Nobreak dupla conversão monofásico isolado em alta frequência com tensão de entrada bivolt e potência de 1kVA, baseado no conceito de circuito multi-portas

Abstract

This research presents a single-phase double conversion Uninterruptible Power Supply (UPS) designed with two alternating voltage levels, alternating output voltage 110V, 24V battery-set, and apparent output power of 1kVA. The UPS topology proposed is based on multi-port circuit concept, which uses an isolated High Frequency Transformer (HFT) that interconnected different power sources. The mentioned multi-port circuit consists in two input ports, and two output ports dedicated to feed the Full-Bridge voltage source inverter, and battery-charger derived from Buck topology. The primary power is connected to the input port through a Full-Bridge converter, and the standby power is connected to another input port through a voltage-feed Push-Pull converter. Some particularities of proposed system are indicated: two conversion stages for each operation mode, and the three levels square voltage waveform at the output inverter. It is also observed the practicality in the way that different sources of energy can be interconnected to the proposed UPS, which is not seen in other works. A prototype from proposed UPS was assembled, it was achieved an efficiency superior to 80% in grid mode for 1kVA, and an efficiency of 74% in battery mode for 860VA. Thus, the proposed uninterrupted system is considered an alternative to applications with power less than or equal to 2kVA.