In electric drive systems, common-mode voltage (CMV) fluctuations cause bearing currents that damage the motor, deteriorate stator winding insulation, and generate electromagnetic interference (EMI) throughout the system. Several methods have been proposed to mitigate this stray voltage, especially in electric vehicles, where reliability requirements are increasingly stringent. At the same time, improving efficiency-by minimizing power losses-is essential to enhance driving range and thermal management. This article presents a novel two-level three-phase inverter topology combined with hybrid modulation techniques for electric vehicle propulsion systems. The proposed architecture aims to significantly reduce CMV variations while maintaining high overall efficiency. Simulation and experimental results confirm that, depending on the specific operating condition, the proposed solution achieves reductions of more than 80% in CMV fluctuations compared with standard space vector-pulsewidth modulation (SV PWM) operation, efficiency improvements between 0.6% and 1.5% relative to a conventional voltage-source inverter (VSI), and a redistribution of switching losses that can reduce the power dissipated per main VSI device by more than 25%. Unlike previously proposed alternatives, the converter preserves full compatibility with standard VSI control schemes and achieves a superior balance between reliability, CMV mitigation, and efficiency. Therefore, it represents a feasible and promising alternative for future electric vehicle drive systems.

Dual Three-Phase (DTP) winding configurations are gaining importance in automotive powertrains, where the DC-Link capacitor plays a critical role in terms of power density and reliability, as it accounts for approximately 40% of the inverter’s volume and about 30% of its failures. This work systematically analyses the influence of various DTP configurations (S0-DTP, A30-DTP, S60-DTP) and DTP-specific Double Zero-Sequence Injection (DZSI) PWM techniques on the DC-Link capacitor current spectrum to minimize its RMS value. Using the Double Fourier Integral formalism, this work derives analytical expressions for input current harmonics, identifies dominant ripple components, and assesses interleaving strategies to suppress these harmonics, thereby reducing RMS current stress on the capacitor. The findings are validated through experimental measurements, which confirm that proper selection of DZSI-PWM techniques and interleaving angles leads to up to 85% reduction in capacitor RMS current stress compared to standard non-interleaved modulation, thus enhancing power converter reliability without additional hardware modifications. These insights offer practical design guidelines for electric vehicle powertrains and high-performance multiphase inverters.

Asymmetrical dual three-phase (ADTP) multiphase arrangements are becoming increasingly important for powertrain applications within the automotive sector. However, further research and development should be carried out in order to improve these arrangements. Lately, there has been a growing interest in exploring enhancements for the pulse-width modulation (PWM) techniques aimed at reducing the current stress of the propulsion system’s DC-Link. In electric vehicle (EV) applications, the voltage-source inverter (VSI) must deliver high power density while meeting stringent reliability requirements. A critical component within the VSI is the DC-Link capacitor, which occupies up to 40% of the inverter volume and contributes to approximately 30% of power converter failures. Reducing the DC-Link ripple current can significantly enhance reliability and reduce system size. However, improvements on the input side often come at the expense of the output side, where excessive current ripple increases Joule losses and induces torque ripple, leading to mechanical vibrations and reduced motor efficiency. Addressing this trade-off is particularly important in ADTP systems, as these configurations are increasingly adopted for high-density, fault-tolerant propulsion systems. In this context, this work evaluates the most relevant carrier-based (CB)PWMtechniques regarding the output current ripple quality of an ADTP. For this purpose, a novel method is proposed to calculate the harmonic distortion factor (HDF) of an ADTP arrangement. It is based on the double Fourier integral formalism, instead of the conventional time-domain analysis. The method developed in this work provides accurate harmonic profiles for a thorough comparison among CB-PWMs and enhances the theoretical understanding of how harmonic cancellation works. This innovative approach not only makes the results insensitive to simulation time resolution but also effectively mitigates errors and offsets that arise over the time-domain integration of the voltage measurement. This type of analysis is particularly meaningful when examining the interleaved variations of these CB-PWMs, as they focus on harmonic reduction or cancellation. The experimental validation of this method demonstrates that the results are consistent, providing confidence in the theoretical analysis. In this sense, this work determines how the interleaving schemes, typically used to benefit the DC-Link capacitor, affect the HDF of the ADTP arrangements. Furthermore, this study points out which PWM technique is most promising for ADTP-based propulsion systems, for both improving the performance of the powertrain input (DC side) and its output (AC side, i.e. VSI + electric machine), thus helping engineers and researchers in this field.

