NONLINEAR-CARRIER CONTROL FOR HIGH-POWER-FACTOR RECTIFIERS BASED ON FLYBACK, CUK OR SEPIC CONVERTERS - Applied Power Electronics Conference and Exposition, 1996. APEC '96.Conference Proceedings 1996.,

In this paper, nonlinear-carrier (NLC) control is proposed for high-power-factor rectifiers based on flyback, Cuk or Sepic converters operated in the continuous conduction mode. In the NLC controller, the switch duty ratio is determined by comparing a signal proportional to the integral of the switch current with a periodic nonlinear carrier waveform. The shape of the NLC waveform is determined so that the resulting input line current follows the input line voltage, as required for unity-powerfactor rectification. A simple exponential carrier waveform generator is described. Using the NLC controller. input line voltage sensing, error amplifier in the current-shaping loop. and the multiplier/divider circuitry in the voltage feedback loop are eliminated. The simple. high-performance controller is well-suited for integrated-circuit implementation. Results of experimental verification on a 150W flyback rectifier are presented. 1 1 1 I 1 I I i