Characterization and SPICE modelling of a transformer for LLC converter based on GaN transistors

The paper describes a method how to measure the high-power, high-voltage transformer that is used in LLC converter based on GaN transistors. These transistors allow high frequency switching which reduces the power losses and minimizes the form factor. On the other hand, this high frequency is challenging due to the parasitic parameters of the transformer. To achieve soft switching with Zero Voltage Switching (ZVS) on the primary side and Zero Current Switching (ZCS) on the secondary side it must have predictable properties and it must be considered in the controller design. This paper presents measurement of real parameters of given transformer and how to consider its properties in the converter’s design using the SPICE simulations. Key words. LLC converter, Real transformer, SPICE simulation, GaN transistors, Electric Vehicle on-board charger