Research On Vehicle Interior Active Noise Control System Based On Notch Filtering Algorithm

With the rapid development of the automobile industry, vehicles bring not only the convenience to people but also some problems such as tail gas pollution, noise pollution and so on. At present,many countries have introduced relevant standards and regulations on vehicle exterior noise to reduce the pollution of the environment. For vehicle interior noise, it is not clearly defined. But vehicle interior noise is an important factor affecting ride comfort,it directly affects the consumer orientation towards to the automotive products.Currently traditional passive noise control method, such as sound absorption, sound insulation, vibration attenuation, is remarkable for vehicle interior high frequency noise control. But for low frequency noise control, the effect is poor. Active noise control technology can make up this shortage, and it has many advantages. This technology is convenient to install and it doesn’t have negative impact for vehicle structure and working performance. Therefore, active noise control becomes an hot topic in the field of noise control.In this paper, vehicle interior noise control method has been studied deeply. Research shows that the engine noise is periodic and it has close correlation with vehicle interior dominant peak noise. Based on these characters, a method using adaptive notch filter algorithm for active noise control was proposed. The prototype for active noise control was developed. An active noise control system was built in a domestic car, and the test was carried out. This paper mainly completed the following research work:First, adaptive filters and adaptive filtering algorithms are studied and derived. After studying the correlation between dominant noise peak value frequency and engine rotation speed in vehicle with four cylinder and four stroke internal combustion engine, a method using adaptive notch filter algorithm for construction of reference input signals was proposed.This algorithm greatly simplifies the structure of the LMS algorithm which is widely used inthe field of active noise control, and improves the stability and convergence speed of the algorithm.An active control method is proposed to reduce the peak value of the noise in the vehicle noise spectrum. This method includes the secondary path sweep frequency identification and adaptive notch filter algorithm based on LMS algorithm. An active noise control system model is built in the Simulink simulation environment. The feasibility of the method is verified by the simulation analysis, and the selection of the basic parameters of the LMS algorithm is completed.Based on the results of simulation analysis, an adaptive active controller, which uses DSP as the main control chip, is designed and developed. The corresponding control software program is compiled based on the adaptive notch filter algorithm. In a domestic car, the adaptive active noise control system is constructed, and the corresponding debugging is completed.Several tests were done using the single channel active noise control system on a domestic car. Results show that the noise active control system developed in this paper can achieve a good performance of noise reduction under the steady state condition of the engine.At different speed of the engine,the peak noise reduction of 9.4d B(Lin) ~15.1d B(Lin) can be achieved in the driver’s head area.