SU1156213A1 - Rectifier with protection against short-circuit currents - Google Patents

Abstract

RECTIFIER WITH A SHORT CIRCUIT CURRENT WITH A 3-phase power transformer, the primary windings of which are intended to be connected via an automatic switch to the corresponding voltage of the network, and the secondary windings connected to the power section of the switches, diagnostics and protection against short-circuit currents, output connected to the power supply the input of the circuit breaker trip control unit, characterized in that, in order to increase maintainability. the top of the switch and the speed of its protection against Short circuits in the power circuits of the diodes, three conductivity sensors are inserted into it, the power part of the rectifier contains diodes connected according to the three-phase center circuit with zero voltage, the three-phase transformer is made according to the Star-Star circuit with zero output on the secondary side, and the diagnostics unit and protection against short-circuit currents includes a signal source of a logical unit, three comparators, three elements NOT, three two-input elements Y-NOT, six delay elements, three two-input elements OR, three synchronized RS-triggers with LED indicators on the output, a three-input element OR, a key element with disconnecting and closing contacts, each conduction sensor connected to the diode of the corresponding rectifier phase, the first and second inputs of the first comparator are designed to be connected respectively to the phases A and B for example network, the first and second inputs of the second comparator are intended to be connected respectively with phases A and C of the network voltage, and the first and second inputs of the third comparator are intended for Connections are respectively to phases B and C of the supply voltage, while the outputs of the first and second comparators are connected to the inputs of the first two-input element AND-NOT and connected to the input of the first and second elements, respectively, the output of the third comparator is not connected to the input of the third element. and connected to the first input of the second two-input element NAND,: the second input of which is connected to the output of the First element NOT, the outputs of the second and third elements are NOT connected to the corresponding inputs of the third two-input element and NAND, the outputs of the first, second, and third two-input elements NAND are connected to the input of the first, second, and third delay elements, respectively, the outputs of which are connected to the first inputs, respectively, of the first.

Description

the second and third two-input OR elements, the second inputs of which are connected to the R-inputs of the ftS-flip-flops and are intended to be connected to the zero potential bus via the contact of the key element, short-circuit contact of which is connected to the signal source of the logical unit, the outputs of the first, second and third two-input elements OR are connected to the C-inputs of the first, second, and third RB triggers, respectively; S, the first, second, and third H5 triggers, respectively, through the fourth, fifth, and sixth elements buckle connected to the output of the diode conduction phase sensor A, B and C, respectively, the outputs of the first, second and third RS-flip-flops are connected to respective inputs trehvhodovogo OR gate, whose output is the output of block diagnostic and protection against short circuit currents.

one

The invention relates to power converter technology and can be applied to power supplies of process control systems.

A known converter of electrical energy, consisting of three parallel operating systems of pulse-phase control (SIFU), diagnostic units and a key switch. The device uses the method of multiple redundancy of SIFUs, the diagnostics of their working capacity is carried out using diagnostic units (CDS), which include a series-connected frequency divider, a proportional differentiating link and a 1J demodulator.

However, the known converter has an insufficiently high reliability due to the absence in it of a high-speed protection against short-circuit currents in the power thyristor block.

The closest to the invention is a device containing a three-phase power transformer, the primary windings of which are intended to be connected to the corresponding voltage of the mains through a circuit breaker and the secondary is connected to the power section of the rectifier, the diagnostic unit and protection against short-circuit currents, output connected to the circuit breaker 2 control unit input.

The disadvantage of this device is also the low response time of the current control. In addition, the current protection circuit of the rectifier does not localize the fault in the rectifier circuit, which deteriorates the maintainability of the device as a whole.

The aim of the invention is to increase the maintainability of the rectifier and the speed of its protection against short-circuit currents in the power diode circuit.