Many modulation techniques have been developed along the years to provide in medium and high-volta ge converters a high power quality and minimum switching frequency. This paper introduces some popular modulation techniques for multilevel converters, whose major challenges are o btain the previous two features. The modulation strategies th at are presented are specially focused in the three-phase three-level Neutral-Point-Clamped convert (NPC), which is one of the most used topology in industry and in renewable applicat ions.

The DC-Link capacitor plays a crucial role as far as power density and reliability are concerned: it occupies approximately 40% of the inverter, and causes approximately 30% of its failures. Asymmetrical dual three-phase (ADTP) multiphase arrangements are gaining relevance in the automotive sector for powertrain applications. This work focuses on reducing the impact that the widely used double zero sequence injection (DZSI) family of PWM techniques have on such a bulky and failure-prone component in an ADTP arrangement by means of interleaving techniques. By using the double Fourier integral formalism, the input current spectra and the overall performance of these PWM techniques have been derived, in terms of current rms value and voltage ripple in the DC-Link capacitor. Simulations have shown that choosing an adequate interleaving scheme and angle considerably relieves both current and voltage stresses on the DC-Link capacitor compared to noninterleaved operation. Reductions of 84% current rms and 86% voltage ripple have been achieved at static operating points. Finally, by averaging the rms current over WLTP standard driving cycle, reductions up to 26% have been obtained under more realistic conditions. All this would enhance the reliability and reduce the size of the onboard capacitors in future electric vehicles.

—In traction applications, particularly in transport electrification, multiphase drives are increasingly being an interesting alternative over their three-phase counterparts due to a range of advantages outweighing the additional cost, e.g. smoother torque performance, higher current capability, enhanced fault tolerance, higher efficiency and lower DC-Link current ripples. This work focuses on the impact this multiphase drives modulated by continuous and discontinuous PWM techniques have in a such a pricey and bulky component as it is the DC-Link capacitor. Taking into account that the equivalent series resistance of the DC-Link capacitor varies with frequency, the typical approximated calculation of the power losses in this component by means of the RMS value of the current is often inaccurate. Therefore, the spectral analysis of the DC-Link current has been carried out for the five-phase two-level VSI in order to estimate more accurately the power losses in the DC-Link capacitor and see which PWM modulation technique benefits this bulky and expensive component depending on its ESR curve and the selected switching frequency.

Neutral point voltage control converters (NPVCC) are being considered for AC drive applications, where their additional degree of freedom can be used for different purposes, such as fault tolerance or common mode voltage (CMV) reduction. For every PWM-driven converter, the CMV is an issue that must be considered since it can lead to shaft voltages between rotor and stator windings, generating bearing currents that accelerate bearing degradation, and can also produce a high level of electromagnetic interference (EMI). In light of these considerations, in this paper a three-dimensional reduced common mode voltage PWM (3D RCMV-PWM) technique is proposed which effectively reduces CMV in five-phase six-leg NPVCCs. The mathematical description of both the converter and the modulation technique, in space-vector and carrier-based approaches, is included. Furthermore, the simulation and experimental analysis validate the CMV reduction capability in addition to the good behaviour in terms of the efficiency and harmonic distortion of the proposed RCMV-PWM algorithm.

