This paper provides a detailed examination of the influence of common-mode voltage (CMV) on leakage and bearing currents in Permanent Magnet Synchronous Motors (PMSMs) for Electric Vehicles (EV) powered by Three-Level Active Neutral-Point Clamped (ANPC) inverters. A comparison of various carrier-based Pulse Width Modulation (PWM) techniques is conducted, evaluating their performance in terms of phase current Total Harmonic Distortion (THD), leakage current, CMV, and bearing voltage. An equivalent circuit model, integrating PMSM’s parasitic capacitances and bearing dynamics, is developed to analyse bearing behaviour under both healthy and fault conditions. Simulation results obtained in the PLECS environment offer valuable insights for selecting the modulation strategies that effectively balance CMV reduction, motor longevity, and inverter output quality, thereby enhancing the reliability of the system.

Hybrid batteries combine cells of complementary chemistries, each offering distinct strengths, resulting in battery designs with intermediate features, tailored for each application. With the aim of contributing to the development of modular and scalable hybrid batteries, this paper proposes a novel hybrid battery configuration consisting of two different battery banks, each formed by three series-connected battery modules, and a four-level neutral-point-clamped dc-dc power converter to interface the two battery banks. A suitable operating principle, a modulation strategy, and a closed-loop control are conceived for the proposed system. The power converter enables bidirectional power flow between the battery banks, and it also enables a lossless battery module state of charge balancing, simply by regulating the contribution of each module to the total power transfer, as this is one of the degrees of freedom of the selected multilevel converter topology. Simulation and experimental results verify the feasibility and good performance of the proposed system, demonstrating a substantial regulation margin of battery module currents, even at high modulation index values.

Accurate aging assessment of switching power semiconductors in power converters is essential due to their critical influence on converter reliability and operational lifespan. Traditional aging evaluation methods rely on intrusive sensors embedded within the power devices, which complicate electromagnetic interference management and limit the practicality of real-time monitoring. This paper proposes a comprehensive digital-twin framework and a simple algorithm to assess the state of health (SOH) of SiC power devices in switching-cell-array based power converters. The digital twin replicates the system electro-thermal behavior from the existing converter control current and voltage measurements and the modulation parameters. The algorithm estimates the power devices on-state resistance through the digital twin outputs and easy-to-integrate temperature sensors within the converter leg printed-circuit board. The on-state resistance provides a direct estimation of the power devices SOH. This framework delivers real-time insights into the converter SOH and degradation patterns, allowing predictive maintenance strategies. The proposed health assessment strategy is validated through simulations.

As electric vehicles (EVs) become central to sustainable transportation, effective thermal management of electric motors is crucial for performance and efficiency. This paper presents a co-simulation framework combining Ansys Motor-CAD and Ansys Twin Builder to model the electro-thermal behavior of an interior permanent magnet (IPM) motor. Several cooling strategies—constant flow, step control, hysteresis, and PID control—are evaluated in terms of energy consumption and thermal stability. Results show that dynamic control, particularly PID, can reduce pump energy use by up to 80% while maintaining safe operating temperatures. The approach also demonstrates potential in minimizing temperature fluctuations, extending motor life, and enhancing overall system efficiency.

Non-isolated integrated chargers take advantage of the electric vehicle’s on-board power electronic for charging purposes: the traction drive inverter is a good candidate to be used in the battery charging process, while the stator windings of the electrical traction motor can be utilized as static inductors. In a typical non-isolated three-phase grid-connected system, there exist a leakage current flowing through the common mode (CM) parasitic path between the vehicle’s chassis and the DC ground. Large leakage current lead to potential electric shocks to the end-users, as well as on-board electronics failures. In this paper, a 3-level Active Neutral Point Clamped (ANPC) inverter is used together with the stator windings of a permanent magnet synchronous machines (PMSM) for charging purposes. The issue of CM leakage current through the parasitic path is analysed for different earthing systems. Different modulation techniques are critically compared in terms of effectiveness in reducing the leakage current, grid currents distortion and capability in reducing the DC current ripple during battery charging. Simulation results are provided in support of the analysis.

The surface-mounted permanent magnet synchronous motor has found widespread use across various sectors, owing to its outstanding characteristics of torque density, efficiency and ease of control. These features, particularly crucial in the aviation field, make this type of machine highly desirable, especially in fixed-speed applications such as single-speed starter-generators. Additional performance metrics usually required nowadays in transportation are the sustainability and the overall environmental impact of components and systems. In this context, this paper proposes the design of a surface-mounted permanent magnet synchronous motor for a fixed-speed starter-generator, emphasizing all these different performance requirements. The design process is based on finite element (FE) optimizations, achieving a number of possible optimal configurations from an electromagnetic point of view, but giving then priority to the most environmentally friendly solutions. The outputs under examination are efficiency, power density, total harmonic distortion, torque ripple, copper and permanent magnet quantities, and temperatures. A motor characterized by a power density exceeding 2,3 kW/kg, 98% efficiency, and reduced copper and permanent magnet content is obtained.

