SU1111223A1 - Device for protecting reversible bridge converter - Google Patents

Abstract

A DEVICE FOR PROTECTION OF THE BRIDGE REVERSIBLE CONVERTER, containing in each channel of the valves of this bridge bridge a three-input element And whose output is connected to the input of the reacting organ, and the first input is connected to the output of the sensor of the on state of the valves of this shoulder of the bridge, the first and second threshold elements, the inputs of which connected, respectively, to the first and second supply terminals, in phase with the switching voltages of the valves of this and the next, commuting with this, of the bridge arm, differing from themes. that, in order to increase reliability and reduce the size, the third and fourth supply terminals of the signals corresponding to the activated state of the first and second bridges, two inverters and four AND-NOT elements were inserted into each channel of the gates of this reversible bridge, and the outputs of the first and second elements AND-NOT connected to the second input element AND, the outputs of the third and fourth element AND-NOT connected to the third input element AND, the first inputs of the first and third elements AND-NOT connected to the third signal terminal, respectively The first inputs of the second and fourth elements of the NAND are connected to the fourth supply terminal of the signals corresponding to the second state of the second bridge, the output of the first threshold element is connected to the second input of the second element of the NAND, and to the input of the first inverter, the output of which is connected to the second input of the first NAND element, the output of the second threshold element. connected to the second input of the fourth NAND element and to the input of the second inverter, the output of which is connected to the second input of the third NAND element. .

Description

The invention relates to electrical engineering, in particular to converter equipment, and is intended for reverse bridge converters operating in rectifying and inverting modes.

A device for protecting a bridge inverter used in converter equipment, based on Hall sensors fll, is known. I The disadvantages of this device are low speed and low reliability of operation, particularly related to the low noise immunity of Hall sensors. In addition, for them, ha: a typical and non-uniformed design, dependent on the nominal current of the converter due to the different shape and dimensions of the busbar. This creates real obstacles in the design of a series of thyristor converters with a developed current scale from 25 to 12500 A.

The closest to the proposed technical entity is a device that contains in each channel of the valves of this shoulder of the bridge a three-input element I, the output of which is connected to the input of the reacting body, and the first input is connected to the output of the sensor of the switched state of the valves of this shoulder of the bridge, the first and second threshold elements The inputs of which are connected respectively to the first and second terminals of the signal supply, in-phase with the switching voltages of the gates of this and the next, switching from the bridge arm data. The operation of the described device is based on the control of approach.

current of each gate of the bridge to a temporary forbidden zone in the range of 300-360 el.grad. mains frequency with respect to the moment of natural commutation (s, O electr. hail. This device registers at an early stage failures of inversion and, in a number of cases, short-circuits from the alternating side during the breakdown of the thyristors or breakdown of the insulation. Implementation of this device for reversible the anti-parallel circuit is only carried out by monitoring the current of each of the twelve anti-parallel bridge valves and processing data 2-.

The disadvantages of such a security device include low reliability due to the large number of components and electrical connections, as well as large dimensions.

The purpose of the invention is to increase the reliability of the device and reduce its size.

The goal is achieved by the fact that the device for protection of the bridge reversing converter contains in each channel of the valves of this arm of the bridge a three-input element I, the output of which is connected to the input of the reacting octane, and the first input is connected to the sensor of the enabled state of the valves of this arm of the bridge, the first and the second threshold elements, the inputs of which are connected respectively to the first and second terminals of the signal supply, in-phase with the switching voltages of the gates of this and the next, switching About this, the bridge arm into each channel of the gates of this reverse arm of the bridge, the third and fourth clamps of the signals corresponding to the switched-on state of the first and second moshOB, two inverters and four IS-NOT elements are inserted, the outputs of the first and second AND elements NOT connected to the second input of the element AND, the outputs of the third and fourth element AND-NOT are connected to the third input of the element AND, the first inputs of the first and: the third element AND-NOT connected to the third signal supply terminal corresponding to the on state on the bridge. The first inputs of the second and fourth elements of the NAND are connected to the fourth terminal of the supply of signals corresponding to the on state of the second bridge, the output of the first threshold element is connected to the second input of the second element NAND and to the input of the first inverter, the output of which is connected to the second input of the first element AND-NOT, the output of the second threshold element is connected to the second input of the fourth element AND-NOT and to the input of the second inverter, the output of which is connected to the second input of the third AND-NO element.

FIG. 1 shows a functional diagram of a device for protecting a bridge reversing converter; in fig. 2 - diagrams of phase voltages and characteristic time intervals.

