Mô phỏng mạch điện

BỘ GIÁO DỤC VÀ ĐÀO TẠO

THÍ NGHIỆM MÔ PHỎNG

MẠCH ĐIỆN

Biên soạn: Hoàng Nguyên Phước

Họ và tên sinh viên: ..................................................................................................................

Mã số sinh viên: ..................................................................................................................

Lớp/nhóm: ..................................................................................................................

www.hutech.edu.vn Tài Liệu Lưu Hành Tại HUTECH

THÍ NGHIỆM MÔ PHỎNG MẠCH ĐIỆN

Ấn bản 2014

MỤC LỤC > I

MỤC LỤC MỤC LỤC ....................................................................................................................................................................................................................................... I

HƯỚNG DẪN ......................................................................................................................................................................................................................... III

SỬ DỤNG ORCAD PSPICE ......................................................................................................................................................................................... V

BÀI 1: MỘT SỐ ĐỊNH LUẬT TRONG MẠCH ĐIỆN ..................................................................................................................... 1

1.1 ĐỊNH LUẬT PHÂN CHIA DÒNG ĐIỆN ................................................................................................................................................... 1

1.1.1 Phần chuẩn bị ở nhà ................................................................................................................................................................................ 1

1.1.2 Phần mô phỏng ............................................................................................................................................................................................. 2

1.2 NGUYÊN LÝ XẾP CHỒNG ................................................................................................................................................................................... 3


1.2.2 Phần mô phỏng ............................................................................................................................................................................................. 4

1.3 ĐỊNH LÝ CHUYỂN VỊ NGUỒN ....................................................................................................................................................................... 5


1.3.2 Phần mô phỏng ............................................................................................................................................................................................. 8

1.4 ĐỊNH LÝ THEVENIN – NORTON ................................................................................................................................................................. 9


1.4.2 Phần mô phỏng ......................................................................................................................................................................................... 15

BÀI 2: CÁC CHẾ ĐỘ LÀM VIỆC CỦA MẠCH ĐIỆN XOAY CHIỀU BA PHA ............................................... 17

2.1 NGUỐN ĐỐI XỨNG, TẢI ĐỐI XỨNG NỐI HÌNH SAO ....................................................................................................... 17

2.1.1 Phần chuẩn bị ở nhà ............................................................................................................................................................................ 17

2.1.2 Phần mô phỏng ......................................................................................................................................................................................... 19

2.2 NGUỒN ĐỐI XỨNG, TẢI KHÔNG ĐỐI XỨNG NỐI SAO .................................................................................................. 21

II | MỤC LỤC


2.2.2 Phần mô phỏng .......................................................................................................................................................................................... 23

2.3 NGUỒN ĐỐI XỨNG, TẢI ĐỐI XỨNG NỐI TAM GIÁC ......................................................................................................... 25


2.3.2 Phần mô phỏng .......................................................................................................................................................................................... 27

2.4 NGUỒN ĐỐI XỨNG, TẢI KHÔNG ĐỐI XỨNG NỐI TAM GIÁC ................................................................................... 29


2.4.2 Phần mô phỏng .......................................................................................................................................................................................... 31

BÀI 3: ĐẶC TUYẾN BIÊN TẦN-PHA TẦN CỦA MẠCH CỘNG HƯỞNG, MẠCH LỌC R-L-C ..... 33

3.1 MẠCH CỘNG HƯỞNG ........................................................................................................................................................................................ 33


3.1.2 Phần mô phỏng .......................................................................................................................................................................................... 35

3.2 MẠCH LỌC R-L-C ................................................................................................................................................................................................... 38


3.2.2 Phần mô phỏng .......................................................................................................................................................................................... 39

BÀI 4: QUÁ TRÌNH QUÁ ĐỘ TRONG MẠCH TUYẾN TÍNH .......................................................................................... 43

4.1 MẠCH QUÁ ĐỘ CẤP MỘT R-C ..................................................................................................................................................................... 43


4.1.2 Phần mô phỏng .......................................................................................................................................................................................... 45

4.2 MẠCH QUÁ ĐỘ CẤP HAI R-L-C ................................................................................................................................................................ 48


4.2.2 Phần mô phỏng .......................................................................................................................................................................................... 50

HƯỚNG DẪN > III

HƯỚNG DẪN MÔ TẢ MÔN HỌC

Thí nghiệm mô phỏng mạch điện là môn học nhằm kiểm chứng các định luật về

mạch điện một chiều, xoay chiều một pha, xoay chiều ba pha, mô phỏng các mạch

điện xác định các chế độ của mạch điện có các phần tử R,L,C.

NỘI DUNG MÔN HỌC

− Bài 1. Kiểm chứng các định luật về mạch điện: giúp sinh viên kiểm chứng các định

luật phân chia dòng điện, nguyên lý xếp chồng, định lý chuyển vị nguồn, định lý

Thevenin–Norton.

− Bài 2: Các chế độ làm việc của mạch điện xoay chiều ba pha: giúp sinh viên phân

tích các chế độ làm việc của mạch xoay chiều ba pha với tải đối xứng và không đối

xứng nối sao, nối tam giác. Khảo sát chế độ quá độ trong mạch điện.

− Bài 3: Đặc tuyến biên-tần, pha-tần của mạch cộng hưởng, mạch lọc R-L-C: giúp

sinh viên khảo sát hiện tượng cộng hưởng trong mạch R,L,C mắc nối tiếp và song

song, xác định tần số cộng hưởng ωo, hệ số phẩm chất Q, tần số cắt, giản đồ

Bode… Khảo sát dạng sóng của các đặc tuyến biên tần-pha tần, đặc tuyến tần số

của các phần tử R,L,C trong mạch điện.

