Abstract
This paper presents a comprehensive investigation on the self-sustained oscillation of silicon carbide (SiC) MOSFETs. At first, based on the double pulse switching test, it is identified that the self-sustained oscillation of SiC MOSFETs can be triggered by two distinct test conditions. To investigate the oscillatory criteria of the two types of self-sustained oscillation, a small-signal ac model is introduced to obtain the transfer function of the oscillatory system. The instability of the oscillation is thereby determined by the two conjugate pole pairs of the transfer function. By analyzing the damping ratios of the two pole pairs, the parametric sensitivity of various circuit and device’s parameters on the two types of self-sustained oscillation are obtained. The analyses reveal the oscillatory criteria of the self-sustained oscillation for SiC MOSFETs. Based on the oscillatory criteria, necessary methods are proposed to prevent the oscillation. The proposed oscillation suppression methods are validated by the experiment at the end of the paper.
Highlights
The recent development of fast switching converters require the power switches to operate at a high switching frequency
This paper presents a comprehensive study on the potential mechanisms and oscillatory criteria of the self-sustained oscillation for silicon carbide (SiC) MOSFETs
The test results show that the self-sustained oscillation can be excited under two different test conditions depending on the common source inductance LS
Summary
The recent development of fast switching converters require the power switches to operate at a high switching frequency. In [3,4]; with the common source inductance LS being neglected, the papers studied the sensitivity of various circuit and device’s parameters on the self-sustained oscillation of SiC. Since the gate-drain capacitance was neglected, the oscillatory criteria was not very accurate and could only provide an approximate estimation on the occurrence condition of self-sustained oscillation for SiC MOSFETs. In Reference [7], the self-sustained oscillation induced by the the common source inductance LS was reported for CoolMOS. This paper presents a comprehensive study on the potential mechanisms and oscillatory criteria of the self-sustained oscillation for SiC MOSFETs. In Section 2, two distinct test conditions which can trigger the self-sustained oscillation are identified by the double-pulse test.
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