A miniature, 500 000 rpm, electrically driven turbocompressor

The trend in compressors for fuel cells, heat pumps, aerospace and automotive heating, ventilation and air conditioning systems, is towards ultra-compact size and high efficiency. This can be achieved by using turbocompressors instead of scroll, lobe or screw compressors, increasing the rotational speed and employing new electrical drive system technology and materials. This paper presents a miniature, electrically driven two stage turbocompressor system running at a rated speed of 500 000 rpm. The design includes the thermodynamic analysis, the electric motor, the inverter, the control and the system integration with rotor dynamics and thermal considerations. Experimental measurements such as the compressor map are presented for air under laboratory conditions. The two stage turbocompressor has been tested up to a speed of 600 000 rpm, where a maximal pressure ratio of 2.3 at a mass flow of 0.5 g/s has been reached. To the authors knowledge this is the highest rotational speed achieved with an electrically driven turbocompressor.