For complying with power distributor regulations, the PWM rectifiers have to address the line current harmonic mitigation problem. Conventional solutions involve either an adequate control strategy like resonant controller or additional hardware such as passive or active filters. In this work we take advantage of a harmonic description for the rectifiers in order to propose a robust optimal state feedback control that solves the line current harmonic mitigation while not measuring it. The performance of the proposed control is compared with an established approach, comparative simulation results show the efficiency of the proposed control strategy.