The goal is achieved by the fact that the short-circuited current protection gate has a three-phase power transducer containing primary windings of which are intended to be connected to the corresponding mains voltage through a circuit breaker, and the secondary windings are connected to the power section} of the rectifier, diagnostics and protection against short-circuit 3afre iKaHiui currents, three conductivity sensors were connected to the output of the circuit breaker, and the power part of the transmitter contains diodes, key s by phase rectifier circuit with zero output, trehfzzsh Transfrm Matora configured in a star-star with nulev1F1 vgaodom on the secondary side, and the diagnosis unit and zgaa} agy

5 from short circuits includes a signal source of a logical unit, three comparators, three NOT elements, three two-input AND-NOT elements, six delay elements, three two-input RSHI elements, three synchronized RS triggers with LED output indicators and a three-input element OR, a key element with opening and closing contacts, each conductivity sensor connected to the diode of the corresponding phase of the miter, the first and second inputs of the first comparator are designed to be connected respectively to the phase A and B of the mains voltage, the first and second inputs of the second end / shrator are designed to be connected to the A and C phases respectively, and the first and second inputs of the third comparator are designed to be connected to the B and C phases of the mains voltage respectively, the outputs of the first and the second comparators are connected to the inputs of the first two-input element NAND and are connected to the input of the first and second elements, respectively, the output of the third comparator is connected to the input of the third element NOT and connected to the first input of the second two-input about the NAND element, the second input of which is connected to the output of the first element NOT, the outputs of the second and third elements are NOT under | Switched to the corresponding inputs of the third two-input element AND-NOT the outputs of the first, second and third two-input elements AND NOT are connected to the input of the first, the second and third delay elements, respectively, whose outputs are connected to the first inputs, respectively, of the first. the second and third two-input OR elements, the second inputs of which are connected to the R-inputs of the ftS-flip-flops and are designed to connect to the zero zero potential through the break contact of the key element, the short-circuit contact of which is connected to the signal source of the logical unit, the outputs of the first, second and third two-input elements OR soino dinen with C-inputs of the first, second and third S-flip-flops respectively, S-inputs of the first, second and third RS-flip-flops, respectively, through the fourth, fifth and sixth delay elements connected to the output of the conductivity sensor of the diode of phase A, B and C, respectively, the outputs of the first, second and third V-triggers are connected to the corresponding inputs of the three-input I 13. 4th OR element, the output of which is the output of the diagnostic and protection unit against short-circuit currents. FIG. Figure 1 shows the functional circuit of the mittel with protection against short-circuit currents; in Fig. 2, a functional diagram of a diagnostic unit and a fault from short-circuit currents; in fig. 3 - time diagrams of the rectifier with protection. The device contains a power transformer 1 with primary 2 and secondary 3 windings, diodes 4, 5 and 6, conductivity sensors 7.8 and 9, rectifier load unit 10, circuit breaker 11c by disconnecting control unit 12, diagnostics and current protection unit 13 short circuit, terminals 14-23 for connecting the diagnostic and protection unit 13, bus 24, 25 and 26. Corresponding. voltage U (t), Uj (t), U (t) of phases A, B, C of the rectifier network, first 27, second 28 and third 29 comparators, first 30, second 31 and third 32 elements NOT, first 33 , the second 34 and the third 35 two-input elements AND-NOT, the first 36, the second 37, the third 38, the fourth 39, pt 40 and the sixth 41 delay elements, the first 42, the second 43 and the third 44 two-input elements OR, the three-input element SH-45, RS triggers 46, 47 and 48, LEDs 49, 50 and 51, key element 52, Knevaty 53 for connecting a signal source of a logical unit and a zero potential bus 54. The power transformer T (Fig. 1) is made according to the Star-Star scheme with an external output on the secondary side. Diodes 4, 5, and 6 are designed to rectify the secondary voltage of a transformer 1. Conductivity sensors 7, 8, and 9 of diodes 4, 5, and 6 have