Fillet Radius Impact of Rectangular Insulated Wires on PDIV for Turn-to-Turn Insulation of Inverter-Fed Motors

This contribution elucidates the impact of the fillet radius, a geometric feature of rectangular insulated wires not commonly considered, on the partial discharge inception voltage (PDIV) in low-voltage machine turn-to-turn winding insulation. Initial PDIV tests involve edgewise-insulated wire samples with a reference fillet radius. These measurements are performed under constant conditions: 30°C temperature, 35% relative humidity, and atmospheric pressure (1000 mbar). These tests are carried out under AC 50 Hz excitations, following IEC 60034-18-41 guidelines for inverter-fed motor insulation system qualification. Subsequently, a probabilistic PDIV predictive model is developed based on Schumann’s streamer inception criterion (SCSIC). This expanded model then analyses and forecasts the impact of the fillet radius on PDIV and its associated dispersion level, within the context of the 2-parameter Weibull distribution and the given environmental conditions. Furthermore, a novel method is presented to understand partial discharge (PD) phenomenology and its destructive potential in rectangular insulated wires with varying fillet radii. This approach employs SCSIC-derived streamer inception parameters (SIPs): critical field line length (CFLL), air effective ionization coefficient (α_eff), PD inception field (Einc), and firing voltage (Vfiring). The developed probabilistic predictive model enables the selection of an optimal fillet radius value, facilitating the creation of a reliable insulation system with maximum PDIV and minimal PD-related damage

Endoscopic snare polypectomy of a pedunculated adenocarcinoma of the duodenal bulb arising from a hyperplastic polyp

Primary non-ampullary adenocarcinoma of the duodenum is a rare occurrence, arising mainly from adenomatous polyps [1].We report the first case of a pedunculated adenocarcinoma of the duodenal bulb, arising from a hyperplastic polyp, treated with endoscopic snare polypectomy.peer-reviewe

A Scalable System Architecture for High-Performance Fault Tolerant Machine Drives

When targeting mission critical applications, the design of the electronic actuation systems needs to consider many requirements and constraints not typical in standard industrial applications. One of these is tolerance to faults, as the unplanned shutdown of a critical subsystem, if not handled correctly, could lead to financial harm, environmental disaster, or even loss of life. One way this can be avoided is through the design of an electric drive systems based on multi-phase machines that can keep operating, albeit with degraded performance, in a partial configuration under fault conditions. Distributed architectures are uniquely suited to meet these challenges, by providing a large degree of isolation between the various components. This paper presents a system architecture suitable for scalable and high-performance fault tolerant machine drive systems. the effectiveness of this system is demonstrated through theoretical analysis and experimental verification on a six-phase machine

Multi-parameter monitoring of electrical machines using integrated fibre Bragg gratings

In this paper a sensor system for multi-parameter electrical machine condition monitoring is reported. The proposed FBG-based system allows for the simultaneous monitoring of machine vibration, rotor speed and position, torque, spinning direction, temperature distribution along the stator windings and on the rotor surface as well as the stator wave frequency. This all-optical sensing solution reduces the component count of conventional sensor systems, i.e., all 48 sensing elements are contained within the machine operated by a single sensing interrogation unit. In this work, the sensing system has been successfully integrated into and tested on a permanent magnet motor prototype

Comprehensive monitoring of electrical machine parameters using an integrated fibre Bragg grating-based sensor system

In this paper a multi-parameter, multi-sensor system for comprehensive electrical machine condition monitoring has been developed and the results of an evaluation reported. The FBG-based system developed allows for the simultaneous monitoring of key parameters including machine vibration, rotor speed and position, torque, spin direction, temperature distribution along the stator windings and on the rotor surface as well as the stator wave frequency. This all-optical sensing solution has been designed to be compatible with being fitted in the tight confines of an electric motor and uses the optical nature of the measurement and the insulating nature of the sensor material to avoid problems of electrical interference. The system reduces the component count over conventional sensor systems, i.e., all sensing elements are contained within the machine and operated by a single sensing interrogation unit, thereby reducing cost and allowing for a convenient interface for the user. The design of the system is presented, as are results on the testing and evaluation of the device the sensing system has been successfully integrated into and tested on a permanent magnet motor prototype

