By using the rectifier model and considering the instantaneous power theory [7], it is possible to predict the behavior of the input active power and reactive power at the input of the converter. Then, by defining an appropriate cost function it is possible to directly control the power flow between the converter and the grid [8].

The switching state of the converter is changed at equidistant time instants and is constant during a whole sampling interval. On each sampling interval, the control strategy selects the switching state that will be applied by minimization of a cost function.

Predictive power control has no internal control loops and does not need external modulators. The currents are forced by directly controlling the active and reactive power.

The block diagram of the control strategy is shown in Figure 6.9. The input currents **i**_{s}(*k*) are measured and the future current **i**_{s}(*k* + 1) is calculated using the applied converter voltage **v**_{afe}(*k*). Predictions of the future current **i**_{s}(*k* + 1) are generated for each one of the seven possible voltage vectors **v**_{afe} generated by the AFE. These predictions are used to calculate the future input active and reactive power, *P*_{in}(*k* + 1) and *Q*_{in}(*k* + 1), using (6.13) and (6.14). Each prediction of *P*_{in}(*k* + 1) and *Q*_{in}(*k* + 1) is evaluated by the cost function *g*_{afe}.

The cost function *g*_{afe ...}

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