Multiphase drives are becoming a viable alternative to three-phase drives in electric traction applications, thanks to a number of benefits that offset the additional cost, e.g. smoother torque performance, higher current capability, enhanced fault tolerance, higher efficiency, and lower DC-Link current ripples. This work focuses on the impact that continuous and discontinuous PWM techniques have on such a costly and bulky component as the DC-Link capacitor, in a multiphase arrangement. Because the equivalent series resistance (ESR) of the DC-Link capacitor varies with frequency, the typical current RMS-based power loss approximation is often inaccurate. Thus, the current spectrum-based power loss estimation has been carried out for the five-phase two-level voltage source inverter (VSI). In this scenario, and switching at about 100 kHz, a MKP capacitor has shown to suffer lower power losses when discontinuous PWM techniques are used.

In the automotive industry, the design and implementation of power converters and especially inverters, are at a turning point. Silicon (Si) IGBTs are at present the most widely used power semiconductors in most commercial vehicles. However, this trend is beginning to change with the appearance of wide-bandgap (WBG) devices, particularly silicon carbide (SiC) and gallium nitride (GaN). It is therefore advisable to review their main features and advantages, to update the degree of their market penetration, and to identify the most commonly used alternatives in automotive inverters. In this paper, the aim is therefore to summarize the most relevant characteristics of power inverters, reviewing and providing a global overview of the most outstanding aspects (packages, semiconductor internal structure, stack-ups, thermal considerations, etc.) of Si, SiC, and GaN power semiconductor technologies, and the degree of their use in electric vehicle powertrains. In addition, the paper also points out the trends that semiconductor technology and next-generation inverters will be likely to follow, especially when future prospects point to the use of "800 V" battery systems and increased switching frequencies. The internal structure and the characteristics of the power modules are disaggregated, highlighting their thermal and electrical characteristics. In addition, aspects relating to reliability are considered, at both the discrete device and power module level, as well as more general issues that involve the entire propulsion system, such as common-mode voltage.

Common-mode voltage (CMV) produces serious reliability and electromagnetic interference (EMI) issues in modern pulse-width modulated (PWM) electric drives. Such issues will become more prominent in the near future, as industry moves towards the introduction of wide-bandgap (WBG) semiconductor technologies operating at higher switching frequencies and also with greater dvdt. In this context, multiphase electric drive technologies can be of great interest, as their additional degrees of freedom can be exploited to reduce CMV. This work aims to study the potential of multiphase electric motor drive systems for CMV mitigation. To do so, a comprehensive review of the most recent scientific literature is conducted, mainly focusing on high impact works published recently. As a result, a clear and up-to-date picture of the most common multiphase technologies, i.e., (m+1)-leg, multiple three-phase, open-end and star-connected multiphase systems is provided along with their CMV reduction potential. Not only the topologies themselves but also modulation techniques are analysed and presented, mainly focusing on star-connected systems. As a conclusion, it can be stated that such multiphase systems are promising candidates to substitute conventional three-phase motor drives as, apart from their well-known advantages (efficiency, power density, power splitting, and fault tolerance), their CMV reduction potential is confirmed. The technical information provided in this work will help researchers and field engineers to design and develop high-performance multiphase electric drives.

The industry and academia are focusing their efforts on finding more efficient and reliable electrical machines and motor drives. However, many of the motors driven by pulse-width modulated converters face the recurring problem of common-mode voltage (CMV). In fact, this voltage leads to other problems such as bearing breakdown, deterioration of the stator winding insulation and electromagnetic interferences (EMI) that can affect the lifespan and correct operation of the motors. In this sense, multilevel converters have proven to be a useful tool for solving these problems and mitigating CMV over the past few decades. Among other reasons, because they provide additional degrees of freedom when comparing with two-level converters. However, although there are several proposals in the scientific literature on this topic, no complete information has been reviewed about the CMV issues and the different multilevel alternatives that can be used to solve it. In this context, the objective of this work is to determine how multilevel power converters provide additional degrees of freedom to make the reduction of the CMV possible by using specific modulation techniques, making it easier for engineers and scientists in this field to find solutions to this problem. This document consists of a descriptive study that collects the strengths and weaknesses of most important multilevel power converters, with special emphasis on how CMV affects each of them. In addition, the differences of modulation techniques aimed to the CMV reduction are explained in terms of output voltage, operating linear range, and generated CMV. Considering this last, it is recommended to use those modulation techniques that allow the generation of CMV levels of 0 V in order to be able to completely eliminate said voltage.