− Bài 4: Quá trình quá độ trong mạch tuyến tính: giúp sinh viên khảo sát quá trình

quá độ với mạch quá độ cấp một R-C, quá độ cấp một R-L, quá độ cấp hai R-L-C.

KIẾN THỨC TIỀN ĐỀ

Sinh viên phải nắm vững lý thuyết giải tích mạch điện và sử dụng được phần mềm

Orcad Pspice.

YÊU CẦU MÔN HỌC

Người học phải dự học đầy đủ các buổi lên lớp và làm bài tập đầy đủ ở nhà.

IV | HƯỚNG DẪN

CÁCH TIẾP NHẬN NỘI DUNG MÔN HỌC

Để học tốt môn này, sinh viên cần tính toán, giải các bài tập về mạch điện trước

khi thực hiện mô phỏng. So sánh kết quả mô phỏng và tính toán.

PHƯƠNG PHÁP ĐÁNH GIÁ MÔN HỌC

Môn học được đánh giá gồm:

− Điểm quá trình: 30%. Hình thức và nội dung do Giáo viên quyết định, phù hợp với

quy chế đào tạo và tình hình thực tế tại nơi tổ chức học tập.

− Điểm thi: 70%. Hình thức mô phỏng mạch điện trên máy tính gồm các bài tập

thuộc bài thứ nhất đến bài thứ tư và nộp báo cáo thí nghiệm.

SỬ DỤNG ORCAD PSPICE > V

SỬ DỤNG ORCAD PSPICE A. VẼ SƠ ĐỒ MẠCH TRONG ORCAD CAPTURE CIS.

1. Khởi động chương trình Capture CIS.

Từ màn hình Windows, nhấp vào biểu tượng để khởi động chương

trình Orcard Pspice.

2. Từ màn hình Orcard Capture, đưa con trỏ vào thanh công cụ, nhấp chuột

vào File/New/Project,

khi đó xuất hiện hộp thoại New Project, nhập tên project cần chạy chương trình mô

phỏng và đường dẫn để lưu file, đánh dấu vào mục Analog or Mixed A/D, sau đó

nhấp OK.

3. Khi đó, sẽ xuất hiện tiếp hộp thoại Create PSpice Project, đánh dấu vào

mục Create a Blank Project, sau đó nhấp OK.

VI | SỬ DỤNG ORCAD PSPICE

4. Các bước cần thực hiện để vẽ một sơ đồ mạch.

a) Chọn linh kiện để vẽ mạch.

- Trên thanh công cụ, nhấp chuột vào Place/Part (hoặc gõ phím P

từ bàn phím).

- Trong cửa sổ Place Part gõ tên linh kiện vào ô Part,

- Nếu không tìm thấy linh kiện, nhấp vào mục Add Library, chọn

thư mục Pspice trong mục Look in, chọn tất cả các linh kiện để bổ sung vào thư

viện.

SỬ DỤNG ORCAD PSPICE > VII

Lưu ý: khi chọn nguồn và nối mass phải đồng nhất để chạy mô phỏng đúng.

CÁC ĐẠI LƯỢNG THƯỜNG DÙNG TRONG MÔ PHỎNG

Đại lượng Part name Library

Điện trở R Analog.olb

Biến trở R _ var Analog.olb

Tụ điện C Analog.olb

Cuộn dây L Analog.olb

Nguồn áp một chiều Vdc Source.olb

Nguồn áp xoay chiều Vac Source.olb

Nguồn áp sin Vsin Source.olb

Nguồn dòng một chiều Idc Source.olb

Nguồn dòng xoay chiều Iac Source.olb

Nguồn xung vuông Vpulse Source.olb

Nguồn phụ thuộc E, F, G, H Analog.olb

Đồng hồ đo dòng, áp IPRINT, VPRINT Special.olb

Switch SW_tClose Anl_misc.olb

SW_tOpen Anl_misc.olb

Lưu ý: các đại lượng cần chọn để mô phỏng phải tương ứng với thư viện nêu trên.

VIII | SỬ DỤNG ORCAD PSPICE

b) Nối mạch.

- Trên thanh công cụ nhấp chuột vào Place/Wire (hoặc gõ phím W

từ bàn phím), lúc này biểu tượng chuột thay đổi có dạng hình dấu cộng, cho phép ta

nối chân các linh kiện lại với nhau.

- Di chuyển chuột để kéo dài dây nối.

- Nhấp phím trái chuột để tạo một góc vuông và tiếp tục vẽ.

- Nhấp phím phải chuột, chọn End wire để kết thúc nối.

- Nếu nối bó dây, nhấn nút Place/Bus trên thanh công cụ.

c) Nối mass cho mạch.

- Trên thanh công cụ nhấp chuột vào Place/Ground (hoặc gõ phím

G từ bàn phím),

lúc này trên màn hình xuất hiện hộp thoại.

SỬ DỤNG ORCAD PSPICE > IX

d) Xử lý sơ đồ mạch khi vẽ xong.

- Sau khi vẽ xong ta tiến hành chỉnh sửa các thông số của linh kiện

trên sơ đồ theo như yêu cầu của đề bài.

- Chỉnh sửa các thông số của linh kiện trên sơ đồ mạch bằng cách

nhấp đôi lên giá trị cần chỉnh sửa của linh kiện. Khi đó xuất hiện hộp thoại Display

Properties.

- Tại đây nhập giá trị mới vào ô Value, và định dạng chế độ hiển thị

(Display Format) rồi chọn OK.

- Để đánh dấu những điểm muốn xem trên mạch khi đã chạy Orcad

Pspice, vào Pspice của Schematics, chọn Markers sau đó chọn đại lượng cần xem.

e) Cách khác.

