SU1390735A1 - Stabilized voltage converter - Google Patents

Description

(21) 4135819 / 24-07

(22) 10/21/86

(46) 04.23.88. Bul Number 15

(72) S.I. Galas

(53) 621.314.57 (088.8)

(5.6) Collection ed. Yu.I. Konev. Radio and Communications: 1983, p. 20,

rice five.

USSR Author's Certificate 1241371, cl. H 02 M 3/335, 1984.

(54) STABILIZED VOLTAGE CONVERTER

(57) The invention relates to electrical engineering, in particular, to power supply devices of electronic equipment, and is intended to convert and regulate the voltage of the power supply of electronic equipment. The purpose of the invention is reliability by

eliminating the influence of the input voltage on the threshold of the protection circuit against overloads and short circuits at the output. The stabilized voltage converter contains a key element 1, a power transformer 2, a control node 3, an overload current transformer 4, a switch off node 5, a pulse-width modulator 6, a rectifier 7, a current sensor 8, a zener diode 9, the first 10 and second 12 resistors , additional winding 11 power transformer. The introduction to power transformer 2 of an additional winding 11 compensates for the change in the amplitude of the signal on the current sensor as the input voltage changes. This makes it possible to stabilize the threshold of the overload protection circuit. 1 il.

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The invention relates to electrical engineering and radio engineering, namely, to sources of sneKTporaiTEHHH apparatus, and can be used in devices for converting and regulating the supply voltage of electronic equipment.

The aim of the invention is to increase reliability by eliminating the influence of the input voltage on the threshold of overload protection and short circuits at the input.

The drawing shows an electrical circuit of a stabilized voltage converter.

The stabilized voltage converter comprises serially connected key element 1, for example, a transistor, a power transformer 2, a control unit S 3, for example, a current transformer with a primary,

20, the resistor 10 is supplied to a power off, which the design acts on element 1, turning off its fill ratio.

secondary, starting and switching off

windings, transformer 4 current pe-25 -k key element

load, shutdown node 5, for example

transistor diode switch, pulse width modulator 6, made 5

for example on an operational amplifier

voltage at a current of key current at a given level.

Similar processes during the short circuit of n converter 5 as well as during the charging time of the converter filter

rectifier 7, current sensor 8, yapri resistor, zener diode 9, first resistor 10, additional winding 11 of power transformer 2 and second resistor 12. Secondary winding 13 of transformer 4 of overload current through rectifier 7 is loaded on current sensor 8 . The Zener diode 9 and the first resistor 10 are connected in series between the V sensor and the input of the switching off node 5 The additional winding 11 of the power transformer 2 is connected to the common output bus of the converter and the second through the second resistor 12 to the current sensor 8.

The stabilized voltage converter operates as follows.

In steady state operation, the output voltage of the converter is maintained at a constant output voltage by controlling the pulse filling factor of the key element j carried out by the modulation of the output voltage using an iridic-pulse modulator in the feedback circuit. Current of the key element t, transforming into secondary winding 13 of transformer 4 overload current

and flow through the rectifier 7 and the current sensor 8, provides for the last voltage drop proportional to the current of the key element 1. The magnitude of the current sensor 8 is chosen so that the voltage on it is not enough to break the Zener diode 9. In this mode, the protection circuit does not renders

influence the operation of the converter. When an overload occurs at the output of the converter, the current of the key element 1 increases and, consequently, the voltage on the current sensor 8. When this voltage reaches the breakdown voltage of the zener diode 9, the latter breaks through.

The voltage from the current sensor 8 through the punch Zener diode 9 and the first resistor 10 is fed to the input of the switch off node 5, which through the control unit 3 acts on the key element 1, turning it off. As a result, the pulse filling coefficient

Decreasing 1

 - key element

thirty

35

45

50

55

voltage while maintaining the amplitude of the current key element at a given level.

Similar processes occur during a short circuit at the output of the converter 5 and also when it is turned on during the flow time of the charging currents of the output filter capacitor J

When the input voltage changes, for example, when it is increased, the amplitude of the current in the circuit of the key element decreases, and the voltage generated on the windings of the power transformer 2 during the open time of the key element 1 increases.

A decrease in the amplitude of the current in the circuit of the key element 1 results in a y1-1 decrease in the amplitude of the voltage generated on the current sensor 8. At the same time, an increase in the voltage on the additional winding 11 of the power transformer 2 transmitted through the second resistor 12 to the current sensor 8 compensates for a decrease in the voltage amplitude on it caused by a decrease in the amplitude of the current in the circuit of the key element 1. As a result, the signal amplitude on the current sensor 8 remains constant for any values of the input compression voltage, which ensures the stability of the threshold

protection circuit against overcurrent and short circuits at the output of the converter, reduces the load factors of the power elements

the reader, which allows to increase May overall dimensions.

Formula of invention

A stabilized voltage converter containing at least one key element, a power transformer, a control node and an overload current transformer included in series, the input of the key element controlling node through the shutdown node and the pulse-width modulator connected to the potential

ten

.

A transducer output busbar, and a current sensor connected through a series-connected Zener diode and a first resistor to an input of the shutdown node, are connected to the secondary winding of the overload transformer, in order to increase reliability by eliminating the input voltage on the threshold actuation of the protection circuit against overloads and short circuits at the output, the power transformer is equipped with an additional winding, one output of which is connected to the common output bus of the converter, and the other is connected via a second resistor to the current sensor.

Claims (1)

Claim A stabilized voltage converter containing at least one key element, a power transformer, a control unit and an overload current transformer connected in series, the input of the control unit of the key element through the shutdown unit and pulse-width modulator connected to the potential output bus of the converter, and the secondary winding of the overload current transformer through a rectifier is connected to a current sensor connected through a zener diode connected in series and a first resistor to the node input switching off, characterized in that, in order to increase reliability by eliminating the influence of the input voltage on the threshold of the overload protection circuit and output short circuits, the power transformer is equipped with an additional winding, one output of which is connected to a common output bus of the converter, and the other output through the second resistor connected to current sensor.