Patent ID: 7102326

Claim:
A motor speed variator, for varying a speed of an induction motor having an induction coil, said motor speed variator comprising: a high-frequency alternate voltage chopper, coupled to said induction coil of said induction motor, said high-frequency alternate voltage chopper is formed by coupling two, bi-directional switches, wherein said bi-directional switch is comprised of two power switches and two fast diodes, gates of said two two-way power switches are coupled to define a control end, sources of said two two-way power switches are coupled to cathodes of said two fast diodes, and anodes of said two fast diodes are coupled separately to drains of said two power switches; an alternate current power supply, coupled to said high-frequency alternate voltage chopper; and a controller, coupled to said high-frequency alternate voltage chopper for outputting a switch signal to said high-frequency alternate voltage chopper; wherein said high-frequency alternate voltage chopper is controlled by said switch signal for a switch, and said switch of said two, bi-directional switches perform a chopper action for said alternate current power supply and then output a drive voltage to change a rotary speed of said induction motor.