A Parameters Design Method of Three-phase Inverter Based on Complex Coefficients Complex Variables

This paper investigates a parameter design method based on the root locus of a three-phase inverter for uninterruptible power supply (UPS). Firstly, a complex model for three-phase inverter is established and proved to be a bounded-input bounded-state stable system. A multi complex variables resonant control is used to achieve asymptotic stability and compensate the voltage harmonic. Moreover, the control coefficient is extended from scalar to complex and a new control freedom is added. The rule of parameter variation, including amplitude and phase angle of each complex coefficient, is discussed by the root locus method to improve the system stability and dynamic performance. Then, the law of parameter design based on complex coefficient complex variables multi resonant controller is summarized. The proposed control strategy and parameters design method guarantee excellent voltage regulation performance, including fast transient response, zero steady-state error, and low THD under sudden load change and nonlinear load. The simulation results validate the excellent dynamic performance.