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Course Info
This course introduces more advanced concepts of switched-mode converter circuits.
Realization of the power semiconductors in inverters or in converters having bidirectional power flow is explained. Power diodes, power MOSFETs, and IGBTs are explained, along with the origins of their switching times. Equivalent circuit models are refined to include the effects of switching loss.
The discontinuous conduction mode is described and analyzed. A number of well-known converter circuit topologies are explored, including those with transformer isolation.
The homework assignments include a boost converter and an H-bridge inverter used in a grid-interfaced solar inverter system, as well as transformer-isolated forward and flyback converters.
Objective:
- Learn how to implement the power semiconductor devices in a switching converter
- Understand the origins of the discontinuous conduction mode and be able to solve converters operating in DCM
- Understand the basic dc-dc converter and dc-ac inverter circuits
- To implement transformer isolation in a dc-dc converter, including the popular forward and flyback converter topologies.
Syllabus
4.1 Switch Realization
How to implement the switches using transistors and diodes, including applications having bidirectional power flow or ac outputs
- Single quadrant switches
- Current- and voltage-bidirectional switches
- Four-quadrant switches
- Synchronous rectifiers
- Homework assignment #1: switch realization
4.2 Power Semiconductor Switches
Basics of power semiconductor switches, including the origins of switching times and switching loss. How to incorporate switching loss into equivalent circuit models. MOSFETs, IGBTs, and gate driver considerations.
- Power diodes
- Power MOSFETs
- Power BJTs and IGBTs
- Switching loss
- Homework assignment #2: simulation
5. Discontinuous Conduction Mode
The discontinuous conduction mode (DCM) arising from unidirectional switch realization. Analysis of mode boundaries and output voltage.
- Origin of DCM and mode boundaries
- Analysis of the conversion ratio M(D,K), with buck converter example
- Boost converter example
- Homework assignment #3: Modeling of switching loss. Analysis of a non ideal boost converter in DCM.
6. Converter Circuits
Some well-known converter circuits and their origins. How to incorporate transformer isolation into a dc-dc converter. Analysis and equivalent circuit modeling of transformer-isolated converters.
- Converter topologies
- Transformers
- The forward and flyback converters
- Homework assignment #4: Modeling of a non ideal flyback converter. Analysis of a forward converter with active-clamp reset