低頻加速度傳感器的技術原理與特點

工程振動量值的物理參數常用位移
、速度和加速度來表示。由於在通常的頻率範圍內振動位移幅值量很小，且位移、速度和加速度之間都可互相轉換，所以在實際使用中振動量的大小一般用加速度的值來度量。常用單位為：米/秒2(m/s2)，或重力加速度(g)。

描miao述shu振zhen動dong信xin號hao的de另ling一yi重zhong要yao參can數shu是shi信xin號hao的de頻pin率lv。絕jue大da多duo數shu的de工gong程cheng振zhen動dong信xin號hao均jun可ke分fen解jie成cheng一yi係xi列lie特te定ding頻pin率lv和he幅fu值zhi的de正zheng弦xian信xin號hao，因yin此ci，對dui某mou一yi振zhen動dong信xin號hao的de測ce量liang，實shi際ji上shang是shi對dui組zu成cheng該gai振zhen動dong信xin號hao的de正zheng弦xian頻pin率lv分fen量liang的de測ce量liang。對dui傳chuan感gan器qi主zhu要yao性xing能neng指zhi標biao的de考kao核he也ye是shi根gen據ju傳chuan感gan器qi在zai其qi規gui定ding的de頻pin率lv範fan圍wei內nei測ce量liang幅fu值zhi精jing度du的de高gao低di來lai評ping定ding。

電荷輸出型加速度計不適合用於低頻測量

由於低頻振動的加速度信號都很微小，而高阻抗的小電荷信號非常容易受幹擾;dangceliangduixiangdetijiyueda，qiceliangpinlvyuedi，zexinhaodexinzaobidewentigengweituchu。yincizaimuqiandaineizhidianlujiasuduchuanganqiriqupubiandeqingkuangxiayingjinliangxuanyongdianzaoshengbijiaoxiao
，dipintexingyouliangdedizukangdianyashuchuxingyadianjiasuduchuanganqi。

傳感器的低頻截止頻率

與傳感器的高頻截止頻率類同，低頻截止頻率是指在所規定的傳感器頻率響應幅值誤差(±5%,±10%或±3dB)內(nei)傳(chuan)感(gan)器(qi)所(suo)能(neng)測(ce)量(liang)的(de)最(zui)低(di)頻(pin)率(lv)信(xin)號(hao)。誤(wu)差(cha)值(zhi)越(yue)大(da)其(qi)低(di)頻(pin)截(jie)止(zhi)頻(pin)率(lv)也(ye)相(xiang)對(dui)越(yue)低(di)。所(suo)以(yi)不(bu)同(tong)傳(chuan)感(gan)器(qi)的(de)低(di)頻(pin)截(jie)止(zhi)頻(pin)率(lv)指(zhi)標(biao)必(bi)須(xu)在(zai)相(xiang)同(tong)的(de)誤(wu)差(cha)條(tiao)件(jian)下(xia)進(jin)行(xing)比(bi)較(jiao)。

dizukangdianyashuchuxingchuanganqidedipintexingshiyouchuanganqiminganxintiheneizhidianludezonghediancanshusuojuedingde。qipinlvxiangyingtexingkeyiyongmonidianludeyijiegaotonglvboqitexinglaimiaoshu，suoyichuanganqidedipinxiangyinghejiezhipinlvwanquankeyiyongyijiexitongdeshijianchangshulaiqueding。congshiyongjiaodulaikan，youyuchuanganqideshendipinpinlvxiangyingdebiaodingbijiaokunnan，ertongguochuanganqiduishijianyuneijieyuexinhaodexiangyingkecedechuanganqideshijianchangshu;因yin此ci利li用yong傳chuan感gan器qi的de低di頻pin響xiang應ying與yu一yi階jie高gao通tong濾lv波bo器qi的de特te性xing幾ji乎hu一yi致zhi的de特te點dian

，通tong過guo計ji算suan可ke方fang便bian地di獲huo得de傳chuan感gan器qi的de低di頻pin響xiang應ying和he與yu其qi對dui應ying的de低di頻pin截jie至zhi頻pin率lv。

傳感器的靈敏度，低頻噪聲特性和動態響應範圍

yongyudipinceliangdechuanganqiyibanyaoqiuyoubijiaogaodelingminduyimanzudipinxiaoxinhaodeceliang。danlingmindudezengjiawangwangshiyouxiande。suiranjiasuduchuanganqilingmindushinengdadao10V/ghuogenggao
，danshilingmindugaowangwangdailaiqitadefumianxiaoying，biruchuanganqidewendingxing
，kangguozainengli，yijiduizhoubianhuanjingganraodeminganxing。yincizhuiqiuguogaolingmindubingbuyidingnengjiejueweixiaoxinhaodeceliang，xiangfangaofenbianlvhedizaoshengdechuanganqizaigongchengyingyongzhongwangwanggengrongyijiejueshijiwenti。suoyixuanyongjuyoudidianzaoshengdechuanganqizaidipinceliangzhongyouweizhongyao。

