Solid-state inverter including a multiple core transformer
First Claim
1. In combination,a source of a direct current potential,a transformer comprising, in combination, a saturating core, first and second non-saturating cores each exhibiting substantially greater reluctance than said saturating core, a center-tapped primary winding wound on said saturating core and said first non-saturating core, a secondary winding wound on said saturating core and said second non-saturating core, and a feedback winding wound on said saturating core,a pair of semiconductor switching devices each having a control electrode and a transconductive path,circuit means for connecting one of said transconductive paths in series with said source across one half of said primary winding,circuit means for connecting the other of said transconductive paths in series with said source across the other half of said primary winding,circuit means for connecting said feedback winding to the said control electrodes to switch the conductivity of said transconductive paths in phase opposition in response to flux reversals in said saturating core,a capacitor connected in parallel with said primary winding, anda load circuit connected to said secondary winding.
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Accused Products
Abstract
A D.C. to A.C. inverter using switching transistors driving a multiple-core transformer which includes a high-permeability saturable core upon which both the primary and secondary windings are wound and one or more lower permeability non-saturating cores upon which the primary and/or secondary windings are wound to provide additional self-inductance. The inverter switching transistors drive the two halves of the transformer'"'"'s center-tapped primary winding on alternate half-cycles under the control of a feedback winding which is wound on the saturable core. A non-saturating core about which the primary winding is wound, and a capacitor connected in parallel with both halves of the primary winding, protects the switching transistors against transients, prevents the saturating core from going into hard saturation, and efficiently transfers energy stored in the leakage inductance of the primary winding from half-cycle to half-cycle. A second non-saturating core about which the secondary winding is wound contributes additional self-inductance to the output circuit to limit output currents to a safe value, allowing the inverter to be operated safely with short-circuited output terminals or an electron discharge lamp, which exhibits dynamic negative resistance. Control windings on the two non-saturating cores and serially connected with a variable impedance are used to control and/or regulate the magnitude of electrical energy delivered to the load. The multicore transformer is assembled by means of bobbin wound primary and secondary windings through which the center leg of ferrite E-core shapes may be inserted to provide the desired saturating and non-saturating flux paths.
65 Citations
20 Claims
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1. In combination,
a source of a direct current potential, a transformer comprising, in combination, a saturating core, first and second non-saturating cores each exhibiting substantially greater reluctance than said saturating core, a center-tapped primary winding wound on said saturating core and said first non-saturating core, a secondary winding wound on said saturating core and said second non-saturating core, and a feedback winding wound on said saturating core, a pair of semiconductor switching devices each having a control electrode and a transconductive path, circuit means for connecting one of said transconductive paths in series with said source across one half of said primary winding, circuit means for connecting the other of said transconductive paths in series with said source across the other half of said primary winding, circuit means for connecting said feedback winding to the said control electrodes to switch the conductivity of said transconductive paths in phase opposition in response to flux reversals in said saturating core, a capacitor connected in parallel with said primary winding, and a load circuit connected to said secondary winding.
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7. In a saturable core DC to AC inverter of the class comprising, in combination, a transformer having primary, secondary and feedback windings wound on a first ferromagnetic core having a substantially square hysteresis characteristic, transistor switching means coupling said primary winding to a source of a direct current potential, the conductivity of said transistor switching means being controlled by the voltage induced in said feedback winding, and a load circuit connected to said secondary winding,
the improvement comprising: a second ferromagnetic core positioned adjacent to said first core inside said primary winding but outside of said feedback winding, said second core being composed of a material having a substantially smaller permeability than said first core and being non-saturable when subjected to a magnetic field strength adequate to saturate said first core. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A high-frequency power supply comprising, in combination,
first and second toroidal ferromagnetic core structures, said first core structure being composed of a magnetically saturable ferromagnetic material having a substantially square hysteresis characteristic and said second core structure being composed of a different ferromagnetic material which possesses substantially less permeability than said first structure and which does not saturate when subjected to a magnetic field of sufficient strength to saturate said first core, a primary winding wound around both said first and said second core structures, a secondary winding wound on at least one of said core structures, a load circuit connected to said secondary winding, a feedback winding wound around said first core but not around said second core structure, a source of a direct current operating potential, at least one transistor switch having a control input and a switchable transconductive path connected between said source and said primary winding, and means connecting said feedback winding to said control input of said transistor to cause said transconductive path to switch conductivity states in response to the saturation of said first core structure.
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17. Apparatus for supplying a controlled level of alternating current electrical power to an electron discharge lamp which comprises, in combination,
first and second cores of ferromagnetic material forming two independent closed magnetic flux paths, a primary winding wound about said first core only, said primary winding being connected to a source of alternating-current energy, a secondary winding wound about said first and said second cores and connected to supply alternating current energy to an electron-discharge lamp, said second core being non-saturable and producing sufficient self-inductance in said secondary winding to limit the flow of current through said lamp.
Specification