Uncertainty in the design space of electric machines
by Tim Miller of Motivity Ltd, Galashiels; University of Glasgow

Prof. Miller will begin with a humorous and somewhat philosophical review of uncertainty in engineering, together with numerous examples ranging from the simple to the advanced, including mathematical uncertainties and a discussion of tolerancing. The importance of measurement is emphasized throughout.

Insulation system design considerations and validation for higher voltage and inverter fed machines
by Ian Cotton of aHV Solutions

The use of higher voltages in aerospace and automotive applications challenges the use of conventional insulation systems – particularly where the voltage exceeds 800V DC. This presentation will explore the key issues that mean the designer has to take special care in the design of such high voltage insulation systems and the solutions that may be required in future platforms.

Characterisation and the effect of manufacturing processes on properties of soft magnetic materials
by Lukasz Mierczak of Brockhaus

Voltage stresses in motor windings of inverter fed machines, their impact and mitigations
by Antonio Griffo of University of Sheffield

Power electronic converter-fed machines and drives are now ubiquitous in transport, renewable energy generations and industrial automation applications. Converters operating with pulse width modulated (PWM) waveforms produce voltage pulses at a high frequency and high voltage slew rate (high dv/dt) which can result in excessive voltage at the machine terminal and non-uniform voltage distribution within the machines windings. These voltage transients can significantly reduce the lifetime of the insulation of the connected machine/generator due to increased voltage overshoot, increased voltage across turns, phases and phase-to-ground, and higher frequencies. These will be exacerbated by the increased use of wide band-gap devices with fast-fronted voltage transients with dv/dt in excess of 10-30kV/us. In this talk, the effects of high frequency PWM voltages produced by fast-switching power electronic converters on voltage distributions in machine winding and insulation systems are analysed and characterised. Both high frequency oscillation modes due to the interaction of inverter, cables and machines, as well as a low frequency oscillation mode associated with the common mode impedance of machines, will be presented. Lifetime test results under partial discharges caused by high voltage slew rate will also be highlighted together with a number of mitigation measures.

Characterisation of Stranded Random Windings and their Impact on AC losses of Electrical Machines
by Josh Hoole of Bristol University

The electrification of the automotive sector demands power dense and volume electric traction motors. These requirements lead to the adoption of stranded random windings. However, mass production results in significant variability in the sources of AC winding loss due to the random transposition of the strands within the winding. Such variability is rarely characterised leading to conservatism in machine design and the inability to accurately predict the long-term reliability of such windings. This presentation will cover recent work that aims to characterise the manufacturing variability in random windings and quantify the impact they have on electrical machine losses.

Design of an Electric Motor Housing, concepts and challenges
by Red Blaylock of iNetic

The talk will focus on the design of an electric motor housing, first by introducing a couple of different housing concepts used in the automotive industry. The talk will then build on this by exploring different coolant concepts and challenges associated with each design.

A chicken and egg problem – uncertainties in thermal design of electrical machines
by Rafal Worbel of Newcastle University

An appropriate thermal management is one of the key considerations when developing new or upgrading existing electrical machines. However, a reliable thermal design of electrical machines is very challenging, frequently requiring numerous redesign and hardware iterations. This results from inherent uncertainties associated with the thermal design process, where empirically derived data is usually needed. Consequently, to experimentally inform design of an electrical machine a legacy hardware (an electrical machine) is required. Hence, the thermal design of electrical machines is something of a chicken and egg problem. This presentation discusses selected sources of uncertainties related to thermal design of electrical machines. The subject matters included in the presentation are focused on, but not limited to the heat source distribution, equivalent material thermal properties, manufacturing and assembly factors, and application specific operating requirements.

Manufacturing effects on NdFeB laminated magnet and how designers can allow for these when designing motors
by Domenico Violante of Arnold Magnetic Technologies

High efficiency motor applications demand best materials and laminated magnets are proven to reduce eddy current losses. Fewer eddy current losses means lower heat and greater efficiency. Manufacturing techniques have a direct impact on NdFeB laminated magnet performance. In this presentation, different manufacturing techniques are examined, analyzing the effect of each of them on the demagnetization curve of the magnet. Based on this investigation, a finite element model of laminated magnet which considers the manufacturing effects is presented, with the aim of determining its demagnetization curve, which represents a key input parameter when designing motors using NdFeB laminated magnet.