Load Current Decoupling Based LQ Control for Three-Phase Inverter

In classical inverter control, load current (disturbance) decoupling control is often used to improve the control performance. Yet, in a recent state-space control structure for multiresonant controllers, the load current decoupling technique is less studied. Moreover, in the classical control, the load current decoupling only has one control degree of freedom. Therefore, in this paper, a load current decoupling control combed linear quadratic (LQ) regulation is investigated, the proposed control structure that manipulates α and β axes as a unified system is adopted to increase the control degree of freedom. The LQ control synthesizes the state feedback control law including gains of the resonant controllers. Two general criteria, namely H
_∞
norm and zero dynamic, are proposed as the design guideline for the load current decoupling control. The effectiveness and robustness of the proposed approach are validated through MATLAB/Simulink simulations and experiments with a 5-kVA testbed. The results prove that some favorable performances, for example, the fast recovering time, the small voltage drop, and the low total harmonic distortion, are achieved by the proposed approach compared to the classical dual-loop proportional-resonant (PR) control with load current decoupling and the optimal H
_∞
control.