This paper presents two novel Modular Multilevel Converter (MMC) configurations for medium-voltage distribution networks, which are achieved by replacing some capacitive cells of each MMC branch with Supercapacitors (SCs) and Battery Packs (BPs), respectively. The first configuration (MMC-SC) is able to exploit SC energy content by preserving MMC branch voltage capability, thus ensuring a suitable dynamic decoupling between grid and DC-link power demands. Steady-state decoupling can be achieved by the second configuration (MMC-BP), which can charge/discharge BP as needed. MMC-SC and MMC-BP functionality is guaranteed by a multi-stage control system architecture, which has been developed in order to ensure proper MMC energy, current and voltage management at any operating conditions. The effectiveness of both MMC-SC and MMC-BP is verified through simulation studies, which regard step-changing active and reactive grid power profiles.

This paper presents a sensorless control scheme for Surface-Mounted Permanent Magnet Brushless AC Machines (PMBACMs), which estimates both electric rotor speed and position through a Model Reference Adaptive Systems (MRAS) approach. In particular, starting from the PMBACM sampled-data model, a priori and a posteriori quantities are introduced, based on which the adaptive law is set in accordance with the Popov’s Hyperstability Criterion. Additionally, the issues arising from the duality of the solution computed by the MRAS-based algorithm are overcome by the support of Hall sensors. The effectiveness of the proposed MRAS-based Hall-assisted sensorless algorithm is verified through numeric simulations, which also regard the employment of a double MRAS-based algorithm to enhance rotor speed and position estimation further.

This paper deals with electromagnetic loss analysis and minimization in an integrated Flywheel Energy Storage System (FESS). The FESS consists of a large-airgap Surface-Mounted Permanent Magnet Synchronous Machine (SPM), whose inner rotor integrates a carbon-fiber flywheel, leading to a compact and efficient FESS. Electromagnetic losses minimization is achieved through an accurate SPM modelling, which accounts for both Joule and core losses, as well as for flux-weakening operation. Consequently, SPM maximum efficiency is obtained by injecting a proper demagnetization current component at each operating condition, which guarantee the optimal trade-off among the different losses’ contributions. The effectiveness of the proposed approach is validated through numerical simulations.

The design of an Inner-Rotor Large-Airgap Permanent Magnet Synchronous Machine (IRLA-PMSM) is presented in this paper, whose distinctive feature consists of integrating a thick carbon-fibre cylindrical layer that acts as both a sleeve and a flywheel. This results in large airgap and makes simplified mechanical modelling generally used for sleeve design no more suitable. Therefore, an advanced mechanical modelling is presented in the paper, which is combined with an electromagnetic and energy modelling in order to make the analytical design procedure compliant with all the design targets and constraints. The proposed IRLA-PMSM is validated through finite element analyses, which regard both mechanical and electromagnetic aspects at different operating conditions.

A hybrid control system for LC network filters is proposed in this paper, which enables coupling energy storage systems with the main grid suitably. The proposed control system is developed by combining both linear and predictive control approaches: particularly, the outer grid current loop is designed by means of PI regulators, whereas the intermediate capacitor voltage and the inner inductor current loops are designed in a deadbeat predictive control fashion. As a result, three nested loops have been achieved, whose performance can be set properly through dynamic decoupling and multi-rate sampling. The effectiveness of the proposed solution is verified through numerical simulations, which refer to different grid operating conditions in terms of active/reactive power exchanges.

An optimization study to reduce the harmonic components of the magnetic flux density due to the modulation effect in a coaxial Magnetic Gear Transmission system (MaGT) is presented in this paper. The results of the harmonic content analysis of a MaGT are used to optimize the design of a double-stage MaGT configuration for automotive applications presented in previous works. In particular, pole arc to pole pitch ratios of the two rotors and of the modulation ring have been tuned in order to reduce the harmonic content of the magnetic flux density. The comparison between two different case studies is presented in regard to core losses, maximum temperatures and overall MaGT efficiency. These analyses have been carried out by means of analytical formulations and finite element simulations using the FEMM software.

