A hybrid phase arm power module with nonlinear resonant tank

A hybrid phase arm power module that can be used in ultrasonic frequency inverters is described. Soft switching is achieved by using a single nonlinear resonant tank per phase arm, and pulse width modulation is achieved by controlling the depth of saturation in the saturating inductor. A prominent feature of this topology is that the installed rating of the switches is close to one per unit, which can be an important economic factor at larger powers. The control possibilities, optimal use of the characteristics of circuit components, and the elimination of the modulated current source are discussed.<>