ABSTRACT

Switched mode power supplies (SMPS) are used to obtain a regulated DC output voltage from an unregulated DC input voltage. Depending on the value of VO, the duty cycle of the pulse width modulation switching pulses adjust to maintain VO almost nearly constant, irrespective of variations in the input DC voltage Vs. In this type of SMPS, the buck converter is always operated in the continuous conduction mode. The switching function concept is used to model the buck converter SMPS. Simulation of the buck converter SMPS was conducted with and without a proportional-integral (PI) controller using the ode23t solver. The buck SMPS with PI controller reduces the number and peak-to-peak value of oscillation cycles in the output voltage as compared with the one without PI controller. However, the problem of the buck SMPS with PI controller is that the change in output voltage for a given change in input voltage is much larger compared with the one without PI controller.