Abstract: Several problems and their solutions of high-performance inverter-fed motor drive systems were

introduced: the features and some matters needing attention of two- closed-loop systems; how to improve speed

following performance during starting and breaking and to improve anti-disturb ability by means of predictive control techniques; tension control systems; position control systems and very low speed control of wide speed range drive systems ; delayless model of converters and quasi-continuous control of current loop; vibration suppression methods of 4 kinds of flexible mechanical connection systems.

Key words: high-performance inverter-fed motor drive systems ; two-closed-loop systems ; industrial applications