Research on the variable speed system of large power alternating current motor

The development status of the variable speed system of large power AC (alternating current) motor drive in China is introduced. The large power AC drive fed by AC AC converters (cycloconverters) has developed greatly, and some innovations on the theory and engineering technique have been realized. They have been applied to rolling mills, mine hoists, and so on, and remarkable economic and social benefit has been achieved. The development of AC drive fed by large power IGCT (integrated gate commutated thyristors) AC DC AC converter is also introduced. It has excellent performance and reliable operation, and has been used in traction.