Abstract |
For LCL-filtered grid-tied inverters, direct pole-placement techniques can combine the fundamentalfrequency current regulation and resonance damping simultaneously. As known, for state-space-based direct pole-placement, to purse sensorless operations, state observers have to be employed, which means heavy computation burden and might limit switching and sampling frequency. While for transfer-function-based one, the number of necessary variables decreases and meanwhile it releases the computation load free from observers. Therefore the latter is more suitable in applications. Based on this, this paper extends and summarizes it for better accessibility, and shows that, compared to previous applications in the stationary frame, transfer-function-based discrete-time domain (z-domain) direct pole placement in the synchronous frame presents better robustness against varying grid impedance, improved phase margin and gain margin, and simplified feed-forward compensation, presuming the cross coupling is ignored. Simulations verified the analysis and design |