In this paper, the development status of the domestic large power AC motor variable frequency speed regulation technology is introduced. The domestic large power AC drivers fed by cycloconverters have been greatly developed, and some innovation on the theory and engineering technique has been realized. They have been applied to rolling mill, mine winder and so on, and remarkable economic and social benefit has been achieved. The development of the first domestic 7.5 MVA IGCT AC-DC (direct current)-AC converter is also introduced. This converter has excellent performance and reliable operation, and it has been used in traction.