【正文】 風(fēng)力發(fā)電領(lǐng)域， PWM 變換器的控制技術(shù)是 其 核心技術(shù)之一 。 在通信領(lǐng)域，由于 PWM 控制有很強的 噪聲抵抗能力 ， 從模擬信號轉(zhuǎn)向 PWM 可以極大地延長通信距離。噪聲只有在強到足以將邏輯 1改變?yōu)檫壿?0或?qū)⑦壿?0改變?yōu)檫壿?1時，也才能對數(shù)字信號產(chǎn)生影響。 PWM 的一個優(yōu)點是從處理器到被控系統(tǒng)信號都是數(shù)字形式的，無需進行數(shù)模轉(zhuǎn)換。模擬電路還有可能嚴重發(fā)熱，其功耗相對于工作元件兩端電壓與電流的乘積成正比。其中一點就是，模擬電路 容易隨時間漂移，因而難以調(diào)節(jié)。 致 謝 .................................................................................................................. 錯誤 !未定義書簽。 signal。 PWM。 本設(shè)計是基于單片機控制的 PWM 信號輸出 系統(tǒng)，系統(tǒng)以 AT89C52 單片機為核心， 采用SPWM 軟件生成法中對稱規(guī)則采樣法 ，用 擴展 按鍵中斷方式 輸入有關(guān)控制信號及參數(shù)，可以實現(xiàn) 頻率、占空比、 輸出時間可調(diào)的直流斬波 PWM 信號和頻率、調(diào)幅比、輸出時間可調(diào)的 SPWM 信號， 并在 LCD1602 上實時設(shè)置參數(shù)及輸出狀態(tài)監(jiān)視 。然后 采用 C 語言編程實現(xiàn)了系統(tǒng)功能，完成設(shè)計目標。首先對 系統(tǒng)結(jié)構(gòu) 和 PWM 軟件算法 進行了研究和分析，包括對各種 PWM 產(chǎn)生方法的對比分析和對稱規(guī)則采樣法的仔細研究以及系統(tǒng)的功能分 區(qū)和總體結(jié)構(gòu)。 PWM 技術(shù)結(jié)合了電力電子技術(shù)、計算機技術(shù)、現(xiàn)代控制理論，具有抗干擾性強、 效率高、可靠性好等顯著 優(yōu)點，已經(jīng)在交流逆變、開關(guān)電源等領(lǐng)域得到廣泛應(yīng)用。摘要 隨著電力電子技術(shù)的飛速發(fā)展， PWM 技術(shù)應(yīng)用越來越廣泛。同時 PWM 技術(shù)本身也發(fā)展迅速，各種新理論層出不窮。 本文在研究 PWM 技術(shù)當前發(fā)展狀況基礎(chǔ)上，設(shè)計了一種基于單片機的 PWM 信號輸出系統(tǒng)。在總體設(shè)計完成后又設(shè)計了硬件電路 各個單元模塊。最后對設(shè)計的系統(tǒng)進行了計算機仿真。 關(guān)鍵詞 ：單片機； PWM； SPWM；信號 ；規(guī)則采樣法 ABSTARCT As the developing of power electronic technology, PWM technology has applying to more and more field. At the same time, PWM technology itself has taken a great progress, lots of new theory has emerged. PWM technology takes advantages of power electronic, puter technology, and modern control theory, has strong ability of antiinterference, and is more efficiency, reliable. It has applied to vast field ,such as AC converter, DC chopper. This paper firstly, analysis the situation of PWM technology’ development, then, designed a PWM signal output system based on SCM. At the beginning, we study the soft algorithm of PWM, including parison and analysis of several PWM algorithm and deep analysis of regularsampling. We also designed the system structure. Following , hardware and software is designed. Every hardware module is designed with the puter, and the software is written in C language. At last, we take a simulation. The system is based on AT89C52. It use buttons to input parameters. It can output single polar PWM signals. The signal’s frequency, dutycycle, output time can be changed. What’s more, all information is showed in a LCD1602, so that it is easier to municated with the system. Index terms: SCM。 SPWM。 regularsampling 目 錄 1 緒論 .............................................................................................................................................. 1 PWM 的背景、應(yīng)用及發(fā)展趨勢 ................................................................................................. 1 PWM 原理 ................................................................................................................................. 1 本文的主要工作 ....................................................................................................................... 2 2 系統(tǒng)方案設(shè)計 ................................................................................................................................ 3 系統(tǒng) PWM 算法 ........................................................................................................................ 3 ............................................................................................................................ 3 ......................................................................................................................... 3 ......................................................................................................................... 3 系統(tǒng)結(jié)構(gòu) .................................................................................................................................. 5 涉及元器件簡介 ........................................................................................................................ 5 AT89C52 介紹 ...................................................................................................................... 5 LCD1602 簡介 ...................................................................................................................... 8 仿真工具介紹 ......................................................................................................................... 9 Protues 簡介 ....................................................................................................................... 9 Keil uVision2 簡介 .............................................................................................................. 11 3 硬件電路設(shè)計 ............................................................................................................................... 13 電源 ....................................................................................................................................... 13 單片機復(fù)位電路 ...................................................................................................................... 14 單 片機時鐘電路 ...................................................................................................................... 14 按鍵中斷 ................................................................................................................................ 15 顯示電路 ................................................................................................................................ 16 輸出電路 ................................................................................................................................ 17 SPWM 測試電路 ...................................................................................................................... 17 4 軟件設(shè)計 ..................................................................................................................................... 19 軟件總流程 ............................................................................................................................. 19 直流斬波 PWM 軟件計算法 .................................................................................................... 19 SPWM 軟件計算法 .