Trigger circuit for solid state switch

• US 4,554,463 A
• Filed: 05/26/1983
• Issued: 11/19/1985
• Est. Priority Date: 05/26/1983
• Status: Expired due to Term

• Current Assignee: York International Corporation (Johnson Controls International plc)
• Original Assignee: BorgWarner Incorporated
• Inventors: Schnetzka, Harold R., Norbeck, Dean K.
• Primary Examiner(s): Zazworsky, John
• Application Number:
  US06/498,366
• Time in Patent Office: 908 Days
• Field of Search: 307/252 R, 307/252 H, 307/252 J, 307/253, 307/268, 307/270, 307/297
• US Class Current: 307/117
• CPC Class Codes: H03K 17/725 for ac voltages or currents H03K17/722, H03K17/735 take precedence
• CPC Class Codes: H03K 17/79 controlling bipolar semiconductor switches with more than two PN-junctions, or more than three electrodes, or more than one electrode connected to the same conductivity region
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption

Abstract

The power dissipated, in a trigger circuit for gating on a semiconductor switch, is minimized by employing a constant current source to provide the gate trigger current. This assures adequate triggering regardless of supply voltage variations or switch intrinsic control voltage requirements. Power is saved by supplying only the current required to drive the semiconductor switch on, thereby preventing overdrive. With constant d-c gate current, the precise amount of power needed to turn on and close the switch is provided while wasting relatively little energy due to gate intrinsic voltage variations of the switch or to input line voltage variations.

Claims

1. A trigger circuit for gating on an SCR having gate, cathode and anode terminals, where the SCR is subject to variations in its intrinsic gate-to-cathode control voltage requirements, said trigger circuit comprising:

a source of d-c supply voltage normally having a fixed magnitude but subject to undesired variations;

an integrated circuit voltage regulator having an input pin, an output pin and a ground pin;

means including the emitter-collector conduction path of a transistor for coupling said d-c supply voltage source to the input pin of said voltage regulator;

a resistor having one end connected to the output pin of said voltage regulator and the outer end connected to the ground pin and also to the SCR'"'"'s gate terminal;

and actuating means for turning said transistor on to apply a d-c voltage, from said d-c supply voltage source, to the input pin of said voltage regulator which functions to maintain a constant d-c voltage between its output and ground pins, thereby translating constant d-c gate current through said resistor and from the SCR'"'"'s gate terminal to its cathode terminal to turn the SCR on despite the presence of any unwanted variations in the d-c supply voltage or variations in the intrinsic gate-to-cathode control voltage requirements.

2. A trigger circuit for gating on an SCR having gate, cathode and anode terminals, where the SCR is subject to variations in its intrinsic gate-to-cathode control voltage requirements, said trigger circuit comprising:

a source of d-c supply voltage normally having a fixed magnitude but subject to undesired variations;

an integrated circuit voltage regulator having an input pin, an output pin and a ground pin;

means including the emitter-collector conduction path of a first transistor for coupling said d-c supply voltage source to the input pin of said voltage regulator;

means including the emitter-collector conduction path of a second transistor for bypassing said voltage regulator and coupling said d-c supply voltage source directly to the regulator'"'"'s output pin;

a resistor having one end connected to the output pin of said voltage regulator and the other end connected to the ground pin and also to the SCR'"'"'s gate terminal;

and actuating means for turning said first and second transistors on to apply d-c voltages, from said d-c supply voltage source, to the input and output pins of said voltage regulator which functions to maintain a constant d-c voltage between its output and ground pins, thereby translating constant d-c gate current through said resistor and from the SCR'"'"'s gate terminal to its cathode terminal to turn the SCR on despite the presence of any unwanted variations in the d-c supply voltage or variations in the intrinsic gate-to-cathode control voltage requirements,

the constant gate current flowing through said resistor being formed by the combination of the current flowing from said regulator and out of the output pin and the current flowing through said second transistor, the combined current through said resistor being held constant by the operation of said voltage regulator.