In traction applications, particularly in transport electrification, multiphase drives are becoming an alternative to their three-phase counterparts due to a range of advantages outweighing the additional cost, e.g. smoother torque performance, higher current capability, enhanced fault tolerance, and higher efficiency. In this context, it is interesting to reevaluate the modulation techniques in order to account for the particularities of multiphase systems. In this work the most widely used modulation techniques are assessed, but assuming a five-phase arrangement, in terms of several well-established figures-of-merit pertaining to the inverter power losses, input performance (current RMS, voltage ripple), and output performance (current ripple and common-mode voltage). Thus, this work provides a global vision of how the selected modulation technique, as well as the modulation index and the load’s current phase angle, affect the performance of the multiphase electric motor drive systems.

Guztion ahotan dauden ezaugarriak dira ibilgailu elektrikoen autonomia, bateriak kargatzeko denbora edota kostua. Baina zer gertatzen da ibilgailuen fidagarritasunarekin? Zer faktorek eragin dezakete ibilgailu elektriko bat matxuratzea eta zirkulaziotik ateratzea? Besteak beste, publiko orokorrarentzat ezezaguna den baina espezialistek ongi ezagutzen duten arazo bati egin behar dio aurre ibilgailu elektriko baten propultsio-sistemak: modu komuneko tentsioari.

Emission of greenhouse gases and scarcity of fossil fuels have put the focus of the scientific community, industry and society on the electric vehicle (EV). In order to reduce CO2 emissions, cutting-edge policies and regulations are being imposed worldwide, where the use of EVs is being encouraged. In the best of scenarios reaching 245 million EVs by 2030 is expected. Extensive use of EV-s requires the installation of a wide grid of charging stations and it is very important to stablish the best charging power topology in terms of efficiency and impact in the grid. This paper presents a review of the most relevant issues in EV charging station power topologies. This review includes the impact of the battery technology, currently existing standards and proposals for power converters in the charging stations. In this review process, some disadvantages of current chargers have been identified, such as poor efficiency and power factor. To solve these limitations, five unidirectional three-phase rectifier topologies have been proposed for fast EV charging stations that enhance the current situation of chargers. Simulation results show that all the proposed topologies improve the power factor issue without penalizing efficiency. The topologies with the best overall performance are the Vienna 6-switch and the Vienna T-type rectifier. These two converters achieve high efficiency and power factor, and they allow a better distribution of losses among semiconductors, which significantly increase the life-cycle of the semiconductor devices and the reliability of the converter.

The demand for more reliable and efficient electric machines and drives is constantly growing in the renewable energy and transport electrification sectors. Such drive systems are usually fed by semiconductor switch-based inverters, which, unlike balanced pure sine-wave AC sources, produce large-amplitude, high-frequency common-mode voltage (CMV) waveforms, as a result of the application of pulse-width modulation (PWM). This can lead to a number of issues, such as high electromagnetic interference, deterioration of stator winding insulation, and leakage current flow through motor bearings, which dramatically reduce the life-cycle of machines and drives. Thus, this topic has been extensively investigated in the scientific literature, where either corrective or preventive mitigation approaches have been proposed. The former attempt to relieve the damage produced, whereas the latter tackle the problem at its root, by minimizing or eliminating the CMV produced by the inverter. This work provides a comprehensive review of the major CMV mitigation/elimination solutions, with emphasis on preventive actions, in the form of inverter topology variants and/or advanced modulation techniques. A wide picture of this subject is provided to researchers and field engineers, with valuable information and practical hints for the design and development of high-performance electric drive systems. Indeed, an in-depth analysis of the most recent literature clearly shows that best results are obtained by conveniently combining alternative topologies and modulation techniques, which, in some cases, make it possible to completely suppress the CMV component.