Wide-bandgap (WBG) power semiconductor devices have acquired more and more interest in power circuits, since they allow to operate at higher switching frequencies and temperatures compared to the conventional silicon-based devices, while also improving efficiency and power density. In electric drive applications they can produce significant electrical stress at the machine terminals due to their inherently elevated voltage gradients (dv/dt), hence resulting in a reduced lifetime of the entire system. Voltage overshoot at the electrical machine terminals depends on many factors, such as voltage dv/dt, cables type and length, electrical machines input impedance etc. In this paper, a novel control based on a recent multilevel drive architecture is presented. This control is able to minimize the voltage overshoot at the terminals of an electrical machine independently form the system layout, increasing the overall reliability and lifetime of the winding’s insulation system.

The work provides a study on the development of algorithms which estimate the degradation rate of battery cells undergoing an extensive aging campaign lasting approximately 2 years. As the cell is progressively used, different degradation mechanisms might take place. Power and Energy fade, together with loss of reliability and safety, are the main consequences of cell degradation. In this work an aging model has been devised for the estimation of resistance increase and capacity loss as function of the cell-working condition. The modelling has been performed in MATLAB by data fitting the results obtained from the experiments using optimization algorithms such as Levenberg-Marquardt. The proposed aging model is combined with thermal and electrical models, which estimate the cell working condition of temperature and state-of-charge starting from the battery current profile measured during operation. A real driving cycle validated the goodness of the results by closely matching the prediction of the resistance increase and capacity loss with a coefficient of determination (R2) value of 0.9476 and 0.9262, respectively. The proposed model will contribute to the improvements of vehicle operation and the assessment of energy management strategies developed on a virtual-only basis, thus lowering costs and improving prediction accuracy.

This work provides an analysis of the impact on AC losses in hairpin conductors, provided by different values of resistivity. Starting from some specific stator geometries, the optimal resistivity which minimizes the AC losses is calculated for each configuration through both analytical and finite element (FE) methods, considering a frequency range typical of automotive applications. Possible applications and conditions where a higher resistivity material, such as aluminum, can be adopted, are discussed. The main sources of discrepancies between the analytical and simulative approach are also discussed.

This work discusses the modelling approach adopted for the estimation of the voltage distribution within hairpin windings of electrical machines. The physical phenomena and the major contributors to the occurrence of the uneven voltage distribution are first described. Then, the equivalent circuit used to predict the voltage distribution is presented in detail. The circuital parameters employed in the equivalent circuit are estimated via finite element electrostatic and electromagnetic analyses. Finally, a numerical tool is used to solve the differential equations describing the equivalent circuit above mentioned. Simulation results are illustrated and discussed. The phenomena under investigation are applied to a pre-defined reference system, consisting of slot motorettes.

One of the challenges brought forward by the gradual electrification undertaken by the aviation sector is the requirement of fault tolerance for machine drive systems to be used for critical on-board tasks such as propulsion or primary flight surface actuation. Their inherent advantages in both volumetric and gravimetric power density makes integrated drives the prime candidates for these applications. Despite the large advances in this field, few key area still need work. Key among which is fault tolerant current control strategies. This paper studies the application of resonant control techniques to achieve a scalable and fault tolerant current control strategy for multiphase machine.

The classical, wound-field, synchronous generator is currently enjoying a revamped interest in its design and development, partly due to the ever-increasing requirements in terms of power quality standards, efficiency and power density and partly due to advances in materials and manufacturing techniques. Also, the significant improvements in the computational resources allow the utilization of modern design techniques and tools. Apart from the design of the machine itself, another area of interest is the system-level optimization. The proposed project is aimed at renewing the power electronics and the control logics in power generating sets featuring the popular brushless configuration. An industrial small-to-medium size power generating set is taken as case study. The considered platform is first analyzed at system-level, by modelling in detail all of the components comprised in it. Then, focus is given to the automatic voltage regulator. A faster, more flexible and more efficient system is proposed, based on a 4-quadrant DC-to-DC converter which permits to improve the dynamic response of the excitation system.

The use of wide band gap devices in power converters is becoming more and more popular since they enable operations at higher switching frequencies, voltages and temperatures compared to traditional power semiconductors, while also improving the efficiency. However, in electric drives, they also tend to increase voltage overshoots at motor terminals and to produce uneven voltage distributions across stator windings, due to their high rate of voltage change over time (dv/dt). In order to mitigate these issues, passive filters can be employed. The aim of this paper is to give an overview of possible solutions based on passive filters, analyzing the main advantages and drawbacks. A comprehensive, qualitative comparative study is carried out taking into account common mode currents reduction, power losses, costs, dimensions and reliability.

