Along the advances of wide-bandgap power devices, the electrical equipment is developing toward higher switching frequencies and more complex switching modes in recent years 1. Accurate prediction of the core loss of magnetic components has been a challenge for electrical equipment as the excitation varies depending on the operating mode of switched-mode power supplies 2. However, few studies provide systems with variable-characteristic-parameters excitations 3. It is not clear how the core loss of soft magnetic materials was affected by the characteristic parameters of complex non-sinusoidal excitations.
Therefore, this paper presents the results of an extensive core loss study performed on nanocrystalline alloy (FT-3KL), amorphous alloy (1K101) and ultra-thin oriented silicon steel (GT-50). Firstly, an automatic experimental setup for core loss measurement of soft magnetic materials fed by a SiC MOSFET full-bridge inverter is built, as shown in Fig 1. This setup can provide real-time voltage waveforms adjustment, data visualization and automatic post-processing, which makes the measurement more rapid and accurate.
Then, the effect of characteristic parameters of square waveforms, rectangular waveforms contained zero-voltage, pulse-width-modulation (PWM) waveforms and sinusoidal-pulse-width-modulation (SPWM) waveforms on core loss are analyzed comparatively. For square and rectangular excitations, the core loss shows regular distributions with duty cycles and phase shift ratios. For SPWM excitations, the effect of the modulation ratios on the core loss is greater than that of the carrier ratios. Meanwhile, the SPWM excitation with bipolar modulation will produce greater loss than that with unipolar modulation. The results are partly shown in Fig 2. In addition, the regular distributions will be interfered by the severe switching oscillations from the inverter, which makes the prediction of core loss more complicated. This paper can provide reference for the performance optimization of high-frequency electrical equipment.
1 J. Wang, N. Rasekh and X. Yuan, IEEE Transactions on Industry Applications., vol. 57, p.650-663 (2021)
2 E. Stenglein and T. Dürbaum, IEEE Transactions on Magnetics., vol. 57, p.1-10 (2021)
3 I. Sirotić, M. Kovačić and S. Stipetić, IEEE Transactions on Industry Applications., vol. 57, p.4796-4804 (2021)
Fig 1: Schematic diagram of the experimental setup for core loss measurement.
Fig 2: Core loss of FT-3KL under SPWM excitations with variable modulation ratios.