Transfer Function of Current Modulator in PWM Converters with Current-Mode Control

Several different expressions have been derived in previouspublications for the transfer function of the current modulator used inpulsewidth modulated (PWM) dc–dc power converters with current-modecontrol. These expressions give results higher than the measured ones andexhibit many other problems, e.g., one expression gives an infinite valuewhen no slope compensation is used. This paper presents a derivation forthe transfer function of the current modulator used in PWM converterswith fixed-frequency, trailing-edge modulation, peak-current-mode controlfor two cases: without and with slope compensation. In addition, feedfor-ward terms are also derived.