Direct Power Control for a Grid Connection of a Three Phase Z-Source Inverter

The Z-Source inverter (ZSI) has proven to be a robust and easy to control inverter. As a drawback it has increased requirements towards the PWM modulator to insert the shoot through states that are necessary for the boost operation. To overcome that restriction a novel direct power control (DPC) scheme that does not require a PWM has been developed and successfully validated by experiment. It works similarly to the well-known direct torque control (DTC) with the difference that the output voltage of the inverter does not directly control the flux and the torque of an electrical machine but the active and reactive power fed into the grid. In addition, the DPC control had to be extended to also manage the shoot through states i.e. the boosting of the ZSI.