為(wei)了(le)表(biao)明(ming)傳(chuan)感(gan)器(qi)所(suo)能(neng)測(ce)量(liang)的(de)最(zui)小(xiao)信(xin)號(hao)大(da)部(bu)分(fen)商(shang)業(ye)化(hua)的(de)加(jia)速(su)度(du)計(ji)也(ye)都(dou)提(ti)供(gong)分(fen)辨(bian)率(lv)或(huo)電(dian)噪(zao)聲(sheng)指(zhi)標(biao)。國(guo)內(nei)絕(jue)大(da)部(bu)分(fen)傳(chuan)感(gan)器(qi)的(de)寬(kuan)帶(dai)電(dian)噪(zao)聲(sheng)指(zhi)標(biao)一(yi)般(ban)都(dou)標(biao)為(wei)20μV，而BW-sensor的寬帶電噪聲指標已降低到10μV。然而對低頻小信號測量來說，僅提供寬頻帶的電噪聲並不能完全反映傳感器在低頻範圍內加速度測量的分辨率;這是因為由內置電路引起的低頻噪聲大小與頻率的倒數成正比，即所謂1/f噪(zao)聲(sheng)，當(dang)測(ce)量(liang)頻(pin)率(lv)很(hen)低(di)時(shi)傳(chuan)感(gan)器(qi)的(de)電(dian)噪(zao)聲(sheng)輸(shu)出(chu)按(an)指(zhi)數(shu)幅(fu)度(du)增(zeng)長(chang)。所(suo)以(yi)傳(chuan)感(gan)器(qi)的(de)低(di)頻(pin)電(dian)噪(zao)聲(sheng)的(de)數(shu)值(zhi)與(yu)寬(kuan)帶(dai)電(dian)噪(zao)聲(sheng)指(zhi)標(biao)是(shi)完(wan)全(quan)不(bu)同(tong)的(de)而(er)且(qie)頻(pin)率(lv)越(yue)低(di)這(zhe)種(zhong)差(cha)別(bie)越(yue)明(ming)顯(xian)。因(yin)此(ci)用(yong)於(yu)甚(shen)低(di)頻(pin)測(ce)量(liang)的(de)傳(chuan)感(gan)器(qi)其(qi)分(fen)辨(bian)率(lv)常(chang)用(yong)傳(chuan)感(gan)器(qi)輸(shu)出(chu)電(dian)噪(zao)聲(sheng)的(de)功(gong)率(lv)譜(pu)密(mi)度(du)表(biao)示(shi)。此(ci)指(zhi)標(biao)的(de)實(shi)用(yong)意(yi)義(yi)是(shi)傳(chuan)感(gan)器(qi)在(zai)特(te)定(ding)頻(pin)率(lv)下(xia)的(de)噪(zao)聲(sheng)大(da)小(xiao)
，其(qi)單(dan)位(wei)是(shi)一(yi)般(ban)用(yong)μV/√Hz或μg/√Hz來表示。BW-sensor內置電路電噪聲功率譜密度的典型值為3μV/√Hz@10Hz。

傳感器的瞬態溫度響應對低頻測量的影響

由you於yu壓ya電dian陶tao瓷ci的de特te性xing，壓ya電dian式shi加jia速su度du計ji對dui溫wen度du的de突tu然ran變bian化hua都dou會hui產chan生sheng不bu同tong程cheng度du的de電dian荷he輸shu出chu。傳chuan感gan器qi的de瞬shun態tai溫wen度du響xiang應ying指zhi標biao就jiu是shi衡heng量liang傳chuan感gan器qi對dui溫wen度du變bian化hua的de敏min感gan程cheng度du。這zhe對dui低di頻pin測ce量liang尤you為wei重zhong要yao。由you於yu低di頻pin測ce量liang的de信xin號hao很hen小xiao，而er傳chuan感gan器qi因yin環huan境jing溫wen度du變bian化hua極ji可ke能neng產chan生sheng與yu低di頻pin振zhen動dong信xin號hao相xiang當dang的de誤wu差cha;zheliangzhongxinhaozaishendipinfanweineihennanqufen，yinciruhejianxiaohuanjingwendubianhuaduichuanganqishuchudeyingxiangzaidipinceliangzhongxiandefeichangzhongyao。chuanganqideshuntaiwenduxiangyingzhibiaodanweishig/oC,表示瞬態溫度每變化一度所相當的加速度輸出，其值是通過電壓(電荷)輸出和傳感器靈敏度之間的換算得到的。

