3.8 Circuit Analysis with PSpice

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3.8 Circuit Analysis with PSpice

PSpice is a computer software circuit analysis program that we will gradually learn to use throughout the course of this text. This section illustrates how to use PSpice for Windows to analyze the dc circuits we have studied so far.

The reader is expected to review the tutorial before proceeding in this section. It should be noted that PSpice is only helpful in determining branch voltages and currents when the numerical values of all the circuit components are known.

A tutorial on using PSpice for Windows can be found in Connect.

Use PSpice to find the node voltages in the circuit of Fig. 3.31. Example 3.10

Solution:

The first step is to draw the given circuit using Schematics. If one follows the instructions given in the PSpice tutorial found in Connect, the schematic in Fig. 3.32 is produced. Because this is a dc analysis, we use voltage source VDC and current source IDC. The pseudocomponent VIEWPOINTS are added to display the required node voltages. Once the circuit is drawn and saved as exam310.sch, we run PSpice by selecting Analysis/Simulate. The circuit is simulated and the results are displayed

Figure 3.32 For Example 3.10; the schematic of the circuit in Fig. 3.31.

on VIEWPOINTS and also saved in output file exam310.out. The output file includes the following:

	NODE VOLTAGE		NODE VOLTAGE NODE VOLTAGE
(1)	120.0000 (2)		81.2900 (3)		89.0320
indicating that V1 = 120 V, V2 = 81.29 V, V3 = 89.032 V.

Practice Problem 3.10 For the circuit in Fig. 3.33, use PSpice to find the node voltages.

Answer: V¹ = −10 V, V² = 14.286 V, V³ = 50 V.

Example 3.11 In the circuit of Fig. 3.34, determine the currents i1, i2, and i3.

For Example 3.11.

Solution:

The schematic is shown in Fig. 3.35. (The schematic in Fig. 3.35 includes the output results, implying that it is the schematic displayed on the screen after the simulation.) Notice that the voltage-controlled voltage source E1 in Fig. 3.35 is connected so that its input is the voltage across the 4- Ω resistor; its gain is set equal to 3. In order to dis play the required currents, we insert pseudocomponent IPROBES in the appropriate branches. The schematic is saved as exam311.sch and simulated by selecting Analysis/Simulate. The results are displayed on IPROBES as shown in Fig. 3.35 and saved in output file exam311.out. From the output file or the IPROBES, we obtain i¹ = i² = 1.333 A and i³ = 2.667 A.

Figure 3.35 The schematic of the circuit in Fig. 3.34.

Use PSpice to determine currents i1, i2, and i3 in the circuit of Fig. 3.36.

Answer: i¹ = −428.6 mA, i² = 2.286 A, i³ = 2 A.

3.9 †