- Muốn thay đổi tên của các linh kiện, ví dụ như R, L, C…, ta nhấp

đúp con trỏ vào linh kiện cần thay đổi, khi đó xuất hiện hộp thoại Properties Editor.

X | SỬ DỤNG ORCAD PSPICE

- Chọn mục Part Reference điền tên của linh kiện vào, sau đó

nhấp Apply.

- Biến trở R _ var có giá trị R = VALUE + SET + 0.001 , khi đặt giá

trị cho biến trở phải đặt giá trị cho VALUE và SET.

- Nguồn áp Vsin, đặt giá trị cho các tham số sau:

DC = (để trống).

AC = biên độ của tín hiệu được sử dụng khi phân tích tần

số (phân tích AC).

Voff = 0.

VAmpl = biên độ của tín hiệu được sử dụng khi phân tích

quá độ.

Freq = tần số của tín hiệu.

td = 0.

tf = 0.

phase = 0.

- Nguồn áp một chiều VSRC đặt giá trị cho các tham số sau:

DC = giá trị nguồn một chiều.

AC = (để trống).

Tran = (để trống).

- Đồng hồ đo IPRINT , VPRINT: để tạo ra bảng giá trị về dòng điện

và điện áp ở phần output file.

- Nhấp đôi chuột vào linh kiện, khi đó xuất hiện hộp thoại

Properties Editor, chọn chế độ phân tích DC, AC hay TRAN bằng cách đánh vào giá

trị “1” vào ô cần khảo sát.

SỬ DỤNG ORCAD PSPICE > XI

- Nếu chọn phân tích AC, chọn các đại lượng cần hiển thị ở dữ liệu

ngõ ra (output file) như sau: MAG (biên độ) , PHASE (góc pha), REAL (phần thực),

IMAG (phần ảo).

f) Một số lưu ý khi đặt giá trị:

Cách ký hiệu đơn vị (cho điện trở, tụ điện, điện áp, dòng điện, tần số …).

f (femto) = 10-15 ; k (kilo) = 103.

p (pico) = 10-12 ; Meg (mega) = 106.

n (nano) = 10-9 ; G (giga) = 109.

u (micro) = 10-6 ; T (tera) = 1012.

m (mili) = 10-3.

Lưu ý: cách ký hiệu trên đều như nhau đối với chữ hoa và chữ thường.

Ví dụ: - R1 có giá trị là 18k tức là 18kΩ.

- C3 có giá trị 100u tức là 100µF.

- Nguồn V1 có giá trị 2 tức là 2V.

- Nguồn I2 có giá trị 30m tức là 30mA.

- Tần số f có giá trị 1MEG tức là 1MHz.

B. CHẠY PSPICE ĐỂ MÔ PHỎNG MẠCH ĐIỆN.

1. Chọn chế độ phân tích.

a) Từ thanh công cụ, chọn Pspice/New Simulation Profile,

khi đó xuất hiện hộp thoại New Simulation. Trong khung Name, đặt tên file cần

chạy mô phỏng, sau đó nhấp chuột vào mục Create.

XII | SỬ DỤNG ORCAD PSPICE

b) Chọn chế độ phân tích (Analysis type).

- Trước khi chạy Orcad Pspice trong Schematics. Tùy thuộc vào yêu

cầu của bài thí nghiệm phải chọn chế độ phân tích thích hợp (phân tích DC, AC,

Transient…) có nhiều chế độ phân tích nhưng trong bài thí nghiệm chủ yếu sử dụng

phân tích AC (AC Sweep/Noise) và phân tích quá độ (Transient).

- Để xác định đáp ứng tần số của mạch, trên thanh công cụ, chọn

Pspice/Edit Simulation Settings

và sau khi xuất hiện hộp thoại Simulation Settings, nhấp chuột vào Analysis Tab,

trong khung Analysis Type chọn mục AC Sweep/Noise để cài đặt như sau:

SỬ DỤNG ORCAD PSPICE >

XIII

Trong AC Sweep Type, chọn Logarithmic/ Decade, rồi

đặt giá trị cho các thông số:

Start Freq. (tần số khởi đầu thường chọn là 1, chú ý phải

khác 0).

End Freq. (tần số kết thúc).

Point/Decade (số lượng điểm tính toán trong một

Decade).

Đáp ứng tần số được tính toán khi nguồn có tần số quét

từ tần số khởi đầu đến tần số kết thúc.

Nhấp chuột vào Apply để chấp nhận, sau đó nhấp Okđể

kết thúc cài đặt hoặc chọn chế độ phân tích khác.

- Để xác định đáp ứng quá độ của mạch (xác định dòng điện, điện

áp tại tất cả các điểm trong mạch theo thời gian) vào menu Pspice của Schematics,

chọn Edit Simulation Settings và xuất hiện hộp thoại Simulation Settings, nhấp

chuột chọn Analysis Tab trong khung Analysis Type và nhấp chuột vào Time

Domain (Transient) để cài đặt như sau:

Run to Time: định thời gian chạy mô phỏng.

Start saving data after: định thời điểm bắt đầu lưu trữ dữ

liệu phân tích.

Maximum step size: định bước phân tích.

XIV | SỬ DỤNG ORCAD PSPICE

Nhấp chuột vào Apply để chấp nhận, sau đó nhấp OK.

2. Chạy Orcad Pspice.

- Sau khi cài đặt các chế độ phân tích và chạy mô phỏng. tên thanh

công cụ, chọn Pspice/Run (hoặc nhấn phím F11 từ bàn phím),

- Sau khi mô phỏng xong, Orcad Pspice sẽ được chạy tự động.

