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In this article, a current control algorithm is conceived for converting solar dc power into ac power of high-quality. This conversion is based only on a dc-ac converter, avoiding the use of two stage converter. The proposed algorithm is founded on tracking the maximum power point which ensures controlling the electrical power exchanged with the grid. To assure a good dynamics and reduce the control errors, a proportional resonant controllers are utilized and a self-tuning founded on particle swarm optimization is utilized. The proposal strategy goodness is verified by means of numerical simulations.

The paper deals with design and control of a fault tolerant and reconfigurable photovoltaic converter integrating a Battery Energy Storage System as a standby backup energy resource. When a failure occurs, an appropriate control method makes the energy conversion system capable of operating in open-delta configuration in parallel with the grid as well as in islanded mode. In case network voltage is lacking due to heavy anomalies or maintenance reasons, the proposed control system is able to quickly disconnect the inverter from the grid while ensuring the energy continuity to the local load and the emergency fixtures by means of the integrated battery packs. In particular, the paper proposes a fast islanding detection method essential for the correct operation of the control system. This specific technique is based on the Hilbert transform of the voltage of the point of common coupling, and it identifies the utility lack in a period of time equal to half a grid cycle in the best case (i.e., 10 ms), thus resulting in good speed performance fully meeting the standard requirements. A thorough numerical investigation is carried out with reference to a representative case study in order to demonstrate the feasibility and the effectiveness of the proposed control strategy.

The full electric/hybrid electric propulsion is nowadays a promising technology for the aircraft. The problems related to the electric flight are inherent the storage system sizing, the design of lightweight motors and the power electronics converters. In this paper is proposed a preliminary study about the on-board wiring system. In particular, the maximum power transferrable with the common aeronautic wires in a distributed propulsion system has been investigated.

This article proposes a space-vector modeling formalism and a harmonic balance control strategy for the voltage equalization of a double-star modular multilevel converter employed as an active interface between a three-phase ac grid and an HVdc grid. The balancing procedure is based on the control of the power flow through the converter legs, with the aim to stabilize the energy stored in each switching module to the same value. By properly exploiting both the space-vector/zero-component and the common/differential mode decompositions, the proposed approach is able to highlight all the viable interactions between the system voltages and currents. The harmonic balance control is then formulated in its most general form in order to effectively increase the degrees of freedom available to the voltage equalization while guaranteeing the hardware constraints and functional requirements of the converter. The resulting control algorithm, based on a subset of the harmonic control variables, has been implemented on a controller board and experimentally validated on a 1.5-kW test bench.

The paper deals with a high performance fast charger system for Zero Electric Vehicles (ZEVs). The proposed converter, which is built upon two interleaved three-leg two-level Voltage Source Converters (VSC), allows for a substantial increase of the total output power, thus leading to a high reliable topology. Furthermore, this approach allows a strong reduction of the output voltage ripple while exhibiting excellent dependability characteristics. The performance of the proposed DC/DC converter is validated by an extended numerical analysis, which confirms the effectiveness of both the control strategy and the system topology.

This paper presents an overview of the most recent state of the art in the field of high-speed electric machines fed through high-frequency converters. This type of systems is rapidly wide spreading in aeronautical and automotive applications, as well as microturbines. Each typology has its own advantages and downsides, which are analytically presented in this paper. Some types of high-speed electric machines require high-frequency voltage supply, highly stressing the dielectric materials of the winding insulation system. For this reason, in high-speed electric drives, premature failure may occur and a reduction of the total system reliability has been observed in the past years. Such issues are comprehensively investigated in this paper.

This paper proposes a new mathematical model of modular multilevel converters for battery electric vehicles with space-vectors enabling a critical analysis of cell balancing for the battery management system. In particular, the requirements for power balancing and the actual number of degrees of freedom of the control are investigated. The paper shows that the traditional approach of cell balancing is a special case of the proposed control methodology. Numerical analyses with Matlab/Simulink™ highlight the reasons of the slow response of the standard balancing technique for specific operating conditions of the battery electric vehicle. The paper suggests potential improvements that could be introduced through the proposed generalised approach.

