Drive circuit for SCR device
First Claim
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1. A drive circuit for controlling operation of an SCR comprising:
- a switching power source connected to a gate of the SCR, which delivers a signal to the gate at predetermined time periods;
a switching reverse bias voltage source connected to the gate of the SCR; and
a polarity sensing circuit connected to an anode of the SCR, to the switching power source and to the switching reverse bias voltage source, to sense when the anode of the SCR is in one of a positive and negative state, wherein the switching power source delivers a signal to the gate sufficient to place the SCR in a conduction state while the polarity sensing circuit senses a positive voltage on the anode and wherein a reverse bias voltage for the gate of the SCR is applied when the polarity sensing circuit senses a reverse anode voltage.
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Abstract
An SCR control circuit which drives the SCR between conduction and non-conduction states in accordance with values sensed by a polarity sensing circuit. The control circuit generating a signal for the gate which is of a constant value, at different temperatures.
19 Citations
19 Claims
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1. A drive circuit for controlling operation of an SCR comprising:
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a switching power source connected to a gate of the SCR, which delivers a signal to the gate at predetermined time periods; a switching reverse bias voltage source connected to the gate of the SCR; and a polarity sensing circuit connected to an anode of the SCR, to the switching power source and to the switching reverse bias voltage source, to sense when the anode of the SCR is in one of a positive and negative state, wherein the switching power source delivers a signal to the gate sufficient to place the SCR in a conduction state while the polarity sensing circuit senses a positive voltage on the anode and wherein a reverse bias voltage for the gate of the SCR is applied when the polarity sensing circuit senses a reverse anode voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A drive circuit for controlling operation of an SCR comprising:
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a supply; a current sensor resistor connected at a first end to a positive supply voltage, Vcc ; a diode having an anode connected to positive Vcc ; a first transistor whose base is connected to a second end of the current sensor resistor and whose emitter is connected to a cathode of the diode; a second transistor having its base connected to the collector of the first transistor, and its emitter connected to positive Vcc ; a third transistor whose base is connected to the collector of the second transistor, whose collector is connected to the base of the first transistor, and whose emitter is connected to the gate of the SCR; a fourth transistor having its drain connected to the base of the second transistor, whose source is connected to the cathode of the SCR, and whose gate is connected through a resistance, to the anode of the SCR; a second diode whose anode is connected to the source of the fourth transistor, and whose cathode is connected to negative Vcc ; and a second resistance whose first end is connected to the cathode of the second diode and to the negative Vcc, and whose second end is connected to the emitter of the third transistor and the gate of the SCR.
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12. A drive circuit for controlling operation of an SCR used in an inrush clamp circuit comprising:
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a switching power source connected to a gate of the SCR, which delivers a signal to the gate at predetermined time periods; a switching reverse bias voltage source connected to the gate of the SCR; and a polarity sensing circuit connected to an anode of the SCR, to the switching power source and to the switching reverse bias voltage source, to sense when the anode of the SCR is in one of a positive and negative state, wherein the switching power source delivers a signal to the gate sufficient to place the SCR in a conduction state while the polarity sensing circuit senses a positive voltage on the anode and wherein a reverse bias voltage for the gate of the SCR is applied when the polarity sensing circuit senses a reverse anode voltage. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification