SU1365236A1 - Protected stabilizing source of secondary power supply - Google Patents

Abstract

The invention relates to electrical engineering and can be used to create secondary power sources for electronic equipment and computer aids. The aim of the invention is to simplify the device. In this technical solution, a signal is used from the information output of the current sensor 7 in each clock pulse for the purpose of controlling the power switch 1 and at the same time for its protection against current overloads. Moreover, this signal contains information both on the current of the power switch 1 and the load on the converter, and on the input mains voltage. This makes it possible to simplify the current protection node, significantly simplify the auxiliary power supply 12, as well as apply a less complex feedback amplifier node 2 and simplify the whole stabilized source circuit as a whole. 2 hp f-ly, 3 ill. from the next

Description

The invention relates to electrical engineering and can be used to create secondary power sources for electronic equipment and computer aids.

The purpose of the invention is to simplify the device.

Figure 1 shows the functional diagram of the device; Fig. 2 is a schematic diagram of a comparator with a memory output; FIG. 3 shows timing diagrams explaining the operation of the device.

The stabilized secondary power supply with protection contains a power switch 1 controlled from the output of the device through the node 2 of the feedback amplifier, a divider of the error signal 3, a comparator 4 with memory of the output signal, the node 5 of the control of the power switch. The input of the power switch 1 is connected to the input mains voltage via the network rectifier 6 with a filter, and the output of the power switch 1 is connected to the output of the device through the current sensor 7, the high-frequency power transformer 8 and the output rectifier 9 with the filter. The comparator 4 by the second input is connected to the output of the current sensor 7, the zeroing input through the comparator zeroing unit 10, with a common connection point for the generator 11 rectangular clock pulses to the input of the power switch node 5. To power the device nodes serves as an auxiliary power source 12, connecting

0 5

is led to the initial state, in which a zero potential is set at its output 22.

In FIG. 3, the following conventions are accepted: U, is the voltage of the generator of rectangular clock pulses; - voltage of comparator 4; - current sensor voltage; U (j is the voltage of the zeroing point of the comparator; uUg is the voltage of the node of the feedback amplifier (the error voltage); uU is the maximum value of the voltage of the node that amplifies 5 l of feedback (the maximum error voltage); uU (jc is the voltage mismatch signal divider; U, j is the power key control voltage; T is the period of the pulse voltage of the rectangular clock pulse; I current flowing through the power key; Ick is the active component

-sk

Q

Ue.c

R

ck

N. (1

(see below); 1 - reagent

current component I

ck

i

i L,

Ktu (see .. below); E is the auxiliary power supply voltage.

The stabilized secondary power supply with protection operates as follows.

The generator 11 generates square-shaped voltage pulses with a period of following T (FIG. 3). At time t, tg, the voltage at the output of the generator 11 takes on a low level value, which removes the prohibition from the node 5 to turn on the power switch 1.

Since its power switch 1 is connected to the output of the rectifier 6 (Fig. 1). through the power transformer 8 and the output rectifier 9, the current flowing through the power switch 1 and the power leads current sensor 7,

The comparator 4 with the memory of the output signal (figure 1) can be performed, for example, as shown in

figure 2. Here, the output of the operational amplifier 13 is connected to its input 14 via a central positive feedback loop 15. The second input 16 of the comparator is connected via a filter 17 to the midpoint of a divider consisting of resistors 18 and 19, connected between a zero potential and an input 14, through a resistor 20 connected to an auxiliary voltage source. Input 21 is connected to the inverting input of one- 55 sawtooth voltage DC with the help of amplifier 13. Input 14 of the current sensor 7 and to the second input of the comparator zeroing, comparator input 4. Voltage p. When a short feedback is fed to this input in a reverse time pulse amplifier, the coupling comparator is compared with the reference voltage 45 has an active reactive character, i.e. I si-ksk. Moreover, the component is determined mainly by the inductance of the transformer 8 and the choke of node 9 (C) and is close to its current magnetics50. Consequently, the shape of the current I is close to the sawtooth, and the amplitude is determined including the discharge of the mains voltage U.. An increase in current I is formed in

The sawtooth voltage DC with the help of the current sensor 7 and is fed to the second input of the comparator 4. The feedback voltage in the feedback amplifier is compared with the reference voltage and has an active-reactive nature, i.e. I si-ksk. Moreover, the component is determined mainly by the inductance of the transformer 8 and the choke of the node 9 (C) and is close to its magnetization current. Consequently, the shape of the current I is close to the sawtooth, and the amplitude is determined including the discharge of the mains voltage U.. An increase in current I is formed in

values determined by voltage

the first input of the comparator 4 (li,). At the moment of time when the voltage DC is equal to uUjjj,, the node of the comparator 4 produces a high voltage

saturation of the operational amplifier node feedback amplifier 2. In this case, the voltage value of the divider

etc.

