Power Electronics, A First Course, 2nd Edition

9 DESIGN OF HIGH-FREQUENCY INDUCTORS AND TRANSFORMERS

9.1 INTRODUCTION

As discussed in Chapter 8, inductors and transformers are needed in switch-mode DC power supplies, where switching frequencies are in excess of 100 kHz. High-frequency inductors and transformers are generally not available off-the-shelf and must be designed based on the application specifications. A detailed design discussion is presented in [1]. In this chapter, a simple and commonly used approach called the area-product method is presented, where the thermal considerations are ignored. This implies that the magnetic component built on the design basis presented here should be evaluated for its temperature rise and efficiency, and the core and the conductor sizes should be adjusted accordingly.

9.2 BASICS OF MAGNETIC DESIGN

In designing high-frequency inductors and transformers, a designer is faced with countless choices. These include the choice of core materials, core shapes (some offer better thermal conduction whereas others offer better shielding to stray flux), cooling methods (natural convection versus forced cooling), and losses (lower losses offer higher efficiency at the expense of larger size and higher weight), to name a few. However, all magnetic design-optimization programs calculate two basic quantities from given electrical specifications:

1. The peak flux density in the magnetic core to ...