傳感器的瞬態溫度響應是由壓電材料直接導致的，因此壓電陶瓷對由溫度突變所致的電荷輸出大小決定了這一指標的好壞。BW-sensor選用目前國外綜合性能指標最好的壓電陶瓷並結合記憶金屬製成的用於低頻測量的加速度傳感器經國防兵器、航(hang)天(tian)和(he)大(da)型(xing)結(jie)構(gou)多(duo)年(nian)的(de)使(shi)用(yong)驗(yan)證(zheng)了(le)傳(chuan)感(gan)器(qi)具(ju)有(you)優(you)越(yue)的(de)低(di)頻(pin)輸(shu)出(chu)穩(wen)定(ding)性(xing)和(he)抗(kang)幹(gan)擾(rao)性(xing)能(neng)。實(shi)際(ji)甚(shen)低(di)頻(pin)測(ce)量(liang)中(zhong)，為(wei)了(le)減(jian)低(di)環(huan)境(jing)溫(wen)度(du)變(bian)化(hua)對(dui)傳(chuan)感(gan)器(qi)低(di)頻(pin)信(xin)號(hao)輸(shu)出(chu)的(de)影(ying)響(xiang)
，傳(chuan)感(gan)器(qi)的(de)外(wai)殼(ke)盡(jin)可(ke)能(neng)采(cai)用(yong)隔(ge)熱(re)保(bao)護(hu)套(tao)。

傳感器的安裝基座和基座應變對測量的影響

由you於yu低di頻pin測ce量liang傳chuan感gan器qi對dui高gao頻pin響xiang應ying的de要yao求qiu不bu高gao因yin此ci傳chuan感gan器qi使shi用yong任ren何he種zhong安an裝zhuang方fang式shi一yi般ban都dou能neng滿man足zu要yao求qiu。但dan需xu要yao注zhu意yi兩liang個ge問wen題ti，其qi一yi是shi傳chuan感gan器qi應ying盡jin量liang考kao慮lv使shi用yong絕jue緣yuan底di座zuo以yi避bi免mian任ren何he由you對dui地di回hui路lu引yin起qi的de噪zao聲sheng影ying響xiang測ce量liang信xin號hao。其qi二er是shi應ying考kao慮lv傳chuan感gan器qi安an裝zhuang處chu的de被bei測ce結jie構gou應ying變bian對dui傳chuan感gan器qi輸shu出chu的de影ying響xiang
，即ji傳chuan感gan器qi應ying變bian靈ling敏min度du大da小xiao。剪jian切qie結jie構gou形xing式shi的de壓ya電dian加jia速su度du傳chuan感gan器qi具ju有you良liang好hao的de基ji座zuo應ying變bian特te性xing，一yi般ban都dou能neng滿man足zu通tong常chang的de低di頻pin結jie構gou測ce試shi。如ru果guo結jie構gou應ying變bian過guo大da對dui傳chuan感gan器qi的de測ce量liang信xin號hao有you影ying響xiang

，可ke通tong過guo減jian小xiao傳chuan感gan器qi與yu被bei測ce結jie構gou之zhi間jian的de接jie觸chu麵mian積ji來lai降jiang低di結jie構gou應ying變bian對dui傳chuan感gan器qi測ce量liang帶dai來lai的de影ying響xiang。

yuchuanganqigaopinzhibiaoxiangduiying
，chuanganqidedipinceliangzhibiaotongchangyoudipinjiezhipinlvlaiqueding，tongyangyidingdipinjiezhipinlvyuduiyingdefuzhiwuchaxiangguan。hegaopintexingbutong
，chuanganqidedipintexingyuchuanganqiderenhejixiecanshuwuguan，erjinqujueyuchuanganqidediantexingcanshu。dangranchuanganqizuoweiceliangxitongdemouyibufen
，celiangxinhaodedipintexinghaijiangshoudaoyuchuanganqipeiyongdehoujiyiqidiancanshudezhiyue。genjushuchuxinhaodebutongxingshi，yixiajiangduidianheshuchuhedizudianyashuchujiasuduchuanganqifenbiegeiyutaolun。

盡(jin)管(guan)電(dian)荷(he)型(xing)輸(shu)出(chu)加(jia)速(su)度(du)傳(chuan)感(gan)器(qi)列(lie)出(chu)低(di)頻(pin)截(jie)止(zhi)頻(pin)率(lv)

