Comparison of Coupled Direct Digital Control and Decoupled Direct Digital Control Based on D-Σ Processes for Three-phase-three-wire Inverter

This paper compares the coupled direct digital control (CDDC) and the decoupled direct digital control (D
³
C) based on D-Σ processes. The comparison is relied on the three-phase three-wire (3Φ3W) inverter, and shows that both control laws are completely identical by modifying the control-law expressions of CDDC and D
³
C. On the knowledge, they are consistent and it is better to select D
³
C for an inverter due to not only its decoupled three-phase control, but its less complexity in programming. The simulated results of a 5 kW 3Φ3W inverter relying on both control laws verify the analysis and discussion. Furthermore, both control laws are implemented by a microprocessor and we have measured that the computation time of the D
³
C is fast then that of CDDC.