Abstract: This paper proposes an energy saving control mode for current source inverter(CSI) induction motor drive system with the motor driving a constant power load.The emphasis are on control scheme,software and hardware design methods forfunction generator suing single chip microcomputer.The experiment results aregiven.When motor carries 30% rated load,the system efficiency may raise about9%.As this control made only optimizes the relationship between voltage andfrequency in an established system,no other circuit is needed in order to maintainthe original static and dynamic performance.