，但(dan)一(yi)般(ban)都(dou)給(gei)予(yu)指(zhi)出(chu)測(ce)量(liang)信(xin)號(hao)的(de)低(di)頻(pin)特(te)性(xing)由(you)後(hou)繼(ji)電(dian)荷(he)放(fang)大(da)器(qi)確(que)定(ding)。在(zai)實(shi)際(ji)應(ying)用(yong)中(zhong)
，當(dang)電(dian)荷(he)型(xing)傳(chuan)感(gan)器(qi)的(de)芯(xin)體(ti)絕(jue)緣(yuan)阻(zu)抗(kang)遠(yuan)大(da)於(yu)電(dian)荷(he)放(fang)大(da)器(qi)輸(shu)入(ru)端(duan)的(de)輸(shu)入(ru)阻(zu)抗(kang)時(shi)，由(you)傳(chuan)感(gan)器(qi)和(he)電(dian)荷(he)放(fang)大(da)器(qi)組(zu)成(cheng)的(de)測(ce)量(liang)係(xi)統(tong)其(qi)低(di)頻(pin)截(jie)至(zhi)頻(pin)率(lv)應(ying)該(gai)由(you)電(dian)荷(he)放(fang)大(da)器(qi)的(de)低(di)頻(pin)特(te)性(xing)所(suo)決(jue)定(ding)。但(dan)是(shi)如(ru)果(guo)傳(chuan)感(gan)器(qi)的(de)芯(xin)體(ti)絕(jue)緣(yuan)阻(zu)抗(kang)下(xia)降(jiang)
，此(ci)時(shi)傳(chuan)感(gan)器(qi)則(ze)可(ke)能(neng)影(ying)響(xiang)整(zheng)個(ge)測(ce)量(liang)係(xi)統(tong)的(de)低(di)頻(pin)特(te)性(xing)。因(yin)此(ci)保(bao)證(zheng)芯(xin)體(ti)的(de)絕(jue)緣(yuan)阻(zu)抗(kang)對(dui)電(dian)荷(he)輸(shu)出(chu)型(xing)加(jia)速(su)度(du)傳(chuan)感(gan)器(qi)的(de)低(di)頻(pin)測(ce)量(liang)非(fei)常(chang)重(zhong)要(yao)。

對於IEPE傳感器配用的恒流電壓源，其通常的低頻截至頻率為0.1Hz(-5%)。因此一般情況下測量係統的低頻特性是由傳感器的低頻截至頻率所決定。通用型傳感器的低頻截止頻率大多為0.5Hz~1Hz,專門用於低頻測量的傳感器低頻截至頻率可擴展到0.1Hz。由於傳感器的低頻校驗比較困難，所以製造廠商一般隻提供10Hz以上的測試數據。但傳感器的低頻特性與一階高通濾波器非常吻合，所以用戶可以通過實測時間常數來檢查傳感器的實際低頻響應。

用IEPE型壓電型加速度傳感器測量甚低頻加速度信號還需要注意的問題有：當dang傳chuan感gan器qi和he恒heng流liu電dian壓ya源yuan交jiao流liu耦ou合he的de低di頻pin截jie至zhi頻pin率lv相xiang當dang時shi，測ce量liang係xi統tong的de低di頻pin特te性xing是shi由you傳chuan感gan器qi和he恒heng流liu電dian壓ya源yuan的de各ge自zi低di頻pin響xiang應ying組zu合he而er成cheng，此ci時shi測ce量liang係xi統tong的de低di頻pin截jie止zhi頻pin率lv要yao高gao於yu傳chuan感gan器qi或huo恒heng流liu電dian壓ya源yuan各ge自zi的de低di頻pin截jie止zhi頻pin率lv。理li想xiang的de測ce量liang係xi統tong傳chuan感gan器qi應ying配pei用yong帶dai直zhi流liu平ping衡heng的de恒heng流liu電dian壓ya源yuan
，這zhe樣yang係xi統tong的de低di頻pin響xiang應ying將jiang完wan全quan取qu決jue於yu傳chuan感gan器qi的de低di頻pin截jie至zhi頻pin率lv。

當dang傳chuan感gan器qi用yong於yu甚shen低di頻pin測ce量liang時shi
，能neng否fou準zhun確que測ce量liang低di頻pin信xin號hao並bing不bu完wan全quan決jue定ding與yu係xi統tong的de低di頻pin響xiang應ying特te性xing，係xi統tong的de低di頻pin電dian噪zao聲sheng大da小xiao也ye將jiang直zhi接jie影ying響xiang低di頻pin信xin號hao的de測ce量liang。另ling外wai傳chuan感gan器qi的de瞬shun態tai溫wen度du響xiang應ying大da小xiao也ye將jiang直zhi接jie影ying響xiang傳chuan感gan器qi的de低di頻pin測ce量liang。