This paper assesses the use of a modified three phase VSI topology with additional switches (H8) together with suitable modulation techniques as a mean for common-mode voltage reduction in electric drives with the aim of mitigating the onset of harmful bearing currents. Bearing currents in inverter-fed motors are related to the high dv/dt variation, induced at the motor terminals by the converters. The problem, already known in industry for Si-Based converters, is now aggravated by the use of wide-bandgap devices in More Electric Aircraft applications. This paper evaluates the use H8 topology for mitigating the phenomenon, comparing its performance against the one of a conventional three-phase full-bridge converter, by means simulation and experimental results.

This paper presents a three-phase converter architecture with a reduced common mode voltage to be used in photovoltaic power systems. The full-bridge architecture is modified by adding two additional switches in the DC path that allow decoupling the load from the source during the freewheeling phases. Optimized modulation strategies are analyzed and compared against the space vector modulation for the full-bridge. Extensive measurements show an improved efficiency when SiC devices are used, and a theoretical analysis links this efficiency to a marked extension of the converter lifetime.

This paper proposes an Active Thermal Control (ATC) method for MOS-gated power switches aimed at reducing temperature swing amplitude during operation. It leverages on the fact that thermal cycle amplitude of many actuation system components (such as power devices) has a large impact on the system reliability and lifetime. These figures can then be improved, which eases the adoption of electrification in markets, such as transportation, where they are still below target values. The proposed ATC method leaves electric load parameters untouched, while acting dynamically on gate parameters, namely voltage and resistance. A model-predictive control (MPC) strategy is used to determine the most suitable parameters to use. Simulations of the control scheme are presented first, to predict the potential benefits on temperature swing amplitude, and the consequent improvements in terms of device lifetime are inferred, using literature models. Then, experimental proof of concept is presented and discussed, together with its limitations and drawbacks.

The Smart Transformer (ST) represents an enabling technology for providing new services to Low Voltage (LV) and Medium Voltage (MV) grid, overcoming the problems that are limiting the widespread diffusion of distributed renewable sources in conventional distribution systems. The ST 3-stage configuration includes a DC/AC 4-wires converter at the LV side, that must be able to cope with the equipment already installed in the LV grid in which ST wants to substitute conventional distribution transformer. Grid converters with capacitance towards ground, when connected to ST-fed LV grid can cause common mode current problems not yet discussed in the literature. This paper aims to fill this gap through an in-depth analysis of the problem and indicating possible solutions.

This paper proposes the comparison among different sensorless position estimation strategies suitable for permanent magnet assisted synchronous reluctance machine drives. A machine of such type was designed and optimized aiming at improving its sensorless performance, besides minimizing the torque ripple and maximizing the power factor. Different sensorless solutions for the estimation of the magnetic flux linkage and for tracking the rotor angle are investigated and their performance compared in computer simulations. Experimental results are reported for the PM-assisted synchronous reluctance motor drive example.

The growing demand for high-performance power converters calls for the adoption of new strategies, not only in architectures, but also in electronic technologies. To take full advantage of wide-bandgap semiconductor (SiC, GaN) power devices, and to exploit their amazing capabilities, dedicated drivers need to be developed. This paper presents a control unit for advanced gate drivers, based on a finite-state machine (FSM), and discusses design criteria; the proposed design is verified by simulation in Matlab-Simulink. The presented automaton not only "follows" the power switch during its state transitions, but features also automatic dead-time insertion when the switch is operated in bridge configurations, and is able to provide important diagnostic and self-test information.

Wide-bandgap power switches, based on SiC and GaN, are emerging on the semiconductor market. Standard resistor drivers are insufficient to exploit all the advantages of these new devices. Fine control over current and voltage waveforms during switching, equivalent on-state resistance and immunity to noisy environments, demand the development of dedicated drivers. This study aims at determining a suitable control topology for the gate (or base) terminal of the power device, in order to enact regulation of the switching waveforms and performances. Four different topologies, both open- and closed-loop are simulated, examined, and compared with the standard resistor driver.

Wide-bandgap devices are under the spotlight of scientific research as they exhibit great performance in terms of efficiency and temperature operation. However, to fully exploit their characteristics, dedicated driving circuits are needed. High-power gate-insulated switching devices exhibit important input capacitance; when fast switching speeds are demanded, high-current pulses are needed to drive the gate terminal. This is particularly true for wide-bandgap devices, capable of lower transition times than conventional silicon devices. The proposed circuit is a voltage controlled resistor, which output can drive wide-bandgap devices. Design criteria, as well as simulation results, are presented.

