This paper proposes a fixed frequency modulation scheme for a three-phase PWM rectifier operating at unity power factor. It provides a constant and reduced switching frequency for all the switches of the rectifier by controlling the occurrence and duration of the zero vector states indirectly. The two legs of the converter are operated in hysteresis current tracking mode and the third leg is controlled by a square pulse of user-defined frequency. The low harmonic distortion and high input power factor are added advantages of this scheme. Also, it offers simplicity, fast response and robustness. The feasibility of the proposed method is verified through extensive simulation results. ©2010 IEEE.