Abstract :
The fast and hard switching IGBT-inverters made it possible to use standard AC motors without any derating as a variable speed drive, but posed in certain cases, especially with long cable connections, high line voltage levels and low motor partial discharge inception voltages, new danger to motor life by increased voltage stress. By studying the nature of this stress and by close examination of the resulting motor failures, it was possible to find measures to cope with this problem. Different solutions were developed for mass fabrication and are now at hand. Their advantages and limits are discussed and compared, proving that it is possible to benefit from the advantages of IGBT-inverter operation without any risk to motor life.
Keywords :
induction motor drives; insulated gate bipolar transistors; invertors; machine insulation; switching circuits; variable speed drives; AC motor insulation stress; IGBT-inverter supply; armature insulation; hard switching; high line voltage levels; induction motors; long cable connections; low motor partial discharge inception voltages; mass fabrication; motor failures; motor life; variable speed drive; voltage stress; wave reflection;
