Abstract:Three-phase Bridge PWM rectifying circuit is transient and nonlinear, which makes it relatively difficult to analyze it mathematically. In this paper the transience of the system as load changes is preliminarily analyzed with the help of a construction of a simple switching function Sx(t) under different control strategies. By analyzing the traditional control strategy and finding out its drawbacks, this paper proposes a PWM control strategy, based on the load current of the DC side, which can identify the load changes and react quickly so that the voltage of the DC side capacitor can stabilize in a short time and with little fluctuation.