DC-link voltage coordinative-proportional control in cascaded converter systems

PI controllers are frequently implemented in cascaded converter system to control the DC-link voltage, because they can achieve zero steady state error. However the PI controller adds a pole at the origin point and a zero on the left half plane, and it increases the control system type number, and then the system is more difficult to control. This paper proposed a DC-link control method for the two stages cascaded converter, and it uses proportional controller for the DC-link voltage control. This control method can achieve zero steady state error on the DC-link voltage; reduce the control system type number; improve the dynamic performance. The proposed control is totally symmetric, It can also be implemented in other general two stages cascaded converter. The effectiveness has been verified by both simulation and experiment results.