SU1417138A1 - D.c. voltage bridge-type converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in high-power power supplies and in converters of electric drives with increased supply voltage. The purpose of the invention is to increase reliability by initially opening the fuse of that pair of switches, the conductive state of which ensures the flow of current in the primary winding of the power transformer II in the direction of the anti-lockable direction of the current flowing when the fuses blown in 4, thyristors 9, 10, the power transformer 13, the current transformer 22, the control unit 23, B1 switch, the master oscillator, the trigger, the logic elements, the formers pulses. Optocouplers 15, 16, 3 were introduced. The control unit 23 introduced logic elements and a trigger. When a transistor fails on the output windings 27, 28 of the current transformer 22 appears voltage, the keys 1-4 close and one of the thyristors 9, 10 opens, forming the circuit of the firing circuit of the failing transistor with the device recovers when key reloading is removed 1 sec. 3 silt of s. Dast: tKoA. 4 lsh & IOBA C # 5

Description

The invention relates to converter equipment and can be used in the development of powerful power sources

The purpose of the invention is to increase the reliability of the converter by first opening the switch and after burning out the fuse of that pair of keys, the conductive state of which provides the JQ generator 33 and the trigger 31. the current flow in the primary winding of the controller is 4-4. power transformer in the direction of-cheny through circuits 36 and 37 electroplating, opposite to the direction of the isolation and logical terminals

of the current flowing during the pre-2I 38 and 39 flushing to the outputs of the logs of the gadgets 15% of the MSHTOB 9 and tO through the formers 40

the output of the trigger 31 connected to the R input. The I input of the trigger 31 sends a signal I, and the C input is connected to the output of the logic element 2I 35 through inputs of the generator 33; Count inputs of the trigger 34 are connected to The outputs of FIG. 1 show an electrical circuit of the proposed constant voltage bridge converter; FIG. 2 shows an electrical circuit of an ultrasound unit 41 of controllable pulses connected to the outputs of logic elements 2I-2ILI 42 and 43e, whose inputs are connected to the outputs according to

 33 and trigger 31. The control of the key inputs 1-4 is connected via circuits 36 and 37 by galvanic output connected to the R-input of the trigger 31. I signal is given to the D-input of the trigger 31, and C input is given via the HE element 32 connected to the output of the back-end generator 33. The counting input of the trigger 34 is connected to the output of the logic element 2I 35, the inputs of which are connected to the outputs of the back 2I 38 and 39 to the outputs of the logic element MSHTOB 9 and tO through the formers 40

and 41 controllable impulses connected to the outputs of logic elements 2I-2ILI 42 and 43e whose inputs are connected to the outputs according to P-g

; The variable dexes correspond to the number of the circuit element shown in FIG. 2)

25

The controls in FIG. 3 are timed 25 25 and 26 and trigger 34 diagrams that explain its operation (the Bridge Constant Voltage Converter works in the following way).

In normal operation, when all the transistors in the keys 1-4 are healthy, alternately switching the diagonally opposite keys 1, 3 and 2, AC, alternating current flowing through the counter-connected ,, primary windings 18, 21 and 19s 20 creates in the transformer magnetic circuit 22 currents oppositely directed magnetizing forces, due to which the total magnetic flux is zero and the secondary windings 27 and 28 voltage is zero. At the inputs of logic elements 2I-2ILI 42 and 43 the signal corresponds to thyristors 9 and 10 are closed. Pa 31 signal corresponds to 1, allowing passage of impulses of the master oscillator 39 to the input; the trigger 34 and the output signals of the trigger 34 to the inputs of the circuits 36 and 37 of galvanic isolation about

. The bridge DC converter contains semiconductor switches 1-4, each of which consists of parallel-connected transistors 5 with fuses 65 included in their collector circuits, and current-leveling elements 7 and 8, two series-connected thyristors 9 and 10 connected to the input terminals through the choke 11, shunted by the diode 12, the primary winding 35 of the power transformer 13 is connected to the middle terminal through current-limiting resistor 14 with the connection point of the thyristors 9 and 10, and the extreme terminals By connecting the diagonally alternating G has a current bridge converter. The radiating elements of the optocouplers 15 and 16 are connected anti-parallel and, through an additional resistor 17, are connected in parallel to the limiting 45 khtsyu resistor 14. The primary windings 18-21 of the current transformer 22 are connected in series with the semiconductor switches 1-4. The control unit 23 contains a logical element 4ILI 50 24, the inputs of which are connected to photo diodes of optocouplers 15 and i6 and via matching circuits 25 and 26 to the secondary windings 27 and 28 of the current transformer 22. Logic output 55

4И11И 24 is connected to the first input and through the element 29 of the delay to the second input of the logic element 2Ж1И 30

The output from the transistor of the bridge converter occurs at the time of their switching. or 11 in the closed state, since in these states they are affected by the maximum level of the switched pulsed power and voltage, thus a short circuit of the collector-emitter junction occurs.

Suppose that at the time of tyfKOi fis. open keys 2 and 4 transistor 5 has failed in the K key. In this case, the output of the bridge transistors of the bridge converter occurs at the moment of their switching. or 11 in the closed state, since in these states they are affected by the maximum level of the switched pulsed power and voltage, thus a short circuit of the collector-emitter junction occurs.

