A Straightforward Controller Design of Voltage-Controlled Converters for High-Bandwidth and Zero-Overshoot Performance

Voltage control with high steady-state and dynamic performances is crucial for the stand-alone and grid-forming (GFM) operations of voltage-controlled converters (VCCs). To achieve high-bandwidth and zero-overshoot performance, this article proposes a straightforward controller design for the VCCs with an output LC filter. The controller is composed of an outer proportional-integral (PI) controller and an inner state-feedback (SF) controller. The accurate discrete transfer function ${G} _{c}$ (z) with complex coefficients is first constructed, considering the digital delay. Besides, the desired closed-loop transfer function ${G} _{\text {obj}}$ (z) is directly determined from its pole and zero locations. The inner loop poles and PI parameters can thus be obtained by equating ${G} _{c}$ (z) and ${G} _{\text {obj}}$ (z). After that, the inner SF control parameters can be calculated by simple pole placement. Therefore, by designing appropriate ${G} _{\text {obj}}$ (z), superior control performance can be easily achieved. The effects of sampling delay and noise on the performance are discussed, which can be evaded by selecting the poles of ${G} _{\text {obj}}$ (z). The current and voltage limiters are adopted to consider the inherent physical limitation of the converters. Besides, the analysis shows that the proposed method is highly robust to parameter variations. Experimental results on a SiC-MOSFET-based prototype demonstrate the superiority of the proposed method. The bandwidth reaches 5 kHz, and the settling time is less than 0.2 ms without any overshoot.