US Patent 7375989 AC/DC converter and method of modulation thereof

A method and apparatus for modulating a discontinuous conduction mode (DCM) Boost Rectifier having a switchable booster section is disclosed. A modulation signal is defined according to the equation, TON(φ)=f1(φ)+f2(φ)+f3(φ). Here, φ defines a phase angle for an input phase voltage of the DCM Boost Rectifier; TON(φ) defines a modulation characteristic for an ON time of the booster section, and is a continuous function; f1(φ) defines a first function from 0≦φ≦π/3; f2(φ) defines a second function from π/3≦φ≦2π/3; and, f3(φ) defines a third function from 2π/3≦φ≦π. The switchable booster section is then modulated using the modulation signal.