An intelligent real-time microcontrolled UPS system

Optimized PWM techniques are being adopted for switch mode power supply systems (SMPS) and for uninterruptible power supplies (UPS). The heart of the UPS system is based on a single chip 16-bit microcontroller, which computes the switching angles online and in a real-time. The PWM switching strategy is based on the regular asymmetric method. In the single-phase inverter configuration the three level PWM is adopted. The system developed provides a soft-start facility and closed-loop voltage and frequency control and also the output voltage is synchronised with the mains using the high speed interrupt based inputs. Finally, in addition to the PWM generation the system provides full protection. The system performance is assessed using a 25 kVA transistorised single-phase bridge inverter