Frequency-sweep experimental method for predicting noise of power capacitor

摘要

A frequency-sweep experimental method for predicting noise of a power capacitor, comprises steps of: (1) loading the capacitor with a sine voltage excitation with a loading frequency value of ½ to 50 times of a power frequency in sequence, at an increase of half of the power frequency for each time, and measuring vibration velocity at various points on a case of the capacitor; (2) under each loading frequency, dividing vibration velocity by a square of each voltage applied to obtain an electromechanical vibration frequency response function value corresponding to a double frequency which has a double value of each loading frequency mentioned above; (3) calculating frequency spectrum of a square of the voltage of the capacitor according to the voltage and a current of the capacitor; (4) multiplying the frequency spectrum of the square of the voltage of the capacitor by the electromechanical vibration frequency response function value of the capacitor to obtain a vibration velocity spectrum of the case of the capacitor; (5) calculating acoustical power of the noise radiated by the capacitor according to the vibration velocity spectrum of the case of the capacitor. The method of the present invention is capable of achieving the problems of lacking a simple and standard method for detecting noise in the capacitor industry, and lacking sufficient investment in noise reduction, so as to provide a fundamental for solving the problems in the capacitor noise.