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DK4141_C02.fm Page 31 Tuesday, January 18, 2005 11:13 AM

2
Fast Design Approach Including
Eddy Current Losses

In today’s power electronics, the active switches can withstand high switching frequencies. This means that the major part of the magnetic component
of power electronics is subjected to eddy current losses. In this chapter we
propose a fast design method that includes eddy current losses—neglecting
eddy currents may result in significant errors. The word fast means that a
decision tree is given to guide the designer and that no time-consuming
mathematical tools are used. The fast design uses methods that do not
achieve the highest accuracy, e.g., the proposed thermal approach. However,
the provided accuracy is sufficient for most power electronics applications.
Moreover, the same design flowchart can also be used with more precise
methods (e.g., a more accurate thermal model or a transverse field computation by finite elements).
The fast design approach is applicable to both transformers and inductors
for a wide range of designs using round wires. The approach simplifies the
design, makes it more systematic, and categorizes it into two major cases:
saturated thermally limited design and non-saturated thermally limited
design. The design procedure is illustrated with two fully calculated design
examples and several other examples that concern specific parts of the design.

2.1

Fast Design Approach

The method includes simplified assumptions and omits certain details in the
design, but the accuracy is usually sufficient for first experiments or as a fast
calculation before a more precise approach.
In the fast design approach presented here the following simplifications
are made:
• the leakage inductance of transformers is neglected for the flux
calculation
• the field pattern is only approximated

Copyright 2005 by Taylor & Francis Group, LLC

DK4141_C02.fm Page 32 Tuesday, January 18, 2005 11:13 AM

32

Inductors and Transformers for Power Electronics

FIGURE 2.1
General flowchart of the fast design approach.

•
•
•
•

the method is limited to round wires
the method looses accuracy when partially filled layers are used
for inductors, only gaps in the center leg are considered
the insulation distances and clearances are considered but not in details

For more details and limits concerning coil windings, refer to Chapter 4
and to standards, e.g., IEC950. The standards are not very restrictive, but
the limits, such as creepage distances, can greatl...
2
Fast Design Approach Including
Eddy Current Losses
In today’s power electronics, the active switches can withstand high switch-
ing frequencies. This means that the major part of the magnetic component
of power electronics is subjected to eddy current losses. In this chapter we
propose a fast design method that includes eddy current losses—neglecting
eddy currents may result in significant errors. The word fast means that a
decision tree is given to guide the designer and that no time-consuming
mathematical tools are used. The fast design uses methods that do not
achieve the highest accuracy, e.g., the proposed thermal approach. However,
the provided accuracy is sufficient for most power electronics applications.
Moreover, the same design flowchart can also be used with more precise
methods (e.g., a more accurate thermal model or a transverse field compu-
tation by finite elements).
The fast design approach is applicable to both transformers and inductors
for a wide range of designs using round wires. The approach simplifies the
design, makes it more systematic, and categorizes it into two major cases:
saturated thermally limited design and non-saturated thermally limited
design. The design procedure is illustrated with two fully calculated design
examples and several other examples that concern specific parts of the design.
2.1 Fast Design Approach
The method includes simplified assumptions and omits certain details in the
design, but the accuracy is usually sufficient for first experiments or as a fast
calculation before a more precise approach.
In the fast design approach presented here the following simplifications
are made:
the leakage inductance of transformers is neglected for the flux
calculation
the field pattern is only approximated
DK4141_C02.fm Page 31 Tuesday, January 18, 2005 11:13 AM
Copyright 2005 by Taylor & Francis Group, LLC
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