An AC Power Supply with Sliding-Mode Control

A sliding-mode control in electronic AC power supplies is presented. This control technique makes it possible to satisfy the increasing demand for the high-level performance of these systems, which include uninterruptible power supplies, test supplies, and fuel cell, and solar cell supplies. The existence and hitting conditions are discussed, and criteria for the selection of the control parameters which define the sliding surface and determine the quality of response are described. Improvements of the method are introduced to accommodate for the time-varying voltage reference and in the presence of an insulation transformer. A three-level, constant-frequency, variable-band dead-beat modulation technique is associated with the sliding control, producing ultrasonic, low-ripple modulation. Tests performed on an experimental prototype confirm the outstanding performance of the adopted control