design process was based on an optimization procedure, which was applied to find the parameters that provide efficiency of 98.5% and power density of 3 kWA/dm3. The 10 kVA prototype, including LCL filter, was built and tested in various operation modes showing very good performance and high efficiency. The AC/DC converter is also able to act as an active power filter compensating high-order harmonics of the grid current caused by diode rectifier.

The paper presents application of two selected algorithms for an online platform for multicriteria optimization of AC/DC converters. The purpose of the platform is to speed up selection of components to satisfy the four main objectives in power electronic circuits: total power loses, weight, volume and total price. The system generates a pareto front for the objectives considering several constraints. It uses a discrete optimization scheme searching the database of available components. The database of components contains magnetic elements, semiconductors and capacitors used in a few typical configurations of ACDC converters. The paper focuses on presenting a concept of the system which allows to put together simulators of different components calculating objectives with modern multicriteria optimization algorithms (NSGAIII, SPEA2). The system proved to be very effective even for large databases of components composed of tens of thousands of items.

This chapter briefly describes possibilities and benefits offered by silicon carbide power transistors, especially SiC MOSFETS, implemented in AC–DC converters dedicated for distributed generation systems. Particular features provided by the wide band gap devices, as high efficiency or high power density, are illustrated by several laboratory prototypes. The chapter presents design parameters of the analyzed demonstrators where different types of SiC MOSFETS are considered. Moreover, experimentally measured efficiency characteristics and current–voltage waveforms are presented for each prototype.

This chapter presents a method of design and optimization dedicated for three-phase AC-DC converters. The main idea of presented work is to provide a tool which supports design process and helps to achieve desired properties: efficiency, volume, weight and system cost. The proposed design method is described in the chapter with special attention to calculations regarding power section of the converter. Newly introduced technology of SiC power devices is in scope of author’s analysis. Features of proposed method are illustrated by three SiC-based laboratory models rated at 10 an 20 kVA respectively. Each model is a result of the optimization process performed at different input requirements related to volume and efficiency. Finally, performance all models is verified during operation with 3 × 400 V AC grid.

Power electronic circuits, in particular AC-DC converters are complex systems, many different parameters and objectives have to be taken into account during the design process. Implementation of Multi-Objective Optimization (MOO) seems to be attractive idea, which used as designer supporting tool gives possibility for better analysis of the designed system. This paper presents a short introduction to the MOO applied in the field of power electronics. Short introduction to the subject is given in section I. Then, optimization process and its elements are briefly described in section II. Design procedure with proposed optimization parameters and performance indices for AC-DC Grid Connected Converter (GCC) interfacing distributed systems is introduced in section III. Some preliminary optimization results, achieved on the basis of analytical and simulation study, are shown at each stage of designing process. Described optimization parameters and performance indices are part of developed global optimization method dedicated for ACDC GCC introduced in section IV. Described optimization method is under development and only short introduction and basic assumptions are presented. In section V laboratory prototype of high efficient and compact 14 kVA AC-DC converter is introduced. The converter is elaborated based on performed designing and optimization procedure with the use of silicon carbide (SiC) power semiconductors. Finally, the paper is summarized and concluded in section VI. In presented work theoretical research are conducted in parallel with laboratory prototyping e.g. all theoretical ideas are verified in laboratory using modern DSP microcontrollers and prototypes of the ACDC GCC.

The paper presents a SiC-based 10 kVA AC/DC converter and its experimental verification during various operation modes when is connected to the 3x 400V grid. Besides a standard feature of the AC/DC converter — bidirectional power flow — new functionalities are enabled: a compensation of highorder harmonics and reactive power, a fast response to step load changes. These features are available due applied control method based on Direct Power Control and the elevated switching frequency (40 kHz). Finally, the conducted measurements show that for the discussed AC/DC converter peak efficiency close to 98.75% is available.

The paper presents advanced grid filters used for AC-DC converters supported distributed generation systems. Analyzed filters are based on the LCL filter and extended by additional frequency traps for attenuation of the harmonics related to switching frequency. For each presented filter methodology of the parameters selection is proposed. Finally, the properties of the discussed filters are verified by simulation analysis and compared to the classical LCL filter.

PurposeThe purpose of this paper is to consider both sides of a back‐to‐back AC‐DC‐AC interface.Design/methodology/approachThe paper presents a mathematical analysis, simulation, laboratory test in scaled model.FindingsThe two main findings comprised concept of control methods for grid AC‐DC‐AC converter applied in renewable energy sources with variable speed operation under distorted grid. Active filtering functionality in case of non‐linear current of a parallel load. Second, a control algorithm dedicated for two‐level AC‐DC converter applied in industrial networks with high‐order harmonics compensation working under hard conditions – balanced and unbalanced voltage dips.Research limitations/implicationsThe paper shows preliminary results for AC‐DC‐AC converter and active filter (AF) during voltage dips and for harmonics compensation. Control methods and/or topology should be improved and tested in scale and after at high‐power system.Practical implicationsPower quality supplied/received to/from the grid can be increased. In case of low‐cost system only AF can be applied to existing non‐linear receivers. Moreover, in case of full AC‐DC‐AC converter energy saving and production is possible.Originality/valuePresented control methods give satisfactory results. Paper presents laboratory results for grid and machine side two different power circuits during steady states and transients. Moreover, active filtering operation during voltage dips is presented.

