Insulated gate transistor drive circuit
First Claim
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1. An insulated gate transistor drive circuit comprising:
- operation-state detecting means including;
a sensor for detecting a collector current of an insulated gate transistor and producing a first output signal indicative of the collector current;
a differentiating circuit coupled to the sensor to produce a second output signal indicative of a rate of change of the collector current; and
operational parameter adjusting means coupled to the operation-state detecting means for adjusting an operational parameter of the insulated gate transistor after a source voltage applied to a gate of the insulated gate transistor is removed and the collector current of the insulated gate transistor is decreasing, in response to the second output signal.
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Abstract
The cutoff process of a collector current of an insulated gate transistor is divided into an emitter-to-collector voltage recovery period and a collector current cutoff period. During the emitter-to-collector voltage recovery period the resistance of a gate resistor of the transistor is reduced, and during the collector current cutoff period the resistance of the gate resistor is increased. With this arrangement, the cutoff time is shortened, thereby reducing switching loss and suppressing surge voltage.
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Citations
9 Claims
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1. An insulated gate transistor drive circuit comprising:
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operation-state detecting means including; a sensor for detecting a collector current of an insulated gate transistor and producing a first output signal indicative of the collector current; a differentiating circuit coupled to the sensor to produce a second output signal indicative of a rate of change of the collector current; and operational parameter adjusting means coupled to the operation-state detecting means for adjusting an operational parameter of the insulated gate transistor after a source voltage applied to a gate of the insulated gate transistor is removed and the collector current of the insulated gate transistor is decreasing, in response to the second output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An insulated gate transistor drive circuit comprising:
operation-state detecting means including; means for detecting a collector-to-emitter voltage of an insulated gate transistor and providing a first output signal indicative of the collector-to-emitter voltage of the insulated gate transistor; and operational parameter adjusting means coupled to the means for detecting, for adjusting an operational parameter of the insulated gate transistor after a source voltage applied to a gate of the insulated gate transistor is removed and a collector current of the insulated gate transistor is decreasing, in response to the first output signal, said operational parameter adjusting means comprising; a comparator coupled to the means for detecting and producing a second output signal when the first output signal is less than a reference voltage and a third output signal when the first output signal is greater than the reference voltage; a resistor coupled in series with the gate of the insulated gate transistor; and a switching circuit coupled to the comparator and in parallel with the resistor, the switching circuit closing and short-circuiting the resistor in response to the second output signal and opening in response to the third output signal, wherein the reference voltage is a steady-state collector-to-emitter voltage in a cutoff state of the insulated gate transistor. - View Dependent Claims (9)
Specification