Using sliding mode controller techniques to design PWM DC-DC

PID controllers have been used in industry for quite a while since they are easy to implement Their ease of implementation is due to the many algorithms that have been designed to work with lower order approximations of more complex systems. However, one disadvantage is the PID controller´s inability to compensate for a nonlinearity. Since many converters are higher order systems, the design for the sliding mode controller (SMC) requires complicated mathematics and results in a higher number of tuning parameters. However, use of a step response to approximate a second order model of the system reduced the number of tuning parameters. Finding simple algorithms to set the tuning parameters makes the SMC as easy to implement as the PID controller and still provide good performance in the presence of nonlinearities and modeling errors. Through the use of algorithms previously established for thermodynamic systems and a paper proposing a design for a second order system, a proposed design for the SMC based on a second order approximate model was derived. This design was used and the results compared to the results of a design of a PID controller based on the second order approximated system.