This paper investigates novel control methods for the squirrel-cage induction generator based variable speed wind power generation system composed of back-to-back connected two-level voltage source converters. A modulated model predictive torque control method is designed by combining the operating principles of direct torque control, predictive torque control and space vector modulation to effectively control the electromagnetic torque and stator flux control of an induction generator. Similarly, a modulated model predictive current control method is designed for the grid-side converter to control the active and reactive powers injected to the three-phase grid. The proposed control methods employ duty-cycle optimized cost functions for fixed switching frequency operation, fast dynamic response and low steady-state errors during a wide-dynamic range operation. Simulation results are presented with a 750-kW wind power generation system to validate the effectiveness of proposed control methods.