In recent years the aerospace industry has made a growing effort to develop a quieter and more environmentally friendly aircraft. In particular, several research activities have been focused on innovative solutions aimed at the design/optimization of an on-board electric system fully compatible with this new approach. A first important step in the evolution towards an All Electric Aircraft (AEA) is the replacement of the hydraulic actuators with fully electric ones. The transition process is not easy to carry out, since weight, size and reliability represent highly critical issues for aircraft applications. In this context, the significant improvements in semiconductor technologies can be exploited as a critical means to overcome the constraints mentioned. Indeed, this work proposes a Silicon Carbide (SiC) based Power Factor Correction (PFC) converter, whose design and control have been tailored in order to properly supply a wide range of on-board Electro-Mechanical Actuators (EMA). In particular, while the adopted circuit topology allows for power factor correction and bi-directional power flow, the SiC technology, thanks to the higher efficiency with respect to other semiconductor-based technologies, leads to a significant reduction in the overall system weight/volume. Furthermore, to meet the strict requirements in terms of dynamic and steady state performance imposed by the application, a novel adaptive regulator is conceived. A reduced-scale laboratory prototype of the SiC-based converter (3 kVA) is realized in order to verify the effectiveness of the proposed design and control approach.

Marine energy sources represent an attractive and inexhaustible reservoir able to contribute to the fulfillment of the world energy demand in accordance with climate/energy regulatory frameworks. Wave energy converter (WEC) integration into the main grid requires both the maximization of the harvested energy and the proper management of the generation variability. The present paper focuses on both these mentioned issues. More specifically, it presents an embedded point pivoted absorber (PPA) and its related control strategy aimed at maximizing the harvested energy. Experimental and numerical investigations have been carried out in a wave/towing tank facility in order to derive the design characteristics of the full-scale model and demonstrate the validity and effectiveness of the proposed control strategy.

In the context of grid connected photovoitaic (PV) generation systems, there are two paramount aspects regarding the Maximum Power Point Tracking (MPPT) of the photovoltaic units and the continuity of the service. The most diffused MPPT algorithms are based on either perturb and observe, or on an incremental conductance approach and need both PV current and voltage measurements. Several topology reconfigurable converters are also associated with the PV plants, guaranteeing fault-tolerant features. The generation continuity can also be assured by interleaved inverters, which keep the system operating at reduced maximum power in case of failure. In this paper, an evolution of a hysteresis based MPPT algorithm is presented, based on the measurement of only one voltage, together with a novel space vector modulation suitable for a two-channel three-phase grid connected interleaved inverter. The proposed MMPT algorithm and modulation technique are tested by means of several numerical analyses on a PV generation system of about 200 kW maximum power. The results testify the validity of the proposed strategies, showing good performance, even during a fault occurrence and in the presence of deep shading conditions.

The paper deals with ball screw actuators used for the electric steering of nose landing gears in civil aircrafts. Design options and performance analyses are carried out with reference to actuators composed by ball screws coupled with two multi-stage axial-flux permanent magnet motors, which are fed by two separate inverters. A redundant configuration of the drives is developed in order to increase the availability of the steering service. Numerical analyses are carried out with reference to some significant operating conditions.

In this paper the control of a grid-tied PV (Photovoltaic) Cascaded H-bridge inverter is discussed. The operation principle of the considered circuit is analyzed and a particular attention is paid to the different modulation techniques well-suited for this configuration. Moreover, some critical implementation issues are addressed, while a fair comparison between the proposed modulation scheme and the Phase Shifted PWM (Pulse Width Modulation) is carried out. The adopted control strategy is based upon a sorting algorithm in order to modulate only one power cell (i.e. H-bridge) per sorting cycle while the others are in fixed state. This technique allows to reduce power switching losses, thus increasing overall system efficiency. The numerical results reported in the paper permit to confirm the feasibility of the proposed modulation strategy and the better performance with respect to PS-PWM in terms of power efficiency.

This paper is focused on the design of a PMSM for the electric steering of a nose landing gear. The traditional hydraulic steering systems utilized in a nose landing gear are usually based on a rack and pinion solution with two hydraulic pistons at the external sides. The main idea proposed in the paper is the substitution of the hydraulic steering system with an electric steering system based on the coupling between an harmonic drive and a three phase double rotor axial flux permanent magnet machine fed by two different three phase inverter.

