所謂霍爾效應,是指磁場作用于載流金屬導體、半導體中的載流子時,產生橫向電位差的物理現象。金屬的霍爾效應是當電流通過金屬箔片時,若在垂直于電流的方向施加磁場,則金屬箔片兩側面會出現橫向電位差。半導體中的霍爾效應比金屬箔片中更為明顯,而鐵磁金屬在居里溫度以下將呈現極強的霍爾效應。利用霍爾效應可以設計制成多種傳感器。//www.ynpax.com
霍爾(er)電位差UH的基本關(guan)系(xi)為
UH=RHIB/d -------- (18)
RH=1/nq(金屬) -------- (19)
式(shi)中(zhong):
RH——霍爾系數:
n ——載流(liu)子(zi)濃度或(huo)自由(you)電(dian)子(zi)濃度;
q ——電子電量(liang);
I ——通過的電(dian)流;
B ——垂直于(yu)I的磁感應強度;
d ——導體的厚度。
由于通電導線周圍存在磁場,其大小與導線中的電流成正比,故可以利用霍爾元件測量出磁場,就可確定導線電流的大小。利用這一原理可以設計制成霍爾電流傳感器。其優點是不與被測電路發生電接觸,不影響被測電路,//www.ynpax.cn不(bu)消耗被測(ce)電(dian)(dian)源的(de)(de)(de)功(gong)(gong)率(lv),特別(bie)適合于大電(dian)(dian)流傳感(gan)。 若(ruo)把(ba)霍爾(er)(er)元件置(zhi)于電(dian)(dian)場(chang)強(qiang)度(du)(du)為E、磁(ci)(ci)(ci)(ci)場(chang)強(qiang)度(du)(du)為H的(de)(de)(de)電(dian)(dian)磁(ci)(ci)(ci)(ci)場(chang)中,則(ze)在該(gai)元件中將產生電(dian)(dian)流I,元件上(shang)(shang)同時產生的(de)(de)(de)霍爾(er)(er)電(dian)(dian)位(wei)差與電(dian)(dian)場(chang)強(qiang)度(du)(du)E成正比,如果再(zai)測(ce)出(chu)(chu)(chu)該(gai)電(dian)(dian)磁(ci)(ci)(ci)(ci)場(chang)的(de)(de)(de)磁(ci)(ci)(ci)(ci)場(chang)強(qiang)度(du)(du),則(ze)電(dian)(dian)磁(ci)(ci)(ci)(ci)場(chang)的(de)(de)(de)功(gong)(gong)率(lv)密(mi)度(du)(du)瞬時值P可由P=EH確定。 利用(yong)這種方法(fa)可以(yi)構成霍爾(er)(er)功(gong)(gong)率(lv)傳感(gan)器。 如果把(ba)霍爾(er)(er)元件集成的(de)(de)(de)開(kai)關按預定位(wei)置(zhi)有規律(lv)地布置(zhi)在物(wu)體(ti)上(shang)(shang),當(dang)裝在運(yun)動物(wu)體(ti)上(shang)(shang)的(de)(de)(de)永磁(ci)(ci)(ci)(ci)體(ti)經過它時,可以(yi)從測(ce)量電(dian)(dian)路上(shang)(shang)測(ce)得(de)脈(mo)沖(chong)信號。根據(ju)脈(mo)沖(chong)信號列可以(yi)傳感(gan)出(chu)(chu)(chu)該(gai)運(yun)動物(wu)體(ti)的(de)(de)(de)位(wei)移。若(ruo)測(ce)出(chu)(chu)(chu)單位(wei)時間(jian)內發出(chu)(chu)(chu)的(de)(de)(de)脈(mo)沖(chong)數(shu),則(ze)可以(yi)確定其運(yun)動速(su)度(du)(du)。 霍爾(er)(er)元件應用(yong)霍爾(er)(er)效應的(de)(de)(de)半導體(ti)。
一、線性霍爾元件檢測 1、改變磁場的大小線性霍爾元件的好壞將線性霍爾元件通電,輸出端接上電壓表,磁鐵從遠到近逐漸靠近線性霍爾元件時,該線性霍爾元件的輸出電壓逐漸從小到大變化,這說明該線性霍爾元件是好的,如果磁鐵從遠到近逐漸地靠近線性霍爾元件,該線性霍爾元件的輸出電壓保持不變,這說明該線性霍爾元件已被損壞。 2、改變(bian)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)恒(heng)(heng)流源的(de)電(dian)流大(da)(da)小判斷線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)的(de)好(hao)壞磁鐵保持(chi)不(bu)(bu)動(dong)(即對線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)加入一個固定(ding)不(bu)(bu)變(bian)的(de)磁場),使得線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)恒(heng)(heng)流源的(de)電(dian)流從(cong)零逐漸地(di)向額(e)定(ding)電(dian)流變(bian)化時(shi)(shi)(不(bu)(bu)能超過線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)的(de)額(e)定(ding)電(dian)流),這(zhe)(zhe)時(shi)(shi)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)的(de)輸(shu)出(chu)電(dian)壓也從(cong)小逐漸地(di)向大(da)(da)變(bian)華,這(zhe)(zhe)說時(shi)(shi)該(gai)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)是(shi)好(hao)的(de),如果(guo)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)恒(heng)(heng)流的(de)電(dian)流從(cong)零逐漸地(di)向額(e)定(ding)電(dian)流變(bian)化時(shi)(shi),這(zhe)(zhe)時(shi)(shi)該(gai)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)的(de)電(dian)壓保持(chi)不(bu)(bu)變(bian),這(zhe)(zhe)說明該(gai)線(xian)(xian)(xian)(xian)(xian)性(xing)(xing)霍(huo)爾元(yuan)(yuan)(yuan)件(jian)(jian)(jian)(jian)已損壞
二、單(dan)極開關型霍爾元件的(de)好壞檢測
將單極開關霍爾元件通電5V,輸出端串聯電阻,當磁鐵遠離開關霍爾元件時,開關霍爾元件的輸出電壓為高電平(+5V),當磁鐵靠近開關霍樂元件時,開關霍爾元件的輸出電壓為低電平(+0.2V左右),這說明該開關開型霍爾元件是好的。如果不認靠近或離開霍爾開關,該霍爾開關的輸出電平保持不變,則說明該霍爾開關已損壞。
三、雙極鎖存霍爾開關元件的好(hao)壞檢(jian)測當磁鐵(tie)N極或S極靠(kao)近霍爾開關,輸出(chu)是高電平(ping)或低電平(ping)
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