An Analytical Method for Fast Calculation of Inductor Operating Space for High-Frequency Core Loss Estimation in Two-Level and Three-Level PWM Converters

Along the advances of wide-bandgap power devices, the pulsewidth modulation (PWM) converters are developing toward higher switching frequencies in recent years. Accurate estimation of the high-frequency power losses of magnetic components, the core loss in particular, has been a challenge for PWM converters. While the conventional approaches based on Steinmetz equation lose the accuracy in PWM excitations, the 'loss map' approach has been proposed recently as a practical method to accurately estimate the inductor core loss. To calculate the core loss, the inputs of the loss map need to be retrieved from the steady-state inductor voltage/current waveforms. As a supplement to the loss map approach, this work proposes an analytical method to rapidly generate the inputs (inductor operating space) for the loss map to replace the efforts in building simulation models and experimental rigs. The proposed approach relies on the operation and modulation principles of PWM converters and enables computerized calculation of the operating space and the inductor core loss. The proposed approach is developed for both two-level and three-level converters and validated by experiments. The results reveal that a three-level converter running the same inductor generates less than half the core loss compared to a two-level converter, when the maximum current ripple is kept equivalent. The proposed approach is based on the operation principles of the converter topology and, therefore, can be applied generally regardless of the core material or the design of the inductor, as long as the loss map of the inductor is preproduced.