4th course in the Power Electronics Specialization

Instructor: Robert Erickson, Ph.D., Professor

This course covers the analysis and design of magnetic components, including inductors and transformers, used in power electronic converters. This course assumes prior completion of ECEA 5700: Introduction to Power Electronics and ECEA 5701: Converter Circuits.

Prior knowledge needed: Able to understand functioning of different Power electronics converters n both DCM and CCM, able to solve and understand complex mathematical equations, have a good understanding of RMS, average quantities and Dutyratio, and familiarity with Maxwell’s equations.

### Learning Outcomes

• Understand the fundamentals of magnetic components, including inductors and transformers.
• Be able to analyze and model losses in magnetic components, and understand design trade-offs.
• Know how to design and optimize inductors and transformers for switched-mode power converters.

### Syllabus

Duration: 6 hours

Magnetics are an integral part of every switching converter. Often, the design of the magnetic devices cannot be isolated from the converter design. The power electronics engineer must not only model and design the converter, but must model and design the magnetics as well. Modeling and design of magnetics for switching converters is the topic of this course. In this module, basic magnetics theory is reviewed, including magnetic circuits, inductor modeling, and transformer modeling. This provides the technical tools needed in the remainder of the course to understand operation of magnetic devices, model their losses, and design magnetic devices for switching converters.

Duration: 5 hours

Eddy currents also cause power losses in winding conductors. This can lead to copper losses significantly in excess of the value predicted by the dc winding resistance. The specific conductor eddy current mechanisms are called the “skin effect” and the “proximity effect”. These effects are most pronounced in high-current conductors of multilayer windings, particularly in high-frequency converters. This module explains these physical mechanisms and provides practical methods to compute these losses.

Duration: 5 hours

The goal of this chapter is to design inductors for switching converters. Specifically, magnetic elements such as filter inductors are designed using the Geometric Constant (Kg) method. The maximum flux density Bmax is specified in advance, and the element is designed to attain a given copper loss. Both single-winding inductors and multiple-winding elements such as coupled inductors and flyback transformers are considered.

Duration: 4 hours

In a substantial class of magnetic applications, the operating flux density is limited by core loss rather than saturation. For example, in a conventional high-frequency transformer, usually it is necessary to limit the core loss by operating at a reduced value of the peak ac flux density. Hence, design of core-loss-limited magnetic devices is characterized by finding the ac flux density that minimizes total core plus copper loss.This module considers the design of transformers and ac inductors for switching converters, including minimization of total loss. Design examples include the isolation transformers of a full bridge two-output converter and of an isolated Cuk converter.

Duration: 2 hours

Final Exam for this course.

*Note: Grading formula will be updated on October 16, 2020 for the October 2020 session*

##### Percentage of Grade
1. Basic Magnetics 15%
2. AC Winding Losses 15%
3​. Inductor Design 10%
4​. Transformer Design 10%

Final Examination

50%

A

92%

A-

90%

B+

88%

B

82%

B-

80%

C+

78%

C

72%

C-

70%

D+

68%

D

56%

F

0%