The Study On Active Control Of Electrical Equipment Noice And Design Of Output Circuit

As one of the three major pollution sources, noise has brought unelectable effect on people's work and life nowadays. It takes serious damage to people's body and spirit. Therefore, how to silence the noise has attracted great attention of specialists from domestic and overseas. Active noise control (ANC) has dynamic response and compensating characteristics. Because of high technology and cost-performance, ANC will substitute passive noise control and become the trend of silencing noise. This paper describes ANC's principle, signal detection, compensating current control and total circuit design respectively in detail.In this thesis, the generation, harm of the noise and the application of the technology of active noise controlling in various fields are reviewed.The development and working principle of active noise controlling are introduced. Especially, the electromagnetic motor noise of transformer and motor are analyzed.According to the response characteristics of microphone and loudspeaker, Fast Fourier Transforming (FFT) is adopted to detect signals. In order to compensate for signal distortion, it is easy to calculate the phase angle and amplitude of signals of various frequencies by FFT. The characteristics and effects of compensation of the Active Noise Control system are determined by the control of the compensation current. In this thesis, the output circuit of the Active Noise Control system is designed, which bridge structure and delay-cycle controlled PWM method of high current tracking speed are adopted.In this thesis, the parameters of main circuit, like the DC voltage, hysteresis width and parameters of filtering circuit, and others are studied deeply, and then the impact of various parameters on the effects of compensation and the requirements of power electronic devices are generated.Finally, a simulation using MATLAB is taken to test the program of the DC voltage, hysteresis width and parameters of filtering circuit, which is proposed in the thesis. The results show that this program gets good compensating effect, and the effects of every control parameters are matched with the theoretical derivation results.