A study on the stability of current-mode control using time-delay model of pulse-width-modulator

This paper concentrates on the dynamic behavior of pulse-width-modulator (PWM) and the time-delay introduced in the modulation process is highlighted. In order to describe this effect, we derive a time-delay model, based on which the closed-loop stability of current-mode control is studied and a novel interpretation of the subharmonic oscillation is presented. Compared to its existing counterpart, the proposed model exhibits the following superiorities: (a) possesses a simpler mathematical expression; (b) gives more physical insight into the sample and hold effect of current loop; (c) provides a better prediction of the critical condition of the current loop stability without slope compensation in engineering practice. This novel time-delay model is validated by simulation results.