A Multi-Stage Energy Management System (MS-EMS) is presented in this paper; it aims at optimizing the operating costs of multi-source Hybrid Electric Vehicles (HEVs) supplied by a Fuel Cell (FC), batteries, supercapacitors and the electric grid. In particular, based on a given HEV cost function, the first stage of the proposed MS-EMS is devoted to FC management as its optimization does not depend on the other energy sources. Then, the second stage of MS-EMS splits the residual power demand among the remaining energy sources optimally, by considering their availability and HEV operating constraints. The reference powers of these energy sources are then tracked by the third stage of MS-EMS, which addresses also DC-link voltage regulation needs through a priority-based deadbeat predictive control approach. The effectiveness of the proposed MS-EMS is proved by a simulation study, which regards the comparison with a rule-filter-based EMS.

A new universal full-directional SiC-GaN-based two-phase DC-DC converter has been recently introduced. It is supposed to replace with DC-DC battery charger and DC-DC traction drive converters in Plug-In Electric Vehicles. The SiC-GaN-based converter is designed to have the advantage of low switching power loss of GaN in hard-switching application and also avoid a high number of paralleled phases for high power multi-phase DC-DC converter applications. Especially in this paper, a dead-time analysis is done for the state-of-the-art high power GaN and SiC components of the proposed converter. To this aim, a new Spice-based simulation method is presented to obtain precise dead-time power loss calculations. Furthermore, the effect of negative OFF gate-source voltage is investigated.

A Highly-Integrated Battery-UltraCapacitor system (HIBUC) is presented in this paper. It consists of a battery pack and an ultracapacitor module, which are coupled to each other through a three-level neutral-point-clamped converter. The latter is connected to the point of common coupling between a microgrid and the main electric grid through a step-up transformer, which enables lower DC-link voltage rating and, thus, eases HIBUC prototyping without affecting its performances significantly. The DC-link is also connected to a dissipative voltage regulator, which has been designed with the dual purpose of preventing DC-link overvoltage and improving DC-link voltage regulation simultaneously. The effectiveness of the proposed configuration has been verified through a simulation study, which has been carried out in the Matlab-Simulink environment and refers to different HIBUC operating conditions.

A design approach of GaN High Electron Mobility Transistor (HEMT) gate driver circuit for electric vehicles based on multi-objective optimization is presented in this paper. It is composed by two design stages, for each of which a number of spice-based simulations enable to obtain the objective functions, i.e. the efficiency and EMI levels. The latter consists of the maximum of the common mode current in the frequency range 150 kHz-30 MHz. Consequently, well-known optimization techniques are applied in order to optimally design the gate on resistances and the high side gate inductor of one leg inverter gate driver circuits. The validity of the proposed design approach has been proved through a simulation study in which the optimized gate driver circuit and a classical symmetrical gate driver circuit have been implemented on one leg inverter for comparison purposes. Simulation results highlight the effectiveness of the proposed design approach, as both higher efficiency and lower EMI level have been successfully achieved.

Modelling, sizing and control of a Hybrid Energy Storage System (HESS) made up of Batteries (B) and Supercapacitors (S) is presented in this paper. The HESS is characterized by an integrated topology through a Three-level Neutral-Point Clamped Converter (NPC), leading to a highly-integrated electric propulsion system. Accurate modelling of both B and S are considered at first, although some simplifications are introduced due to automotive application. Then, a suitable sizing procedure is introduced and discussed in detail, which is based also on an experimental S characterization. The HESS control approach is described as well, which is quite robust against the non-linear model of S due to the integrated topology. The effectiveness of all the design solutions has been validated through a simulation study, which refers to a vehicle start and stop.

An advanced Frequency-Based energy Management (FBM) suitable for Hybrid Energy Storage Systems (HESSs) in Microgrids (MGs) is presented in this paper. The HESS is made up of Batteries (B) and Supercapacitors (S) and it has to provide both peak shaving and power quality. A frequency-based power split criterion is introduced, namely the B power profile is synthesized through an appropriate low-pass filter, while S has to cope with sudden and fast power fluctuations. In addition, in order to enable a suitable peak shaving capability, an appropriate management algorithm is developed based on the forecasted MG power profile. As a result, suitable B power thresholds can be defined in accordance with both B power and energy constraints over a given time horizon. This can be adapted also in real-time in order to benefit from more accurate forecasting and B energy status. The effectiveness of the proposed FBM is proved by numerical simulations, which refer to the MG of the German island of Borkum.

