Chap. 4 Techniques of Circuit Analysis

1 / 39

# Chap. 4 Techniques of Circuit Analysis - PowerPoint PPT Presentation

Chap. 4 Techniques of Circuit Analysis. C ontents. 4.1 Terminology 4.2 Introduction to the Node-Voltage Method 4.3 The Node-Voltage Method and Dependent Sources 4.4 The Node-Voltage Method: Some Special Cases 4.5 Introduction to the Mesh-Current Method

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Chap. 4 Techniques of Circuit Analysis' - hall-lee

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Chap.4 Techniques of Circuit Analysis

Contents

4.1 Terminology

4.2 Introduction to the Node-Voltage Method

4.3 The Node-Voltage Method and Dependent Sources

4.4 The Node-Voltage Method: Some Special Cases

4.5 Introduction to the Mesh-Current Method

4.6 The Mesh-Current Method and Dependent Sources

4.7 The Mesh-Current Method: Some Special Cases

4.8 The Node-Voltage Method Versus the Mesh-Current Method

4.9 Source Transformations

4.10 Thévenin and Norton Equivalents

4.11 More on Deriving a Thévenin Equivalent

4.12 Maximum Power Transfer

4.13 Superposition

Objectives

1. 了解並能夠使用節點電壓法求解電路。

2. 了解並能夠使用網目電流法求解電路。

3. 對於特定電路能夠決定節點電壓法或網目電流法何者是較佳的求解方式。

4. 了解電源轉換，並能夠使用它來求解電路。

5. 了解戴維寧和諾頓等效電路的觀念，並能針對電路建立等效電路。

6. 了解電阻負載最大功率轉移之情況，並能計算滿足此情況之負載電阻值。

4.1 Terminology

Node

Essential node

Path

Branch

Essential branch

Loop

Mesh

Planar circuit

A point where two or more circuit elements join

A node where three or more circuit elements join

A trace of adjoining basic elements with no elementsincluded more than once

A path that connects two nodes

A path which connects two essential nodes without passingthrough an essential node

A path whose last node is the same as the starting node

A loop that does not enclose any other loops

A circuit that can be drawn on a plane with no crossingbranches

Nonplanar

Planar

EX4.1 Identifying Node, Branch, Mesh and Loop

Node

Essential node

Branch

Essential branch

Mesh

a, b, c, d, e, f, and g.

b, c, e, and g.

v1, v2, R1, R2, R3, R4, R5, R6, R7, and I .

v1 –R1 , R2 –R3 , v2 –R4 , R5, R6, R7, and I .

v1 –R1 –R5 –R3 –R2 , v2 –R2 –R3 –R6 –R4 , R5 –R7 –R6 , and R7 –I .

Find two paths that not loops or essential branches.

Find two loops that not meshes.

Simultaneous Equations—How Many?

b:

c:

e:

Essential

nodes:

KCL

Meshes: KVL

4.2 Introduction to the Node-Voltage Method

1. 找出必要節點。

2. 選取有最多分支的節點為參考點。

3. 定義節點電壓。

4. 套用KCL，針對非參考點之節點列出方程式。

▼: reference node

Node 1:

Node 2:

EX4.2 Using the Node-Voltage Method

1

a)

Node 1:

Branch currents:

b)

4.3 TheNode-Voltage Method and Dependent Sources

EX4.3 A Circuit with Dependent Source

1

2

Node 1:

Node 2:

8

4.4 TheNode-Voltage Method: Some Special Cases

Case A.

Node 2:

9

4.4 Case B

Supernode (超節點)

1

Case B.

2

3

Node 2:

Node 3:

( +

The Concept of a Supernode

10

4.4 Case B Contd.

Supernode

Node 1:

Supernode:

11

Node-Voltage Analysis of the Amplifier Circuit

Node a:

Supernode:

12

4.5 Introduction to the Mesh-Current Method

[7-(4-1)] = 4

1. 定義網目電流。

2. 套用KVL於各網目上建立 be- (ne -1)個聯立方程式。

3. 求解網目電流。

4. 由網目電流求解分支電流。

13

Evolution of the Mesh-Current Technique

KCL:

KVL:

14

EX4.4 Using the Mesh-CurrentMethod

b-(n-1)=7-(5-1)=3

a)

Mesh a:

Mesh b:

Mesh c:

b)

15

4.6 TheMesh-Current Method and Dependent Sources

EX4.5 A Circuit with Dependent Source

Find the power dissipated in the 4 resistor.

b-(n-1)=6-(4-1)=3

Mesh 1:

Mesh 2:

Mesh 3:

16

4.7 TheMesh-Current Method: Some Special Cases

Case A.

Mesh 1:

Mesh 2:

Mesh 3:

17

4.7 Case B

Case B.

Mesh a:

Mesh c:

( +

The Concept of a Supermesh

18

4.7 Case B Contd.

Case B.

Supermesh:

Mesh b:

19

Mesh-Current Analysis of the Amplifier Circuit

Supermesh:

Mesh b:

20

4.8 TheNode-Voltage Method Versus the Mesh-Current Method

◆ 何者聯立方程式數目較少？

◆ 有超節點嗎？考慮節點電壓法。

◆ 有超網目嗎？考慮網目電流法。

◆ 要求解的電路部分適用何者解法？

Find the power dissipated in the 300 resistor in the following circuit.

be-(ne-1) = 8-(4-1) = 5

ne-1 = 4-1 = 3

21

EX4.6 Understanding the Node-Voltage Method v.s. Mesh-Current Method

a)

Supernode:

b)

Node a:

Node b & 相依電源控制變數:

Node c:

Node 2:

22

EX4.7 Comparing the Node-Voltage and Mesh-Current Methods

a)

Node o:

Node a:

Node b:

ne-1 = 4-1 = 3

be-(ne-1) = 6-(4-1) = 3

b)

Supermesh:

2個電流源限制式與相依電源控制變數:

23

4.9 Source Transformations

24

Special Source Transformation Techniques

EX4.9 Using Special Source Transformation Techniques
• Use source transformations
• to find the voltage vo.
• b) Find the power developed by the 250-V source.
• c) Find the power developed by the 8-A source.

+

-

b)

(參考原圖)

a)

(supplied 2800W)

c)

27

(參考原圖)

(supplied 480W)

4.10 Thévenin and Norton Equivalents

Thévenin equivalent circuit

RTh = VTh / isc。

28

Finding a Thévenin Equivalent

a, b 端開路，求解VTh = v1 = vab。

a, b 端短路，求解isc。

29

The Norton Equivalents

30

4.11 More on Deriving a Thévenin Equivalent

32

vT為測試電壓源，vT/ iT就是RTh。

33

4.12 Maximum Power Transfer

The derivative is zero and

pis maximized when

CONDITION FOR MAXIMUM POWER TRANSFER

(最大功率轉移時的條件)

35

EX4.12 Calculating the Condition for Maximum Power Transfer

Also,

The percentage of the source power delivered to the load is

36

4.13 Superposition

1)

37

4.13 Contd.

v3

v4

2)

38