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

Item7PWMCircuit项目七PWM电路7.1TheBasicPrincipleofPWMControl7.1PWM控制的基本原理TeachingResourcesDatabaseof

NationalVocationalEducationPowerSupplyTechnologyBilingualcourses.Powerelectronicstechnology电力电子技术PWM控制就是脉宽调制技术：即通过对一系列脉冲的宽度进行调制，来等效的获得所需要的波形（含形状和幅值)。PWMcontrolisPulseWidthModulationTechnology:thatis,bymodulatingthewidthofaseriesofpulses,toequivalentlyobtainthedesiredwaveform(includingshapeandamplitude).PWM控制的思想源于通信技术，全控型器件的发展使得实现PWM控制变得十分容易。ThethoughofPWMcontrolcomesfromCommunicationTechnology,thedevelpomentoffullcontrolledelectronicdevicesmakeiteasytorealizePWMcontrol.PWM技术的应用十分广泛，它使电力电子装置的性能大大提高，因此它在电力电子技术的发展史上占有十分重要的地位。现在使用的各种逆变电路都采用了PWM技术。PWMtechnologyiswidelyused,itmakestheperformanceofpowerelectronicdevicesgreatlyimproved.Thus,itoccupiesaveryimportantpositioninthehistoryofthedevelopmentofpowerelectronictechnology.PWMtechnologyisusedinallkindsofinvertercircuits.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlPWM控制的基本思想ThebasicideaofPWMcontrol1）重要理论基础——面积等效原理Importantandbasicthoery-areaequivalenceprinciple冲量相等而形状不同的窄脉冲加在具有惯性的环节上时，其效果基本相同。Narrowpulsesofthesameimpulsebutdifferentshapeareappliedtoaninertiallink,andtheeffectisbasicallythesame.冲量impulse窄脉冲的面积Theareaofthenarrowpulse效果基本相同theeffectisbasicallythesame.环节的输出响应波形基本相同Theoutputresponsewaveformofthelinkisbasicallythesame图6-1形状不同而冲量相同的各种窄脉冲

Fig.6-1Anyofvariousnarrowpulsesofdifferentshapesandofthesameimpulsed)单位脉冲函数unitimpulsefunctionf(t)d(t)tOa)矩形脉冲rectangularpulseb)三角形脉冲triangularpulsec)正弦半波脉冲half-sinewavepulsetOtOtOf(t)f(t)f(t)7.1PWM控制的基本原理TheBasicPrincipleofPWMControl若要改变等效输出正弦波幅值，按同一比例改变各脉冲宽度即可。Inordertochangetheamplitudeoftheequivalentoutputsinusoidalwave,thewidthofeachpulsecanbechangedinthesameproportion.Ouωt>SPWM波SPWMwaveOuωt>如何用一系列等幅不等宽的脉冲来代替一个正弦半波HowdoyoureplaceasinusoidalhalfwavewithaseriesofpulsesofequalamplitudeandunequalwidthOuωt>脉冲的宽度按正弦规律变化丽和正弦波等效的PWM波形，也称SPWM波形。Thewidthofthepulsechangesaccordingtosinusoidallaw.ItisequivalenttosinewavePWMwaveform,alsoknownasSPWMwaveform.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlThearea(impulse)isequalWidthaccordingtothesinusoidalregulationchangesdifferentWidthequalamplitudecoincidenceofmidpointOwtUd-Ud对于正弦波的负半周，采取同样的方法，得到PWM波形，因此正弦波一个完整周期的等效PWM波为：Forthenegativehalfcycleofsinusoidalwave,thesamemethodisadoptedtoobtainthePWMwaveform.Therefore,theequivalentPWMwaveofacompletecycleofsinusoidalwaveis:OwtUd-Ud根据面积等效原理，正弦波还可等效为下图中的PWM波，而且这种方式在实际应用中更为广泛。Accordingtotheprincipleofareaequivalence,thesinusoidalwavecanalsobeequivalenttothePWMwaveinthefigurebelow,andthiswayismorewidelyusedinpractice.7.1PWM控制的基本原理TheBasicPrincipleofPWMControlPWM逆变电路PWMinvertercircuitPWM整流电路PWMrectifiercircuitOwtUd-UdUoωtPWM波分类TheclassificationofPWMwave等幅PWM波Constant-amplitudePWMwave不等幅PWM波VariableamplitudesPWMwave斩控式交流调压电路ChoppingcontrolACvoltageregulatingcircuit矩阵式变频电路Matrix-typefrequencyconversioncircuit7.1PWM控制的基本原理TheBasicPrincipleofPWMControl2）PWM电流波PWMcurrentwave电流型逆变电路进行PWM控制，得到的就是PWM电流波。CurrentSourceTypeInverter-CSTIcarriesoutPWMcontrol,thenyou'llgetthePWMcurrentwave.PWM波可等效的各种波形

PWMwavecanbeequivalenttovariouswaveforms直流斩波电路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

NationalVocationalEducationPowerSupplyTechnologyBilingualc