Wide Voltage Input DC-DC Power Converter

Abstract

Researchers at the University of Central Florida have developed a modified LLC resonant DC-DC converter that achieves high power efficiency for wide input voltage applications. The technology improves the widely-used resonant converter topology and maximizes performance for PV panels or any wide voltage converters. There is high demand for DC-DC power conversion across a wide variety of applications, including solar and wind power generation, consumer electronics, and defense. Current DC-DC converters consist of a switching network for receiving an unregulated input voltage that is coupled to a resonant circuit, including a capacitor, inductor, and a single transformer that drives an output capacitor. However, achieving peak gain results in a smaller inductance index that leads to increased conduction loss and thus lower overall efficiency.

Advantages

Compared to previous methods for wide input converter applications, this wide voltage input DC-DC power converter from UCF improves power efficiency. It narrows operating frequency variation, which can help to increase the power density. This resonant power converter provides both high DC gain and high power conversion efficiency while also maintaining a wide input voltage range. The design method provides a straightforward and effective way to choose the converter parameter, which can be easily adopted and utilized for general LLC design.

Technical Details

This multi-transformer LLC resonant power converter has two transformers in series with one switched transformer that adaptively changes the magnetizing inductance (L_m) based on the V_in to provide different operation configurations. With this converter, the added transformer T2 can be enabled or disabled by controlling the bidirectional switch, S5 and S6, parallel to it. In addition, the converter can operate in two modes with different L_m values. For V_in below a certain threshold voltage (V_th), T2 is disabled and the operation of the converter is the same as the conventional LLC. For V_in above V_th, T2 is enabled, and the equivalent L_m is increased from L_m1 to L_m1+L_m2 so that the converter has lower gain and can keep the circulating current low.

Benefit

Market Application