Deadbeat Control for a Three-Phase Solar T-Type Inverter and Comparison with PI Control

This paper proposes a deadbeat-based current control method for a three-phase T-type solar inverter to improve transient performance and harmonic immunity compared with conventional PI control. The control framework adopts a double-loop structure, in which the photovoltaic (PV) voltage is regulated by a perturb-and-observe (P&O)-based maximum power point tracking (MPPT) algorithm in the outer loop, while d–q axis currents are controlled in the inner loop. A performance comparison between the PI control and the proposed deadbeat control was conducted using an ESS T-type inverter with an inner current control loop, and the results were validated through combined simulation and experimental investigations. Under experimental conditions, when the d-axis reference current was stepped from 5.2 A to 9.2 A, the deadbeat controller achieved a transient settling time of approximately 1.89 ms, representing a 47.5% reduction compared to the 3.6 ms observed with the PI control. Furthermore, under 7th harmonic injection (0.225), the total harmonic distortion (THD) was reduced from 12.9% to 4.3%. These results demonstrate that the proposed deadbeat control strategy provides faster transient response and enhanced robustness against harmonic disturbances in three-phase T-type inverter applications.