Discrete time integral sliding mode control for discrete pulse modulated converters

Sliding mode control for resonant link converters is introduced in a formal manner through a specific example of a buck resonant link DC-DC converter. The use of variable structure systems theory as a valuable tool to characterize the dynamic behavior of discrete pulse modulated systems in demonstrated. The suboptimal steady-state behavior of discrete pulse modulated converters under conventional control methods is brought out. The discrete time integral sliding mode control as an alternative control method with better performance attributes is proposed. It is demonstrated that the sliding mode control methods developed for the control of a PWM (pulse width modulation) power converter can be extended to the resonant link converter operating under discrete pulse modulation, and the performance can be improved by adding the integral-error term to the sliding surface. The conditions for sliding mode to exist under integral sliding control are obtained. All the results are verified by simulation, and experimental results confirming the concepts are presented.<>