A modified discrete control law for UPS applications

This paper presents a repetitive controller with parameters tuned a priori by a robust controller for uninterruptible power supply applications. The proposed control scheme can minimize periodic distortions resulted from unknown periodic load disturbances. The implemented PWM inverter system with sinusoidal reference employs a low cost microcontroller. Due to the fact that most of the low cost microcontrollers available in the market presents low processing speed, it is imperious to develop simple algorithms with few operations, so that its implementation is realizable. Stability and special features of the control scheme are discussed. Simulation and experimental results (110 V/sub RMS/, 1 kVA) are presented to demonstrate the performance of the proposed control approach under periodic load disturbances.