This paper proposes a fully digital high performance variable speed drive of induction motor implementing based on a single chip DSP motor controller. Some important models and features of the classic FOC are analyzed deeply and the implementing flowchart is given. The proposed speed control algorithm programming in C++ is realized by the TMS320F2812 DSP within 25us offering a fast current response. Experimental results show that very well static-and transientperformance can be obtained by the proposed variable-speed drive with reduced hardware and higher reliability. Index Terms -Induction motor, vector control, DSP. NOMENCLATURE Us, Ur Stator and rotor voltage space phasor im,iS, ir Magnetizing, stator and rotor current space phasor /V[s ' r Stator and rotor flux-linkage space phasor Lm, Ls, Lr Magnetizing, stator and rotor inductance respectively Rs Rr Stator and rotor resistance at)e Ct)r The angular speed of stator flux and rotor te the electromagnetic torque Rotor leakage factor (JLr / Lm,) and total leakage factor (1 -L2 I LL) Rotor time constant (Lr I Rr) and stator transient time constant (uL, I Rs ) Subscripts denoting M-and T-axis of the rotor -flux-oriented reference frame