Suppose that at the time of tyfKOi fis. open keys 2 and 4 transistor 5 failed in the K key. In this case

In this case, two circuits are formed through which the currents flow.

The first circuit; positive input terminal —drosssel 11 — winding 19 — key 2 — primary winding of a power transformer 13 — key A — winding 20 — 1-schnus input terminal, corresponds to the normal operation mode of a bridge converter

Second circuit; positive input terminal - choke 11 - winding 18 - fuse 6 - short-circuited transistor 5 - resistor 8 - switch 4 - winding 20 - negative input terminal due to the emergency state of transistor 5 switch -1 o

In the first circuit, windings 19 and 20 of the current transformer 22 are connected in opposite direction, which corresponds to the normal mode, and in the second circuit, windings 18 and 20 are turned on according, so voltage appears on secondary windings 27 and 28. At the output of the matching circuit 26, a signal appears corresponding to 1, which leads to the appearance of a single signal at the R input of the trigger 31, the output of which is set to O. The zero signal at the input of logic element 2I 35 leads to a zero signal at input of the trigger 34 and the latter remains in the state corresponding to the on position of the keys 2 and L. Since the inputs of the logic elements 2I 38 and 39 show a zero signal, then on their outputs also O, which leads to the closing of the keys 2 and 4 ,

Single signals on. the output of the matching circuit 26 and the output Q of the flip-flop 34 lead to the appearance of 1 at the output of the logic element 2I-2ILI 42 The control pulse shaper 40 produces a trigger pulse at the input of the thyristor 10 The latter opens, forming a circuit for current flow; positive input terminal - choke 11 - winding 18 .- fuse 6 - short-circuiting transistor 5 - resistor 8 - left section of the primary winding of the power transformer 13 - resistor 14 - thyristor 10 - minus input terminal The current direction is shown in Fig. 1 with an arrow.

For the delay time of closing the keys 2 and 4, the current rise is limited by the choke 11, and then by the power transformer 13, after saturation of the trans-

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p 5 p

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0

38V

of the formatter 13, the current in the circuit is limited by the resistor 14. At the same time, the signals at one of the inputs and the output of the log of the AILI 24 corresponding to the output correspond to 1, since the photo diode of the optocoupler 16 is open.

After the fuse 6 is blown, which lasts for units — tens of milliseconds and tens to hundreds of conversion periods, stops the circuit at a time, the current in the LED of the optocoupler 16 also stops, the output of the logic element 4IL 24 is set to O. With the delay required for reliable closure of the thyristor 10 and detected by element 29, at time t the output of element 2ILI 30 also sets to

On the falling edge of the pulse generator 33 at time C, the trigger 31 switches to 1, which leads to the resolution of the output signals of the trigger 34 to the inputs of circuits 36 and 37 of galvanic isolation. The trigger 34 is in the state of pre-emergency position, so the keys 2 are reopened and 4 and the current in the first. The primary winding of the power transformer 13 has a direction opposite to the current; occurring when burning fuse. At the output of the logic element 2 and 35 from the moment of time t, clock pulses appear and the normal operation of the device is restored. Since the duration of a clock pulse is a small part of the half period, the time interval is t. -t / j practically corresponds to the half-period and the magneto-conductor of the power transformer from the first imp-lsa enters the established mode

The logical sequence of operation of the elements of the bridge converter is given in the state table.

Thus, in a bridge voltage converter, greater reliability is ensured, since the overloading of the transistors of the keys is avoided when restoring the device operation after the burnout prevents it from fading.

Claims (1)

Invention Formula DC bridge converter containing semi-5U Vodieik keys, each of which consists of N parallel-connected transistors with fuses included in their collector circuits, two series-connected thyristors connected to the input terminals of the converter, a power transformer, the primary winding of which is connected to the thyristor connection point via the middle terminal and the extreme leads are connected to the diagonal of the alternating current of the bridge converter, a current transformer, the primary windings of which are included In conjunction with semiconductor switches, the control node, which includes the master oscillator, the first trigger, the first and second logic elements 2I, 2OR, the outputs of KotopbK, are connected to the control inputs of the thyristors through the drivers, and the inputs are connected to the outputs of the first trigger and through the matching circuit with the secondary windings of the transformer. current, characterized in that, in order to increase reliability, the first and second opto ™ are introduced into it 386 pairs, radiating elements of which are connected in anti-parallel and connected through an additional resistor in parallel to the current limiting resistor, the first9 second and third logic elements 2I, the second trigger and logic elements 4IL, ZHIIH, NOT, are entered into the control unit the inputs of the logical element 4IL are connected to the outputs of matched circuits and photodiodes of optocouplers, and the output is connected to the first input and through the delay element to the second input of the element 2IL, the output connected to the input of the second trigger, to the D input of which a logical single signal is applied - nits a C-input through a logical element is NOT connected to the output of the driver generator counter input-first trigger is connected to the first logic element 2I, whose inputs are connected to the outputs of the master oscillator and the second trigger, outputs of the second and third logic elements 2I are connected to the control inputs of the converter keys through galvanic isolation circuits, and inputs are connected to the outputs first and second triggers. M 5l t : j "Sr