For small to medium sized machines, nothing surpasses the efficiency and power density of the permanent magnet machine, especially when designed to use high energy rare-earth materials. Key to the PM’s superior efficiency is its ‘energy-for-free’ self excitation.
However, this comes with a loss penalty, even when the machine is inactive, which demands careful balancing of its attributes during the design process.
PM machines are highly versatile, and used across all areas of industry, but cost is always a consideration, requiring very careful optimisation to realise a commercially viable cost/performance ratio.
EMX has analysed and designed all the main categories of PM machines and some less familiar types. In particular, our practical experience with very high speed machines gives us a deep understanding of the limitations of permanent magnets which are not immediately obvious to those more familiar with off-the-shelf products.