This paper presents a comparison of two controllers applied to a nonminimum phase Buck and Boost converter. The design of controllers come from reduced order models and combine an Internal Model Structure (IMS) with Sliding Mode Control (SMC). This combination of control schemes solves the nonminimum phase problem in the system. The first controller proposed is based on a First order plus dead time (FOPDT) model of system and the second controller is based on a second order model of system with the right half plane zero (SOPRHZ). The tuning parameters of controllers are obtained using the tuning equations designed for chemicals processes. Additionally, they are obtained with Particle Swarm Optimization (PSO) algorithm to improve the results obtained with tuning equations. The performance of the controllers is analyzed and compared by simulation.