DESIGN AND IMPLEMENTATION OF PASSIVE AND MULTI-CHANNEL ACTIVE NOISE TREATMENT OF A 2kW DIESEL GENERATOR

摘要

This paper investigates the design, implementation, and performance results for acoustically treating a small, portable diesel single-cylinder generator. The emphasis is primarily on the systematic approach to employing a complete, practical noise-control treatment which is scalable to other systems. Substantial passive treatment design was required that balanced acoustic performance, machine cooling, and active noise control (ANC) source space requirements. A microphone array was used to measure the near-field sound pressure levels to obtain a full model of the complex radiated sound in the far-field using spherical harmonic decomposition. Using a genetic algorithm, this model was used to compute the optimal location for the ANC speakers, their output requirements, and numerically-predicted performance. The ANC system employed was a 4 input, 4 output selectable harmonic filtered-X least-mean-square (LMS) feed-forward algorithm utilizing virtual error sensing with all reference generation, error signal conditioning and power electronics integrated into the machine. The complete system was designed, built, and experimentally measured and shown to have performance comparable to the model predictions. Passive performance was approximately lOdBA and the ANC system provided an additional 5dBA with physical error sensors, or 2dBA with virtual-error sensors. Over the control bandwidth only, the ANC system provided 6.5dBA with physical error sensors, or 3dBA with virtual-error sensors.