The control scheme for the VOC of an AFE using predictive control for the current control loop is shown in Figure 6.4. A PI controller is used for DC link voltage regulation and generates the amplitude of the input current reference. The reference current is calculated by multiplying the output of the PI controller by the grid voltage waveform.
The predictive current controller must achieve the smallest current error with fast dynamics. An appropriate cost function is a measure of the predicted input current error. The following cost function considers the absolute error between the reference current and the predicted current, expressed in orthogonal coordinates:
where is the input current prediction at time k + 1 for a given converter voltage vafe(k), and the current corresponds to the reference current at time k.