Gate driver for a full-bridge lossless switching device

• US 4,912,622 A
• Filed: 03/07/1988
• Issued: 03/27/1990
• Est. Priority Date: 03/07/1988
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Steigerwald, Robert L., Ngo, Khai D. T.
• Primary Examiner(s): Salce, Patrick R.
• Assistant Examiner(s): Sterrett, Jeffrey
• Application Number:
  US07/164,600
• Time in Patent Office: 750 Days
• Field of Search: 363/17, 363/56, 363/98, 363/132, 363/16, 307/254, 307/300, 307/571
• US Class Current: 363/98
• CPC Class Codes: H02M 7/5387 in a bridge configuration

Abstract

A control circuit for a full bridge switching converter including power FET switching devices. The control circuit including a gate driver with a voltage sensor circuit which senses the precise instant to gate the power FET on in order to achieve substantially lossless switching by the converter.

Claims

1. A control circuit adapted to drive one switching device of an edge resonant converter bridge circuit comprising:

a first switch means directly coupled to said switching device and comprising a series of transistors for turning on said switching device;

a second switch means directly coupled to said switching device and comprising a series of transistors for turning off said switching device;

said first switch means including means for disabling operation of said second switch means;

said second switch means including means for disabling operation of said first switch means; and

a voltage sensing means directly coupled to said switching device and comprising a unidirectional current device connected in series relationship with a small switching device for sensing the voltage across said switching device and for turning on said switching device at a time which ensures substantially lossless switching.

2. The control circuit of claim 1 wherein said voltage sensing means is adapted to turn said switching device on when the voltage across said switching device is approximately zero.

3. A control circuit adapted to drive a switching device of an edge resonant voltage converter bridge circuit wherein said control circuit comprises:

a first circuit means directly coupled to said switching device and comprising a series of transistors arranged to turn on said switching device;

a second circuit means directly coupled to said switching device and comprising a series of transistors arranged to turn off said switching device; and

a voltage sensing means directly coupled to said switching device and comprising a unidirectional current device connected in series relationship with a small switching device for turning on said switching device when the voltage across said switching devices reaches a predetermined minimum level.

4. The control circuit of claim 3 wherein said switching device constitues a field effect transistor.

5. The control circuit of claim 3 wherein said voltage sensing means further comprises:

an input connected to one side of said switching device, said unidirectional current device being connected to said input;

an output connected to said first circuit means;

said small switching device being connected between said output and a predetermined reference voltage; and

an input to said small switching device connected to said unidirectional current device and to said predetermined reference voltage through the parallel combination of a resistor and a second unidirectional current device.

6. The voltage sensing means of claim 5 wherein said small switching device is a field effect transistor.

7. The voltage sensing means of claim 6 wherein said unidirectional current device is a diode.

8. The control circuit of claim 3 wherein said control circuit further comprises:

a second switching device connected to said switching device to form one leg of a voltage converter bridge;

a third circuit means directly coupled to said switching device and comprising a series of transistors arranged to turn on said second switching device;

a fourth circuit means directly coupled to said second switching device and comprising a series of transistors arranged to turn off said second switchig device;

a second voltage sensing means connected to said second switching device and comprising a third unidirectional switching device connected in series relationship with a second small switching device for turning on said second switching device when the voltage across said second switching device reaches a predetermined minimum level; and

inputs to said voltage sensing means and said second voltage sensing means being connected to the junction between said switching device and said second switching device.