- Dựa vào Orcad Pspice để xem đáp ứng tần số hoặc quá độ tại tất

cả các điểm trong mạch.

- Sau khi chạy Orcad Pspice, sẽ xuất hiện đồ thị của những điểm đã

được đánh dấu trên mạch (đánh dấu bằng cách vào Menu Pspice của Schematics,

chọn markers, chọn tiếp Voltage Level).

- Để xem đồ thị của những điểm khác, trên thanh công cụ chọn

Trace/Add Trace, khi đó xuất hiện một danh sách các điểm trên mạch.

SỬ DỤNG ORCAD PSPICE > XV

- Nhấn chọn bất kỳ điểm nào mà ta muốn xem trong hộp thoại

danh sách. Nhấp OK để chấp nhận.

- Để xác định giá trị tại một vị trí trên đồ thị, trên thanh công cụ,

chọn Cursor/Display, khi đó xuất hiện cửa sổ Probe Cursor.

- Sử dụng con trỏ của chuột xác định các giá trị trên đồ thị.

- Muốn xem các kết quả chi tiết khác, trên thanh công cụ chọn

View/Output File.

- Để xem các nút phân bố các linh kiện trong mạch, trên thanh

công cụ chọn Pspice/View Netlist.

BÀI 1: MỘT SỐ ĐỊNH LUẬT TRONG MẠCH ĐIỆN > 1

BÀI 1: MỘT SỐ ĐỊNH LUẬT

TRONG MẠCH ĐIỆN

Sau khi thí nghiệm mô phỏng bài này, học viên có thể:

- Kiểm chứng hai định luật Kirchoff;

- Kiểm chứng nguyên lý xếp chồng và định lý chuyển vị nguồn;

- Kiểm chứng định lý Thevenin - Norton;

1.1 ĐỊNH LUẬT PHÂN CHIA DÒNG ĐIỆN 1.1.1 Phần chuẩn bị ở nhà.

Tính toán các dòng điện I1, I2, I3 qua các nhánh rẽ trong mạch hình 1.1.

(Hình 1.1)

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R23

R3

6

V16Vdc

0

IPRINT

R1

2

IPRINTIPRINT

2 | BÀI 1: MỘT SỐ ĐỊNH LUẬT TRONG MẠCH ĐIỆN

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1.1.2 Phần mô phỏng.

a) Vẽ trong Orcad – Pspice sơ đồ mạch hình 1.1; dùng IPRINT trong thư viện

SPECIAL.OLB để xác định dòng điện trong các nhánh.

b) Chọn chế độ phân tích Bias Point.

c) Chạy mô phỏng ghi kết quả vào bảng 1.1.

Bảng 1.1

I1 (A) I2 (A) I3 (A) I2/I3 R3/R2 Ghi chú

d) Nhận xét kết quả tính toán với kết quả mô phỏng.

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1.2 NGUYÊN LÝ XẾP CHỒNG 1.2.1 Phần chuẩn bị ở nhà.

Tính toán các dòng điện I1, I2, I3 qua các nhánh rẽ trong mạch hình 1.2 với các

trường hợp:

(Hình 1.2)

• Hai nguồn V1, V2 cùng tác động.

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• Giữ nguyên nguồn V1 và các thông số trong mạch, triệt tiêu nguồn V2.

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V28Vdc

IPRINT IPRINT

0

R33

R1

3

R2

6

V15Vdc

IPRINT


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a) Vẽ trong Orcad – Pspice sơ đồ mạch như trên, dùng IPRINT trong thư viện

SPECIAL.OLB để xác định dòng điện trong các nhánh.

b) Chọn chế độ phân tích Bias Point cho ba trường hợp:

• Hai nguồn V1, V2 cùng tác động.





Bảng 1.2

I1 (A) I2 (A) I3 (A) Ghi chú

Hai nguồn tác động

Nguồn V1 tác động

Nguồn V2 tác động

d) Nhận xét và so sánh kết quả tính toán với kết quả mô phỏng.

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1.3 ĐỊNH LÝ CHUYỂN VỊ NGUỒN 1.3.1 Phần chuẩn bị ở nhà.

Tính toán các dòng điện I1, I2, I3, I4, I5, I6 qua các nhánh trong mạch điện hình

1.3a,b với các trường hợp:

I2

12Adc

I1

R1

0.25

I2 I3

IPRINT

V1

6Vdc

I4

I5

IPRINT

I6

IPRINT

R3

1

0

IPRINT

IPRINT

V2

2Vdc

I1

8Adc

R2

0.125

IPRINT

(Hình a)


(Hình 1.3)

• Phương pháp thông thường (hình 1.3a).

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I2

IPRINT

I4

IPRINT

I6

I2

12Adc

IPRINT

I1

I3

IPRINTV4

2Vdc

I5

R2

0.125

V2

6Vdc

I1

8Adc

V3

2Vdc

0

IPRINTR3

1

IPRINT

(Hình b)

R1

0.25

V16Vdc


• Phương pháp chuyển vị nguồn (hình 1.3b).

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a) Vẽ trong Orcad – Pspice sơ đồ mạch như trên, dùng IPRINT trong thư viện

SPECIAL.OLB để xác định dòng điện trong các nhánh và lắp mạch như

hình 1.3a,b.

b) Chọn chế độ phân tích Bias Point cho hai trường hợp:

• Phương pháp thông thường (hình a).

• Phương pháp chuyển vị nguồn. Chuyển vị hai nguồn áp V1 , V2 (hình b).

c) Chạy mô phỏng và ghi kết quả vào bảng 1.3.

