Great online free course: https://www.coursera.org/course/powerelectronicsIntroduction to Power Electronics from University of Colorado Boulder:
The course is an introduction to switched-mode power converters. 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.