In this chapter operation of a reliable control method of a Grid Connected Converter (GCC) under grid voltage disturbances is presented. As a GCC authors understand power electronic AC-DC converter with AC side filter and DC-link capacitor operating as an interface between the electrical grid and Active Loads (AL). At the beginning short introduction to selected grid voltage disturbances is given. Afterwards, the chosen modeling approach of a GCC is discussed and the example of passive components calculation are provided. In the next sections a brief review of a basic GCC control methods is described. A control method: Direct Power Control with Space Vector Modulation (DPC-SVM) is chosen for further development process. For the basic scheme of DPC-SVM special control modules for voltage dips and higher harmonics compensation are presented. Due to the development of new control modules and its integration with the classical DPC-SVM a new reliable (robust to selected grid voltage disturbances such as dips, higher harmonics) control method is proposed: Robust Direct Power Control with Space Vector Modulation (RDPC-SVM). The term “robust” in the name of proposed control refers to the fact that the RDPC-SVM method is expected to operate in an uncertain environment with respect to the system dynamics. This new control method can assure sinusoidal like and balanced AC current in extremely distorted grid voltage. Based on the case study from series 5–400 kVA of Voltage Source Converters (VSCs) it was verified that the control dynamic and features of the RDPC-SVM fulfill requirements of sinusoidal and balanced currents under uncertain grid voltage distortions. Moreover, the quality of current and power is significantly improved in comparison to classical methods. Hence, the negative impact of the GCC on the grid voltage (through its inner impendence) is significantly reduced i.e.: lower Total Harmonics Distortion (THD) factor of a grid current, control of active and reactive power flow assure good quality of integration with a grid even in case of increased impedance within operation limits.

The paper presents a simulation study of the Support Converter (SC) for passive front-end 55 kVA AC drive, which is aimed to improve the system performance. Most of time, the converter acts as a parallel Active Power Filter (APF) taking advantage from fast SiC devices application. During the regenerative breaking the SC may feed energy back to the supply grid. The complete system, including an advanced control system based on Direct Power Control with Space Vector Modulation concept, is modeled with the use of Saber package. Moreover, an estimation of the power losses is presented on the base of simulation results and switching performance tests of SiC MOSFETs and Schottky diodes. When harmonic compensation mode is considered semiconductor power losses are expected to be on the level of 120W (0.22% of nominal drive power). The converter is also expected to restore major part of energy from regenerative braking (power limit up to 28 kW) of the drive with total efficiency around 97.5%.

This paper presents a method for improving the design procedure of AC-DC power converters for power generation applications. The proposed methodology is based on selection of the most convenient configuration, in terms of switching frequency and design of the line filter, in order to minimize the overall losses in the system. In this work two types of semiconductor devices are considered: silicon IGBT and silicon carbide MOSFET for the design of a 100 kVA system, and they performance is compared. The AC-DC converter parameters, the design methodology and preliminary simulation results for representatives of Si IGBT and SiC MOSFET modules are presented.

The paper presents control algorithm for AC-DC converter operating as an interface between the Grid and Distributed Sources. Control algorithm is intended to be applied for serially manufactured AC-DC converters. Algorithm is based on Direct Power Control Space Vector Modulated extended with harmonic and dips compensation functionalities. Simulation and selected experimental results in various operation stages for the converter are presented.

This paper presents complete control algorithm for grid-connected Pulse Width Modulated (PWM) 3-level BtB (back to back) converter intended for industrial drives and renewable energy applications. The objective of control is to limit current harmonics distortion and provide ride through capability during voltage dips. Moreover, Maximum Power Point Tracking (MPPT) and Active Power Feedforward (PF) has been implemented end tested for optimizing energy flow control. Grid Side Converter (GSC) is controlled by Voltage Oriented Control (VOC) supported by synchronization loop with positive sequence extraction, resonant current controllers for higher harmonics compensation, grid voltage feedforward loop for dips compensation and DC voltage filter. At Machine Side Converter (MSC) Direct Torque Control Space Vector Modulated (DTC-SVM) has been used. Algorithm is tested in simulations and experiment from 3kVA up to 15kVA platform using three-level BtB NPC converter with LCL filter. Both controls of GSC and MSC are interacting by Power Feedforward for energy flow optimization between grid and active load.

This paper presents complete control algorithm for grid-connected Pulse Width Modulated (PWM) AC/DC converter intended for industrial drives and renewable energy applications. The objective of control is to limit current harmonics distortion and provide ride through capability during voltage dips. Following improvements to Voltage Oriented Control are presented: synchronization loop with positive sequence extraction, resonant current controllers for higher harmonics compensation, grid voltage feedforward loop for dips compensation and DC voltage filter. Algorithm is tested in simulations and on experimental 15kVA platform using three-level NPC converter with LCL filter.