AC losses reduction in Hairpin Windings produced via Additive Manufacturing

One of the key challenges of hairpin windings is the reduction of their high losses at high-frequency operations. Hairpin layouts comprising conductors with variable cross sections have proven good loss performance in previous studies. However, they come at the cost of significant manufacturing complications. The aim of this work is to design hairpin layouts featuring reduced losses compared to classical configurations, exploiting the flexibility enabled by additive manufacturing. In this context, the choice of a proper material with relatively high conductivity and low ecological impact plays an important role. Hence, this article first presents an overview of materials that can be used for the winding additive manufacturing, aiming to select the most suitable one for the application at hand. Then, the loss performance is evaluated and compared against classical copper hairpins. The results demonstrate that opportunely selected alloys featuring asymmetric configurations can compete against classical hairpin windings. © 20XX IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper reflects only the author's view. JU is not responsible for any use that may be made of the information it contains

Modifications to PM-assisted Synchronous Reluctance Machine to Achieve Rare-Earth Free Heavy-duty Traction

Automotive applications require electrical machines designed for high torque density, wide speed range, and low cost. NdFeB magnets can achieve a high torque density and wide speed range, and however, they have a high cost. Therefore, this article explores the capability of rare-earth-free (REF) design through a PM-assisted synchronous reluctance (PM-SynRel) motor. A PM-SynRel design with NdFeB has been used in this study where the NdFeB magnets have been replaced with ferrite magnets. Then, several modifications on the rotor have been made to ensure mechanical safety. Thermal analysis has been conducted last to evaluate the temperatures in the different machine parts to avoid exceeding the required limits. Finally, a prototype has been made and tested to validate the simulation results

Design and Mathematical Modeling of Gearless SMC Flux Reversal Motor

This paper considers the design of a three-phase gearless flux reversal machine (FRM) with permanent magnets (PM) mounted on the stator. Its stator magnetic core is made of a solid soft magnetic composite material (SMC) with a slot for laying the winding in the middle. 48 magnetic poles are located on the surface of each stator tooth, while the rotor has 24 teeth. This paper describes the mathematical model and the results of the performance calculation of the three-phase SMC FRM operating in motoring mode. Finally, comparison of the SMC FRM with the characteristics of the conventional surface mounted permanent magnet machine (SM-PMSM) made of laminated steel is performed. For fair comparison, both the SMC FRM and SM-PMSM have the same outer stator diameter and approximately the same volume. © 2018 IEEE

Turn-turn short circuit fault management in permanent magnet machines

This paper presents a systematic study on turn-turn short circuit fault and ways to manage them to provide a basis for comparison of the various options available. The possible methods to reduce the likelihood of the winding SC fault and the fault mitigation techniques related to such faults are discussed. A Finite Element (FE) analysis of a surface-mount Permanent Magnet (PM) machine under application of different mitigation techniques during a turn-turn fault is presented. Both machine and drive structural adaptations for different fault mitigation techniques are addressed. Amongst the investigated fault mitigation techniques, the most promising solution is identified and validated experimentally. It is shown that the shorting terminal method adopting vertical winding arrangement is an effective method in terms of the implementation, reliability and weight

4MW Class High Power Density Generator for Future Hybrid-Electric Aircraft

This paper describes the underpinning research, development, construction and testing of a 4MW multi-three phase generator designed for a hybrid-electric aircraft propulsion system demonstrator. The aim of the work is to demonstrate gravimetric power densities around 20 kW/kg, as required for multi-MW aircraft propulsion systems. The key design choices, development procedures and trade-offs, together with the experimental testing of this electrical machine connected to an active rectifier are presented. A time-efficient analytical approach to the down-selection of various machine configurations, geometrical variables, different active and passive materials and different thermal management options is first presented. A detailed design approach based on 3D Finite Element Analysis (FEA) is then presented for the final design. Reduced power tests are carried out on a full scale 4 MW machine prototype, validating the proposed design. The experimental results are in good agreement with simulation and show significant progress in the field of high power density electrical machines at the targeted power rating