2 results about "Notch band" patented technology

This application discloses a grid-connected inverter control method based on a notch filter phase-locked loop (PLL) for weak grid conditions. The method first designs a notch filter with adjustable notch depth and bandwidth, setting its notch frequency to the grid power frequency. It then acquires the three-phase voltage at the grid connection point, subtracts the voltage after notching, and extracts the power frequency component of the three-phase voltage. The power frequency component is phase-locked in a synchronous reference frame to obtain the modulation wave phase signal. The inverter output voltage and current are acquired, and active and reactive power are calculated. A dual closed-loop control circuit with an outer power loop and an inner current loop is constructed, outputting the modulation wave voltage amplitude signal. Finally, the modulation wave phase signal and amplitude signal are combined to generate a pulse modulation wave signal. Thus, this invention can accurately lock the grid phase when the weak grid voltage contains harmonics and DC components, effectively improving the stable grid-connected operation capability of the grid-connected inverter under large disturbances.

This application relates to the field of electronic manufacturing technology, specifically to a method and system for detecting alignment errors in a film coating process. The method includes: acquiring a grayscale image of a coated substrate and a local film thickness gradient along the substrate transport direction; determining the center frequency and notch bandwidth of interference fringes in the image frequency domain based on the local film thickness gradient, and filtering the spectrum of the grayscale image of the coated substrate according to the center frequency and the notch bandwidth to obtain a cleaned image; extracting the gradient amplitude of the cleaned image within the region of interest of a marked point, and determining a calculation window based on the statistical characteristics of the gradient amplitude, calculating the sub-pixel center coordinates of the marked point within the calculation window; performing error calculation based on the sub-pixel center coordinates, and verifying the result by combining a preset alignment tolerance, thereby obtaining the alignment error detection result. This application can adaptively separate interference frequency components and achieve accurate detection and correction of alignment errors.