賦能(neng)工業智能(neng)化升級 | 基(ji)于(yu)ACM32 MCU的工業通用變(bian)頻(pin)器方(fang)案
近年(nian)來,隨(sui)著智能(neng)制造對(dui)節能(neng)的更高要(yao)求,通用變頻器在工業領域的應用愈加廣泛。變頻器是一(yi)種先進的調(diao)(diao)速(su)控(kong)制設(she)備,通過(guo)對(dui)電源頻率的控(kong)制可以實(shi)現對(dui)電機轉速(su)的精確調(diao)(diao)節,從(cong)而提高設(she)備的性(xing)能(neng)和(he)節能(neng)效果。
變頻器(qi)概述(shu)
變頻(pin)(pin)器(qi)(Variable-Frequency Drive,VFD)是應用變頻(pin)(pin)技(ji)術和微(wei)電子技(ji)術,通過改(gai)變電機工作電源(yuan)頻(pin)(pin)率方式來(lai)控制交流電動機的電動設備。
對(dui)于交流電機而言(yan),其轉速表(biao)達式為:
其(qi)中,n表(biao)(biao)(biao)示(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)轉速(su),f表(biao)(biao)(biao)示(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)(ji)電(dian)(dian)(dian)源(yuan)信(xin)號(hao)頻(pin)(pin)率,s表(biao)(biao)(biao)示(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)轉速(su)差,p表(biao)(biao)(biao)示(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)極對數。從上(shang)式(shi)(shi)可以(yi)看出,電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)轉速(su)和電(dian)(dian)(dian)源(yuan)信(xin)號(hao)頻(pin)(pin)率成正比關(guan)系(xi)。因此,只更改(gai)頻(pin)(pin)率即可改(gai)變(bian)(bian)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)轉速(su)。變(bian)(bian)頻(pin)(pin)器正是依(yi)據該公(gong)式(shi)(shi)來(lai)實現(xian)對電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)變(bian)(bian)速(su)控制(zhi)。通常,變(bian)(bian)頻(pin)(pin)器由整流(liu)電(dian)(dian)(dian)路,濾波電(dian)(dian)(dian)路,逆變(bian)(bian)電(dian)(dian)(dian)路以(yi)及(ji)控制(zhi)電(dian)(dian)(dian)路4個部分組成。外部輸入的(de)三(san)相(xiang)電(dian)(dian)(dian)會(hui)經過整流(liu)電(dian)(dian)(dian)路和濾波電(dian)(dian)(dian)路得(de)(de)到(dao)穩(wen)定(ding)的(de)直(zhi)(zhi)流(liu)電(dian)(dian)(dian)。直(zhi)(zhi)流(liu)電(dian)(dian)(dian)再通過逆變(bian)(bian)電(dian)(dian)(dian)路得(de)(de)到(dao)用(yong)以(yi)驅動交(jiao)流(liu)電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)三(san)相(xiang)電(dian)(dian)(dian)。逆變(bian)(bian)電(dian)(dian)(dian)路一(yi)般(ban)會(hui)選用(yong)IGBT來(lai)實現(xian),以(yi)期得(de)(de)到(dao)足夠的(de)驅動電(dian)(dian)(dian)流(liu),其(qi)電(dian)(dian)(dian)路結構示(shi)(shi)意(yi)圖(tu)如(ru)下(xia)圖(tu)所示(shi)(shi):
逆變電路結(jie)構示意圖
經過整(zheng)形和(he)濾波之(zhi)后的(de)(de)(de)直流信(xin)(xin)號(hao)接入到上圖的(de)(de)(de)環境V+和(he)V-端,控制(zhi)(zhi)電路(lu)通(tong)過Y1~Y6端口(kou),控制(zhi)(zhi)IGBT的(de)(de)(de)開關得到交流電機的(de)(de)(de)三(san)相交流控制(zhi)(zhi)信(xin)(xin)號(hao),以完成對電機的(de)(de)(de)控制(zhi)(zhi)。
航芯ACM32 MCU工業變(bian)頻器方案
