| 摘要 |
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, which is particularly suited for operating fluorescent or high-intensity discharge (H.I.D.) lamps, includes switching transistors which 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. The addition of a non-saturing 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-saturing 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 a load, such as an electron discharge lamp, which exhibits dynamic negative resistance characteristics. Control windings wound on the two non-saturating cores and serially connected with a variable impedance may be 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. |