a zero output voltage (terminals 14, 15, and 16) in the case of a nonconductive diode 4 5 and 6. In the open state of the diodes 4, 5 and 6, the signal at the output of sensors 7, 8 and 9 corresponds to the logic level 1. The circuit breaker 11 is turned on and off manually. In addition, when a logical unit signal is applied to the input of block 12, automatic switching off of the mains voltage from the mains voltage occurs, KoNmaparopbi 27, 28 and 29 (Fig. 2) have an output signal of logic level 1 when the signal at their first input (terminals 17, 19 and 21) exceeds the signal level at the second input (terminals 18, 20 and 22), otherwise the output signal of the compilers 27, 28 and 29 is zero. Elements 30, 31 and 32 do NOT invert the level of the output signals of comparators 27, 28 and 29. Elements 33, 3 and 35 AND-NOT form a signal of a logical unit in the absence of signals at their inputs. The delay elements 36-41 function in such a way that the leading edge of the output signal is delayed by the time t with respect to the leading edge of the input signal, and the falling edges of the input and output effects coincide. The permission to change the state of the P5-flip-flops 46, 47 and 68 is performed by applying the synchronous 1 signal to the synchronization of the inputs C, and a logical 1% signal is output at the output if the logical t is fed to the S input and the logical O signal is fed to the R input. The translation of the flip-flops 46, 47 and 48 is carried out by applying to; the inputs C and R of the signal a logical 1 with a zero level of influence on the input S. Logical 42, 43, and 44 two-input OR elements and three-input SHSh 45 element form a logical 1 signal at the output if at least one of the inputs has a logical 1 effect. The device works in the following way. Diodes 4.5 and 6 are in the conducting (open) state in time intervals, lying on the m & d by the points of natural commutation of 55-57, 57-5, and 59-55 diodes (Fig. 3). As a result, in the load circuit 10 (Fig. 1), a rectified voltage is generated with a frequency of pulse 19, exceeding three times the frequency of the mains voltage. The conductivity sensors 7, 8, and 9 of diodes 4, 5, and 6 form a logical 1 signal in the case when the corresponding valve is in the conducting state. 13 The diagnostics and protection unit 13 performs the functions of a high-speed protection circuit of the top of the sensor against short-circuit currents in the power diodes 4, 5 and 6. The principle of diagnosing the state of the diodes 4, 5 and 6 is based on the following positions. In the time interval bounded by points 55 and 57 (Fig. Zog), the diode 4 of phase A is in a conducting state. It is obvious that within this range there is no need to monitor the state of diode 4, since the device is dangerous for operation short circuit in the circuit of diodes 5 and 6, when as a result of failure of the circuit, they can be elements with two-way conductivity. Similarly, during the time limited by the points of natural switching 57, 59 and 59, 55 (Fig. 3A), it is necessary to diagnose the state of diodes 4, 6 and 4, 5, respectively. The control of diodes 5 (interval 55-59) and 6 (interval 59-55) from the standpoint of preserving the properties of unilateral conductivity in this case is inexpedient, since from the point of view of the efficiency of the rectifier circuit, this is not fundamental. In addition, the principle of diagnosing the state of diodes 4, 5 and 6 in the proposed device is not based on a quantitative analysis of the parameters of events (the magnitude of the current through the valve, the short for a live (CC) current in the valve chain, etc.), as is usually the case It is realized in known devices, and in the statement of the fact of the occurrence of an event. Indeed, it is hardly advisable, for example, in the time interval 55-57 (fcg. Za) to measure the current through diode 5 or 6, when the mere presence of current through one of these diodes already speaks of the inoperability of the rectifier circuit and the need to turn it off. from the mains voltage for the minimum possible time. Such an approach to the principle of randomizing the state of the sylvic elements of the rectifier circuit significantly simplifies the design of the device as a whole and ensures the maximum performance of the rectifier protection circuit against short circuit currents in the diodes, 5 and 6.

The process of diagnosing the state and the power components of the rectifier proceeds as follows.

Using the comparator 27 (Fig. 2), the levels of the voltages Ud (t) and Ug (t) are compared (Fig. 3a). When U, (t) Ug (t) at the output of the comparator 1) and 27, a signal (t) of logical 1 is generated (Fig. 3S).

