Dissipativity Enhancement for Multisampled LCL-Type Inverter Using a Low-Delay Ripple-Removal Method

Multisampling is considered as a direct path toward inherent admittance passivity because it can directly reduce the control delay. However, the phase lag caused by the switching ripple suppression filter weakens the advantage of multisampling, making it difficult to extend the dissipativity of the high-frequency band. In this article, to address the challenge of phase lag limiting the dissipativity enhancement, a low-delay ripple-removal method based on sliding discrete Fourier transform (SDFT) is proposed. The application of this method in eliminating switching ripples is analyzed theoretically. It also explains why there is a low delay in the control loop. Accordingly, based on the proposed method and multisampling, the dissipativity of the high-frequency band is enhanced greatly with the single-loop control of inverter-side current feedback. When combining voltage proportional feedforward of the point of common coupling (PCC), the dissipative region can be extended to switching frequency. Finally, the experimental results verify the effectiveness of the proposed method and its application effect in enhancing dissipativity.