Application of Tan-Sun Coordinate Transformation to Three-Phase Voltage-Source Inverters

In isolated island conditions, the presence of asymmetric loads can lead to distortions in the output voltages waveform of three-phase voltage-source inverter. The primary objective of this article is to employ Tan-Sun coordinate transformation to a three-phase inverter to maintain output capacitor voltages balanced under asymmetric load conditions, simplify the control system structure, and enhance overall control performance. Based on Tan-Sun coordinate transformation, the phases of the output capacitor voltages are effectively locked. The corresponding imbalance index is adjusted according to the capacitor voltages imbalance index to maintain the balanced state of the capacitor voltages. Finally, the experimental results of the three-phase inverter system are provided to validate the correctness and effectiveness of Tan-Sun coordinate transformation.