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Under normal circumstances, the driving waveform of IGBT oscillates at the rising edge for the following reasons:
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1, the IGBT driving capacity (current) is insufficient, the charging current to the Miller capacitor is small when it is opened;
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2, the drive line is too long, introducing interference signals or forming LC oscillation;
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3, DC bus stray inductance is too large, Vce oscillation peak is too large, crosstalk causes the drive waveform oscillation.
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Common IGBT-driven oscillation is usually the above three reasons, of which 1 and 2 most engineers will think of the first time, and give the corresponding solution, and the third reason is easy to be ignored, so as not to find the right solution as soon as possible. According to the reasons for the above IGBT drive oscillation, the following solutions are given:
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1, reduce the length of the drive line (reduce the inductance);
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2, appropriately reduce the driving resistance value (increase the driving current);
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3, from the LC point of view, under the premise that the speed meets the requirements, add a suitable gate capacitance (between 100pf-1nf) between ge;
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4, Optimize the DC bus structure design, reduce stray inductance. At the same time, the non-inductive absorbing capacitance is increased between the CE electrode of IGBT to reduce the peak voltage.