A general constant-frequency pulsewidth modulator and its applications

Constant-frequency pulsewidth modulation (PWM) is the most frequently used method in the control of switching converters. This paper proposes a general PWM modulator that realizes various control schemes with either trailing-edge or leading-edge modulation. Based on that a general double-edge modulator ran be constructed. The proposed modulator is applied to feedforward control of a family of converters, current-mode control with linear or nonlinear compensating slope, and a family of unity-power-factor rectifiers at continuous or discontinuous conduction mode to demonstrate its generality. Experimental and PSPICE verifications are provided.