The paper presents an accurate efficiency assessment of a novel Permanent Magnet Synchronous Machine (PMSM) to be employed in a High-Speed Flywheel Energy Storage System (HS-FESS). Particularly, the proposed machine configuration aims to minimize core losses by reducing the overall amount of steel. In this regard, some of the specific design solutions adopted are introduced and briefly discussed. Much more details are given on PMSM core losses estimation, which is carried out through an extensive Finite Element Analysis (FEA) by means of JMAG. The FEA results allow the definition of a suitable lumped-parameter electrical model of the proposed PMSM, based on which a detailed PMSM efficiency assessment can be achieved. This is particularly important for identifying the most suitable PMSM operating speed range, within which the overall HS-FESS performance can be optimized.

This paper presents a smart energy management of a Hybrid Energy Storage System (HESS) that supplies a highly integrated electric propulsion system. The HESS consists of Batteries (BT) and Supercapacitors (SC), which are integrated to each other through the traction inverter, namely a Three-level Neutral-Point Clamped Converter (NPC). The proposed management strategy consists of exploiting SC over the low-speed operating range, thus coping with vehicle acceleration and deceleration needs for urban mobility mostly. Consequently, BT is preserved successfully from excessive cycling, it being also supported over the mid speed range. Both these goals are achieved by suitable SC sizing, which accounts for both energy and voltage constraints. The proposed energy management is validated through a simulation study, which refers to vehicle acceleration and stop.

An optimal control strategy devoted to manage the daily charging/discharging profiles of Energy Storage Systems (ESSs) is described in the present paper. The proposed approach aims to minimize Microgrids (MGs) daily electricity costs considering both the real-time price evolution and the effects of intermittent Renewable Energy Sources (RESs). Referring to MGs and electricity market modeling as well as to their main physical and economic constraints, an optimal ESS charging/discharging strategy has been developed. The effectiveness of the proposed ESS management is verified on a MG case study. Particularly, the electricity demand and RES production measured on a small-scale MG are used to compare the daily MG electricity costs and energy balances with and without the proposed optimal control strategy of ESS.

A novel Hybrid Energy Storage System (HESS) for Electric Vehicles (EVs) is proposed in this paper. It consists of a battery pack and an ultra-capacitor module (UC), which are suitably coupled through a Three-Level Neutral-Point Clamped Converter (NPC). Particularly, although the UC is integrated within the DC-link, its voltage can be varied within a wide range, thus assuring its full exploitation without the need of any DC-DC converter. This is achieved by means of an appropriate HESS control system, which also prevents the battery pack from handling sudden power fluctuations. The effectiveness of the proposed HESS is verified through a simulation study, which refers to an electric propulsion system based on a Surface-Mounted Permanent Magnet Synchronous Machine (SPM), which is supplied by the proposed HESS through the NPC.

A novel current control strategy for Brushless DC machines (BLDCs) is presented in this paper. It aims to increase BLDC exploitation compared to conventional current commutation (two-phase-on) and three-phase-on control approaches. The proposed current control strategy consists in injecting a suitable zero-sequence current in order to exploit the BLDC zero-sequence back-emfs. Thus, increased torque capability and/or reduced Joule losses can be achieved compared to conventional control approaches. As a result, BLDC competitiveness can be increased, even in comparison with Brushless AC machines (BLACs). The effectiveness of the proposed approach is validated through both theoretical and finite element analyses, the latter being carried out by means of JMAG. The analyses regard the comparison between BLAC and BLDC driven by different control strategies.

An average modeling approach for DC-DC power converters is presented in this paper. It allows the achievement of accurate averaged models of DC-DC converters, which account for dynamic and steady state operations, over both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). In particular, appropriate equivalent switching signals are introduced in order to account for each converter operating state. In addition, a suitable inductor model is introduced in order to improve inductor losses estimation. As a result, the proposed averaged modeling enables an enhanced power losses estimation by accounting for switching and current ripple phenomena. The worth and effectiveness of the proposed modeling approach has been validated through a simulation study, which is performed in the Matlab-Simulink environment and refers to the case of a boost DC-DC converter.