This paper investigates two winding concepts for Permanent Magnet (PM) machines used for more electric aircraft systems where reliability is a concern. Analysis is carried out using two different surface mounted PM machines designed for low and high speed applications: a 12 slot, 10 pole machine with concentrated windings for rotorcraft swashplate actuation and a 36-slot 6-pole machine with distributed winding arrangement for an aircraft starter-generator. The impact of the winding arrangement for the low speed machine is investigated with a focus on turn-turn Short-Circuit (SC) faults. Implications of the SC fault and methods to restrain the resulting SC current are discussed. A prognostics method for potential turn-turn SC faults for the high speed application is then investigated. It is shown that potential winding faults can be detected at an early stage of fault inception and thus measures can be taken to limit propagation.

This paper presents an AC/AC active power filter based on a single-phase matrix converter (SPMC). The use of a matrix topology allows to eliminate the reactive components normally used for temporary energy storage, reducing the size of the power converter and improving its reliability. The filter operates in series with the load through a step-down transformer, also allowing for a limited regulation of the fundamental voltage (boost/reduction). Several control methods are evaluated; in particular, a novel zero voltage compensation technique is introduced in order to reduce distortion around the input voltage zero crossing. Simulations and experiments are used to validate the considered control methods, and confirm the feasibility of the proposed solution.

Early detection of incipient faults in AC drives is one of the most difficult challenges for condition monitoring, especially for faults related to insulation degradation of the windings. This is because insulation degradation is very difficult to be detected on-line, so these faults may pass unnoticed before turning into a major faults. This paper looks at the feasibility of using coaxially insulated windings not only to increase reliability against winding insulation problems, but as an alternative to advance condition monitoring that may be suitable for the detection of insulation degradation, and other faults not easily detected by conventional schemes such as demagnetization issues, and the presence of inter-turn short circuits. The concept of insulation degradation for the case of coaxially insulated windings is analytically considered in this work and a novel condition monitoring alternative proposed. The proposed scheme and winding topology are extensively evaluated numerical to determine their feasibility to drive condition monitoring.

Many transformerless topologies for photovoltaic systems were proposed in order to minimize power losses and avoid high levels of ground leakage current (that can arise in such systems). The most efficient PWM strategies achieve this goal by decoupling the grid from the DC Link during the freewheeling phases of the output current. These strategies usually operate only with a unity power factor. However, as solar inverters have penetrated into power distribution networks, new issues have arisen and modifications of regulations governing grid connection of distributed systems were introduced in some countries. One of the new requirements for the inverters connected to the low-voltage grids is the possibility to provide reactive power. This paper proposes a transformerless inverter topology with a wide-range power factor operation. Simulation results and extensive experimental results, focused mainly on ground leakage current analysis, showed the effectiveness of the proposed solution.

In the recent years the research on photovoltaic converters has been focused on topologies that do not feature a line frequency transformer, in order to reduce costs and successfully increase the overall efficiency. The main problem in removing the galvanic isolation is that the parasitic capacitance present between the cell and the metal frame enclosing the panel (usually earth-connected) enables a common-mode current to be injected into the grid by the converter. This paper proposes an active common-mode filter able to compensate the high-frequency common-mode voltage variations at the output of the power converters, that represent the principal cause of ground leakage current. The advantage of this solution concerns the capability to operate with an arbitrary power factor. In this work it is applied in cascade to a converter with standard full-bridge topology driven by a three-level PWM strategy. Simulation and experimental results shows the feasibility of the proposed approach.

The design of a photovoltaic (PV) grid-connected converter usually comprehends a galvanic isolation between the grid and the photovoltaic panels. Recently, in low power systems, the galvanic isolation has been removed with the aim to increase efficiency and reduce the cost of the converter. Due to the presence of a parasitic capacitance between the photovoltaic cells and the metal frame of the PV panel, usually connected to earth, a high value of common mode current (i.e., ground leakage current) can arise. In order to limit the ground leakage current (which deteriorates the power quality and generates EMI), new converter topologies have been proposed. Their effectiveness is based on the symmetrical (ideal) commutations of the power switches and some of them adopt a further voltage level derived from a capacitive divider of the DC bus voltage. Unfortunately, in actual implementations, asymmetrical power switches transients and variations of this added voltage lead to higher ground leakage current with respect to the ideal case. After a review of the state of the art this paper investigates these two issues and presents a particular solution (based on digital control and PWM strategy) that, in conjunction with a compensation strategy of power switches actual commutations, guarantees low ground leakage current regardless the parameters tolerance of the power circuit. Simulation and experimental results confirm the effectiveness of the proposed solution.