This paper presents the real-time monitoring of the degradation parameters of the DC-DC boost converter by utilizing the Digital Twin (DT) method. The DT is a real-time high-fidelity mathematical (digital) model that runs in parallel to the physical DC-DC boost converter, providing information for its monitoring and control using the measurement data coming from the sensors already existing in the asset. The digital model is obtained by means of the Backward Euler numerical methodology for discrete-time representation of the mathematical switching model of the physical system. The estimation of degradation parameters of the physical system is based on the data analysis carried out by comparing the data measured by the sensors existing in the physical system and the data coming from the digital model. The data analysis is done by applying the heuristic algorithm like Particle Swarm Optimization (PSO) method. The proposed method is validated through the digital-switching model realized by means of the FPGA and it runs on a suitable control board. Experimental tests on the converter prototype are illustrated. For further validation, a sensitivity analysis is carried out.

Nowadays, multilevel converter represents a good idea for commercial and industrial applications, where small size and cost, low maintenance, reliability in a wide range of environments and good efficiency are required. Furthermore, the multilevel converter can provide control for both maximum power tracking and output power factor reducing the filter weight and volume. The proposed power converter topology, called Five-Level E Type Inverter (5L E-Type Inverter), for grid connected applications is presented and analyzed in this paper. The performance of the three-phase 5L E-Type Inverter has been theoretically investigated. The thermal models of the power semiconductor have been created taking into account the parameters provided by the manufactures and employing multi-dimensional look-up tables in Plexim/PLECS environment. The design and selection of passive components have been described in order to obtain amazing performances in terms of weight, volume and efficiency and power quality. New control strategy, named concurrent control, for 5L E-Type Inverter has been implemented and validated in LabVIEW development environment. The peak efficiency of the converter above 98.3% and the total harmonic total harmonic distortion current (THDi) less than 3% have been achieved.

Grid-connected and stand-alone applications need inverters that accurately control the filter output voltages. Nowadays, resonant controllers (RCs) represent a good tradeoff between implementation issues and control performances. However, the unknown nature and size of supplied loads affect the dynamic control behavior and may reduce the effectiveness of the control system. A new structure of RC is introduced with the purpose of providing three degrees of freedom and allowing us to select independently the controller's magnitude, width, and phase. In order to fully take advantage of the proposed RC form, the online tuning procedure based on the output filter analysis is also proposed. According to that, several resonant compensators can be placed in the loop to achieve a better output voltage waveform (i.e., lower total harmonic distortion).

The last few decades have seen a significant increase in the number of electric vehicles (EVs) for private and public transportation around the world. This has resulted in high power demands on the electrical grid, especially when fast and ultra-fast or flash (at the bus-stop) charging are required. Consequently, a ground storage should be used in order to mitigate the peak power request period. This paper deals with an innovative and simple fast charging infrastructure based on supercapacitors, used to charge the energy storage system on board electric buses. According to the charging level of the electric bus, the proposed fast charging system is able to provide the maximum power of 180 kW without exceeding 30 s and without using DC–DC converters. In order to limit the maximum charging current, the electric bus is charged in three steps through three different connectors placed between the supercapacitors on board the bus and the fast charging system. The fast charging system has been carefully designed, taking into account several system parameters, such as charging time, maximum current, and voltage. Experimental tests have been performed on a fast charging station prototype to validate the theoretical analysis and functionality of the proposed architecture.

Power electronic systems present a non-linear behavior mainly due to their switching nature. This is often combined with their interaction with non-linear systems, such as other switching converters, diode rectifiers, motor drives, etc. and with possible non linearities of the power grid in the case of grid connected systems. The major effect of these non-linear interactions is the generation of harmonic distortion on voltages and currents (both in DC and AC), which needs to be compensated to achieve high power quality systems. The use of passive filters is often the simplest and most immediate solution; however, this decreases converter efficiency and increases its weight and volume. Thus, the use of a control strategy capable of tracking periodic signals, rejecting periodic disturbance and largely improving steady state behavior and harmonic distortion with a limited bandwidth is a very desirable feature. Repetitive Control (RC) represents an extremely practical and efficient solution for the aforementioned issues, and it is widely employed in many different applications. This paper focuses on state of the art of RC used in power electronics and drives. RC basic concepts, different control structures, design methods, fixed and variable frequency operating conditions, etc. are investigated. Furthermore, many example applications and existing control approaches developed in recent years for power electronics and drive systems based on RC, have also been discussed in detail.