High Frequency Switched Phase Controlled DC-AC Inverter

Abstract

With the increased power to weight ratio, corresponding to the developments in technology and material science, the demand for small uninterruptible power supply and high frequency transformers in transport vehicles and device technologies where the weight is particularly important has increased. An analysis of the high frequency switched phase-controlled DC-AC inverter and the high frequency transformer is presented. This inverter has a pair of switches in each side of the primary and the secondary of the transformer. The voltage conversion ratio is controlled by the phase difference between the two pairs of switches. The transformer is miniaturized by increasing the switching frequency. Thus the volume and weight of the system have been reduced. Current and voltage jumps in similar studies were reduced by using faster elements and opto-coupler, and these jumps were minimized by using snubber circuits. This DC-AC inverter and the high frequency transformers is especially suitable for small uninterruptible power supply systems. The circuit performed in the application is a 110 W DC-AC converter, the output voltage is 220 V, the efficiency is 93%. The high frequency transformer used in the application circuit has a physical size of 1/7 and a weight of 1/10 according to the sheet metal core transformer. When the circuit's power supply, driving circuits, switches, fans and filters were taken into consideration, its physical size was reduced by 1/5 and its weight by 2/3.