Semiconductor device drive circuit with voltage surge suppression
First Claim
1. A semiconductor device driving circuit being connected to a control electrode of an insulated gate bipolar transistor for controlling a conduction state between main electrodes thereof in response to a voltage applied to the control electrode, said semiconductor device drive circuit comprising:
- driving control means for driving the insulated gate bipolar transistor at higher driving speed and lower driving speed, the output of the driving means being supplied to the control electrode of the insulated gate bipolar transistor for controlling a conduction state; and
current decrease start point detection means, connected to said driving control means, for detecting a current decrease start point when a transition is made from a first period in which change in a current flowing into the main electrodes is at a first level to a second period in which a change in current is at a second higher level when a voltage of the control electrode is lowered for making a transition from a conduction state to a non-conduction state between the main electrodes;
wherein said driving control means outputs at the higher driving speed in the first period and outputs at lower the driving speed in the second period in response to output of said current decrease start point detection means.
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Accused Products
Abstract
A semiconductor device drive circuit comprises first drive means for driving an IGBT, second drive means for driving the IGBT at lower speed than the first drive means, switch means for switching output of the first drive means and output of the second drive means for supply to a gate of the IGBT, and current decrease start point detection means for detecting a current decrease start point when a transition is made from a first period in which change in a collector current is moderate to a second period in which change in the collector current is abrupt when the IGBT is turned off. The switch means is operated so as to use the first drive means in the first period and the second drive means in the second period in response to output of the current decrease start point detection means.
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Citations
14 Claims
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1. A semiconductor device driving circuit being connected to a control electrode of an insulated gate bipolar transistor for controlling a conduction state between main electrodes thereof in response to a voltage applied to the control electrode, said semiconductor device drive circuit comprising:
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driving control means for driving the insulated gate bipolar transistor at higher driving speed and lower driving speed, the output of the driving means being supplied to the control electrode of the insulated gate bipolar transistor for controlling a conduction state; and current decrease start point detection means, connected to said driving control means, for detecting a current decrease start point when a transition is made from a first period in which change in a current flowing into the main electrodes is at a first level to a second period in which a change in current is at a second higher level when a voltage of the control electrode is lowered for making a transition from a conduction state to a non-conduction state between the main electrodes; wherein said driving control means outputs at the higher driving speed in the first period and outputs at lower the driving speed in the second period in response to output of said current decrease start point detection means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A semiconductor device driving circuit being connected to an insulated gate bipolar transistor having a control electrode and main electrodes, comprising:
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a drive circuit connected to the control electrode of the insulated gate bipolar; current rate change detection means, connected to the drive circuit, for detecting a change in the rate of current flowing into one of the main electrodes when a voltage applied to the control electrode is lowered for making a transition from a conduction state to a non-conduction state; and a switch circuit, connected to the drive circuit, and the means for switching between drive states of the drive circuit. - View Dependent Claims (12, 13)
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14. A method of operating a drive circuit for driving an insulated gate bipolar transistor having a control electrode and main electrodes, comprising:
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detecting a change in a rate of current flowing into one of the main electrodes; and switching between driving states of the drive circuit using the change; wherein detecting the change comprises; detecting one of a voltage of the control input and a current flowing into the control input; and differentiating one of the voltage of the control input and a voltage related to the current flowing in the control input to produce a differentiated voltage; and comparing the differentiated voltage to a reference voltage.
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Specification