The circuit contains a reversing bridge converter.

parallel circuit with valve arms 1-6, sensor 7 of the on state of shoulder 1, supply terminals 8 and 9 of signals corresponding to the activated state of the first and second axles (Forward and Back), respectively, terminals 10 and 11 of the signals in-phase with switching voltages the speakers AC and VA valves 1 and 3, the threshold elements 12 and 13, respectively, the inverters 14 and 15, the elements AND-NOT 16-19, the element 20 and the reacting body 2 T,

The output of the sensor 7 of the on state of the arm 1 is connected to the first input of the element I 20. The first inputs of the logical signals I and NOT 16 and 18 are connected to the signal supply terminal 8 corresponding to the first-bridge enabled state, the second inputs of which through inverters 14 and 15 connected respectively with the outputs of the threshold elements 12 and 13 and at the same time with the second inputs of the elements AND NOT 17 and -19. The first inputs of the AND-HEY elements 17 and 19 are connected to the signal supply terminal 9 corresponding to the on state of the second bridge. The inputs of the threshold elements 12 and 13 are connected respectively to the signal terminals 10 and 11, in phase with the switching voltages AC and VA of the arms 1 and 3, and the outputs of the elements y-HE-16 and 17, 18 and 19 are pairwise connected and connected respectively to the second and third input of the element I 20, the output of which is connected to one of the six inputs of the reacting authority 21.

FIG. 2, the sinusoidal voltages A, B, C are phase mains voltages. The moment of natural commutation of the valve 1 of the first bridge is taken as the zero time reference point. The prohibited zone of this valve is in the range; zone 300360 e. hail.

The forbidden zone of the second bridge valve, connected in parallel with the above mentioned one, is in the range of 120-180 electrical degrees.

The need to distinguish these two zones depending on the direction of the current is obvious.

The device works as follows.

The open state of arm 1 corresponds to a single signal at the output of sensor 7.

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The on position of the first bridge corresponds to a single signal at terminal 8, and consequently, at the first inputs of the elements AND-NOT 1 (6 and 18. At the time the second bridge is switched off, therefore at terminal 9 there is a zero signal that simultaneously hits the first inputs of the elements I- NOT 17 and 19 and causes the output

IQ of these elements are single signals.

When signals in phase with the switching voltages of valves 1 and 3 become negative, the outputs of threshold elements 12 and 13

J5 there are single signals, which fall respectively on the second inputs of the elements AND NOT 17 and 19 and on

the inputs of inverters 14 and 15, when the outputs of the latter are zero signals that fall on the second inputs of the elements AND-NOT 16 and 18, causing the output of the last single signals. Since in the considered phase, at the output of all elements of NAND, there are single signals, they fall on the second and third inputs of the AND 20 element, respectively.

Two single signals at the outputs of indicators 12 and 13 exist simultaneously only in the forbidden zone of the valve 1 of the first bridge, two zero signals at the outputs of the indicated indicators exist simultaneously only in the forbidden zone of the valve of the second bridge, connected opposite 5 parallel to the one mentioned.

Any of these prohibited zones correspond to single signals at the second and third inputs of the element And 20.

0 If the first open zone of the first bridge or the second of the forbidden zones coincides with the first of the prohibited zones. but the open state 5 of the valve of the counter-parallel second bridge coincides, then on all three inputs of the element I 20 there appear single signals, and a single emergency signal also appears on its output

3 signal acting on the reacting body 21.

The construction of a device for protection of a bridge reversing converter is possible by logical conversion of the signals of six sensors of the included switch of the reversing arm depending on two signals corresponding to the switched on state of the first and second bridges, or the generation of signals of forbidden zones shifted by 180 al. depending on the two signals corresponding to the plugged state of the first and second bridge. To form the forbidden zones of all the bridge gates, they use only three line voltages, which process threshold elements and invert them. Therefore, when generating the forbidden zones of all the gates of the first and second bridges, depending on the two signals corresponding to the switched on state of the bridges, it is enough to process (in this case, the inverters) from the outputs of three threshold elements whose inputs are connected to common mode terminals with three line voltages. This way and pea-. Listed in the proposed device. As signals corresponding to the on state of the first and second bridges, it is convenient to use signals from a logic switching device or a polarity signal of the load current of the reversing converter. The device allows protection against two-phase overturning of the reversing bridge converter, increasing reliability, as well as reducing the size of the protective equipment.

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Claims (1)

DEVICE FOR PROTECTING A BRIDGE REVERSE CONVERTER, containing in each channel of the gates of this bridge arm a three-input element And, the output of which is connected to the input of the reacting organ, and the first input is connected to the output of the on-state sensor of the valves of this bridge arm, the first and second threshold elements, the inputs of which are connected respectively 'with the first and second signaling terminals,. in-phase with the switching voltages of the gates of the given and the next bridge arm commuting with the data, characterized in that, in order to increase reliability and reduce the dimensions, the third and fourth signal supply terminals corresponding to the switched on state of the first and the second bridges, two inverters and four AND-NOT elements, the outputs of the first and second AND-NOT elements connected to the second input of the AND element, the outputs of the Third and fourth AND-NOT elements connected to the third mu input of the AND element, the first inputs of the first and third elements AND are NOT connected to the third terminal of the signal supply corresponding to the on state of the first bridge, the first inputs of the second and fourth elements of the NAND are connected to the fourth terminal of the signal supply corresponding to the enabled state of the second bridge, • the output of the first threshold element is connected to the second input of the second AND-NOT element and to the input of the first inverter, the output of which is connected to the second input of the first AND-NOT element, the output of the second threshold element. connected to the second input of the fourth AND-NOT element and to the input of the second inverter, the output of which is connected to the second input of the third AND-NOT element. 11223