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1. WO1980001445 - CONVERTISSEUR COURANT CONTINU/COURANT CONTINU

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

What is claimed is:

1. In a converter for providing direct current at a relatively high voltage to a load connected to first and second output terminals of the converter from direct current supplied at a relatively lower voltage from a source connected to first and second input terminals of the converter of the type including a saturable-core square-wave oscillator connected* to the converter input terminals for generating an alternating, square-wave electromotive force in an oscillator secondary winding of a saturable transformer, * forming a portion- of the oscillator, in response to direct current supplied at the converter input terminals and having rectifier means connected between the converter output terminals and the oscillator secondary winding for providing direct current to a load connected to said output terminals in response to an alternating electromotive force supplied thereto, the improvement wherein the converter further comprises amplifier means, interposed between the oscillator secondary winding and the rectifier means and connected to the converter input terminals, for generating and supplying to the rectifier means an electromotive force having an amplitude greater than a potential difference applied to the converter input terminals in response to the alternating, square-wave electromotive force generated in the oscillator secondary winding.

2. The converter of claim 1 wherein the oscillator secondary winding is center-tapped and connected via the center tap thereof to the first input terminal of the converter so as to provide two square-wave oscillator output signals in phase opposition at opposing first and second ends thereof and wherein the amplifier means is charcterized as comprising a push-pull power amplifier comprising:
an amplifier transformer having a center-tapped amplifier primary winding connected via the center tap thereof to the second input terminal of the converter and an amplifier secondary winding connected to the rectifier means; a first switching transistor connected between one end of the amplifier primary winding and the first input terminal of the converter, the collector - of the first switching transistor connected to the amplifier primary winding and the emitter thereof connected to the first input terminal of the converter, and the base of the first switching transistor connected to one end of the oscillator secondary winding to receive one of the square-wave oscillator output signals, whereby the first switching tran- sistor alternates between conducting and non-conducting states corresponding to the two states of the square-wave signal supplied to the base thereof; and
a second switching transistor connected between the other end of the amplifier primary winding and the first input terminal of the converter, the collector of the first switching transistor connected to the amplifier primary winding and the emitter,, thereof connected to the first input terminal of the converter, and the base of the second switching transistor connected to the other' end of the oscillator secondary winding to receive the other of the square- wave oscillator output signals, whereby the second switching transistor alternates between conducting and non-conducting states.

OM corresponding to the state of the square-wave signal supplied to the base thereof, in phase opposition with the alternation between conducting and non-conducting states by - the first switching transistor.

3. The converter of claim 2 wherein the amplifier means further comprises:
a first shaping circuit interposed betwen the oscillator secondary winding and the base of the first switching transistor, comprising:
a first shaping circuit forward current
branch, comprising:
a diode connected in series with the
base-emitter junction of the first
switching transistor so as to
transmit a forward biasing current
thereto;
a resistor connected in series with the
base-emitter junction of the first
switching transistor; and
a capacitor connected in parallel across
the base-emitter junction of the
first switching transistor; and
a diode connected between the base of the
first switching transistor and the
oscillator secondary winding so as to
transmit electrical current in a direction opposite . the direction wherein a
current is transmitted by the diode of
the first shaping circuit forward current
branch; and
a second shaping circuit interposed between the oscillator secondary winding and the base of the second switching transistor, comprising:
a diode connected in series with the base- emitter junction of the second switching
transistor so as to transmit a forward
biasing current thereto;
a resistor connected in series with the base- emitter junction of the second switching
transistor; and
a capacitor connected in parallel across the
base emitter .junction of the second
switching transistor; and
a diode connected between the base of the second switching transistor and the oscillator secondary winding so as to transmit electrical current in a direction opposite the direction wherein a current is transmitted by the diode of the second shaping circuit forward current branch.

4. The converter of claim 3 wherein the resistor of the first shaping circuit forward current branch comprises two, serially connected resistive elements; wherein the resistor of the second shaping circuit for-ward current branch comprises two, serially connected resistive elements; and wherein the amplifier means further comprises:
a diode connected between the collector of the first switching transistor and the junction of the resistive elements of the resistor of the first shaping circuit forward current branch so as to conduct current in the same direction with respect to the oscillator secondary winding as the conduction direction of the diode of the first shaping circuit forward current branch; and
a diode connected between the collector of the second switching transistor and the junction of the resistive elements of the resistor- of the second shaping circuit forward current branch so as to conduct current in the same direction with respect to the oscillator secondary winding as the conduction direction of the diode of the second shaping circuit forward current branch.

5. The converter of claim 1 wherein the saturable transformer of the oscillator is further characterized as having a center-tapped primary winding wrapped on the core thereof and a center-tapped feedback winding wrapped on the core thereof and wherein each of the primary winding, the secondary winding and the feedback winding of the saturable transformer of the oscillator are characterized as being bifilarly wrapped on the core of said transformer.

6. The converter of claim 2, 3 or 4 wherein the amplifier secondary winding is characterized as being center-tapped and wherein each of the primary winding and the secondary winding of the amplifier transformer are characterized as being bifilarly wrapped on the core thereof.

7. The converter of claim 2 wherein the core of the amplifier transformer is characterized as having a lower squareness ratio and a higher saturation flux den-sity than the core of the saturable transformer of the oscillator.