Physical Investigation Into Effective Voltage Balancing by Temporary Clamp Technique for the Series Connection of IGBTs

The series connection of IGBTs is essential for high-voltage applications where fast switching performances need to be maintained. However, unbalanced voltage sharing is a major resistance to the converter application of this structure. There are a number of causes leading to voltage unbalance, such...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2018-01, Vol.33 (1), p.248-258
Main Authors: Xin Yang, Jin Zhang, Weiwei He, Zhiqiang Long, Palmer, Patrick R.
Format: Article
Language:English
Subjects:
Active control
Active voltage control (AVC)
Automatic voltage control
Carrier density
Clamps
Computer simulation
Current carriers
Electric potential
Electrical equipment
Fourier series
IGBT
Insulated gate bipolar transistors
Logic gates
Mathematical model
physical model
series connection
Switches
Switching
Unbalance
voltage unbalance
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Summary:The series connection of IGBTs is essential for high-voltage applications where fast switching performances need to be maintained. However, unbalanced voltage sharing is a major resistance to the converter application of this structure. There are a number of causes leading to voltage unbalance, such as different signal delays, parasitic parameters, tail currents, and so on. A temporary clamp scheme performed by active voltage control (AVC) has been proven to be effective in solving the unbalanced voltage-sharing issue. However, the basic physics has not been investigated. In this paper, the physical principle of voltage unbalance within IGBTs series operation is discussed. The carrier storage region differences are concluded to be the intrinsic cause of unbalanced voltage sharing. By using an accurate Fourier-series-based IGBT simulation model with appropriate assumptions, a physical explanation for temporary clamp is provided in detail. At the end of the tail current period when the excess carrier concentration becomes close to the intrinsic doping density, the temporary clamp is able to achieve satisfactory equal voltage sharing.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2017.2673849