電阻、電容(rong)和電感的電壓與電流相位(wei)關系(xi)
① 電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)：電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)兩(liang)端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)與流(liu)過的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)是同相(xiang)關(guan)系(xi)（可理(li)解為(wei)：有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)流(liu)過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)兩(liang)端馬上有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)大時電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)高）。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)相(xiang)位關(guan)系(xi)如圖(tu)所(suo)示。
② 電(dian)(dian)容：電(dian)(dian)容兩端電(dian)(dian)壓與流過的電(dian)(dian)流的相位(wei)關系(xi)(xi)是(shi)電(dian)(dian)流超前電(dian)(dian)壓 90°（可理解為：先(xian)有(you)電(dian)(dian)流對電(dian)(dian)容充電(dian)(dian)，而后電(dian)(dian)容兩端有(you)電(dian)(dian)壓）。電(dian)(dian)容的電(dian)(dian)壓與電(dian)(dian)流的相位(wei)關系(xi)(xi)如圖(tu)所示。
圖 電阻的電壓與(yu)電流的相(xiang)位(wei)關系(xi)圖 電容的電壓與(yu)電流的相(xiang)位(wei)關系(xi)
③ 電(dian)(dian)感：電(dian)(dian)感兩端電(dian)(dian)壓(ya)(ya)與流過電(dian)(dian)流的(de)相(xiang)(xiang)位關系是電(dian)(dian)流滯后電(dian)(dian)壓(ya)(ya)90°（可(ke)理解為：電(dian)(dian)感與電(dian)(dian)容(rong)是性質相(xiang)(xiang)反的(de)元器(qi)件(jian)，電(dian)(dian)壓(ya)(ya)和電(dian)(dian)流的(de)相(xiang)(xiang)位關系也相(xiang)(xiang)反）。電(dian)(dian)感的(de)電(dian)(dian)壓(ya)(ya)與電(dian)(dian)流相(xiang)(xiang)位關系如
圖所示。
（3）rlc串聯電(dian)路的(de)電(dian)壓與電(dian)流的(de)相位關(guan)系
rlc串(chuan)(chuan)聯電路如圖所示(shi)，圖中rlc電路的諧(xie)振頻(pin)率為fo，輸入信號頻(pin)率為f。rlc 串(chuan)(chuan)聯電路電流(liu)與電壓(ya)的相(xiang)位關系(xi)如圖6-19所示(shi)。
圖rlc串聯(lian)電路(lu)電流與電壓(ya)的相(xiang)位關系
①當f=f時，rlc串聯電路諧振(zhen)，lc電路相當于短路，電路只剩下電阻，因此電流與電壓(ya)的(de)相位關系是：電流與電壓(ya)同相，矢量表示如圖（a）所示。
②當f>6時，輸入(ru)信號頻率偏高，電(dian)容(rong)c可(ke)視為短路（電(dian)容(rong)容(rong)易(yi)通過高頻信號），剩下電(dian)感(gan)與電(dian)阻，rlc 電(dian)路呈感(gan)性，因此(ci)電(dian)流(liu)與電(dian)壓(ya)的相位關(guan)系(xi)是：電(dian)壓(ya)超(chao)前電(dian)流(liu)θ角（0°<θ<90°），矢量表示如圖（b）所示。
③當≤6時(shi)，輸入信號(hao)頻(pin)率偏(pian)低，電(dian)(dian)感l可視為短路(lu)（電(dian)(dian)感容易通過低頻(pin)信號(hao)），剩(sheng)下(xia)電(dian)(dian)容與(yu)電(dian)(dian)阻(zu)，rlc電(dian)(dian)路(lu)呈容性，因此電(dian)(dian)流(liu)與(yu)電(dian)(dian)壓的(de)相(xiang)位關系(xi)是(shi)：電(dian)(dian)壓滯后電(dian)(dian)流(liu)θ角（0°<θ<90°），矢量表示如(ru)圖（c）所(suo)示。
（4）rlc并聯電(dian)路電(dian)壓(ya)與(yu)電(dian)流的相位關系(xi)
rlc并聯電路(lu)如(ru)圖(tu)(tu)6-20所示，圖(tu)(tu)中rlc電路(lu)的(de)諧振頻率為(wei)6。rlc并聯電路(lu)電流與電壓的(de)相位關系如(ru)圖(tu)(tu)所示。
圖 rlc并聯電(dian)路(lu)(lu)圖 rlc并聯電(dian)路(lu)(lu)電(dian)流與(yu)電(dian)壓的(de)相位關系(xi)
①當(dang)f=6時(shi)，rlc并聯電路諧振，rlc并聯電路呈阻(zu)性，相(xiang)當(dang)于(yu)一個阻(zu)值很大的電阻(zu)，因(yin)此電流與(yu)電壓同相(xiang)位，矢(shi)量表示如圖（a）所(suo)示。
②當f>f時，輸入信號(hao)頻(pin)率偏高(gao)，電感(gan)(gan)可視為開路（電感(gan)(gan)對(dui)高(gao)頻(pin)信號(hao)阻抗大(da)），剩下電容和(he)電阻，rlc并聯(lian)電路呈容性，因(yin)此電流與電壓的相位關系(xi)是(shi)：電流超(chao)前電壓θ角（0°<θ<90°），矢量表示(shi)如圖(tu)（b）所(suo)示(shi)。
③當時，輸入(ru)信號頻率(lv)偏(pian)低(di)，電容可視為開路（電容對低(di)頻信號阻抗大），剩(sheng)下電感和電阻，rlc并聯(lian)電路呈感性，因此電流(liu)與電壓(ya)的(de)相位(wei)關系(xi)是：電流(liu)滯后電壓(ya)θ角（0°<θ<90°），矢量(liang)表(biao)示如圖（c）所示。
