High-speed inverter-fed AC drives

High speed drives offer advantages such as small size, low noise, integrated and thus compact design for many industrial applications due to the fact, that as direct drives they avoid the mechanical gear. Inverter supply provides variable speed, which allows high efficient operation for compressors and pumps. A wide speed and power range from 0.1 kW up to 80 MW is covered with circumference speeds of 100 ... 250 m/s. Recent progress is discussed and details of the design of high speed electric machinery are addressed, such as electromagnetic utilization, loss components, types of motors, bearing aspects and inverter-motor interaction.