主動式噪音控制技術於風扇與壓縮機噪音降低之應用

Abstract

本論文針對箱型氣冷式冷氣空調系統的噪音問題，嘗試以主動式噪音 控制的方法並應用已有的實驗成果來達成減低噪音的目的。本論文大致可 分為三個部分：第一部分是介紹主動式噪音控制 (ANC) 的消音原理及其 發展過程，同時也對其遭遇的問題作一簡略的說明。 第二部分則是本論文中所使用的數學公式和理論基礎，主要包括內模型原 理、適應前饋控制以及適應內模型原理。內模型原理適用於所欲消除的噪 音雜訊為固定頻率的窄頻訊號。適應前饋則當我們可獲得與噪音雜訊有很 好相關性的前饋訊號時，可達成寬頻的消音效果。至於適應內模型則配合 Youla 參數化的方法使得經適應內模型運算法所調整出來的控制器仍能保 證內部穩定的要求，可消除具緩慢時變特性的窄頻噪音雜訊。 第三部分則為實驗結果以及結論，針對不同架構的實驗結果依序列示，包 括室內機和室外機部分。此外並就消音結果說明進一步改善的方向。 The purpose of this thesis is aimed at reducing the noise of air conditionerby applying the methods of active noise control (ANC) and utilizing some experiment results. In general, this thesis can be divided into three parts :First part of the thesis is a brief introduction of ANC theorem and its historical review. Besides, a summary account about the main problems that ANCencounters is presented .The second part contains mathematical formulas and algorithms used in this thesis.Internal-model principle, adaptive feedforward algorithm and adaptive internal-model algorithm are the main topics in this part. Internal-model principle is applicable to cancel noises if the noises consist of narrow-band signals with fixed frequencies.If a good coherence feedforward signal is available, then adaptive feedfword structure can attain the broad-band noise cancellation. The adaptive internal-model algorithm in combination with Youla parametrization can ensure the adaptive controller to keep up the internal stability and cancel narrow-band noises with slowly time-varying properties. Experiment results and conclusions are embodied in thethird part. Experiment results are listed in order for different experiment structures , including the in-door and out- door part of the air conditioner. Moreover,according to cancellation results, methods of further improvement arediscussed.