Abstract: Permanent magnet synchronous motor drive system with small DC-link capacitor has advantages such as low cost and good reliability. However, DC-link voltage pulsation, a side effect of the system, reduces the control system's performance. To improve the system's input power factor and reduce harmonics in input currents, an improved power control strategy is put forward in this paper. Differing from traditional speed feedback control method, this strategy uses power as the input control variable. An improved PID controller is selected to reduce control error. Additionally, an active suppression strategy is applied in the system to suppress the integral saturation and achieve the goal of precise control effect. This improved motor drive system was tested in simulation platform and its control performance proved that the control system improved by power control strategy can maintain a high input power factor and suppress integral saturation effectively.

Key words: Permanent magnet synchronous motor, Small DC-link capacitor, Input power factor, Integral saturation