SU771641A1 - Stabilized dc voltage source - Google Patents

Description

The present invention relates to electrical engineering and can be used to power various electronic circuits. A stabilized DC voltage source is known, which contains a master oscillator, a sawtooth voltage generator, an error amplifier, a comparator, frequency dividers, pulse selectors and a power amplifier with rectifier-i. filter 1; The disadvantage of this source is its low reliability due to the absence of protection of transistors of the power amplifier against through currents. The closest in technical essence to the invention is a stabilized constant voltage source containing a power bridge voltage converter on transistors connected via a rectifier a driver and a filter to the output for connecting the load connected to one of the inputs of the error amplifier, the other input of which is connected to the reference source voltage, and the output to one of the inputs of the comparator, another input connected to the output of the sawtooth generator, the input connected to the clock generator and the counting input T - a trigger, to the outputs of which are connected the first inputs of two AND-NOT elements, the second inputs of which connected to the output of the comparator, and the outputs of the elements AND-NOT connected to the inputs 1 of the trigger, the outputs of which are connected to the inputs of the first power amplifier with a transformer output, the output windings of which are connected in series with you The input windings of the second power amplifier and connected to the base circuits of the two-stroke power transducer 2 J transistors. A disadvantage of this device is that to eliminate the through currents in the converter's shoulders, a constant delay is introduced in the operating mode, the value of which is determined by the pulse duration at the inverse output clock generator. A constant delay value does not guarantee the exclusion of through currents due to the variation in the turn-off time of transistors from sample to sample.

and the dependence of this pyrameter on the modes and conditions of operation, which reduces the reliability of the device

The aim of the invention is to increase the reliability of operation of a stabilized source of constant voltage by eliminating the possibility of the occurrence of pass-through current transistors — a two-stroke power converter in an operating mode.

This goal is achieved by the fact that a stabilized DC voltage source is equipped with optocouplers, resistors, OR elements and a trigger device, with a series-connected resistor and LED: pairwise to the inputs of two OR elements, the third inputs of which are connected to the outputs T - of the trigger, and the outputs of the eleN HTOB OR are connected to the inputs of the T15-flip-flop, the outputs of which are connected to the inputs of the second power amplifier.

FIG. 1 shows a fundamental. on the stabilized source circuit. constant voltage; 2, time diagrams of pulses at various points in the circuit.

The power part of the stabilized voltage source circuit contains a push-pull power voltage converter on traction, resistors 1-4, transformer 5, rectifier b, filter 7. The voltage from the output of the filter 7 is fed to the terminals for connecting the load.

The control part consists of an 8-clock pulse generator connected to, a 9-saw pulse voltage generator, and a T-trigger. 10. The output of the meter unit 9 of the sawtooth voltage is connected to one of the inputs of the comparator 11, the second input of which is connected to the output of the error amplifier 12; One of the inputs of the error amplifier 12 is connected to the source 13 of the reference voltage, the second input of the amplifier is connected to the output for connecting the load. The output of the comparator 11 is connected to the inputs of the elements AND-HE 14, 15, the second inputs of which are connected to the outputs of the T-flip-flop 10. The outputs of the elements AND-NOT 14, 15 are connected to the inputs of the Kb-flip-flop 16, the outputs of which are connected to the inputs of the first power amplifier 17 with transformer 18. The inputs of the elements OR 19, 20 are connected to the outputs of the T-trigger 10, and the outputs of these elements are connected to the inputs of the TIS trigger 21, the outputs of which are connected to the inputs of the second power amplifier 22 with a transformer 23. Windings of transformers 23, 23

18, 18 are connected in series to the base circuits of transistors 1-4.

In parallel, transistor 1 is connected in series with resistor 24 and an optocoupler LED 25, transistor 2 — a resistor 26 and an optocoupler LED 27, a transistor 3, a resistor 28 and an optocoupler LED 29, transistor 4 — a resisor 30 and an optocoupler 31 LED. 29, 31 are included anti-parallel. The outputs of the optocouplers 25, 29 are connected to the inputs of the element OR 20, and the optocouplers 27, 31 - on the entrance of the element OR 19.

FIG. Figure 2 shows the timing diagrams of the pulses at the output of the blocks of a stabilized DC voltage source: 32 - generator 8; 33 — sawtooth generator 9; 34 - T-flip-flop 10; 35 - comparator 11; 36 at the base of the transistor 1 (4) power converter; 37 - on the basis of the transistor 2 (3) power converter; 38 - on the collector-emitter of transistor 1 (4)

39- on

output optocoupler 25 (29)

40- on

output optocoupler 2 7 (31)

41- on T, trigger 16; 42 - R, -trigger

21; 43 - at the output of the element OR 19.

The stabilized constant voltage source operates as follows.

A sawtooth voltage, taken from the generator 9, is converted in the comparator 11 into rectangular pulses, the duration of which is determined by the signal from the error amplifier 12, the Latitude-modulated pulses from the output of the comparator 11 and. the pulses from the T-flip-flop 10 are fed to the input of the elements AND-HEN 14.1 from the outputs of which the pulse-modulated pulses with opposite phases arrive at the inputs of the RS flip-flop 16. The rectangular pulses from the T1 & trigger 16 are shifted in time relative to the pulses c t-trigger outputs Id. The magnitude of the shift is equal to the duration of the latitude-modulated pulses from the output of the comparator 11. Signals from optocouplers 25, 29 and 27, 31, the duration of which is equal to the open-state time of the transistors in the diagonal bridge 1, 4 and 2, 3, and pulses from the T-trigger 10 are supplied to the inputs of the elements OR 19, 20. In the case when the open state of the bridge transistors is shorter than half of the working period of the power converter, the inputs of the R) -trigger 21 pass through the elements OR 19, 20 pulses from the outputs of the T-trigger 10 Switching the RS trigger 21 occurs simultaneously. with the T-flip-flop 10, and to the inputs of the amplifiers 17, 22 the power will be

apply two sequences of pulses shifted by the magnitude of the width-modulated signal from the output of comparator 1.1, the phasing of the amplifiers 17, 22 and transformers 18, 23 are selected so that the voltage on the bases of the transistors of the power converter has the form similar to the signals on the diagrams 36, 37 As seen from the diag / m, the opening of the transistors

1.4 and 2, 3 in the bridge diagonal occurs when the T.-flip-flop 21 is switched, and the open time of the transistors is equal to the sum of the pulse duration from the output of the comparator and the turn-off time of the transistors.

In the case when the duration of the pulses from the output of the comparator approaches half the working period and the switching off of the transistors in the bridge diagonal will occur after the switching of the T-flip-flop 10, the switching of the CB-flip-flop 21 will occur already at the instants of the pulses from the optocouplers 25, 29 and 27 , 31, that is, after locking the transistors

2,3 and 1, 4, Thus, the simultaneous opening of the transistors of the shoulders of the power converter and the emergence of through currents are excluded for any value of the time of connecting the transistors.

Testing of the device, made according to the proposed scheme, showed that its reliability significantly increased compared with similar, made according to the well-known scheme, the name “a large variation in the turn-off time of power transistors.

Claims (1)

1. Authors certificate of the USSR 591846, cl. G 05 F 1/64, 1978. 2, Author's certificate of the USSR No. 548929, class, H 02 M 7/12, 1977. five