7.1 PWM控制的基本原理 The basic principle of PWM control中英版

Item7PWMCircuit項(xiàng)目七PWM電路7.1TheBasicPrincipleofPWMControl7.1PWM控制的基本原理TeachingResourcesDatabaseof

NationalVocationalEducationPowerSupplyTechnologyBilingualcourses.Powerelectronicstechnology電力電子技術(shù)PWM控制就是脈寬調(diào)制技術(shù)：即通過對(duì)一系列脈沖的寬度進(jìn)行調(diào)制，來等效的獲得所需要的波形（含形狀和幅值)。PWMcontrolisPulseWidthModulationTechnology:thatis,bymodulatingthewidthofaseriesofpulses,toequivalentlyobtainthedesiredwaveform(includingshapeandamplitude).PWM控制的思想源于通信技術(shù)，全控型器件的發(fā)展使得實(shí)現(xiàn)PWM控制變得十分容易。ThethoughofPWMcontrolcomesfromCommunicationTechnology,thedevelpomentoffullcontrolledelectronicdevicesmakeiteasytorealizePWMcontrol.PWM技術(shù)的應(yīng)用十分廣泛，它使電力電子裝置的性能大大提高，因此它在電力電子技術(shù)的發(fā)展史上占有十分重要的地位?，F(xiàn)在使用的各種逆變電路都采用了PWM技術(shù)。PWMtechnologyiswidelyused,itmakestheperformanceofpowerelectronicdevicesgreatlyimproved.Thus,itoccupiesaveryimportantpositioninthehistoryofthedevelopmentofpowerelectronictechnology.PWMtechnologyisusedinallkindsofinvertercircuits.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlPWM控制的基本思想ThebasicideaofPWMcontrol1）重要理論基礎(chǔ)——面積等效原理Importantandbasicthoery-areaequivalenceprinciple沖量相等而形狀不同的窄脈沖加在具有慣性的環(huán)節(jié)上時(shí)，其效果基本相同。Narrowpulsesofthesameimpulsebutdifferentshapeareappliedtoaninertiallink,andtheeffectisbasicallythesame.沖量impulse窄脈沖的面積Theareaofthenarrowpulse效果基本相同theeffectisbasicallythesame.環(huán)節(jié)的輸出響應(yīng)波形基本相同Theoutputresponsewaveformofthelinkisbasicallythesame圖6-1形狀不同而沖量相同的各種窄脈沖

Fig.6-1Anyofvariousnarrowpulsesofdifferentshapesandofthesameimpulsed)單位脈沖函數(shù)unitimpulsefunctionf(t)d(t)tOa)矩形脈沖rectangularpulseb)三角形脈沖triangularpulsec)正弦半波脈沖half-sinewavepulsetOtOtOf(t)f(t)f(t)7.1PWM控制的基本原理TheBasicPrincipleofPWMControl若要改變等效輸出正弦波幅值，按同一比例改變各脈沖寬度即可。Inordertochangetheamplitudeoftheequivalentoutputsinusoidalwave,thewidthofeachpulsecanbechangedinthesameproportion.Ouωt>SPWM波SPWMwaveOuωt>如何用一系列等幅不等寬的脈沖來代替一個(gè)正弦半波HowdoyoureplaceasinusoidalhalfwavewithaseriesofpulsesofequalamplitudeandunequalwidthOuωt>脈沖的寬度按正弦規(guī)律變化麗和正弦波等效的PWM波形，也稱SPWM波形。Thewidthofthepulsechangesaccordingtosinusoidallaw.ItisequivalenttosinewavePWMwaveform,alsoknownasSPWMwaveform.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlThearea(impulse)isequalWidthaccordingtothesinusoidalregulationchangesdifferentWidthequalamplitudecoincidenceofmidpointOwtUd-Ud對(duì)于正弦波的負(fù)半周，采取同樣的方法，得到PWM波形，因此正弦波一個(gè)完整周期的等效PWM波為：Forthenegativehalfcycleofsinusoidalwave,thesamemethodisadoptedtoobtainthePWMwaveform.Therefore,theequivalentPWMwaveofacompletecycleofsinusoidalwaveis:OwtUd-Ud根據(jù)面積等效原理，正弦波還可等效為下圖中的PWM波，而且這種方式在實(shí)際應(yīng)用中更為廣泛。Accordingtotheprincipleofareaequivalence,thesinusoidalwavecanalsobeequivalenttothePWMwaveinthefigurebelow,andthiswayismorewidelyusedinpractice.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlPWM逆變電路PWMinvertercircuitPWM整流電路PWMrectifiercircuitOwtUd-UdUoωtPWM波分類TheclassificationofPWMwave等幅PWM波Constant-amplitudePWMwave不等幅PWM波VariableamplitudesPWMwave斬控式交流調(diào)壓電路ChoppingcontrolACvoltageregulatingcircuit矩陣式變頻電路Matrix-typefrequencyconversioncircuit7.1PWM控制的基本原理TheBasicPrincipleofPWMControl2）PWM電流波PWMcurrentwave電流型逆變電路進(jìn)行PWM控制，得到的就是PWM電流波。CurrentSourceTypeInverter-CSTIcarriesoutPWMcontrol,thenyou'llgetthePWMcurrentwave.PWM波可等效的各種波形

PWMwavecanbeequivalenttovariouswaveforms直流斬波電路DCchoppercircuit

直流波形DCwaveformsSPWM波SPWMwaves

正弦波形Sinusoidalwaveform等效成其他所需波形，如:Equivalenttootherrequiredwaveforms,suchas:

所需波形

Requiredwaveforms

等效的PWM波TheequivalentPWMwave7.1PWM控制的基本原理TheBasicPrincipleofPWMControlTeachingResourcesDatabaseof

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