針對工(gong)業自動(dong)化電(dian)機驅動(dong)需求(qiu)的客戶,上海航芯(xin)推出了工(gong)業通用(yong)變頻器(qi)應用(yong)方(fang)案,該方(fang)案采用(yong)ACM32F4/ACM32G1系列MCU,最(zui)高工(gong)作頻率(lv)(lv)可(ke)達(da)180MHz/120MHz,內置最(zui)大512KB的eFlash和最(zui)大192KB SRAM。其中(zhong)ACM32F4帶(dai)(dai)(dai)有一個(ge)(ge)可(ke)輸出4路帶(dai)(dai)(dai)死區(qu)的互(hu)補PWM信號的高級(ji)定時器(qi)以(yi)及采樣(yang)速率(lv)(lv)最(zui)高可(ke)到(dao)2Msps的12位ADC。而ACM32G1帶(dai)(dai)(dai)有兩個(ge)(ge)可(ke)輸出4路帶(dai)(dai)(dai)死區(qu)的互(hu)補PWM信號的高級(ji)定時器(qi)以(yi)及兩路采樣(yang)速率(lv)(lv)最(zui)高可(ke)到(dao)3Msps的12位ADC。可(ke)實(shi)現(xian)高性能、高精度(du)的電(dian)機驅動(dong)控(kong)制(zhi)(zhi),是工(gong)業設備電(dian)機驅動(dong)控(kong)制(zhi)(zhi)應用(yong)的理想選擇。
基于ACM32F4/ACM32G1系列(lie)MCU的控制電路結構(gou)框(kuang)圖,如下圖所示:
控(kong)制電路(lu)的(de)顯(xian)示(shi)輸出(chu),采用(yong)SPI接(jie)口的(de)LED顯(xian)示(shi)屏。ACM32F4/ACM32G1系(xi)列(lie)的(de)MCU,其標準SPI通(tong)(tong)信速率可到50MHz,能及時(shi)將顯(xian)示(shi)數(shu)(shu)據刷新(xin)到LED顯(xian)示(shi)屏上。變頻器的(de)設(she)置(zhi)參數(shu)(shu)有兩種設(she)置(zhi)模式,在脫機(ji)情況(kuang)下(xia),用(yong)戶(hu)可以(yi)通(tong)(tong)過(guo)外(wai)部(bu)按鍵來(lai)設(she)置(zhi)工(gong)(gong)作參數(shu)(shu)。而在線模式下(xia),變頻器通(tong)(tong)過(guo)UART接(jie)口和上位機(ji)相連。用(yong)戶(hu)通(tong)(tong)過(guo)上位機(ji)將設(she)定的(de)工(gong)(gong)作參數(shu)(shu)輸入至設(she)備(bei)中,設(she)備(bei)運行時(shi),也會將實(shi)時(shi)工(gong)(gong)作情況(kuang)反饋給上位機(ji),以(yi)便用(yong)戶(hu)對設(she)備(bei)進行實(shi)時(shi)調整。
逆變電路部分(fen)的(de)(de)(de)(de)(de)(de)控(kong)(kong)制(zhi)(zhi)是(shi)整(zheng)個控(kong)(kong)制(zhi)(zhi)邏(luo)輯(ji)中(zhong)的(de)(de)(de)(de)(de)(de)核心部分(fen),其本質是(shi)通過MCU中(zhong)的(de)(de)(de)(de)(de)(de)高(gao)級定時器輸出3對互補PWM信(xin)號(hao)給(gei)到(dao)Y1~Y6。利用(yong)SPWM技術驅動(dong)輸出三相交(jiao)流信(xin)號(hao)來(lai)控(kong)(kong)制(zhi)(zhi)電機(ji)工作(zuo)。而三相交(jiao)流電的(de)(de)(de)(de)(de)(de)換相操(cao)作(zuo),則是(shi)根據MCU內置的(de)(de)(de)(de)(de)(de)12位(wei)的(de)(de)(de)(de)(de)(de)ADC對U,V和W三項(xiang)進行電流采樣(yang)來(lai)判定換項(xiang)的(de)(de)(de)(de)(de)(de)時間。ACM32F4系(xi)列的(de)(de)(de)(de)(de)(de)MCU,ADC的(de)(de)(de)(de)(de)(de)采樣(yang)頻(pin)率能到(dao)2Msps,能滿(man)足大多數設備的(de)(de)(de)(de)(de)(de)運行需求。而面對高(gao)性能需要的(de)(de)(de)(de)(de)(de)應(ying)用(yong)場(chang)合,則可(ke)使用(yong)ACM32G1系(xi)列MCU。該系(xi)列MCU有兩(liang)路ADC,最高(gao)采樣(yang)率為3Msps,采用(yong)交(jiao)叉采樣(yang)方式提高(gao)對信(xin)號(hao)的(de)(de)(de)(de)(de)(de)采樣(yang)速率,精確(que)控(kong)(kong)制(zhi)(zhi)換相參數并做出相應(ying)的(de)(de)(de)(de)(de)(de)控(kong)(kong)制(zhi)(zhi)動(dong)作(zuo)。