Development of Active Noise Control System Optimized for Road Noise Reduction

Abstract

In this paper, a newly developed Active Noise Control (ANC) system is introduced, that effectively reduces road noise, which becomes a major issue with electrified vehicles, and that enhances vehicle interior sound levels matching seamless acceleration by electric drive. Conventionally, reducing road noise using ANC requires numerous sensors and speakers, as well as a processor with high computing power. Therefore, the increase in system cost and the complexity of the system are obstacles to its spread. To overcome these issues, this system is developed based on four concepts. The first is a modular system configuration with unified interface to apply to various vehicle types and grades. The second is the integration and optimal placement of noise source reference sensors to achieve both reduction in number of parts and noise reduction performance. The third is the application of digital communications that combine power superposition, low latency, and high throughput to reduce wiring. The fourth is the development of control technologies that specialize in in-vehicle acoustic characteristics to achieve both computational efficiency and noise reduction performance. The one is a technology to integrate control paths based on the sound field mode characteristics in the vehicle cabin, and another one is the frequency band restrain control technology that matches speaker output characteristics. It is confirmed that this proposed system achieves quietness improvement equivalent to the difference of vehicle segmentation with a minimum system configuration, and that this system has a high superiority in weight efficiency compared to conventional vehicle body measures.