Bảng 1.3

I1 (A) I2 (A) I3 (A) I4 (A) I5 (A) I6 (A) Ghi chú

Hình a

Hình b


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1.4 ĐỊNH LÝ THEVENIN – NORTON Một mạng một cửa bất kỳ đều có thể đưa về một mạch tương đương đơn giản

gồm:

Một nguồn áp mắc nối tiếp với trở kháng Z gọi là mạch tương đương Thevenin.

Nguồn áp này có giá trị bằng điện áp hở mạch của mạng một cửa và trở kháng Z có là

trở kháng nhìn vào cửa khi triệt tiêu tất cả các nguồn độc lập.

Một nguồn dòng mắc song song với trở kháng Z gọi là mạch tương đương Norton.

Nguồn dòng có giá trị bằng dòng điện ngắn mạch qua hai đầu mạng một cửa.

1.4.1 Phần chuẩn bị ở nhà.

Tính toán các đại lượng dòng điện và điện áp theo các giá trị biên độ, góc pha,

phần thực, phần ảo như mạch điện hình 1.4 a,b,c,d,e,f với các trường hợp:

a) Dùng phương pháp thông thường: tính toán điện áp ở hai đầu tải URtải và

dòng điện qua tải IRtải trong mạch điện hình 1.4a.

(Hình 1.4a)

V1 25VacACPHASE = 90

b

IPRINT

0

a

L1

4

R13

R210

I1 4AacACPHASE = 45

Rtaûi5


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b) Dùng mạch tương đương Thevenin–Norton: tính toán điện áp hở mạch Uhở

ở hai đầu (a-b) trong mạch điện hình 1.4b.

(Hình 1.4b)

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L1

4

a


0

I1 4AacACPHASE = 45

b

R13

R210


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c) Dùng mạch tương đương Thevenin–Norton: tính toán dòng điện ngắn mạch

Ingắn ở hai đầu (a-b) trong mạch điện hình 1.4c.

(Hình 1.4c)

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a

L1

4


0

I1 4AacACPHASE = 45

IPRINT

b

R13

R210


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d) Dùng mạch tương đương Thevenin–Norton: xác định trở kháng Thevenin

Zthevenin trong mạch điện hình 1.4d.

(Hình 1.4d)

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a

0

b

I1

1Aac

L2

4

R1

3 R2

10


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e) Xây dựng sơ đồ tương đương Norton và Thevenin, tính điện áp ở hai đầu

tải URtải và dòng điện qua tải IRtải trong mạch điện hình 1.4e và 1.4f.

Hình 1.4e: mạch Thevenin Hình 1.4f: mạch Norton

• Mạch Thevenin.

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I=Ingan

ZT

0

I1

IPRINT

ZTV1

Rtai=5 Rtai=5V=Uho

IPRINT

0


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• Mạch Norton.

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a) Vẽ trong Orcad – Pspice sơ đồ mạch điện, dùng IPRINT và VPRINT trong

thư viện SPECIAL.OLB để xác định dòng điện, điện áp theo hai phương

pháp sau:

• Phương pháp thông thường.

• Phương pháp mạch tương đương Thevenin và mạch tương đương

Norton.

b) Giả sử ω = 1rad/s. Chọn chế độ phân tích AC với tần số bắt đầu bằng

0.159, Tần số kết thúc bằng 0.159 và số điểm bằng 1.

c) Ghi các kết quả mô phỏng vào bảng 1.4.

Bảng 1.4

Đại lượng Biên độ (MAG)

Góc pha (PHASE)

Phần thực (REAL)

Phần ảo (IMAG)

URtải

IRtải

Uhở

Ingắn

Zthevenin

A. Phương pháp thông thường.

Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 1.4a; dùng VPRINT và IPRINT để

xác định điện áp hai đầu URtải và dòng điện qua tải IRtải.

Chạy mô phỏng, ghi kết quả vào bảng 1.4.

B. Tìm dòng điện và điện áp trên tải dùng mạch tương đương

Thevenin – Norton.

a) Bỏ điện trở tải (Rtải), cho hai điểm a, b hở mạch hình 1.4b; xác định điện

áp hai đầu ab (Uhở) dùng VPRINT2. Chạy mô phỏng và ghi kết quả vào

bảng 1.4.


b) Cho hai điểm a, b ngắn mạch hình 1.4c; xác định dòng ngắn mạch Ingắn.

Chạy mô phỏng và ghi kết quả vào bảng 1.4.

c) Xác định trở kháng Thevenin: triệt tiêu tất cả các nguồn độc lập trong

mạch, cấp vào hai đầu a, b một nguồn dòng AC có biên độ 1A và góc pha

là 0o, xác định điện áp hai đầu a, b trong mạch điện hình 1.4d. Đây chính

là giá trị trở kháng ZT giữa hai điểm a, b; (vì ). Chạy mô phỏng và

ghi kết quả vào bảng 1.4.

d) Xây dựng sơ đồ tương đương Thevenin và Norton: mắc vào hai đầu a, b

của mạch tương đương Thevenin một điện trở tải có giá trị Rtải = 5Ω. Xác

định các giá trị điện áp trên tải và dòng điện trong mạch điện hình 1.4e.

Ghi kết quả mô phỏng vào bảng 1.5.

e) Mắc vào hai đầu a, b của mạch tương đương Norton một điện trở tải có giá

trị Rtải = 5Ω. Xác định các giá trị điện áp trên tải và dòng điện trong mạch

điện hình 1.4f. Ghi kết quả mô phỏng vào bảng 1.5.

Bảng 1.5

Mạch mô phỏng Đại lượng Biên độ Góc pha Phần thực Phần ảo

Thevenin URtải

IRtải

Norton URtải

IRtải

f) Nhận xét và so sánh kết quả tính toán với kết quả mô phỏng.

