DRIVES, CONTROLS & MOTORS


FEATURE


AMCs: A new spin on rotor teChnology


There is increasing pressure on design engineers and manufacturers to


improve the sustainability of their products while also meeting stringent cost and performance requirements. Out of this has sprung a drive to


improve the capability of products through material innovation, with recent electric motor developments bringing weight saving and energy efficient solutions, as Richard Thompson, commercial director of Alvant, explains


A


recent IPCC report has placed industries including the


transportation and industrial sectors under greater scrutiny, escalating the need to make products lighter and develop efficient electric sources of power, reducing fuel consumption and emissions. Now, thanks to emerging innovative material and manufacturing solutions, there is a means to achieve some of these high-level targets whilst increasing product capabilities, such as improved efficiency and power density (kW/kg).


rotor sleeve innovAtion


One area of interest is a solution harnessing Alvant’s low loss rotor technology which improves the performance of permanent magnet radial flux motors. Electric motors typically require a magnet retention system including a mechanical rotor sleeve, which generates unwanted eddy currents and/or acts a thermal insulator depending on material. Alternatively, slotted steel laminates are used, limiting the proximity of the magnets to the stator. This can lead to increasing losses and increased temperatures, reducing the overall efficiency and limiting the power of the electric machine. Manufacturing and assembly costs can


also be high, with the use of carbon fibre composites, adhesives and heat-shrink metallic sleeves. Typical rotor sleeve materials include stainless steel, titanium, Inconel and carbon fibre composite, all of which can add to the detrimental impact on the effectiveness of the machine. Alvant, a specialist in AMCs (aluminium matrix composites), a class of metal matrix composite (MMC), has eyed a significant opportunity through its development of core technology that retains surface-mounted magnets which minimises the magnetic bridge element of an interior magnet motor. Alvant’s own patented process, known as


Advanced Liquid Pressure Forming (ALPF), sees the company’s technology and know-how bring together aluminium with a high-functioning fibre, to create AlXal, an aluminium composite


which are precisely combined within the composites, and therefore not deemed worthwhile to separate them in order to recycle. Not so AMCs, which offer an increased opportunity to recycle. They are considered more sustainable thanks to the ability to separate the fibres from the aluminium at the end-of-life stage, therefore providing low life-cycle costs.


A CollAborAtive pArtnership


Alvant’s recent strategic, collaborative agreement with 3M, signals its


that provides an opportunity to significantly reduce component mass, improve performance and increase efficiency of the world’s most demanding products.


AMC CApAbilities


AMCs are a family of materials whose properties can be tailored through matrix and reinforcement selection. Alvant’s current material development effort is focused on AlXal (pronounced Al-Zal), the continuous fibre AMC material, the metal equivalent of Carbon Fibre Reinforced Plastic (CFRP). As an ultra-low-density material, it has compelling mechanical properties, and is well-matched to rotor sleeve applications owing to its preferential electrical and thermal conductivity for electric motors. It also offers high strength and stiffness up to


350°C, a lower magnet operating temperature compared to carbon composite sleeves, and enhanced fatigue performance. AMCs are also lightweight – more than 50% lighter than steel and up to 40% lighter than titanium – making the material an exceptional proposition for design engineers and manufacturers who are tasked with finding alternative weight-saving and energy-efficient solutions.


A CirCulAr solution


The entire product lifecycle and the ability to reuse are now very much key factors in design development, as designers must increasingly incorporate ‘whole life cost’ into design. There is now a better understanding of materials such as carbon composites and polymer composites, as they are made of two or more materials with distinct phases such as a matrix and fillers,


growing position in the sector as an influential materials innovation and technology partner. The partnership will focus on advancing core technology in the areas of electric machines (motor and generator) and lightweight metallic components which require enhanced performance characteristics. Through harnessing Alvant’s expertise in the design, development, testing and manufacture of AMC materials and components, the partnership will enable both parties to jointly develop applications which will bring energy and cost-saving benefits to manufacturers and design engineers across sectors including automotive and industrial.


Alvant www.alvant.com


AMCs vs CArbon fibre CoMposite


As well as benefits that place design engineers and manufacturers at a competitive advantage, such as reduced manufacturing and operating costs, they can leverage numerous gains and savings in key areas versus typical metallic and carbon composite solutions:


• 20% increase in peak power • 60% reduction in rotor losses • High strength and stiffness at up to 350°C • Lower magnet operating temperature • Higher thermal conductivity and coefficient of thermal expansion


• Enhanced fatigue performance • Up to 40% lighter than titanium


OCTOBER 2021 DESIGN SOLUTIONS 37


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