Bài giảng Electrical and electronic principles - Week 3

TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT 
TP. HỒ CHÍ MINH 
ELECTRICAL AND ELECTRONIC 
PRINCIPLES 
WEEK 3 
Cuong Q. Ngo 
Last classes 
• Branch; node; loop 
• KCL 
• KVL 
• Methods of analysis 
• Thevenin’s theorem 
• Norton theorem 
2 
CONTENTS (Today) 
• T, 𝜋, Y, delta networks 
• Network of complex impedance 
• Maximum power transfer 
3 
1. T, 𝜋, Y, delta networks 
• Two forms of the same network – Y, T 
• Two forms of the same network – ∆, 𝜋 
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1. T, 𝜋, Y, delta networks 
• Delta to Wye conversion 
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1. T, 𝜋, Y, delta networks 
• Wye to Delta conversion 
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1. T, 𝜋, Y, delta networks 
• Convert the network in the figure below to an equivalent Y 
network 
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1. T, 𝜋, Y, delta networks 
• Answer 
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1. T, 𝜋, Y, delta networks 
• Transfer the wye network to delta network 
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1. T, 𝜋, Y, delta networks 
• Answer 
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1. T, 𝜋, Y, delta networks 
• Obtain the equivalent resistance Rab for the circuit in Figure 
below and use it to find current i. 
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1. T, 𝜋, Y, delta networks 
• Answer: R = 9.63 Ω 
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1. T, 𝜋, Y, delta networks 
• Answer: R = 9.63 Ω 
13 
2. Network of complex impedance 
• Sinusoids 
• Phasor 
– A phasor is a complex number that represents the 
amplitude and phase of a sinusoid. 
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2. Network of complex impedance 
• A complex number can be expressed in 3 ways 
15 
2. Network of complex impedance 
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2. Network of complex impedance 
• The impedance Z of a circuit is the ratio of the phasor voltage 
V to the phasor current I, measured in ohms. 
• The admittance Y is the reciprocal of impedance, measured 
in siemens (S). 
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2. Network of complex impedance 
• Find v(t) and i(t) in the circuit 
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2. Network of complex impedance 
• Answer 
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2. Network of complex impedance 
• Exercise 2.1 
• Find the input impedance of the circuit. Assume that the 
circuit operates at 𝜔 = 50 𝑟𝑎𝑑/𝑠 
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2. Network of complex impedance 
• Answer 
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2. Network of complex impedance 
• Exercise 2.2 
• Determine vo(t) of the circuit 
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2. Network of complex impedance 
• Answer 
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2. Network of complex impedance 
• Steady state analysis 
– Mesh analysis 
– Thevenin and Norton equivalent circuit 
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2. Network of complex impedance 
• Exercise 2.3 
• Find Io using mesh analysis 
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2. Network of complex impedance 
• Answer: 
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2. Network of complex impedance 
• Exercise 2.4 
• Solve for Vo using mesh analysis 
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2. Network of complex impedance 
• Answer 
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2. Network of complex impedance 
• Exercise 2.5 
• Obtain the Thevenin equivalent circuit at terminal a-b 
29 
2. Network of complex impedance 
• Answer 
30