Direct control of capacitor current for AC-DC-AC PWM converter

In traditional control of AC-DC-AC PWM converter, the sudden change of the motor results in the fluctuating of the dc-link voltage. In order to maintain the dc-link voltage, a big capacitor is added, however, affecting the dynamics of the system. Considering the dc-link voltage and the dynamics, a new co-control strategy is given in this paper. With the control of the dc-link capacitor, the current out of the converter side can equal to that in the inverter side, which not only reduce the dc-link capacitor, but also improves the dynamics of the system. For further research in the control strategy, the small-signal model is introduced for study of the robustness and dynamics of the system.