Assessment of MOSFET switching losses in an LLC converter by a calorimetric method

Abstract

The present work aims to implement a calorimetric method to measure the power dissipated during MOSFET switching in a high efficiency LLC resonant converter. The power dissipated from switching can significantly impact the total power dissipated by the device and consequent efficiency, so correct quantification is fundamental for optimizing the devices and increasing the efficiency of the converters. In LLC converters, this type of dissipated power cannot be measured with standard methods such as measurement with oscilloscopes as some of the energy that is recovered and not dissipated. The calorimetric method requires reasonably accurate measurement of thermal resistance and the temperature of the die. To facilitate accurate temperature measurement, we used a device in an ACEPACK™ SMIT package module, which incorporates a complete half-bridge and an NTC thermistor for reading the temperature.