A novel DC-link voltage and current control algorithm for Three-Level Neutral-Point-Clamped converters (NPCs) is proposed in this paper. It is developed with the aim of sharing the overall DC-link voltage among DC-link capacitors as needed, without impairing NPC load performances. The proposed algorithm consists of an external DC-link voltage control loop, which synthesizes an appropriate reference DC-link current profile on the basis of the reference DC-link voltages. Such a current profile is then tracked by means of an inner DC-link current control system. This last synthesizes the most suitable PWM pattern for DC-link voltage regulation, prioritizing NPC load requirements at the same time. The effectiveness of the proposed DC-link voltage and current control algorithm is verified through extensive simulations, which refer to the case study of a three-phase NPC that feeds a Surface-Mounted Permanent Magnet Synchronous Machine.

A model predictive control algorithm (MPC) suitable for Surface-Mounted Permanent Magnet Synchronous Machines (SPMs) is presented in this paper. It is based upon an accurate discrete-time model of the drive, accounting for both voltage saturation and current limitation constraints. It aims to properly manage these constraints in order to guarantee a good exploitation of both transient and steady state SPM performances, especially over flux-weakening operation. The effectiveness of the proposed MPC is first validated by a simulation study, in which the sensitivity of the proposed MPC against un-compensated inverter un-idealities and parameter uncertainties is properly highlighted and discussed, as well as the effects of sudden load torque variations. Then, an experimental study is performed on a radial-flux SPM driven by a Field Programmable Gate Arrays (FPGA) control board. The performances achievable by the proposed MPC are compared with those obtained by a conventional PI-based control system in order to highlight the improvements, especially regarding transient and flux-weakening operation.

A novel flux-weakening approach suitable for Surface-Mounted Permanent Magnet Synchronous Machines (SPMs) is presented in this paper. It consists in directly synthesizing the square magnitudes of the current and voltage vectors on the basis of an accurate SPM sampled-data model and of the reference torque profile. This enables optimal and easy management of SPM operating constraints, i.e. current limitation and voltage saturation, on the basis of which the dq reference current profile can be achieved, whatever the SPM speed and Constant Power Speed Ratio (CPSR) is, i.e. finite or infinite. The effectiveness of the proposed flux-weakening approach is highlighted by both simulation and experimental results, which refer to SPMs with finite and/or infinite CPSR and driven by a predictive control algorithm.

A novel DC-link voltage equalization algorithm for Three-Level Neutral-Point-Clamped Converters (NPCs) is presented in this paper. It mainly consists of appropriate pulse width modulation patterns, which are alternatively employed in order to exploit the DC-link capacitors differently, for a given reference voltage space vector. Thus, the most suitable PWM pattern is chosen in each sampling time interval in accordance with DC-link voltage equalization needs, without affecting NPC performances in terms of output voltage and current waveforms. The worth and effectiveness of the proposed equalization algorithm are verified through a simulation study, which refers to the case of a Surface-Mounted Permanent Magnet Synchronous Machine (SPM) fed by a three-phase NPC.

A novel continuous-time equivalent circuit suitable for boost DC-DC converters is presented in this paper. It has been developed on the basis of the averaging technique with the aim of achieving a good ripple-free representation of the state variables of the system, whatever the converter operating mode is, i.e. Continuous Conduction Mode (CCM) or Discontinuous Conduction Mode (DCM). This goal can be achieved on condition that an appropriate PWM pattern is introduced, which enables an almost perfect matching between state variables and their corresponding equivalent ones at the start of each sampling time interval. Apart from the inductor and the capacitor, the proposed circuit consists of some equivalent input voltage and output current sources, together with several constant and/or variable resistors, which depend on converter switching signals and circuital parameters. The proposed continuous-time equivalent circuit has been validated through a simulation study, which is performed by means of the software PLECS. Simulation results highlight the worth and the effectiveness of the proposed modelling approach, over both transient and steady state operations.

An improved averaged model suitable for boost DC-DC converters is presented in this paper. It is developed on the basis of the averaging technique with the aim of appropriately taking into account the effects of switching phenomena. Thus, two appropriate trapezoidal signals have been introduced in order to model the transient evolutions of voltages and currents of the DC-DC converter devices over both turn-on and turn-off of the switch. This enables the synthesis of an appropriate averaged model of boost DC-DC converters, which can be usefully employed in determining average voltage and current evolutions, as well as steady state average powers. The worth and effectiveness of the proposed modelling approach has been validated through a simulation study, which refers to the case of a traditional boost DC-DC converter.