High Frequency Transformers with Adjustable Leakage Inductance using Wire Guides

High frequency transformers are used for isolated power converters such as LLC resonant converters since a leakage inductance of the transformer can be utilized as a part of a resonant inductance in addition to electrical isolation. In order to perform ZVS, the leakage inductance of a transformer is designed so that the current phase flowing in switching devices and Q factor of the resonant circuit are appropriate values. However, it is usually difficult to fabricate properly windings, while managing the leakage inductance precisely. In addition, it is necessary to suppress the stray capacitance which flows leading phase current to switching devices. This paper proposes a high frequency transformer with an adjustable leakage inductance and stray capacitance by only changing the thickness and height of the wire guides.