[課業] 電路學-開關電路

看板Examination作者 (電路圖)時間7年前 (2017/03/02 11:31), 7年前編輯推噓3(3推 0噓 23→)
留言26則, 6人參與, 最新討論串1/1
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補習班老師出的題目 沒有公佈解答 我想破頭了還是不知道怎麼解... 希望高手解救 -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 49.218.80.130 ※ 文章網址: https://www.ptt.cc/bbs/Examination/M.1488425490.A.0D1.html ※ 編輯: DianLuTu (49.218.80.130), 03/02/2017 11:33:02
推
03/02 12:54, , 1F
是不是寫反了 時間小於零是直流 時間大於零是交流？
03/02 12:54, 1F
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03/02 12:58, , 2F
沒寫反 t<0 交流 t>0直流
03/02 12:58, 2F
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03/02 18:19, , 3F
有開關的二階電路
03/02 18:19, 3F
推
03/02 21:32, , 4F
不會考這種吧。
03/02 21:32, 4F
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03/12 20:56, , 5F
歡迎善用此信箱 https://goo.gl/uiYHvS
03/12 20:56, 5F
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05/29 01:36, , 6F
以下為個人想法僅供參考
05/29 01:36, 6F
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05/29 01:39, , 7F
t<0時 是交流電壓 I=2 / [1+(1+j)//(1-j)]=2/3
05/29 01:39, 7F
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05/29 01:41, , 8F
接下來要求IL跟Vc 因為需知道iL(0+) vc(0+)
05/29 01:41, 8F
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05/29 01:43, , 9F
IL=I*(1-j)/[1+j+1-j]=(2/3)*(1-j)/2=(1-j)/2
05/29 01:43, 9F
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05/29 01:44, , 10F
寫錯 是 (1-j)/3
05/29 01:44, 10F
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05/29 01:45, , 11F
Vc=2*[(-j)/(1-j)]*[(1+j)//(1-j)]/[1+(1+j)//(1-j)]
05/29 01:45, 11F
→
05/29 01:50, , 12F
Vc=1/(1-j)
05/29 01:50, 12F
推
05/29 01:53, , 13F
上面I跟IL算錯 修正為 I=1 IL=(1-j)/2
05/29 01:53, 13F
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05/29 01:54, , 14F
得i(t)=cost
05/29 01:54, 14F
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05/29 01:54, , 15F
iL(t)=0.707cos(t-45度)
05/29 01:54, 15F
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05/29 01:56, , 16F
修正Vc=1/(1+j) 得vc(t)=0.707cos(t-45度)
05/29 01:56, 16F
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05/29 01:57, , 17F
可得開關後初始值 iL(0+)=0.707*cos(-45)=1/2
05/29 01:57, 17F
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05/29 01:57, , 18F
vc(0+)=vc(0-)=0.707cos(-45度)=1/2
05/29 01:57, 18F
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05/29 02:01, , 19F
t>0 必須用Laplace轉換後用迴路分析求解即可
05/29 02:01, 19F
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05/29 02:07, , 20F
(4/s)+(s/2)=I1*(1+1+s)
05/29 02:07, 20F
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05/29 02:08, , 21F
(s/2)-(1/2s)=I2*(1+1/s+s+1)
05/29 02:08, 21F
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05/29 02:08, , 22F
寫錯了 = =
05/29 02:08, 22F
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05/29 02:09, , 23F
(4/s)+(s/2)=I1*(1+1+s)-I2*(1+s)
05/29 02:09, 23F
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05/29 02:09, , 24F
(s/2)-(1/2s)=-I1*(1+s)+I2*(1+1/s+s+1)
05/29 02:09, 24F
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05/29 02:09, , 25F
先求I1後反拉式得解 0.0自己算
05/29 02:09, 25F
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05/29 02:11, , 26F
算一題需要半小時~1小時 不會考
05/29 02:11, 26F
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