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•

•

=I

UZ

BÀI 2: CÁC CHẾ ĐỘ LÀM VIỆC CỦA MẠCH ĐIỆN XOAY CHIỀU BA PHA > 17

BÀI 2: CÁC CHẾ ĐỘ LÀM VIỆC

CỦA MẠCH ĐIỆN XOAY

CHIỀU BA PHA

Sau khi học xong bài này, học viên có thể:

- Nắm được các đại lượng về dòng điện, điện áp và góc pha trong hệ thống ba

pha với nguồn và tải đối xứng hoặc không đối xứng trong mạch mắc hình sao

hoặc tam giác.

2.1 NGUỐN ĐỐI XỨNG, TẢI ĐỐI XỨNG NỐI HÌNH SAO.


Tính toán các đại lượng dòng điện, điện áp theo các giá trị biên độ, góc pha,

theo mạch điện hình 2.1a.

(Hình 2.1a)

R2

20

V3 220Vac

ACPHASE = -240

R1

20

IPRINT

IPRINT

0

IPRINT

V2 220Vac

ACPHASE = -120

R3

20

V1 220Vac

ACPHASE = 0

18 | BÀI 2: CÁC CHẾ ĐỘ LÀM VIỆC CỦA MẠCH ĐIỆN XOAY CHIỀU BA PHA

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2.1.2 Phần mô phỏng. a) Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 2.1a.

b) Dùng VPRINT1, VPRINT2 và IPRINT lắp trong mạch để xác định điện áp và

dòng điện pha, điện áp giữa trung tính tải và trung tính nguồn, theo hai

trường hợp: trung tính tải nối và không nối với trung tính nguồn (sinh viên

tự vẽ mạch).

c) Chọn chế độ phân tích AC với tần số 50Hz, số điểm bằng 1. Chạy mô

phỏng và ghi kết quả vào bảng 2.1.

Bảng 2.1.

Đại lượng

Trung tính tải không nối trung tính nguồn

Trung tính tải nối trung tính nguồn

Biên độ Góc pha Biên độ Góc pha

UA

UN0

IA

IB

IC

I0


............................................................................................................................................................................................................................................................................................................................................................

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e) Thay nguồn Vac bằng nguồn Vsin như mạch điện hình 2.1b; chọn chế độ

phân tích Transient với thời gian chạy khoảng 0.1s. Khảo sát và vẽ dạng

sóng dòng điện, điện áp (khi trung tính tải không nối trung tính nguồn).


(Hình 2.1b)

Dạng sóng điện áp khi tải đối xứng, đấu hình sao.

Dạng sóng dòng điện khi tải đối xứng, đấu hình sao.

V4

FREQ = 50VAMPL = 220VOFF = 0PHASE = 0

V6


R1

20

R2

20

0R3

20

V5

FREQ = 50VAMPL = 220VOFF = 0PHASE = -120


2.2 NGUỒN ĐỐI XỨNG, TẢI KHÔNG ĐỐI XỨNG NỐI SAO.



theo mạch điện hình 2.2.

(Hình 2.2a)

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............................................................................................................................................................................................................................................................................................................................................................

L1

301 2

V3

173VacACPHASE = 120

IPRINT

R3

30

V1

173VacACPHASE = 0

R2

30

IPRINT

R1

30

V2

173VacACPHASE = -120

R4

30

C1

0.0333

0

IPRINT

N


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a) Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 2.2a.

b) Lặp lại các bước mô phỏng như trong phần tải đối xứng. Vẽ mạch ứng với

hai trường hợp: trung tính tải nối và không nối với trung tính nguồn.


Bảng 2.2.

Đại lượng

Trung tính tải không nối trung tính nguồn

Trung tính tải nối trung tính nguồn

Biên độ Góc pha Biên độ Góc pha

UA

UB

UC

UN0

IA

IB

IC

I0


............................................................................................................................................................................................................................................................................................................................................................

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sóng dòng điện, điện áp (khi trung tính tải không nối trung tính nguồn).


(Hình 2.2b)

Dạng sóng điện áp khi tải không đối xứng, nối hình sao.

Dạng sóng dòng điện khi tải không đối xứng, nối hình sao.

L1

301 2

V1


0

R1

30

R3

30

V2


C1

3

V3


R4

30

R2

30


2.3 NGUỒN ĐỐI XỨNG, TẢI ĐỐI XỨNG NỐI TAM GIÁC




(Hình 2.3a)

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IPRINT

R1

2

R2

2

IPRINT

V2

10VacACPHASE = -1200

V3

10VacACPHASE = 120

IPRINT

V1

10VacACPHASE = 0

R3

2

B

IPRINT

IPRINT

A

IPRINTC


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b) Dùng VPRINT2 và IPRINT lắp trong mạch để xác định điện áp, dòng điện

dây và dòng điện pha.

c) Chọn chế độ phân tích AC với tần số 50Hz, số điểm bằng 1. Chạy mô

phỏng và ghi kết quả vào bảng 2.3.

Bảng 2.3.

Đại lượng Biên độ Góc pha

UAB

UBC

UCA

IA

IB

IC

IAB

IBC

ICA


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sóng dòng điện, điện áp.


(Hình 2.3b)

Dạng sóng điện áp khi tải đối xứng, nối tam giác.

Dạng sóng dòng điện khi tải đối xứng, nối tam giác.

