APPLICATION OF SLIDING MODE CONTROL TO SWITCH-MODE POWER-SUPPLIES

Switch-mode power supplies represent a particular class of variable st ructure systems (VSS). Thus, they can take advantage of non-linear con trol techniques developed for this class of systems. In this paper the so called sliding mode control is reviewed and its application to swi tch-mode power supplies is discussed. Sliding mode control extends the properties of hysteresis control to multi-variable environments, resu lting in stability even for large supply and load variations, good dyn amic response and simple implementation. Application to dc-dc converte rs, as well as rectifiers and inverters, is analyzed and provisions to overcome the inherent drawbacks of sliding mode control, i.e. variabl e switching frequency and possible steady-state errors, are described. Experimental results are also reported, which allow a comparison betw een the sliding mode approach and other standard control techniques, e .g. current-mode control, showing its effectiveness.