A new sliding mode control for single-phase UPS inverters based on rotating sliding surface

A new sliding mode control for single-phase UPS inverters is introduced based on rotating sliding surface. It is shown that the sliding surface can be rotated in the phase plane in such a direction that the tracking capability of the inverter is improved when it is subjected to load variations. It should be noted that the sliding surface rotation is possible with a time-varying slope which is computed with the help of a first order function introduced in. Each time the slope is modified, the sliding surface rotates in clockwise or counterclockwise direction so as to achieve the desired performance. The performance of the proposed control method has been tested through computer simulations using a triac-controlled resistive load and a diode bridge rectifier load. Simulation results verify the correct operation of the proposed control method.