第5章電壓測量

1、第第5 5章章 電壓測量電壓測量5.1 概述5.2 電壓標(biāo)準(zhǔn)5.3 交流電壓的測量5.4 直流電壓的數(shù)字化測量及A/D轉(zhuǎn)換原理5.5 電流、電壓、阻抗變換技術(shù)及數(shù)字多用表5.6 數(shù)字電壓表測量的不確定度及 自動校準(zhǔn)、自動量程技術(shù)5.7 電壓測量的干擾及抑制技術(shù)5.1 5.1 概述概述電壓測量的重要性電壓測量的重要性電壓測量的重要性電壓測量的重要性211( )NkVukNt tu(t)Vp0UmTU01( )TUu t dtT01( )TUu t dtT20.637ppUVV2VTR20( )Tu tdtR201( )TVu t dtT10.7072ppVVVppVKV峰值有效值21.41/2p

2、ppVKVFVKV有效值平均值(1/2)1.112/2 2pFpVKV（）TTDVpCRLu(t)CDRLu(t)VpabVPu(t)tcminmax(),sdLRr CTR CTI0u(t)D1D2D3D4CCu(t)D1D2I001( )( )22Todmdmu tu tIdtTrrrroI( )u t201( )TVu t dtT2( )ut0TAu(t)Vrms2212(.)kVkVV峰峰值值檢檢波波表表頭頭( (讀讀數(shù)數(shù)= =) )Vpu(t)V22pVV2ppVV任意pV任意2pppVVKK任意任意任意任意2,pppppppppVVK VKVkkKKKKK任意任意任意任意任意任意任

3、意21.4121.41ppKKp（任意波）峰值V（任意波）有效值V221222ppppKKKKV平平均均值值檢檢波波表表頭頭( (讀讀數(shù)數(shù)= =) )u(t)V0.91.112 2FVVVKV0.9VV任意V任意0.9FFVKVK任意任意任意任意V,FFFFVVKVKVKkK任意任意任意任意任意0.91.11FFFFKKkKK任意任意任意0.90.9FK（任意波）均值V（任意波）有效值V0.910.91.1110.90.9FFFFFKKKKK1 1.4100%29%1.4 FVKV方波VVVVFK方波1 0.9100%11%0.9411( )(sinsin3sin5.)35pu tVtttVP

4、0T=1uStu(t)224111.352ppVVV1pPVKV方波22224111110.9735792ppVV100%3%VV 峰峰值值檢檢波波器器步步進(jìn)進(jìn)分分壓壓器器直直流流放放大大器器uA步步進(jìn)進(jìn)分分壓壓器器斬斬波波穩(wěn)穩(wěn)零零式式放放大大器器uA(a)峰峰值值檢檢波波器器( (探探頭頭內(nèi)內(nèi)) )(b)步步進(jìn)進(jìn)分分壓壓器器寬寬帶帶交交流流放放大大器器均均值值檢檢波波器器uA輸輸入入電電路路A A/ /D D轉(zhuǎn)轉(zhuǎn)換換器器數(shù)數(shù)字字顯顯示示器器邏邏輯輯控控制制電電路路時時鐘鐘發(fā)發(fā)生生器器模模擬擬部部分分?jǐn)?shù)數(shù)字字部部分分Vx1420.1mV100%0.05%200mV1100%0.05%2000(

5、 %)xmVVV ( %)mxxVVVV %xV%mV%mV( %)xVVn 字V%mV%(0.01%0.005%)mxVV 斜斜波波電電壓壓發(fā)發(fā)生生器器QQSETCLRSR&000時時鐘鐘計計數(shù)數(shù)器器主主門門VrVx+-+-門門控控信信號號輸輸入入比比較較器器接接地地比比較較器器a計計數(shù)數(shù)輸輸入入0VxVx、V Vr r門門控控信信號號計計數(shù)數(shù)輸輸入入NV Vr rt1bT0T0 xVkTkT NrVkRCrVkRC0 xVkTkT N0rxVVT NRC0rVTRCxVN主主門門計計數(shù)數(shù)器器邏邏輯輯控控制制電電路路數(shù)數(shù)字字輸輸出出時時鐘鐘S1S2CRVx-VrVr積積分分器器比比較

6、較器器-+-+S S1 1 S S2 2Vot0t1復(fù)復(fù)零零t2t3VoVomT1T2N1N2t積積分分波波形形計計數(shù)數(shù)器器輸輸入入a.b.清清零零T0f0T011T02111tomxxtTVV dtVRCRC 10TxxVV dt1TRC32210()tomromrtTVV dtVVRCRC21xrTVVT221xrNVVeNN121xxrNNVVVe1rVeN21111()tsmomxsmxtTTVVvdtVvRCRCRC Ix9009090.90.1(200mV)200A A(200mV)2mA A(200mV)20mA A(200mV)200mA A(200mV)2A A恒恒流流源源( (可可調(diào)調(diào)) )A A/ /D DR Rx xIr-+A Am mp p恒恒流流源源( (可可調(diào)調(diào)) )A A/ /D D-+A Am mp pIrVrR1Rx精精密密電電阻阻VoVr取取樣樣電電阻阻1xorRVVR 1oxrVRRV A AC C/