The course is an introduction to switched-mode power converters. It is offered every fall semester. It provides a basic knowledge of circuitry for the control and conversion of electrical power with high efficiency. These converters can change and regulate the voltage, current, or power; dc-dc converters, ac-dc rectifiers, dc-ac inverters, and ac-ac cycloconverters are in common use. Applications include electronic power supplies, aerospace and vehicular power systems, and renewable energy systems.
The first part of the course treats basic circuit operation, including steady-state converter modeling and analysis, switch realization, discontinuous conduction mode, and transformer-isolated converters. Next, converter control systems are covered, including ac modeling of converters using averaged methods, small-signal transfer functions, and classical feedback loop design. Finally, magnetics design for switched-mode applications is discussed, including: basic magnetics, the skin and proximity effects, inductor design, transformer design.
1. Introduction
- Introduction to Power Processing
- Several Applications of Power Electronics
- Elements of Power Electronics
I. Converters in Equilibrium
2. Principles of Steady State Converter Analysis
- Inductor Volt-Second Balance, Capacitor Charge Balance, and the Small-Ripple Approximation
- Boost Converter Example
- Cuk Converter Example
- Estimating the Output Voltage Ripple in Converters Containing Two-Pole Low-Pass Filters
3. Steady-State Equivalent Circuit Modeling, Losses, and Efficiency
- The DC Transformer Model
- Inclusion of Inductor Copper Loss
- Construction of Equivalent Circuit Model
- Example: Inclusion of Semiconductor Conduction Losses in the Boost Converter Model
4. Switch Realization
- Switch Applications
- Single-Quadrant Switches
- Current-Bidirectional Two-Quadrant Switches
- Voltage-Bidirectional Two-Quadrant Switches
- Four-Quadrant Switches
- Synchronous Rectifiers
- A Brief Survey of Power Semiconductor Devices
- Power Diodes
- Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)
- Bipolar Junction Transistor (BJT)
- Insulated Gate Bipolar Transistor (IGBT)
- Thyristors (SCR, GTO, MCT)
- Switching Loss
- Transistor Switching with Clamped Inductive Load
- Diode Recovered Charge
- Device Capacitances, and Leakage, Package, and Stray Inductances
- Efficiency vs. Switching Frequency
5. The Discontinuous Conduction Mode
- Origin of the Discontinuous Conduction Mode, and Mode Boundary
- Analysis of the Conversion Ratio M(D,K)
- Boost Converter Example
6. Converter Circuits
- Circuit Manipulations
- Inversion of Source and Load
- Cascade Connection of Converters
- Rotation of Three-Terminal Cell
- Differential Connection of the Load
- A Short List of Converters
- Transformer Isolation
- Full-Bridge and Half-Bridge Isolated Buck Converters
- Forward Converter
- Push-Pull Isolated Buck Converter
- Flyback Converter
- Boost-Derived Isolated Converters
- Isolated Versions of the SEPIC and the Cuk Converter
- Converter Evaluation and Design
- Switch Stress and Utilization
- Design Using Computer Spreadsheet
II. Converter Dynamics and Control
7. AC Equivalent Circuit Modeling
- Introduction
- The Basic AC Modeling Approach
- Results for Several Basic Converters
- Example: A Nonideal Flyback Converter
- State-Space Averaging
- The Canonical Circuit Model
- Modeling the Pulse-Width Modulator
8. Converter Transfer Functions
- Review of Bode Plots
- Single pole/zero/RHP zero Responses
- Frequency Inversion
- Combinations
- Quadratic Pole Response: Resonance
- The Low-Q Approximation
- Approximate Roots of an Arbitrary-Degree Polynomial
- Analysis of Converter Transfer Functions
- Example: Transfer Functions of the Buck-Boost Converter
- Transfer Functions of Some Basic CCM Converters
- Physical Origins of the RHP Zero in Converters
- Graphical Construction of Impedances and Transfer Functions
- Series Impedances: Addition of Asymptotes
- Series Resonant Circuit Example
- Parallel Impedances: Inverse Addition of Asymptotes
- Parallel Resonant Circuit Example
- Voltage Divider Transfer Functions: Division of Asymptotes
- Graphical Construction of Converter Transfer Functions
- Measurement of AC Transfer Functions and Impedances
9. Controller Design
- Introduction
- Effect of Negative Feedback on the Network Transfer Functions
- Feedback Reduces the Transfer Functions from Disturbances to the Output
- Feedback Causes the Transfer Function from the Reference Input to the Output to be Insensitive to Variations in the Gains in the Forward Path of the Loop
- Construction of the Important Quantities 1/(1 + T ) and T/(1 + T ) and the Closed-Loop Transfer Functions
- Stability
- The Phase Margin Test
- The Relationship Between Phase Margin and Closed-Loop Damping Factor
- Transient Response vs. Damping Factor
- Regulator Design
- Lead (PD) Compensator
- Lag (PI ) Compensator
- Combined (PID) Compensator
- Design Example
- Measurement of Loop Gains
- Voltage Injection
- Current Injection
- Measurement of Unstable Systems
III. Magnetics
13. Basic Magnetics Theory
- Review of Basic Magnetics
- Transformer Modeling
- Loss Mechanisms in Magnetic Devices
- Core Loss
- Low-Frequency Copper Loss
- Eddy Currents in Winding Conductors
- Introduction to the Skin and Proximity Effects
- Leakage Flux in Windings
- Foil Windings and Layers
- Power Loss in a Layer
- Example: Power Loss in a Transformer Winding
- Interleaving the Windings
- PWM Waveform Harmonics
- Several Types of Magnetic Devices, Their B-H Loops, and Core vs. Copper Loss
14. Inductor Design
- Filter Inductor Design Constraints
- The Core Geometrical Constant Kg
- A Step-by-Step Procedure
- Multiple-Winding Magnetics Design via the Kg Method
- Window Area Allocation
- Coupled Inductor Design Constraints
- Design Procedure
- Example: Coupled Inductor for a Two-Output Forward Converter
- Example: CCM Flyback Transformer
15. Transformer Design
- Transformer Design: Basic Constraints
- Optimum Flux Density
- A Step-by-Step Transformer Design Procedure
- Example 1: Single-Output Isolated Cuk Converter
- Example 2: Multiple-Output Full-Bridge Buck Converter
- AC Inductor Design
Layout and grounding principles (1 lecture)
One midterm exam and one final exam. Ten to twelve one-week homework assignments.