Polynomial Sliding Surfaces to Control a Boost Converter With Constant Power Load

The unstable ON and OFF state trajectories of a boost converter supplying a constant power load (CPL) are appropriately combined using sliding-mode control (SMC) with a suitable surface to yield a stable trajectory that reaches a specified equilibrium point. Selecting the optimum surface involves a comparative analysis among potential candidates in terms of stability, disturbance rejection, conduction losses and inrush current. The performance as switching function of polynomials of degree zero (non-zero constant), degree one (affine function) and degree 2 (quadratic function) are analyzed in depth to conclude that the affine function leads to the best static and dynamic results. The theoretical predictions are verified by means of simulations and measurements in a prototype.

Automated summary

In this study, the unstable ON and OFF state trajectories of a boost converter supplying a constant power load are addressed using sliding-mode control with a suitable surface. The selection of the optimum surface involves a comparative analysis among different candidates. The performance of polynomials of different degrees as switching functions is analyzed, and it is concluded that the affine function leads to the best static and dynamic results. The theoretical predictions are verified through simulations and measurements in a prototype.