變頻器是運動控製係統中的功率變換器。當今的運動控製係統包含多種學科的技術領域,總的發展趨勢是:驅動的交流化,功率變換器的高頻化,控製的數字化、智能化和網絡化。因此,變頻器作為係統的重要功率變換部件,提供可控的高性能變壓變頻的交流電源而得到迅猛發展。
隨sui著zhe新xin型xing電dian力li電dian子zi器qi件jian和he高gao性xing能neng微wei處chu理li器qi的de應ying用yong以yi及ji控kong製zhi技ji術shu的de發fa展zhan,變bian頻pin器qi的de性xing能neng價jia格ge比bi越yue來lai越yue高gao,體ti積ji越yue來lai越yue小xiao,而er廠chang家jia仍reng然ran在zai不bu斷duan地di提ti高gao可ke靠kao性xing實shi現xian變bian頻pin器qi的de進jin一yi步bu小xiao型xing輕qing量liang化hua、高性能化和多功能化以及無公害化而做著新的努力。變頻器性能的優劣,一要看其輸出交流電壓的諧波對電機的影響;二要看對電網的諧波汙染和輸入功率因數;三要看本身的能量損耗(即效率)如何。這裏僅以量大麵廣的交—直—交變頻器為例,闡述它的發展趨勢:
主電路功率開關元件的自關斷化、模塊化、集成化、智能化;開關頻率不斷提高,開關損耗進一步降低。
變頻器主電路的拓撲結構方麵。變頻器的網側變流器對低壓小容量的裝置常采用6脈衝變流器,而對中壓大容量的裝置采用多重化12maichongyishangdebianliuqi。fuzaicebianliuqiduidiyaxiaorongliangzhuangzhichangcaiyongliangdianpingdeqiaoshinibianqi,erduizhongyadarongliangdezhuangzhicaiyongduodianpingnibianqi。duiyusixiangxianyunxingdezhuandong,weishixianbianpinqizaishengnengliangxiangdianwanghuikuihejieshengnengliang,wangcebianliuqiyingweikenibianliuqi,tongshichuxianlegonglvkeshuangxiangliudongdeshuangPWM變頻器,對網側變流器加以適當控製可使輸入電流接近正弦波,減少對電網的公害。
脈寬調製變壓變頻器的控製方法可以采用正弦波脈寬調製控製、消除指定次數諧波的PWM控製、電流跟蹤控製、電壓空間矢量控製(磁鏈跟蹤控製)。
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微wei處chu理li器qi的de進jin步bu使shi數shu字zi控kong製zhi成cheng為wei現xian代dai控kong製zhi器qi的de發fa展zhan方fang向xiang。運yun動dong控kong製zhi係xi統tong是shi快kuai速su係xi統tong,特te別bie是shi交jiao流liu電dian動dong機ji高gao性xing能neng的de控kong製zhi需xu要yao存cun儲chu多duo種zhong數shu據ju和he快kuai速su實shi時shi處chu理li大da量liang信xin息xi。近jin幾ji年nian來lai,國guo外wai各ge大da公gong司si紛fen紛fen推tui出chu以yiDSP(數字信號處理器)為基礎的內核,配以電機控製所需的外圍功能電路,集成在單一芯片內的稱為DSP單片電機控製器,價格大大降低,體積縮小,結構緊湊,使用便捷,可靠性提高。DSP和普通的單片機相比,處理數字運算能力增強10~15bei,kequebaoxitongyougengyouyuedekongzhixingneng。shuzikongzhishiyingjianjianhua,rouxingdekongzhisuanfashikongzhijuyouhendadelinghuoxing,keshixianfuzakongzhiguilv,shixiandaikongzhililunzaiyundongkongzhixitongzhongyingyongchengweixianshi,yiyuyushangcengxitonglianjiejinxingshujuchuanshu,bianyuguzhangzhenduan、加強保護和監視功能,使係統智能化(如有些變頻器具有自調整功能)。
交(jiao)流(liu)同(tong)步(bu)電(dian)動(dong)機(ji)已(yi)成(cheng)為(wei)交(jiao)流(liu)可(ke)調(tiao)轉(zhuan)動(dong)中(zhong)的(de)一(yi)顆(ke)新(xin)星(xing),特(te)別(bie)是(shi)永(yong)磁(ci)同(tong)步(bu)電(dian)動(dong)機(ji),電(dian)機(ji)獲(huo)得(de)無(wu)刷(shua)結(jie)構(gou),功(gong)率(lv)因(yin)數(shu)高(gao),效(xiao)率(lv)也(ye)高(gao),轉(zhuan)子(zi)轉(zhuan)速(su)嚴(yan)格(ge)與(yu)電(dian)源(yuan)頻(pin)率(lv)保(bao)持(chi)同(tong)步(bu)。同(tong)步(bu)電(dian)機(ji)變(bian)頻(pin)調(tiao)速(su)係(xi)統(tong)有(you)他(ta)控(kong)變(bian)頻(pin)和(he)自(zi)控(kong)變(bian)頻(pin)兩(liang)大(da)類(lei),自(zi)控(kong)變(bian)頻(pin)同(tong)步(bu)電(dian)機(ji)在(zai)原(yuan)理(li)上(shang)和(he)直(zhi)流(liu)電(dian)機(ji)極(ji)為(wei)相(xiang)似(si),用(yong)電(dian)力(li)電(dian)子(zi)變(bian)流(liu)器(qi)取(qu)代(dai)了(le)直(zhi)流(liu)電(dian)機(ji)的(de)機(ji)械(xie)換(huan)向(xiang)器(qi),如(ru)采(cai)用(yong)交(jiao)—直—交變壓變頻器時叫做“直流無換向器電機”或稱“無刷直流電動機”。傳(chuan)統(tong)的(de)自(zi)控(kong)變(bian)頻(pin)同(tong)步(bu)機(ji)調(tiao)速(su)係(xi)統(tong)有(you)轉(zhuan)子(zi)位(wei)置(zhi)傳(chuan)感(gan)器(qi),現(xian)正(zheng)開(kai)發(fa)無(wu)轉(zhuan)子(zi)位(wei)置(zhi)傳(chuan)感(gan)器(qi)的(de)係(xi)統(tong)。同(tong)步(bu)電(dian)機(ji)的(de)他(ta)控(kong)變(bian)頻(pin)方(fang)式(shi)也(ye)可(ke)采(cai)用(yong)矢(shi)量(liang)控(kong)製(zhi),其(qi)按(an)轉(zhuan)子(zi)磁(ci)場(chang)定(ding)向(xiang)的(de)矢(shi)量(liang)控(kong)製(zhi)比(bi)異(yi)步(bu)電(dian)機(ji)簡(jian)單(dan)。