EP0257404A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Power conversion with reduced switching loss
Assignee: International Business Machines Corp
•
Filing: 1987-08-06
•
Granted: —
•
Expires: 2007-08-06
Abstract
Abstract A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET (31) as the switching device in series with an inductor (33) and a second FET (32) as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor (33) is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry (40) is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter. An over-voltage protection circuit for the output of the converter is also provided.
Inventors
- 👤 Robert John Huljak
- 👤 Stephen Francis Newton
- 👤 Kenneth Andrew Wallace
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:00
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H02M3/156; H02M3/158; H02M3/1588; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
114 words
A method for converting a DC voltage at a source to a DC voltage of a different value at an output, comprising the steps of: supplying current from the source through an inductor, which is coupled to the source, by turning on a semiconductor switch coupled to the inductor at a node; turning off the semiconductor switch; supplying current from the inductor to the output via conduction through a semiconductor device which is coupled to the node; and turning on the semiconductor switch after the current in the inductor has reversed direction, altering the voltage at the node so that there is substantially no voltage across the semiconductor switch when it is turned on.
Claim 2
Independent Claim
114 words
A method for converting a DC voltage at a source to a DC voltage of a different value at an output, comprising the steps of: supplying current from the source through an inductor, which is coupled to the source, by turning on a semiconductor switch coupled to the inductor at a node; turning off the semiconductor switch; supplying current from the inductor to the output via conduction through a semiconductor device which is coupled to the node; and turning on the semiconductor switch after the current in the inductor has reversed direction, altering the voltage at the node so that there is substantially no voltage across the semiconductor switch when it is turned on.
Claim 3
Dependent Claim
40 words
The method of claim 1 in which the step of supplying current from the inductor to the output comprises turning on the semiconductor device which is coupled to the node when there is substantially no voltage across the semiconductor device.
Claim 4
Dependent Claim
96 words
The method of claim 2 wherein said semiconductor switch and said semiconductor device are first and second FET's respectively, said first FET being operable to couple current in a forward direction from the source to the node when the first FET is gated on and having an internal diode permitting the flow of current in a reverse direction, and said second FET being operable to couple current in a forward direction from the node to circuit common when the second FET is gated on and having an internal diode permitting current flow in a reverse direction.
Claim 5
Dependent Claim
146 words
A power converter comprising an input couplable to a DC voltage source, an output couplable to a DC voltage load, an inductor coupled to the input and to the output, a switch coupled in series with the inductor having (a) a closed condition in which current can flow from the input through the inductor and the switch and (b) an open condition, means for permitting at least unidirectional current flow through the inductor to the output when the switch is in its open condition, and means for placing the switch alternately in its closed and open conditions at a frequency greater than 100 kilohertz, the inductor having an inductance, sized relative to a DC load voltage at the output and to the inductor current when the switch is placed in its open condition, which permits the current in the inductor to reverse direction at said frequency.
Claim 6
Dependent Claim
146 words
A power converter comprising an input couplable to a DC voltage source, an output couplable to a DC voltage load, an inductor coupled to the input and to the output, a switch coupled in series with the inductor having (a) a closed condition in which current can flow from the input through the inductor and the switch and (b) an open condition, means for permitting at least unidirectional current flow through the inductor to the output when the switch is in its open condition, and means for placing the switch alternately in its closed and open conditions at a frequency greater than 100 kilohertz, the inductor having an inductance, sized relative to a DC load voltage at the output and to the inductor current when the switch is placed in its open condition, which permits the current in the inductor to reverse direction at said frequency.
Claim 7
Dependent Claim
48 words
The power converter of claim 4 in which the means for placing the switch alternately in its closed and open conditions includes means for maintaining the switch in its closed condition for a suitable period of time to produce a selected peak to peak current through the inductor.
Claim 8
Dependent Claim
24 words
The power converter of claim 5 which further comprises means for establishing a limit value for one of the peaks of the inductor current.
Claim 9
Dependent Claim
82 words
The power converter of claim 4 wherein said switch is a first semiconductor switch and wherein a second semiconductor switch is provided between circuit common and the node at which said first semiconductor switch is coupled in series with the inductor said first and second semiconductor switches having a conductive condition and a non-conductive condition said power converter further including means for alternately placing the switches in a conductive condition for times which produce a substantially constant peak-to-peak current in the inductor.
Claim 10
Dependent Claim
31 words
The power converter of claim 6 which further comprises means for latching the second semiconductor switch in its conductive condition when the voltage at the output exceeds a selected reference value.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.