Transistor drive control for a multiple input D.C. to D.C. converter
First Claim
1. In a D.C. to D.C. voltage converter adapted for energization by various input D.C. voltages each having different D.C. voltage levels relative to each other and each having a positive and negative potential, said positive potential being connected to a center-tap of a primary winding of a saturable transformer, said saturable transformer having a first secondary or base drive winding having a first and a second end and a second secondary winding having a first and a second end with a tap positionable between its first and second ends, said saturable transformer having a core with a substantially square magnetic hysteresis loop characteristic, said negative potential being connected to first and a second transistor diode combinations, each comprising a transistor having a base electrode, said first and said second transistor diode combinations sequentially operating to couple said negative potential to opposite ends of said primary winding causing the core of the saturable transformer to be sequentially excited into its positive and its negative saturation conditions, said first and second transistor diode combinations being controlled by a base drive circuit having a starting resistor with a first end connected to said positive potential and a second end, said base drive circuit being arranged in series with the transistor diode combinations and said base drive winding of said saturable transformer, said base drive winding having an A.C. voltage across its first and second ends representative of the D.C. voltage present at a said primary winding, said second end of said base drive winding being coupled to said base electrode of said second transistor diode combination, said base drive winding voltage experiencing a rapid reversal as the transformer is excited into its negative and positive saturation conditions, said rapid reversal causing the base drive circuit to sequentially render conductive and non-conductive the first and the second transistor diode combinations, said sequential conduction of said first and second transistor diode combinations allowing said transformer to be sequentially driven into its saturation conditions, which, in turn, develops a time-varying signal at the second secondary winding of said transformer which is rectified by an A.C. to D.C. rectifier to develop a desired D.C. output voltage, said base drive circuit further comprising:
- means for converting said A.C. voltage of said base drive winding into a representative D.C. output voltage, said means for converting having a first end coupled to said first end of said base drive winding and a second end coupled to said second end of said starting resistor and to said base electrode of said first transistor diode combination, said D.C. output voltage of said means for converting being coupled across a multiple level current limiting circuit;
said multiple level current limiting circuit developing a current representative of said coupled D.C. output voltage, said current having a first and a second range representative of a first and a second range of said coupled D.C. output voltage, said first and second ranges of said coupled D.C. output voltage being respectively representative of a range of D.C. voltage levels of a first input D.C. voltage and a range of D.C. voltage levels of a second input D.C. voltage;
said means for converting and said multiple level current limiting circuit being arranged to supply as a base drive current said first and second ranges of currents to said base electrodes of said first and second transistor diode combinations, said first and second ranges of currents correspondingly controlling the saturation condition of said first and second transistor diode combinations, said first and second ranges of currents being such as to adapt the saturation condition of said first and second transistor diode combinations to the ranges of said first and second input D.C. voltages;
said adaptation of said saturation condition of said first and second transistor diode combinations to the first and second input D.C. voltages applied to said D.C. to D.C. converter reduces the extent of any increase to the commutational losses for each of the first and second transistor diode combinations that would otherwise occur for major and minor positive increases in the D.C. voltage levels of the applied first and second D.C. voltages.
1 Assignment
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Accused Products
Abstract
A D.C. to D.C. voltage converter is disclosed that operates with various applied D.C. input voltages, each having a different voltage level, to develop a desired D.C. output voltage. The D.C. to D.C. voltage converter has a saturable transformer that is sequentially excited into its positive and negative saturation conditions under control of sequentially operating first and second transistor diode combinations. The D.C. to D.C. converter has a base drive current circuit comprised of a full-wave rectifier and a multiple level current limiting circuit. The base drive current circuit is interposed between a base drive winding of the saturable transformer and the base electrodes of the transistors of first and second transistor diode combinations. The base drive circuit adapts the saturation condition of the first and second transistor diode combinations to the level of the applied D.C. input voltages so as to reduce the level of increase of the commutational losses of the transistor-diode combination that may otherwise occur for increases in the level of the applied D.C. input voltages.
20 Citations
6 Claims
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1. In a D.C. to D.C. voltage converter adapted for energization by various input D.C. voltages each having different D.C. voltage levels relative to each other and each having a positive and negative potential, said positive potential being connected to a center-tap of a primary winding of a saturable transformer, said saturable transformer having a first secondary or base drive winding having a first and a second end and a second secondary winding having a first and a second end with a tap positionable between its first and second ends, said saturable transformer having a core with a substantially square magnetic hysteresis loop characteristic, said negative potential being connected to first and a second transistor diode combinations, each comprising a transistor having a base electrode, said first and said second transistor diode combinations sequentially operating to couple said negative potential to opposite ends of said primary winding causing the core of the saturable transformer to be sequentially excited into its positive and its negative saturation conditions, said first and second transistor diode combinations being controlled by a base drive circuit having a starting resistor with a first end connected to said positive potential and a second end, said base drive circuit being arranged in series with the transistor diode combinations and said base drive winding of said saturable transformer, said base drive winding having an A.C. voltage across its first and second ends representative of the D.C. voltage present at a said primary winding, said second end of said base drive winding being coupled to said base electrode of said second transistor diode combination, said base drive winding voltage experiencing a rapid reversal as the transformer is excited into its negative and positive saturation conditions, said rapid reversal causing the base drive circuit to sequentially render conductive and non-conductive the first and the second transistor diode combinations, said sequential conduction of said first and second transistor diode combinations allowing said transformer to be sequentially driven into its saturation conditions, which, in turn, develops a time-varying signal at the second secondary winding of said transformer which is rectified by an A.C. to D.C. rectifier to develop a desired D.C. output voltage, said base drive circuit further comprising:
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means for converting said A.C. voltage of said base drive winding into a representative D.C. output voltage, said means for converting having a first end coupled to said first end of said base drive winding and a second end coupled to said second end of said starting resistor and to said base electrode of said first transistor diode combination, said D.C. output voltage of said means for converting being coupled across a multiple level current limiting circuit; said multiple level current limiting circuit developing a current representative of said coupled D.C. output voltage, said current having a first and a second range representative of a first and a second range of said coupled D.C. output voltage, said first and second ranges of said coupled D.C. output voltage being respectively representative of a range of D.C. voltage levels of a first input D.C. voltage and a range of D.C. voltage levels of a second input D.C. voltage; said means for converting and said multiple level current limiting circuit being arranged to supply as a base drive current said first and second ranges of currents to said base electrodes of said first and second transistor diode combinations, said first and second ranges of currents correspondingly controlling the saturation condition of said first and second transistor diode combinations, said first and second ranges of currents being such as to adapt the saturation condition of said first and second transistor diode combinations to the ranges of said first and second input D.C. voltages; said adaptation of said saturation condition of said first and second transistor diode combinations to the first and second input D.C. voltages applied to said D.C. to D.C. converter reduces the extent of any increase to the commutational losses for each of the first and second transistor diode combinations that would otherwise occur for major and minor positive increases in the D.C. voltage levels of the applied first and second D.C. voltages. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification