Variable-input-voltage converter with delay proportional to V .sub.in / V .sub.out
First Claim
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1. A power converter circuit, comprising:
- a transformer having primary and secondary windings;
a controllable switch connected to vary current, from an input voltage connection, through said primary winding;
wherein said input voltage varies substantially continuously;
a power output connection operatively connected to draw power from said secondary winding of said transformer; and
control logic operatively connected to control switching of said switch in a control relationship which, under at least some circumstances, includes a delay which is dependent on the ratio between the input voltage and the voltage of said power output connection, and is not dependent on direct sensing of the current across said switch nor of the current across said primary winding.
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Abstract
A variable-frequency converters with very wide input voltage tolerance using of variable delays which are proportional to the ratio between the input voltage and the output voltage. This variable delay provides good tolerance for variation in Vin, as well as for variation in Vout. This ratio-dependent delay is used by a secondary-side control subsystem to simulate the current on the primary side, without using any dissipative current sensing techniques.
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Citations
26 Claims
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1. A power converter circuit, comprising:
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a transformer having primary and secondary windings; a controllable switch connected to vary current, from an input voltage connection, through said primary winding;
wherein said input voltage varies substantially continuously;a power output connection operatively connected to draw power from said secondary winding of said transformer; and control logic operatively connected to control switching of said switch in a control relationship which, under at least some circumstances, includes a delay which is dependent on the ratio between the input voltage and the voltage of said power output connection, and is not dependent on direct sensing of the current across said switch nor of the current across said primary winding. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A power conversion method, comprising the steps of:
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(a.) repeatedly switching a transistor to switch an input voltage, which varies over a voltage range of at least 3;
1, onto an inductance, whilekeeping the frequency of said switching step substantially fixed whenever said input voltage falls within a first range of magnitudes, and varying the frequency of said switching step in dependence on said input voltage, whenever said input voltage falls within a second range of magnitudes;
wherein said magnitudes of said second range are all greater than said magnitudes of said first range, andunder at least some circumstances, delaying said switching step by a duration which is proportional to the ratio between said input voltage and the voltage of said output connection, and is not dependent on direct sensing of the current through said transistor; and (b.) coupling power out from said inductance to provide an output of converted power. - View Dependent Claims (8, 9, 10, 11)
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12. A power converter circuit, comprising:
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a transformer having primary and secondary windings; a controllable switch connected to vary current, from an input voltage connection, through said primary winding;
wherein said input voltage varies substantially continuously;a power output connection operatively connected to draw power from said secondary winding of said transformer; and secondary-side control logic operatively connected to draw power from said secondary winding of said transformer, and configured to control switching of said switch in a control relationship which, under at least some circumstances, includes a delay which is proportional to the ratio between the input voltage and the voltage of said output connection, and is not dependent on direct sensing of the current across said switch. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A computer system, comprising:
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memory, and a microprocessor operatively connected to read and write said memory; a graphics controller connected to said microprocessor; a video display connected to said graphics controller; a transformer having primary and secondary windings; a controllable switch connected to vary current, from an input voltage connection, through said primary winding;
wherein said input voltage varies substantially continuously;a power output connection operatively connected to draw power from said secondary winding of said transformer; and control logic operatively connected to control switching of said switch in a control relationship which, under at least some circumstances, includes a delay which is dependent on the ratio between said input voltage and the voltage of said power output connection, and is not dependent on direct sensing of the current across said switch nor of the current across said primary winding. - View Dependent Claims (20, 21, 22, 23)
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24. A power conversion circuit, comprising:
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means for repeatedly switching an input voltage, which varies over a voltage range of at least 3;
1, onto an inductance, whilekeeping the frequency of said switching substantially fixed whenever said input voltage falls within a first range of magnitudes, and varying the frequency of said switching in dependence on said input voltage, whenever said input voltage falls within a second range of magnitudes;
wherein said magnitudes of said second range are all greater than said magnitudes of said first range, andunder at least some circumstances, delaying said switching by a duration which is proportional to the ratio between said input voltage and the voltage of said output connection, and is not dependent on direct sensing of the current across said switch; and means for coupling power out from said inductance to provide an output of converted power. - View Dependent Claims (25, 26)
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Specification