Electric power conversion systems – Current conversion – With means to introduce or eliminate frequency components
Reexamination Certificate
2000-03-15
2001-04-24
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
With means to introduce or eliminate frequency components
C363S049000
Reexamination Certificate
active
06222744
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of power supplies, and more particularly, to a power supply drive circuit for use with isolated gate drivers.
BACKGROUND OF THE INVENTION
A gate driver is an interface circuit used to provide a control voltage (and resulting current) to dual metal oxide semiconductor (DMOS) and insulated gate bipolar transistor (IGBT) devices used to drive motors and other devices. During operation, the gate driver input can be driven with either a logic level signal or some other low level signal. A special kind of gate driver is an isolated gate driver, where isolation is provided between the input and output, but otherwise the circuit has all the characteristics of a typical gate driver.
Isolated gate drivers generally require isolated power supplies. When gate drivers are used in a motor drive circuit, six isolated power supplies might be used, with one per each IGBT used. The power supply increases the cost of the circuit and reduces the reliability of an already complicated circuit. The wiring attached at nodes with fast changing signals also acts as an antenna for radiating radio frequency interference (RFI), which is detrimental to both the internal circuitry and radio reception in the vicinity of the circuit. Two solutions that have been proposed in the past are the use of a DC/DC converter or a charge pump. The DC/DC converter has high efficiency (80%-90% conversion efficiency), but it is relatively large and expensive. The charge pump is simple and very economical, but has low (40%) efficiency.
SUMMARY OF THE INVENTION
One circuit according to the present invention simply, efficiently and economically provides isolated power for gate drivers of IGBT and DMOS transistors, such as those used in inverters for motor drivers (VSD), uninterruptible power systems (UPS), and other devices. The isolated gate power provided is floating with respect to ground (i.e. it is independent of the potentials at the control input to the gate driver, which may be connected to a microcontroller).
In one embodiment, an isolated gate driver receives a control voltage, and in response to the control voltage, uses power from a drive circuit to output a gate control signal that is coupled to an isolated gate bipolar transistor. The drive circuit comprises a start-up circuit coupled to a supply voltage, a resonant circuit coupled to the start-up circuit and the supply voltage, and a rectifier circuit coupled to the start-up circuit and the resonant circuit, and having logic to output a power signal that is coupled to the isolated gate driver. The rectifier circuit is also coupled to the isolated gate driver at a common node.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
REFERENCES:
patent: 5550436 (1996-08-01), Houk
patent: 5612860 (1997-03-01), Meszlenyi
patent: 5615093 (1997-03-01), Nalbant
patent: 5892673 (1999-04-01), Delgado et al.
patent: 5940287 (1999-08-01), Brkovic
General Electronics Applications, Inc.
Riley Shawn
Townsend and Townsend / and Crew LLP
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