Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Patent
1986-11-04
1988-02-23
Salce, Patrick R.
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
315411, H02M 3335
Patent
active
047274646
DESCRIPTION:
BRIEF SUMMARY
The point of departure for the invention is a deflection mains-supply concept for television sets, wherein the various operating voltages for the television receiver are generated from the line transformer and the losses from horizontal deflection during line flyback and during part of the first half of the forward stroke are rectified by one section of the switching network that obtains energy by periodically closing an electronic switch that is in series with the primary winding of a transformer and the magnetic energy stored in the primary winding while the electronic switch is open is subsequently transmitted to the primary inductance of the line transformer, whereby the primary winding of the television-receiver line transformer is wired parallel to the same electronic switch through a separating diode, with the horizontal-deflection winding connected to the primary winding, whereby the positive deflection current that flows through the deflection winding also flows through the same electronic switch and the negative deflection current flows through a diode that is wired in parallel with the deflection winding and the generated operating voltage is stabilized during fluctuations in the mains voltage because the conductive phase of the electronic switch is pulse-width modulated by a control circuit in such a way that the energy needed for each horizontal deflection is stored in the primary inductance at the end of the conductive phase of the electronic switch or, in other words, at the end of the horizontal forward stroke.
A circuit of this type is specified in German patent No. 2 130 902. It has the advantage that not only mains function but also deflection function are combined in a single circuit, whereby the switch is exploited not only for the switching-network section but also for horizontal deflection. The circuit, however, also has the drawback that the generated operating voltages for the switching-network section are connected to the same ground as the horizontal-deflection circuit due to the start-up of the line switch, which must in principle be connected to the mains. Mains separation is accordingly possible only when an additional switching-network section is employed. This means, however, the expense of an additional power transistor plus a heat sink and additional driving stages. A separate mains transformer can also be involved, which is very heavy and expensive.
The necessity for separating the mains in television equipment has arisen only recently because the equipment is increasingly being employed as monitors for playing back video recordings, for connection to video games and as displays for home computers for example. Mains separation is also an absolute prerequisite for the connection of a headset. Since the connection for peripherals of this description relates strictly to the signal-processing components of the television set, complete mains separation is unnecessary, and it is sufficient when only these components of the equipment are mains separated.
The object of the invention is to ensure mains separation while retaining the cost-effective concept of the circuit constructed in accordance with the preamble to the claim. This object is attained by the invention recited in the claim. The advantage of the invention is that no expensive additional components are needed.
The essentials of the invention will now be specified with reference to the drawings.
FIG. 1 illustrates one way of realizing the invention and
FIG. 2. illustrates a variant of FIG. 1 with integrated switching circuits.
An operating voltage UO rectified from mains alternating-current voltage source 1 is applied through an inductance 2 to a switch 3 that is periodically opened and closed in accordance with line frequency by a driver circuit 4. Switch 3 is also employed to generate operating voltages U1-Un for the television receiver and to generate a deflection current through horizontal-deflection winding 5. This circuit is completely specified in German patent No. 2 130 902. The magnetic energy stored in induct
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patent: 4188568 (1980-02-01), Manners
patent: 4213166 (1980-07-01), Watanabe
patent: 4398133 (1983-08-01), Beaumont et al.
patent: 4628429 (1986-12-01), Walker
Hartmann Uwe
Mai Udo
Deutsche Thomson-Brandt GmbH
Fogiel Max
Hoff Marc S.
Salce Patrick R.
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