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US 5,210,479 AGranted
Drive circuit for an insulated gate transistor having overcurrent detecting and adjusting circuits
AssigneeHitachi, Ltd.
InventorsShin Kimura, Norikazu Tokunaga, Nobuyoshi Mutoh, Satoshi Ibori, Shuuji Musha, Yasuo Matsuda, Yutaka Suzuki
Life of this patent
Estimating the term…
Abstract
An ON holding circuit is provided which outputs a signal which identifies an ON state of an insulated gate transistor to a gate voltage input circuit, and inhibits the gate voltage input circuit from being responsive to an input signal which identifies an OFF state of the insulated gate transistor when an overcurrent adjusting circuit operates continuously.
Claims27
A drive circuit for an insulated gate transistor having a gate comprising:
- a gate voltage input circuit connected to the insulated gate transistor for converting an input signal which identifies an ON or OFF state of the insulated gate transistor to a gate voltage, and for supplying the gate voltage to the gate of the insulated gate transistor;
- an overcurrent adjusting circuit connected to the insulated gate transistor for detecting an overcurrent of the insulated gate transistor and for adjusting the overcurrent of the insulated gate transistor to a predetermined value;
- and
- an ON holding circuit connected to the gate voltage input circuit and the overcurrent adjusting circuit for outputting a signal which identifies the ON state of the insulated gate transistor to the gate voltage input circuit and for inhibiting the gate voltage input circuit from being responsive to the input signal which identifies the OFF state of the insulated gate transistor when the overcurrent adjusting circuit operates continuously;
- wherein the gate voltage input circuit is responsive to a logical OR of an output signal of the ON holding circuit and the input signal.
2 more elements
An overcurrent detecting circuit for an insulated gate transistor having a gate responsive to an input signal comprising:
- a transistor having a base connected to a first voltage source with a predetermined value through a first resistor, having a collector connected to a collector of the insulated gate transistor through a second resistor and a first diode, and having an emitter connected to the gate of the insulated gate transistor through a second diode;
- wherein a voltage at a connection node between the first diode and the second resistor is output as a first overcurrent detection signal.
A drive circuit for an insulated gate transistor having a gate comprising:
- a gate voltage input circuit connected to the insulated gate transistor for converting an input signal to a gate voltage, and for supplying the gate voltage to the gate of the insulated gate transistor;
- an overcurrent detecting circuit connected to the insulated gate transistor for detecting an overcurrent of the insulated gate transistor;
- and
- an overcurrent adjusting circuit connected to the gate voltage input circuit and the overcurrent detecting circuit for adjusting the overcurrent of the insulated gate transistor to a predetermined value;
- wherein said overcurrent detecting circuit comprises:
- a transistor having a base connected to a first voltage source with a predetermined value through a first resistor, having a collector connected to a collector of the insulated gate transistor through a second resistor and a first diode, and having an emitter connected to the gate of the insulated gate transistor through a second diode;
- wherein a voltage at a connection node between the first diode and the second resistor is output as a first overcurrent detection signal.
4 more elements
A switching circuit comprising:
- an insulated gate transistor having a gate and having a main current path for switching a main current of a load;
- and
- a drive circuit for the insulated gate transistor, said drive circuit comprising:
- a gate voltage input circuit connected to the insulated gate transistor for converting an input signal to a gate voltage, and for supplying the gate voltage to the gate of the insulated gate transistor;
- an overcurrent detecting circuit connected to the insulated gate transistor for detecting an overcurrent of the insulated gate transistor;
- and
- an overcurrent adjusting circuit connected to the gate voltage input circuit and the overcurrent detecting circuit for adjusting the overcurrent of the insulated gate transistor to a predetermined value;
- wherein said overcurrent detecting circuit comprises:
- a transistor having a base connected to a first voltage source with a predetermined value through a first resistor, having a collector connected to a collector of the insulated gate transistor through a second resistor and a first diode, and having an emitter connected to the gate of the insulated gate transistor through a second diode;
- wherein a voltage at a connection node between the first diode and the second resistor is output as a first overcurrent detection signal.
7 more elements
A current switching apparatus comprising:
- a load;
- and
- a switching circuit connected to the load for controlling a main current of the load, said switching circuit comprising:
- an insulated gate transistor having a gate and having a main current path for switching the main current of the load;
- and
- a drive circuit for the insulated gate transistor, said drive circuit comprising:
- a gate voltage input circuit connected to the insulated gate transistor for converting an input signal to a gate voltage, and for supplying the gate voltage to the gate of the insulated gate transistor;
- an overcurrent detecting circuit connected to the insulated gate transistor for detecting an overcurrent of the insulated gate transistor;
- and
- an overcurrent adjusting circuit connected to the gate voltage input circuit and the overcurrent detecting circuit for adjusting the overcurrent of the insulated gate transistor to a predetermined value;
- wherein said overcurrent detecting circuit comprises:
- a transistor having a base connected to a first voltage source with a predetermined value through a first resistor, having a collector connected to a collector of the insulated gate transistor through a second resistor and a first diode, and having an emitter connected to the gate of the insulated gate transistor through a second diode;
- wherein a voltage at a connection node between the first diode and the second resistor is output as a first overcurrent detection signal.
10 more elements
An induction motor system comprising:
- an induction motor;
- and
- a control circuit connected to the induction motor for controlling a current to operate the induction motor, said control circuit comprising:
- an insulated gate transistor having a gate;
- a drive circuit connected to the insulated gate transistor for driving the insulated gate transistor;
- and
- a control side circuit connected to the drive circuit for providing an input signal for the drive circuit, the input signal identifying an ON state or an OFF state of the insulated gate transistor;
- wherein said drive circuit comprises:
- a gate voltage input circuit connected to the insulated gate transistor for converting the input signal identifying the ON state or the OFF state of the insulated gate transistor to a gate voltage, and for supplying the gate voltage to the gate of the insulated gate transistor;
6 more elements
Dependencies are inferred from the claim text.