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Chapter 3
Review of Basic Electrical and
Magnetic Circuit Concepts
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-1
Symbols and Conventions
• Symbols
• Polarity of Voltages; Direction of Currents
• MKS SI units
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-2
Sinusoidal Steady State
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-3
Three-Phase Circuit
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-4
Steady State in Power Electronics
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-5
Fourier Analysis
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-6
Distortion in the Input Current
• Voltage is assumed to be sinusoidal
• Subscript “1” refers to the fundamental
• The angle is between the voltage and the current fundamental
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-7
Phasor Representation
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-8
Response of L and C
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-9
Inductor Voltage and Current in
Steady State
• Volt-seconds over T equal zero.
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-10
Capacitor Voltage and Current
in Steady State
• Amp-seconds
over T equal zero.
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-11
Ampere’s Law
• Direction of magnetic field due to currents
• Ampere’s Law: Magnetic field along a path
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-12
Direction of Magnetic Field
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-13
B-H Relationship; Saturation
• Definition of permeability
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-14
Continuity of Flux Lines
1  2  3  0
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-15
Concept of Magnetic
Reluctance
• Flux is related to ampere-turns by reluctance
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-16
Analogy between Electrical and
Magnetic Variables
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-17
Analogy between Equations in
Electrical and Magnetic Circuits
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-18
Magnetic Circuit and its
Electrical Analog
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-19
Faraday’s Law and Lenz’s Law
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-20
Inductance L
• Inductance relates flux-linkage to current
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-21
Analysis of a Transformer
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-22
Transformer Equivalent Circuit
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-23
Including the Core Losses
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by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-24
Transformer Core
Characteristic
Copyright © 2003
by John Wiley & Sons, Inc.
Chapter 3 Basic Electrical and
Magnetic Circuit Concepts
3-25