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  • Hybrid Voltage Balancing Approach for Series-Connected SiC MOSFETs for DC–AC Medium-Voltage Power Conversion Applications
Title: Hybrid Voltage Balancing Approach for Series-Connected SiC MOSFETs for DC–AC Medium-Voltage Power Conversion Applications
Due to its fast switching speed, the voltage sharing of series-connected SiC MOSFETs is more sensitive to the parasitic components from the power modules and the system, which results in more challenges for voltage balancing control. For two series-connected SiC MOSFETs realized by one half-bridge module, the detailed analysis and measurement indicate that the unbalanced parasitic capacitors inside the power module comprise the dominant factor causing the difference of turn-off dv/dt. In this paper, the traditional gate turn-off delay-time control is first used as an example to analyze the limitation of the existing active voltage balancing (AVB) control methods under AC load current: 1) AVB control has a limitation to adjust delay time accurately under AC current; 2) the voltage imbalance of the body diodes cannot be solved by AVB control. To achieve voltage balancing control of series-connected SiC MOSFETs and body diodes, this paper proposes a new two-part hybrid approach: 1) passive dv/dt compensation: one small compensation capacitor is applied to balance the non-uniform distribution of parasitic capacitors inside the power module, so the series-connected MOSFETs can have the same turn-off dv/dt; 2) active gate signal turn-off time adjustment: a closed-loop delay time control is applied to compensate the gate signal mismatch of MOSFETs. To verify the proposed balancing approach, a single-phase pump-back test is conducted to show the improvement of voltage sharing of both MOSFETs and body diodes.  more » « less
Award ID(s):
2143488
PAR ID:
10500284
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
IEEE
Date Published:
Journal Name:
IEEE Transactions on Power Electronics
Volume:
37
Issue:
7
ISSN:
0885-8993
Page Range / eLocation ID:
8104 to 8117
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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