This paper analyses the effect of a seawater environment in an Inductive Wireless Power Transfer (IWPT) system based on a real case development kit. Its main focus is to model the effect of a resonant IWPT system in a seawater environment for different frequency values and evaluate its optimal frequency range. Additionally, an enclosing ferrite core is added to the evaluate improvement in the efficiency of the power transfer.

Switched Reluctance Machines (SRM) are emerging as a possible alternative in terms of cost and supply stability to rare earth based electric vehicle traction systems. However, because of the huge amounts of energy stored and transferred back and forth between the DC source and the SRM, large DC-link capacitors must be used as buffers, which increases overall costs and size. This paper proposes a novel modulation technique which forces the exchange of energy between phases while decreasing the energy transfer between the DC bus and the SRM. This means lower DC bus currents (capacitor size and cost reduction) and lower Joule-effect conduction losses (better efficiency). The proposed modulation has been validated experimentally in a test bench and compared with the conventional torque-sharing function.

Wide-bandgap (WBG) transistors provide better switching performance and higher operating temperatures compared to state-of-the-art Si devices and are suited for high-frequency applications due to very short switching times. The main obstacle for implementation of WBG transistors at full potential is the high-frequency oscillation in voltage and current during switching transients. Oscillations arise from resonance due to parasitic and device inductances and capacitances. Introduction of WBG transistors depends on the elimination of these oscillations and their negative effect on the performance of power converters. Good layout practice is mandatory, but there is a limit to the reduction of these parasitics, and often, slowing of the semiconductor switching time must be applied. This article presents a simple methodology for the attenuation of the negative effects of WBG transistor high-frequency oscillations without increasing rise and fall times. The proposed methodology is based on determination of the source of feedback resonant frequency between gate and power loops using network analyzer measurement on printed circuit board and utilization of a tuned RLC filter. Experimental application of the methodology shows a direct relationship between loop resonant frequency and voltage and current oscillations. The proposed method reduces power losses, high-frequency oscillations, and electromagnetic interference.

Switched Reluctance Machines (SRM) are considered promising rare-earth free candidates for the next generation electrified vehicles. One of the main drawback of this technology is the need of a large DC-link capacitor to balance the energy transferred back and forth between the DC source and the SRM. There are interesting novel modulations to reduce the current of the DC bus, focused on the capacitor size and cost reduction but leaving aside the thermal analysis and lifetime improvements. Carrying out the required dynamic multi-physics simulations for that purpose becomes highly time consuming and complex, especially when standardized or real driving conditions are needed to be taken into account. This article proposes a simulation methodology, simple to implement and with a relatively low computational cost, to estimate the lifetime of an automotive DC-link capacitor, with the current load it delivers as the starting point. The presented methodology has also been used to validate a novel SRM modulation technique and to compare it, in terms of reliability, with the conventional torque sharing function.

In recent decades, several factors such as environmental protection, fossil fuel scarcity, climate change and pollution have driven the research and development of a more clean and sustainable transport. In this context, several agencies and associations, such as the European Union H2020, the United States Council for Automotive Research (USCAR) and the United Nations Economic and Social Commission for Asia (UN ESCAP) have defined a set of quantitative and qualitative goals in terms of efficiency, reliability, power losses, power density and economical costs to be met by next generation hybrid and full electric vehicle (HEV/EV) drive systems. As a consequence, the automotive electric drives (which consists of the electric machine, power converter and their cooling systems) of future vehicles have to overcome a number of technological challenges in order to comply with the aforementioned technical objectives. In this context, this paper presents, for each component of the electric drive, a comprehensive review of the state of the art, current technologies, future trends and enabling technologies that will make possible next generation HEV/EVs.