Practical methods for tuning PI controllers in the DC-link voltage loop in Back-to-Back power converters

This paper provides two options for the design of the Proportional + Integral (PI) controller for the DC-link voltage loop, which is found in several topologies, such as AC/DC voltage source converters and Back-to-Back converters among others. The proposed methods are based in the bandwidth approach. For the design of the DC-link voltage loop, the Back-to-Back topology is used and two cases the studies are analyzed. In the first case the converter controls the power transfer between the mains and the load; in the second it controls the active and reactive power as a PWM Rectifier with active filter function (PWM-VSR-C). In both cases the dq reference frame is used for the design of the controllers. The proposed methods are practical and clearly explained. The designs are validated with simulations and experimental results.