For aerospace electrical machines (EMs), the partial discharge (PD) risk is becoming much more severe due to higher dc link voltage levels and faster switching devices. Traditionally, EMs for safety-critical applications mainly rely on overengineering methods guarantee reliability. However, a recent shift toward reliability-oriented design, which based understanding physics of failure, allows meeting reliability requirements while ensuring performance. From perspective methodology, PD-free...

Increasing current density is a common way to improve the power of electrical machines (EMs) which also boosts winding temperature. Higher temperature accelerates thermal degradation insulation and increases risk partial discharge (PD). Commonly, hotspot constraint decided based on an over-engineering approach (i.e., 30°C below wire class) constraining EM's performance. In this paper, margin precisely determined focusing mainly issues through experimental investigation. The inception voltage...

The low-voltage electric machine (EM) is a core technology for transportation electrification, and features like high power density compact volume are essential prerequisites. However, these requirements usually in conflict with the reliability property of EM, especially safety-critical industry such as aviation. Therefore, an appropriate balance between high-performance needs to be found. Often, over-engineering method applied ensure safety, although it might have detrimental effect on EM...

This article endeavors to illuminate the variations of various streamer inception parameters (SIPs) with respect air pressure based on Schumann's criterion (SCSIC). The results measured partial discharge voltage (PDIV) values and using electric field distribution obtained via electrostatic simulations ionization swarm reveal that Schumann constant, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$...

Partial discharge (PD) is the main issue challenging electrical machine (EM) insulation system for more electric aircraft (MEA) applications. Indeed, trend of adopting higher DC link voltage and fast switching device further boost risk PD. inception (PDIV) mostly dominated by ambient conditions (i.e., temperature, pressure, humidity), their influence accounted through experimentally determined enhancement factors. For non-impregnated windings, factors are suggested both IEC 60034-18-41...

The humidity role in the partial discharge (PD) inception mechanism is quite complex, and there no widely accepted theory that can describe effect on PD. In this article, PD activity of interturn insulation electric motor winding experimentally investigated for different relative (RH) conditions at 30 °C ambient temperature. Since leads to a boost dissipation factor (i.e., tan <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math...

Higher dc link voltage and shorter rise time keep challenging the insulation system of inverter-fed low-voltage electrical machines (EMs). In more electric aircraft (MEA) applications, low-pressure working environment faced by EMs further increases risk partial discharge (PD) endangering drive reliability. Through an additional inorganic layer, corona-resistant (CR) wires reveal ability to withstand PD represent a potential solution for aerospace applications. this article, CR wire is...

The trend towards higher onboard DC link voltage keeps increasing the partial discharge (PD) risk of electrical machines (EMs) for more electric aircraft (MEA) applications. Compared to traditional Type I insulation, corona-resistant (CR) wire with an additional inorganic layer boosts lifetime EMs under PD regime and enables design capable safely operating at bus voltage. In this paper, CR wires is estimated. A starter/generator meant applications selected as study case, whose windings...

Abstract The humidity role in the partial discharge (PD) inception mechanism is quite challenging, especially when considering environmental temperature. Indeed, there no general rule to explain effect on PD phenomenon. In this paper, activity inter‐turn insulation experimentally investigated for different relative (RH) conditions at three ambient temperatures, that is, 30°C, 60°C, and 90°C. Partial voltage (PDIV) directly measured through a photomultiplier tube (PMT), whereas tip‐up tests...

Considering the turn-to-turn insulation as most susceptible part to failure of electrical machine's system in inverter-fed motors, this article aims elucidate effect temperature <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {({T})}$ </tex-math></inline-formula> on streamer inception parameters (SIPs), including Schumann constant {({K})}$ , critical field line length (CFLL), air effective...

Compact and efficient electric drives are desirable in transport applications an increased dc-link voltage value combined with fast-switching devices represents a promising solution for achieving light energy-efficient systems. Nonetheless, the higher dc bus wide-bandgap device greatly raise electrical stress (i.e., maximum interturn voltage) of inverter-fed machines (EMs) insulation jeopardizing overall reliability. Thus, lifetime prediction EMs gained more attention recently. Short-duty...

This paper models the partial discharge inception voltage (PDIV) as a function of ambient humidity ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> ) at various temperatures xmlns:xlink="http://www.w3.org/1999/xlink">Ts</i> using Schumann's streamer criterion (SCSIC) for turn-to-turn insulation, which is most vulnerable part in inverter-fed motors' insulation system. The Schumann constant (i.e., natural logarithm critical electron...

Transportation electrification has kept pushing low-voltage inverter-fed electrical machines to reach a higher power density while guaranteeing appropriate reliability levels. Methods commonly adopted boost (i.e., current density, faster switching frequency for high speed, and DC link voltage) will unavoidably increase the stress insulation system which leads decrease in reliability. Thus, trade-off is required between during machine design. Currently, it challenging task evaluate design...

Throughout the years, humidity effect on Partial Discharge Inception Voltage (PDIV) has been investigated revealing complexity of interaction between moisture and insulation material. Although importance these studies, Electrical Machine (EM) system experiences combined stresses when in service. Thus, attention is paid to impact PDIV under different thermal aging levels, since hygroscopicity material might change during its lifetime. For experimental investigation, three groups twisted pairs...

Rapid growth of electric stress boosts the partial discharge (PD) risk insulation and leads to electrical aging. For transportation applications (i.e., safety-critical), reliability is top-priority which means lifetime machines (EMs) should be accurately estimated. Electrical aging Type II insulated EMs caused by PD activity greatly affected ambient pressure. During accelerated tests, an improper test voltage selection might result in misleading estimation. In this paper, allowable levels...

With the increasing interest in adopting higher DC link voltage and fast switching devices electric drives for electrified transportation, partial discharge (PD) risk of electrical machines boosts compromising drive integrity. The PD inception mechanism is simultaneously affected by both ambient conditions characteristics. By determining dominant influencing factor on (PDIV), preliminary reliability assessment would be made easier since impact secondary factors could temporarily neglected....

Electrical machines operated on high-voltage DC buses for contemporary transportation applications are significantly exposed to the risk of partial discharge (PD). The inception mechanism PD is influenced by various factors, including pressure, temperature, and humidity. With increasing interest in SiC-based inverters, impact rise time has garnered significant attention. In this study, a comprehensive measurement voltage (PDIV) conducted using test voltages with five different values under...