A R3

2

V2

FREQ = 50VAMPL = 10VOFF = 0

V3


C

B

0

R2

2

V1

FREQ = 50VAMPL = 10VOFF = 0 R1

2


2.4 NGUỒN ĐỐI XỨNG, TẢI KHÔNG ĐỐI XỨNG NỐI TAM GIÁC.




(Hình 2.4a)

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V2

10VacACPHASE = -120

C1

0.5F

C

R2

2

L1

2H

A

V3

10VacACPHASE = 120

R1

20

B

V1

10VacACPHASE = 0


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b) Lặp lại các bước mô phỏng như trong phần tải đối xứng nối tam giác.


Bảng 2.4.

Đại lượng Biên độ Góc pha

UAB

UBC

UCA

IA

IB

IC

IAB

IBC

ICA

d) Nhận xét kết quả mô phỏng trong hai trường hợp.

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sóng dòng điện, điện áp.


(Hình 2.4b)

Dạng sóng điện áp khi tải không đối xứng, nối tam giác.

Dạng sóng dòng điện khi tải không đối xứng, nối tam giác.

V3


R1

2

0

C1

0.5F

V2


R2

2

L1

2H1 2

V1


BÀI 3: ĐẶC TUYẾN BIÊN TẦN – PHA TẦN CỦA MẠCH CỘNG HƯỞNG, MẠCH LỌC R-L-C > 33

BÀI 3: ĐẶC TUYẾN BIÊN TẦN –

PHA TẦN CỦA MẠCH

CỘNG HƯỞNG, MẠCH

LỌC R-L-C


- Nắm được các thông số trong mạch khi cộng hưởng xảy ra, các đặc tuyến biên-

tần, pha tần, hệ số phẩm chất và xác định tần số cắt trong các mạch, giản đồ

Bode…

3.1 MẠCH CỘNG HƯỞNG 3.1.1 Phần chuẩn bị ở nhà.

Tính giá trị điện áp (đối với mạch cộng hưởng nối tiếp), dòng điện (đối với mạch

cộng hưởng song song) trên các phần tử R,L,C và xác định tần số cộng hưởng fo, hệ

số phẩm chất Q, trong các mạch điện hình 3.1a,b.

(Hình 3.1a)

R1

100V11Vac0Vdc

0

C1

10u

L1

500m1 2

34 | BÀI 3: ĐẶC TUYẾN BIÊN TẦN – PHA TẦN CỦA MẠCH CỘNG HƯỞNG, MẠCH LỌC R-L-C

• Mạch cộng hưởng nối tiếp (hình 3.1a).

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(Hình 3.1b)

• Mạch cộng hưởng song song (hình 3.1b).

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R1

100

I1

0Adc1Aac

L1

400m

1

2

C120u

0


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A. Mạch cộng hưởng nối tiếp.


b) Chọn chế độ phân tích AC, kiểu logarithmic (decade), tần số bắt đầu là

1Hz, tần số kết thúc là 10kHz, số điểm là 20. Đo điện áp trên các phần tử

R, L, C (giá trị biên độ và góc pha).

c) Chạy mô phỏng và vẽ các đặc tuyến biên tần, pha tần của UR, UL, UC. Từ

đó, xác định tần số cộng hưởng của nhánh trên đặc tuyến fo = ………………… Hz.


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e) Vẽ các đặc tuyến biên tần và pha tần của UR , UL , UC.

Đặc tuyến biên tần của UR , UL , UC.

Đặc tuyến pha tần của UR , UL , UC.

B. Mạch cộng hưởng song song.

a) Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 3.1b.


10Hz, tần số kết thúc là 1kHz, số điểm là 20. Đo dòng điện trên các phần

tử R, L, C (biên độ và góc pha).

c) Chạy mô phỏng và vẽ các đặc tuyến biên tần, pha tần của IR, IL, IC. Từ đó,

xác định tần số cộng hưởng của nhánh fo = ………………… Hz.



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e) Vẽ các đặc tuyến biên tần và pha tần của IR, IL, IC.

Đặc tuyến biên tần của IR , IL , IC.

Đặc tuyến pha tần của IR , IL , IC.


3.2 MẠCH LỌC R-L-C. 3.2.1 Phần chuẩn bị ở nhà.

Xác định tần số cắt fc của mạch lọc thông thấp, mạch lọc thông cao trong mạch

điện hình 3.2a,b.

(Hình 3.2a)

• Mạch lọc thông thấp (hình 3.2a).

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(Hình 3.2b)

L1

1H

1

2

V11Vac

0

R1

100

R1

1k

C115u

V11Vac0Vdc

0


• Mạch lọc thông cao (hình 3.2b).

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A. Mạch lọc thông thấp dùng R-C.



1Hz, tần số kết thúc là 1kHz, số điểm là 20.

c) Chạy mô phỏng và vẽ các đặc tuyến biên tần, pha tần của R, C. Từ đó, xác

định tần số cắt từ giản đồ Bode fc = ………………… Hz.


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e) Vẽ đặc tuyến tần số của mạch R-C.

Đặc tuyến tần số của mạch R-C.

Thay nguồn Vac bằng nguồn Vsin như hình 3.2c. Chọn chế độ phân tích

Transient với thời gian chạy khoảng 0.5s. Khảo sát và vẽ dạng sóng tín hiệu vào, ra

trên tụ điện C1 của mạch.

(Hình 3.2c)

Dạng sóng điện áp trên tụ C1.

C115u

R1

1kV2


0

BÀI 3: ĐẶC TUYẾN BIÊN TẦN – PHA TẦN CỦA MẠCH CỘNG HƯỞNG, MẠCH LỌC R-L-C > 41 B. Mạch lọc thông cao dùng R-L

a) Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 3.2b.

b) Chọn chế độ phân tích AC, logarithmic, tần số bắt đầu là 1Hz, tần số

kết thúc là 20kHz, số điểm là 20.

c) Chạy mô phỏng và vẽ các đặc tuyến biên tần, pha tần của R, C. Từ đó, xác

định tần số cắt từ giản đồ Bode fc = ………………… Hz.


