Microprocessor-based modified discrete integral variable-structure control for UPS

This paper presents a digital signal processor microprocessor-based high-performance uninterruptible power system (UPS). It also modifies the integral variable-structure control (IVSC) approach to be more suitable for the UPS, which is tracking a sinusoidal AC voltage with specified frequency and amplitude. Since the implementation of the control laws has tended to the digital microprocessor, the paper extends the modified IVSC to the discrete time domain. Procedures are developed for determining the control function, the switching plane and the integral control gain, so that the system has desired properties. Simulation and experimental results show that the proposed scheme can supply a high-quality voltage power source in the presence of load disturbance and parameter variation.