Development of a Novel Battery-Powered DC-AC System

Abstract

We introduce a novel DC-AC system to interface the battery power to emerging load such as household appliances. Conventional methods, in which using non-isolated cascade DC-DC converters as a front-end of the DC-AC system can achieve high voltage gain but compromise efficiency, while the situation of employing isolated converters is just opposite. To combine the merits of these two type converters and overcome the disadvantages, a novel isolated push-pull LLC resonant DC-DC converter is developed. To cover the wide input voltage range in battery-powered systems, this converter, besides possessing all advantages of conventional LLC converters, the secondary-side resonant operation emerges as a higher efficiency can be achieved for the low battery capacity condition. Then the low side gate driving merit of the conventional push-pull converter endows simplification of circuit and ability of cost-effective. Therefore, the proposed front-end converter is very suitable for step-up conversion in DC-AC systems. Furthermore, a full-bridge sinusoidal pulse-width modulated (SPWM) inverter is also implemented as a back-end stage to produce the pure sinusoidal AC waveform with low total harmonic distortion (THD). The operation principle and analysis of the proposed system are presented and the validity and applicability are also verified by a power rating of 500W hardware prototype.