A novel approach to current-mode control of the constant frequency power converters

This paper presents new methods of current mode control for pulse width modulated (PWM) converters. Proposed approaches of control expands the band of duty-cycle ratio variations without any deteriorating influence on system stability. Furthermore, in the case of the quasi-charge control, system becomes inherently stable. Small-signal models are developed for both control circuits. The models are derived for converters operating in the continuous conduction mode. The models are accurate up to half of the switching frequency. The proposal small-signal models are used to assess system stability considerations. The proposed control circuits are suitable for all applications where the average inductor current needs to be controlled, as it is the case in the power factor correction circuits as well as in the battery charger/dischargers. The subharmonic oscillations, present in true average control scheme, are eliminated by using proper compensation network in the current loop. Model predictions are well confirmed through simulation results.