The comparator 28 performs a comparison of the voltages U (t) and U (- (t) (Fig. Za). As a result, during the time limited by points 1-4, the output of the comparator 28 generates a signal Xd (. (1) logical 1 (Fig. 3S).

With the help of the element 33, AND-NOT signals (t) (Fig. 3 (5) and Xdc (t) (Fig. 3B) are compared. As a result, the output of block 33 is a signal X | (t) (Fig. Zg) , the interval of the pause (the state of the logical O) which corresponds to the time interval bounded by the points of natural switching 55-57 (Fig. 3a).

The comparator 29, which compares the voltage Un (t) and. (T), generates a logical 1 signal in the code, the duration of which (Fig. 3) corresponds to the time interval between the switching points 56-59 (Fig. 3a). Using block 30, the signal Xd (t) (Fig. DZ) at the output of the comparator 27 (. 2) is inverted (Fig. Zf) and compared using the AND-NE element with the signal Xgc (t) (Fig. Sv).

As a result, at the output of the H – NE 34 element, a signal Xp (t) (Fig. 3) is formed, the pause interval of which corresponds to the duration of the operating state of the diode 5 (Fig. 3, interval 57-58),

With elements 3t and 32, it is not possible to invert the output signals of comparators 2.8 and 29 (Fig. 3, c) the formation of pulses (t) (Fig. Gc, block 31) and Xcg, (t) (Fig. 3, block 32), the duration of which corresponds to the time intervals between points 58-55 and 59-56 (Fig. 3a).

Comparison of the signals (t) and Xte (t) (Fig. 3k, l) leads to the formation of the output element AND-NOT 35

interval of pause, which corresponds to the duration of the operating state of the valve 6 (Fig. 3Q, Ai) points 59-55.

The delay elements 36, 37 and 38 (Fig. 2) lead to a delay in the formation of the leading edge of the logic-1 signal at the output of the elements 42, 43 and 44 OR and the synchronization input C of the triggers 46, 47 and 48. The magnitude of the delay f; (Fig. 3, W, H, signals X (t), X (t), X (t) at the output of blocks 36, 37 and 38, respectively) are selected from the condition of terminating the transient process in the conductivity sensors 7, 8 and 9 (Fig 1) when their output signal decreases to the level of logic O when diodes 4, 5 and 6 are turned off. The output signal of elements 42, 43 and 44 completely repeats the form.

output pulses of blocks 36, 37 and | 38 (Fig. Zd, m, k).

 The delay elements 39, 40 and 41 delay the leading edge of the output signal p (t), f (t), f (t)

Sensors 7, 8, and 9 of logical level 1 by the value when diodes 4, 5, and 6 are turned on (Fig. D, i, n).

Elements 36-41 avoid the ambiguity of the state of the elements

diagnostic circuits at the time of switching currents through diodes 4, 5 and 6 ..

At the same time, the output signals of the logical (t) (Fig. 3d), pg (t)

(Fig. 3c), (t) (Fig. 3n) of sensors 7, 8 and 9 are, as it were, within power intervals (logical O) of signals Xd (d), X (t), X (t) (fig, H ,) synchronization triggers 46j 47 and 48.

During the time t. interval 55-58 (Fig. 3a), at the input C of the trigger, a signal Xd (t) is generated (Fig. 3d)

logical Oh, who carried out the prohibition of its switching on it. state of logic 1. At the same time, the input signal S arrives at the signal ft (t), which does not switch the trigger 46, since X (t) 0 (FIG. 3d).

