Electrical engineering

Physics

Topology (electrical circuits)

Electromagnetic coil

Copper loss

Energy efficient transformer

Computer graphics (images)

Engineering

Planar

Voltage

Composite material

Power (physics)

Flyback transformer

Materials science

Power density

Electronic engineering

Converters

Gallium nitride

Layer (electronics)

Computer science

Quantum mechanics

Transformer

IEEE Transactions on Power Electronics

This article proposes an isolated LLC resonant converter with MHz-level switching frequency that can achieve zero-voltage switching in the full-load range. In the proposed converter, conventional silicon devices are replaced with wide band-gap gallium nitride devices to reduce switching losses in the power device. A planar transformer structure with reduced winding length on the secondary side is proposed, which utilizes flux cancellation and reduces core loss while maintaining a low core volume. The path of the secondary winding is a fraction of a full turn, which reduces secondary-side losses while maintaining a turns ratio of 16:1. This planar transformer achieves the goals of decreasing core loss and volume while increasing power density. Within a limited circuit layout area, optimal points for the efficiency of core loss and copper loss were calculated. The magnetic simulation software ANSYS Maxwell was employed to verify whether the actual circuit behavior of this planar transformer conformed to the design theory. Finally, a resonant converter was achieved with a switching frequency operating at 1 MHz, input voltage of 380 V, output voltage of 12 V, output power of 800 W, power density of 55 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , and maximum efficiency of 96.5%.

Design and Implementation of a Planar Transformer With Fractional Turns for High Power Density <i>LLC</i> Resonant Converters

Design and Implementation of a Planar Transformer With Fractional Turns for High Power Density LLC Resonant Converters