It is amplified to the required value uUo (;. This reinforced feedback voltage through the divider 3 of the error signal is fed to

The 3 error signals L, fed to the inverting input of the comparator 4 remain constant with a further increase in the load current of the state and, thus, gives an inhibitory bilized source. In this case, the UKO signal to the control unit 5, the magnitude of the load current, is stabilized by the power key 1 and the latter is transferred at the level (points c, d, e, Fig. 3), is in a non-conducting state. Through an appropriate triggering level, some time equal to the time of the overcurrent ignition, and the output time Ujjj, after the time tg, 15

will begin to decline sharply. Since this protection has a high speed and is determined only by the inertial cycle. When the generator 11 again issues a high voltage, the comparator zeroing unit 10, with its short low pulse, applied to the zeroing input of the comparator 4, translates the latter into the initial state corresponding to the low voltage. its output, and the power switch 1 remains off until time t,. Further processes

are repeated (point a, fig. 3).

The interval between times t and tj determines the duration of the control pulse tu, which, in turn, determines the time of the current 30 key 1, and, therefore, the value of the output voltage of the stabilized source. Time of conduction of power switch

By the operation of the electronic components 20 of the feedback amplifier assembly, comparator 4 and power switch control node 5, it is effective both with prolonged overloads and with relatively short extracurrent 25 overload transistors of power

key 1, which take place, for example, in the first moment after switching on the stabilized source when charging the capacities of the output rectifier 9.

Thus, in the proposed technical solution, a signal is used from the information output of the current sensor 7 in each clock pulse for the purpose of controlling the power switch 1 and

1 depends both on the input voltage 35 at the same time to protect it from the current-stabilized source, the magnitude of the saw-tooth voltage, and the output voltage and load current, i.e. the amplitude of the sawtooth voltage and the magnitude of the error signal depend on the reduced load resistance R c of the converter, on KOTOJ & IX.

The overcurrent protection of the source is as follows.

Since the magnitude of the error voltage uUpj. depends on the magnitude of the current delivered by the stabilized source to the load, as well as on the division ratio of the divider 3 of the error signal, then at a certain value of the magnitude of the current nag-

oh overloads. Moreover, this signal contains information both about the current through the power switch and the load of the converter, and about the input mains voltage. This makes it possible to simplify the current protection node in the proposed device, substantially simplify the auxiliary power source, and also apply a less complex node

45 feedback amplifier and simplify the whole stabilized source circuit as a whole.

Claims (3)

1. Stabilized source of ithric power supply with protection containing connected in series between the input and output terminals of the control cable corresponding to the level of the network power supply rectifier with filter, current protection power, key ratio, current sensor, power transformer and an output rectifier with a filter, a feedback amplifier, the input of which is connected to the output of the separator 3, is set such that the magnitude of the error voltage 4 DOC reaches its maximum values determined by voltage saturation of the operational amplifier node feedback amplifier 2. In this case, the voltage value of the divider etc. 3, the error signal L, supplied to the inverting input of the comparator 4 remains constant with a further increase in the load current of the stabilized source. In this case, the magnitude of the load current is stabilized at the level (points c, d, e, fig. 3), corresponding to the level of operation from the current overload, and the output voltage of the stabilized source The operation of the electronic components of the feedback amplifier unit, comparator 4 and power key control unit 5, it is effective both for long-term overloads and for relatively short extracurrent overloads of the power transistor key 1, which take place, for example, in the first moment after switching on the stabilized source when charging the capacities of the output rectifier 9. Thus, in the proposed technical solution, a signal is used from the information output of the current sensor 7 in each clock pulse for the purpose of controlling the power switch 1 and 50 oh overloads. Moreover, this signal contains information both about the current through the power switch and the load of the converter, and about the input mains voltage. This makes it possible to simplify the current protection node in the proposed device, substantially simplify the auxiliary power source, and also apply a less complex node 45 feedback amplifier and simplify the whole stabilized source circuit as a whole. Invention Formula point, power key control unit, output connected to control key power input, equipped with two control inputs, first of which is connected to the output of a square clock generator, characterized in that, in order to simplify the source, a comparator is inserted with the storage signal storage, equipped with a zeroing input, a comparator zeroing node, an adjustable error divider, and the output of the feedback amplifier through the error signal divider is connected to the first input of the comparator, the second input of which is connected to the current sensor output, the zeroing input through the comparator zeroing node is connected to the generator output p rectangular clock pulse, and an output coupled to a second control input of the power key control node. 2. The secondary power source according to claim 1, characterized in that an auxiliary power source is inserted, and the comparator with and about the output signal is mined as an operational amplifier, five resistors, a capacitor and a filter, the output of the operational amplifier connected to the comparator output, connected in series first and second resistors, one of which is bridged by a capacitor, connected to a non-inverting input a comparator connected via a third resistor to the output to connect an auxiliary power source, and through connected in series the fourth and fifth resistors to the bus non-zero potential, the first input of the comparator through the filter is connected to the junction point of the fourth and. five resistors, and the second input is connected to the inverting input of the operational amplifier. 3. The source of the secondary power supply, pripp. 1 and 2, is also distinguished by the fact that the zeroing unit of the comparator is made in the form of a pulse shaper. 15 22 .. UDG 1