開關電源“電壓型”與“電流型”控制的區別在哪?
總有人會對開關電源電壓型控制與電流型控制是什么有不了解,回答的方式也各式各樣,為了澄清相關概念,這里發表一下對這兩個概念的理解。
電(dian)(dian)壓(ya)(ya)型(xing)控(kong)制與電(dian)(dian)流型(xing)控(kong)制是指對反(fan)(fan)饋(kui)(kui)信號的(de)不同取樣方法(fa),電(dian)(dian)壓(ya)(ya)型(xing)控(kong)制以電(dian)(dian)源的(de)輸(shu)出(chu)電(dian)(dian)壓(ya)(ya)為反(fan)(fan)饋(kui)(kui)信號,該(gai)反(fan)(fan)饋(kui)(kui)信號與給定值的(de)偏差經比(bi)較(jiao)器放(fang)大后與鋸齒波比(bi)較(jiao)產(chan)(chan)生(sheng)(sheng)控(kong)制脈(mo)沖。而電(dian)(dian)流型(xing)控(kong)制是以高頻變壓(ya)(ya)器原邊輸(shu)出(chu)電(dian)(dian)流為采樣反(fan)(fan)饋(kui)(kui)信號組成(cheng)電(dian)(dian)流閉環,以電(dian)(dian)壓(ya)(ya)反(fan)(fan)饋(kui)(kui)信號組成(cheng)電(dian)(dian)壓(ya)(ya)外環,電(dian)(dian)壓(ya)(ya)外環的(de)輸(shu)出(chu)偏差作為電(dian)(dian)流內(nei)環的(de)給定,與電(dian)(dian)流反(fan)(fan)饋(kui)(kui)信號比(bi)較(jiao)產(chan)(chan)生(sheng)(sheng)控(kong)制脈(mo)沖,兩種(zhong)控(kong)制方式的(de)系(xi)統(tong)結構框圖如圖1和圖2所示(shi):


兩種控制方式的實現原(yuan)理如圖(tu)(tu)3和圖(tu)(tu)4所示(shi):


電壓型控制將輸(shu)出(chu)電壓與VR參考電壓Vref的(de)偏差信(xin)號(hao)e經PI型誤差放大器處理后與振蕩器產生的(de)鋸齒(chi)波(bo)進(jin)行比較,產生PWM控制脈沖,其輸(shu)出(chu)波(bo)形如(ru)圖5所(suo)示。

電(dian)流(liu)型(xing)控制(zhi)有兩個閉環通(tong)道,電(dian)壓(ya)(ya)與(yu)VR參考電(dian)壓(ya)(ya)Vref的偏(pian)差信號(hao)e經(jing)PI型(xing)誤差放大(da)器得以電(dian)壓(ya)(ya)Ve,該(gai)電(dian)壓(ya)(ya)與(yu)開關管漏(lou)極(ji)輸出電(dian)流(liu)進行比較(jiao),產生PWM控制(zhi)脈(mo)沖,其輸出波形如(ru)圖6所示。