During the time t., When diode 4 must be closed, the signal X d (t) is logical t and flip-flop 46 can switch to the logical 1 state from the output of conductivity sensor 7. The latter will be possible if diode 4 in the interval t goes out of order and becomes an element with two-way conductivity. Then the output signal of the trigger 46 will become logical 1, the output of the element OR 45 will also generate a voltage of logical 1, which, acting on block 12 (Fig. 1), will cause the tme of the automaton 11 to turn off. Anatomically, the time tg (Fig. 3 m) and t (FIG. 3H) of the operating state of diodes 5 and 6 prohibit the switching of the flip-flops 47 and 48 to the logical 1 state, and the state of their conductivity is monitored during the time intervals Zi and 1e (FIG. 3H). If during the time t (t) the diode 5 (6) goes into the open state, then the corresponding one of the triggers 47 or 48 goes into the state of logical 1, and the circuit breaker is disconnected from the mains voltage. Simultaneously with the transition of the flip-flops 46, 47 and 48 to the state Logic 1, the light indications are turned on based on LED blocks 49, 50 and 51, the presence of which at once 1310 indicates an inoperative diode. For example, the inclusion of the indicator 50 indicates the need to replace the diode 5 of phase B. Thus, the fault location in the circuit of the mitten is localized and the time for its repair is shortened, thus increasing the serviceability of the device. The key 52 serves to set the flip-flops 46, 47 and 48 to the initial zero state. For this, the contact of the key 52 is closed and a logical 1 signal is sent to the inputs C and R of the flip-flops, while at the input S there is a logical O signal, since the power unit of the rectifier is turned on and CPA (t) p (t) "fj. (t) - to logical O. Thus, the proposed device has an enhanced repair power of the miter and the speed of its protection from short amykani currents.

Claims (1)

RECTIFIER PROTECTED FROM SHORT-CIRCUIT CURRENT PROTECTION, containing a three-phase power transformer, the primary windings of which are designed to be connected through the circuit breaker to the corresponding phase of the mains voltage, and the secondary ones are connected to the power part of the rectifier, a diagnostic and protection against short circuit currents, connected to the input of the unit control circuit breaker, characterized in that, in order to improve the maintainability of the rectifier and the speed of its protection against short-circuit currents a short circuit in the circuit of power diodes, three conductivity sensors are introduced into it, the power part of the rectifier contains diodes connected according to the three-phase rectifier circuit with a zero output, a three-phase transformer is made according to the Star-star circuit with a zero output on the secondary side, and the diagnostic and protection unit short circuit currents includes a logic unit signal source, three comparators, three NOT elements, three two-input AND elements, six delay elements, three two-input OR elements, three synchronized RS-flip-flops with LED indicators at the output, a three-input OR element, a key element with opening and closing contacts, with each conductivity sensor connected to the diode of the corresponding phase of the rectifier, the first and second inputs of the first comparator are designed to connect the mains voltage phases A and B, respectively, the first and the second inputs of the second comparator are designed to connect the mains voltage phases A and C, respectively, and the first and second inputs of the third comparator are designed to connect respectively to phases B and C, the voltage of the network, while the outputs of the first and second comparators are connected to the inputs of the first two-input element AND NOT connected to the input of the first and second elements NOT, respectively, the output of the third comparator is connected to the input of the third element NOT and connected to the first the input of the second two-input element AND NOT, the second input of which is connected to the output of the first element NOT, the outputs of the second and third elements are NOT connected to the corresponding inputs of the third two-input element AND, the outputs of the first, second and third I-NOT inputs and inputs are connected to the input of the first, second and third delay elements, respectively, the outputs of which are connected to the first inputs of the first, second and third two-input elements OR, the second inputs of which are connected to the R-inputs of the RS-flip-flops and are intended for connection to the bus of zero potential through the NC contact of the key element, the NC contact of which is connected to the signal source of the logic unit, the outputs of the first, second and third two-input elements OR are connected to With the inputs of the first, second and third RS triggers, respectively, the S inputs of the first, second and third J5 triggers, respectively, through the fourth, fifth and sixth delay elements are connected to the output of the conductivity sensor of the phase A, B and C diodes, respectively, the outputs of the first, second and the third RS-flip-flops are connected to the corresponding inputs of the three-input OR element, the output of which is the output of the diagnostic and protection against short circuit currents.