A DC Bus Oscillation Suppression Strategy Based on Series Voltage Compensator for Diode Rectifier

Series compensation is an effective way to reduce the dc side passive filters of diode rectifier (DR), but the stability judgement of such series compensation system (SCS) by the impedance-ratio-based stability criteria is complicated, because this kind of system has many cascade forms and complex coupling interactions. This article proposes a stability analysis method for the SCS composed of DR and series voltage compensator, based on which an impedance optimization strategy is present to solve the instability problem. First, the simplified two-port small-signal model of SCS is established. The stability analysis is based on common characteristics of the system, which can fully reveal the dc bus oscillation mechanism combined with equivalent loop gain and the stable condition can be obtained for control system optimization. From the point of view of reshaping the impedance of series loop, a virtual-impedance-based control strategy with simple implementation is adopted to improve the system stability without affecting its dynamic performance, and the controller and parameters design are given considering the requirements of impedance optimization. An experimental prototype is established to validate the accuracy of stability analysis and the effectiveness of proposed control.