AN OUTPUT-FEEDBACK SLIDING MODE SPEED REGULATOR FOR DC DRIVES

Synthesis of the switching surface equation in a variable structure sp eed controller is accomplished by using a phase lead type compensator. In addition, the switching control is designed using only the sign of the switching surface function and an estimate of the maximum value o f the equivalent sliding control. As a result, the proposed variable s tructure controller relies only upon output feedback. The problem of c ontrol chattering is addressed by substituting a saturation function f or the switching control. The practical significance of the work is de monstrated by designing a robust speed regulator for a dc drive, witho ut direct acceleration measurement or the use of a state estimator. Re sults from a control experiment complement the discussion.