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| Quaternary alloy |
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| Regenerator temperature control |
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FET power converter with reduced switching loss
| Details |
Inventors: Huljak, Robert J.; Newton, Stephen F.; Wallace, Kenneth A.;
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Examiner: Beha, Jr.; William H.
Assistant Examiner:
Attorney, Agent or Firm: McArdle, Jr.; John J.
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 as the switching device in series with an inductor and a second FET 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 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 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. |
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DETAILED DESCRIPTION While the invention is susceptible to various modifications and alternative forms, certain illustrative embodiments thereof have been shown by way of example in the drawings and will herein be described in detail.
It should be understood that it is not intended to limit the invention to the particular forms disclosed, but the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention, as defined by the appended claims.
With initial reference to FIG.
1, a power supply arrangement 10 includes a single output off-line switcher 11 which converts an AC input to a single level DC output.
The output of the off-line switcher 11 is then coupled to a number of power modules 12, 13, 14, etc.
, which are DC-to-DC converters for producing different DC output voltages.
As many converters 12-14 are employed as are necessary to produce the required different DC outputs such as outputs 1, 2 and 3.
With additional reference to FIG.
2, prior power modules, or DC-to-DC converters, have taken a number of forms, including that of the buck converter 20 of FIG.
2a.
In FIG.
2a, a conventional buck converter, or current step-up power converter, 20 utilizes an FET 21 for the series switch and a diode 22 for the flywheel rectifier.
During normal operation of this standard converter, the FET 21 is turned on, impressing the input voltage, less the output voltage, across an inductor 23.
Placing this voltage across the inductor causes the current in the inductor to increase, charging an output capacitor 24 while also delivering current to any load connected in parallel with the capacitor.
When the FET 21 is turned off, the voltage at node 1 (the connection point for the FET 21, the diode 22 and the inductor 23) falls until the diode 22 becomes forward biased.
Current then flows through the diode 22 and the inductor 23 with decreasing amplitude until the FET 21 is again turned on and the cycle repeated.
Switching loss occurs when the FET 21 is turned on and off because of the finite time required for the current to start and stop flowing
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Fuel Cells 
