A high power factor tuned Class D converter

An approach for achieving high power factor in a zero-current/zero-voltage-switching tuned converter is presented. A tuned 90 degrees C phase shift section at the switching frequency fundamental of the Class D converter is used to render the power line into a current source. As a result, rectification occurs over the full AC cycle, drawing a constant line current over each half cycle. A 93%-power-factor, 1700 W, 300 kHz converter is discussed to demonstrate practicability.