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e) Vẽ giản đồ Bode.

Giản đồ Bode.


Thay nguồn Vac bằng nguồn Vsin như hình 3.2d. Chọn chế độ phân tích

Transient với thời gian chạy khoảng 0.5s. Khảo sát và vẽ dạng sóng tín hiệu vào, ra

trên cuộn dây L1 của mạch.

(Hình 3.2d)

Dạng sóng điện áp trên cuộn dây L1.

f) Nhận xét độ dịch pha giữa tín hiệu vào và ra.

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V2


R1

100L1

1H

1

2

0

BÀI 4: QUÁ TRÌNH QUÁ ĐỘ TRONG MẠCH TUYẾN TÍNH > 43

BÀI 4: QUÁ TRÌNH QUÁ ĐỘ

TRONG MẠCH TUYẾN

TÍNH


- Nắm được các dạng sóng trong quá trình khảo sát quá độ cấp 1, cấp 2 trong

mạch gồm các phần tử R, L, C với các thời hằng tương ứng.

- Tùy theo sự tương quan giữa điện trở R của mạch và điện trở tới hạn Rth , ta

khảo sát các chế độ trong mạch quá độ.

4.1 MẠCH QUÁ ĐỘ CẤP MỘT R-C 4.1.1 Phần chuẩn bị ở nhà.

Xác định điện áp trên tụ C1 uc(t) và dòng điện trong mạch ic(t). Vẽ dạng sóng trên

tụ C1 ứng với hai trường hợp tụ C1=200µF và C1=30µF trong mạch điện hình 4.1a.

(Hình 4.1a)

0

R1

1kC1

U1

TCLOSE = 0.11 2

V15Vdc

44 | BÀI 4: QUÁ TRÌNH QUÁ ĐỘ TRONG MẠCH TUYẾN TÍNH

• Tụ điện C1 = 200µF.

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• Tụ điện C1 = 30µF.

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a) Vẽ trong Orcad – Pspice sơ đồ mạch điện hình 4.2a ứng với trường hợp:

C1 = 200µF

C1 = 30µF.

b) Chọn chế độ phân tích Transient với thời gian chạy là 2s.

c) Chạy mô phỏng và vẽ các dạng sóng điện áp trên tụ C1; dòng điện trong

mạch ứng với hai trường hợp của tụ C1.

• Tụ C1 = 200µF.

Dạng sóng điện áp trên tụ.

Dạng sóng dòng điện trong mạch.


• Tụ C1 = 30µF.



Thay nguồn một chiều Vdc bằng nguồn xung vuông Vpulse với các thông số trong

mạch điện hình 4.1b. Chọn chế độ phân tích Transient, thời gian chạy là 2s. Khảo

sát và vẽ các dạng sóng điện áp trên tụ C1 và dòng điện trong mạch.

(Hình 4.1b)

V1TD = 0

TF = 0PW = 100mPER = 200m

V1 = 0

TR = 0

V2 = 5

0

K1

TCLOSE = 0.11 2

C1200u

R1

1k




d) Nhận xét các đồ thị và tính toán các hằng số thời gian của mạch.

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4.2 MẠCH QUÁ ĐỘ CẤP HAI R-L-C 4.2.1 Phần chuẩn bị ở nhà.

Xác định điện áp trên tụ C1 uc(t) và dòng điện trong mạch ic(t). Vẽ dạng sóng trên

tụ C1 ứng với các trường hợp điện trở R1=80Ω, R1=Rth và R1=0,4Ω trong mạch điện

hình 4.2a.

(Hình 4.2a)

• Điện trở R1 = 80Ω.

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R1

L1

10m

K1

TCLOSE = 50m1 2 C1

1m

V15Vdc

0


• Điện trở R1 = Rth = ………………… Ω.

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• Điện trở R1 = 0,4Ω.

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a) Vẽ trong Orcad – Pspice sơ đồ mạch như trên với R1 = 80Ω.

b) Chọn chế độ phân tích Transient, thời gian chạy là 1s.

c) Chạy mô phỏng và vẽ dạng sóng điện áp trên tụ C1 và dòng điện trong

mạch với các trường hợp:

Chế độ không dao động R1 = 80Ω.

Chế độ tới hạn R1 = Rth = ………………… Ω.

Chế độ dao động R1 = 0.4Ω.

• Chế độ không dao động R1 = 80Ω.




• Chế độ tới hạn R1 = Rth = ………………… Ω.



• Chế độ dao động R1 = 0.4Ω.




d) Nhận xét các đồ thị và tính toán các hằng số thời gian của mạch.

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Thay nguồn một chiều Vdc bằng nguồn xung vuông Vpulse với các thông số

trong mạch điện hình 4.2b.

Chọn chế độ phân tích Transient, thời gian chạy là 100s. Khảo sát và vẽ các

dạng sóng điện áp trên tụ C1 và dòng điện trong mạch ứng với các trường hợp:

Chế độ không dao động R1 = 20Ω.

Chế độ tới hạn R1 = Rth = ………………… Ω.

Chế độ dao động R1 = 0.4Ω.


(Hình 4.2b)

• Chế độ không dao động R1 = 20Ω.



0

V1TD = 0

TF = 0PW = 3PER = 6

V1 = 0

TR = 0

V2 = 2 L1

4

1

2

C1

1

R1

U1

TCLOSE = 21 2


• Chế độ tới hạn R1 = Rth= ………………… Ω.



• Chế độ dao động R1 = 0.4Ω.




e) Nhận xét các đồ thị.

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Mô phỏng mạch điện

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