With reference to light railways transportation systems, in the paper a comparison is carried out between vehicles equipped with Induction Motor (IM) drives and Permanent Magnet (PM) brushless motor drives. The attention is particularly focused on the deceleration phase of the speed diagram, which consists of an interval of “coasting” followed by a braking interval. The analyses carried out aim to contribute in understanding possible disadvantageous aspects of PM drives if they are taken into consideration to replace traditional IM drives in propulsion systems. In order to comparatively evaluate energetic and dynamic performance, some numerical results are obtained and discussed with reference to different operating conditions of an effective case-study.

The paper deals with acoustic noise in permanent magnet synchronous motors (PMSM) with tooth concentrated armature windings. In particular, the noise emitted by this kind of motors is investigated with reference to high-torque low-speed applications. In these cases, due to the high number of poles, the stator yoke is usually thin and it is characterized by low natural frequencies that could lead to undesired amplifications of mechanical resonance phenomena. The paper analyzes the effects of variations of stator yoke thickness on vibrations and noise emitted by the machines. The aim is to investigate the relation between noise emission and stator yoke thickness without any other variation of the machine configuration. The analysis is led by the mathematical model of PMSM, used to characterize analytically the time behavior of the radial forces that excite the machine vibrations; FEM analysis and numerical extrapolation of the machine acoustic response are performed by the software “Manatee”.

The paper concerns the analysis of urban electrical mini-bus power configurations based on two different energy storage systems. Full electrochemical battery power solution and hybrid power configuration based on battery and fuel cell are considered, modelled and analyzed. Performance analyses are carried out by modeling the two different powered mini-buses running along the same drive cycle experimentally tested in actual traffic conditions. The results are compared and discussed in term of performance.

The study deals with a novel torque derivative control of induction motor drives. The proposed technique is mainly finalised to improve the motor dynamic response regardless of speed operating conditions, ensuring satisfactory values of both motor currents distortion and torque ripple. The core of the discussed approach is a special look-up table, in which the converter voltage space vectors are sorted with respect to their influence on the torque derivative, taking also into account their influence on the flux magnitude. The table is indeed accessed by a desired torque derivative value, obtained by properly processing the output of hysteresis controllers. Moreover, a variable duty-cycle technique is implemented in order to ensure a satisfactory torque ripple in steady-state conditions. The proposed algorithm, suitable for a general multilevel inverter, is numerically tested on a three-level neutral point clamped inverter and its performance are compared with the ones obtained by a traditional direct torque control method based on three speed ranges look-up tables. The control is then validated experimentally by means of a reduced scale laboratory prototype fixing the same condition used for numerical analysis.

This paper deals with a Power Electronic Transformer (PET) topology for a 3-phase AC distribution grid. In the discussed topology, a Modular Multilevel Converter (MMC) and a Full-Bridge converter are employed for the medium voltage (MV) and the low voltage (LV) side, respectively. By using the space vector, approach a mathematical model for the MMC is presented and a grid-synchronous algorithm is implemented to easily control the power flow through the structure. The MV and LV side converters are linked through a High Frequency (HF) transformer, whose control strategy is a Dual-Active Phase-Shift Control (PSC) with Square Wave Modulation (SQM). This technique is combined with a predictive algorithm, which is able to keep each leg’s capacitors’ voltages balanced both in stationary and in transient conditions. The proposed algorithm is numerically validated in the Matlab/Simulink® environment.

This work deals with the design of a three-phase grid-tied photovoltaic (PV) cascade H-bridge inverter for distributed power conversion. The power balancing among the phases must be properly addressed. In fact, an intra-phase power imbalance—arising from uneven irradiance and temperature conditions—generates a per-phase power imbalance. This latter can be compensated by the injection of a proper zero-sequence voltage, while the intra-phase balance is ensured by means of a hybrid modulation method which is able to guarantee the handling of unequal DC (Direct Current) sources, stable circuit operation, and maximization of PV power production. The digital controller is developed and tested in Matlab/Simulink environment integrated with XSG (Xilinx System Generator), thus allowing an easy transfer on a field-programmable gate array (FPGA) platform and accurately describing the behavior of a real hardware implementation. Thus, numerical results have been considered to prove the effectiveness of the proposed approach.