Input-output linearization based versus classic PI control of a three-phase AC/DC converter

In this paper the input-output linearization technique is used to synthesize a control system for an AC/DC three-phase converter. The control system is composed of two control loops connected in cascade. The inner loop, the current control loop, is realized in a synchronous reference frame. The outer control loop maintains the dc capacitor voltage in a required level. As there are only two input control functions and three output state variables to be controlled, the d component of the AC reference current is added with the required current to control the dc voltage. As the first synthesized current control loop, based on the input-output linearization, is very dependent on parameters, a second current control loop was developed based on the same technique and on PI controllers. The classic PI control of the three-phase AC/DC converters is obtained.