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

Abstract

Along the advances of wide-bandgap power devices, the pulse width modulation (PWM) converters are developing towards 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 2-level and 3-level converters and validated by experiments. The results reveal that a 3-level converter running the same inductor generates less than half the core loss compared to a 2-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 pre-produced.

Operation and Efficiency Analysis of a Five-Level Single-Phase Hybrid Si/SiC Active Neutral Point Clamped Converter

“…Considering the DC bias performance of the core and the number of turns, the inductance behavior of the inductor can be calculated [33], and consequently, the current ripple in Lc is obtained based on (5). As a result, the magnetizing field (H), flux density (B) and core loss can be calculated through equations provided in [33], [34]. The specifications of inductors are listed in TABLE VI.…”

A New Method for Offline Compensation of Phase Discrepancy in Measuring the Core Loss With Rectangular Voltage

“…In the two-winding method, the core loss is obtained by integrating the product of the secondary voltage and the primary current of the CUT, which reflects the area of a closed B-H loop. To excite the CUT, a half-bridge structure proposed in [28][29][30] is utilized in this work, which is shown with the experiment setup in Appendix A. A discontinuous test procedure called triple pulse test (TPT) is applied, which is proposed in [28], [29].…”

“…PS_Com= PD -PS_Ref To shift the raw waveform towards the reference phase shift leads to a different reference phase angle. There are many standardized inductors supplied these days, which means only one or a few representative samples need to be tested in this way to represent the property of a whole batch of inductors with the same core and winding arrangements [30]. Table I summarizes the phase variables involved in the proposed offline compensation method.…”

“…To excite the CUT, a half-bridge structure is utilized and depicted in Fig. A1 [28][29][30]. This structure enables the compensation of the asymmetric square voltage caused by the device voltage drops, just by adjusting the output voltages of the two dc power supplies (VDC1 and VDC2).…”

Full Analytical Topology-Device Selection and Multi-objective Optimization of a 27 kVA Aircraft Inverter

“…The tool is fully based on analytical models to avoid real-time simulations and minimize the computation load. Compared with existing studies, this work uniquely incorporates the latest analytical models that recently became available, such as the device loss model under the special modulation scheme in threelevel converters [10] and the accurate core loss modelling of the filter inductors [11] that are neglected in [8], [12], which factors in more unneglectable elements to improve the accuracy and meaningfulness of the estimation. These latest research advances enable such a full analytical tool to rapidly and accurately evaluate the design space to inform the optimal design choices.…”