Control circuit for a switching transistor using a tapped coil with oppositely wound coil parts
US5892671A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 14, 1997 |
| Grant date | Apr 6, 1999 |
| Priority date | — |
| Expiry date | Jan 14, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K4/62
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A line deflection circuit for a television receiver or a switched-mode power supply operate with a switching transistor that is connected in series with the primary winding of a transformer and is periodically switched on and off by a switching voltage. In such a circuit, appreciable turn-on and turn-off losses, which reduce the overall efficiency of the circuit, are produced at the switching transistor, particularly at higher operating frequencies. Within a control circuit a DC voltage source is connected to the base of the switching transistor via a periodically actuated switch element and a coil having a core and a tap. The two parts of the coil are wound in opposite senses, and the tap is connected via a diode to ground or to the emitter of the switching transistor. The control circuit further includes a charge-reversal path via which, during a demagnetization phase of the coil, the energy stored in the coil in the form of a current is transferred in the form of a negative voltage to a capacitor that is coupled via a second diode to a first part of the coil. The negative voltage is applied during a residual time subsequent to the demagnetization phase as a reverse voltage to th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.