Abstract: Aiming at the periodic disturbance during uniform scanning of space camera，the disturbance rejection of permanent magnet synchronous motor（PMSM）was studied．In order to solve the problem that traditional state observer and internal model methods are complicated with large amount of calculation，a feedforward compensation method was deduced．First，the disturbance was deduced based on the sensor output and system model．Then the feedforward compensation strategy was adopted to suppress the disturbance quickly．Compared with other suppression methods，this method is simple and has less computation．Finally，numerical simulation and experimental results illustrate that the sinusoidal disturbance is rapidly diminished after using this feedforward compensation method，and the scanning accuracy of space camera is evidently improved．

Key words: space camera, scanning control, permanent magnet synchronous motor(PMSM), periodic disturbance, thrust ripple