SU1504761A1 - Rectifying and inverting converter - Google Patents

Abstract

The invention relates to a converter technique and can be used on railway rolling stock as a main converter in traction and regenerative braking modes. The purpose of the invention is to increase the reliability of operation by increasing the shutdown time of forcibly locked thyristors, reducing the weight and dimensions and increasing efficiency. The device contains a rectifying bridge on thyristors 1-4, the diagonal of the alternating current of which includes sections of the secondary winding 6 of the power transformer, shunted by capacitors 7, 8. The switching node of the device consists of switching capacitor 12 and thyristors 10, 11, 13-15. The transistor thyristor 9 is connected to the anode of thyristor 1, 10, 11, 2 by anode and the cathode to the connection point of capacitors 7, 8. One capacitor 12 is connected to the cathode of thyristor 10 and the anode of thyristor 13, and the other to the anode of thyristor 11 and anode thyristor 14. The cathodes of the thyristors 13, 14 are connected to the ends of the secondary winding 6. Said execution of the switching node ensures the regulation of the duration of the recharging intervals of the capacitor 12 depending on the load current and regardless of the duration of the intervals in which the introduction is made and removing the load current into the winding 6. This allows the use of a smaller capacitor 12, eliminating a recharge choke and increasing reliability. 2 Il.

Description

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the recharge intervals of the capacitor winding 6. This allows the use of 12 depending on the load current and the output of the capacitor 12 of a lower power regardless of the duration of the injection, to exclude the overcharge choke

; Intervals that increase reliability. 2 Il. removal and removal of the load current in

The invention relates to a power thyristor converter technology and is intended primarily for use on a railway-mounted vehicle as a main AC-to-constant converter (in traction mode) and back (in recuperative braking mode).

The purpose of the invention is to increase the reliability of operation by increasing the off time of forcibly locked thyristors, reducing the overall dimensions and increasing the efficiency of the converter.

FIG. 1 shows the electrical circuit of the converter; on fn.2 time diagrams of his work in the mode of .. vypr ml.

The rectifier-inverter converter contains a rectifier bridge consisting of thyristors, through which a load of 5 (traction electric machines) is connected to the secondary sectional winding 6 of a power transformer, parallel to each section of which are included capacitors 7.8. The middle point of the secondary winding 6 of the power transformer is connected to the cathode of the transition thyristor 9, the anode connected to the anode group of shoulders above the thyristor bridge and to the anodes of the first 10 and fourth 11 switching thyristors. The cathodes of the thyristors 10 and 11 are connected by their own terminals to a switching capacitor 12. Moreover, The anodes of the second 13 and third 14 switching thyristors connected by the cathodes to the extreme terminals of the secondary winding 6 of the transformer are also connected to the cathode of the thyristor 10, and the cathode of the thyristor 1 1 is connected to the anode th switching thyristor 15. The cathode of the latter is connected to the cathode group shoulders thyristor bridge rectifying unit (with cathodes of thyristors 3 and 4).

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The rectifier operation in rectification mode is illustrated by the timing diagrams shown in FIG. 2

The curves and. And i are characteristic for this type of converter, respectively, the voltage on the secondary winding 6 of the power transformer and the current in its primary winding (consumed from the mains). The curve U is the voltage of the switching capacitor. 12. The polarity of the voltages U, and U is denoted conventionally and corresponds to their designations in FIG. 1. The remaining diagrams show the open and closed intervals of the thyristors 1-4 of the rectifying bridge, the transition thyristor 9 and the switching thyristors 10, 11, 13-15 (the numbers of the diagrams correspond to the numbers of the thyristors).

In the time intervals t and t, the load current closes outside the windshield 6 of the transformer (buffer period). At the same time, in the interval t /, the switching thyristors 10 and 15 are unlocked, and the thyristors 4 and 9 are locked by voltage and + Uj ,,,. The capacitor 12 is recharged by the load current to a predetermined voltage level. Then the thyristors 1.3 are unlocked and the interval t of the buffer period begins, which continues until the transition thyristor 9 is unlocked. In this case, one section of the secondary winding 6 of the transformer is unlocked. A load current is instantaneously introduced into the indicated section, which excites / waits for an oscillating process in the input circuit formed by capacitors.7.8, the dissipation inductance of the power transformer and the resistance of the supply network brought to them. In the interval t, there is a gradual increase in the current i, up to the magnitude of the load current (excluding attenuation, the oscillatory process in the input circuit). At the moment of termination of the first half cycle, the oscillation of the current in the input circuit unlocks the thyristor 2. Transitional thyristor 9 is blocked by the voltage of the semi-winding 6 of the transformer. The load current is instantly introduced into the entire secondary winding 6 of the transformer, which interrupts the oscillatory process in the input circuit, and the rectification period begins - t4, in which thyristors 2 and 3 are unlocked. In the interval t, the thyristors 1 1 and 14 are unlocked, so that 15 enter the load current into the capacitor 12 and recharge it, with the voltage U locking the thyristor 2. In the interval t, the thyristor 9 is turned on, and the thyristors 11 and 14 are locked with voltage U -. The load current jumps suddenly from one section of the secondary winding 6 of the transformer. This causes an oscillatory process in the input circuit, as a result of which the current i, according to the cosine law, decreases to the forced current of the same circuit, without taking into account the damping of the oscillatory process. At this moment, 30 thyristors 10 and 15 turn on. The thyristors 3 and 9 are locked by the voltage U + Uwj, the load current is instantly derived from the entire secondary winding 6 of the transfimator. The oscillating process 35 in the input circuit is terminated and the buffer interval of the next negative half-period of the supply voltage starts, in which the converter workflows are similar to those described above, except that in the corresponding intervals instead of the thyristor 1 the thyristor 2 is unlocked (and vice versa) instead of thyristor 3 - thyristor 4 and instead of 45 thyristor 14 - thyristor 13.

The average value of the rectified voltage at the load 5 is controlled by changing the moment of switching on the load into the windings 6 of the power transformer 50 (interval t), as well as off (interval t).

In the forced locking intervals of thyristors 1 and 2, for example, tj, these thyristors are locked directly by the voltage U, voltage 1); The secondary winding sections 6 of the transformer are not counter to this process. Thyristors 4 and 9 (3 and 9 in the next half-period) are locked at the beginning of the half-period by voltage} i / i and the resistors 11 and 14 (13) are locked by voltage U and, /, but the discharge of capacitor 12i is not discharged by voltage U of the latter in the interval tj thyristors 10 and 15 are locked.

From the analysis above, it follows that all forcibly lockable thyristors of the converter have a sufficiently long time to restore their locking properties.

The duration of the intervals t, and the t recharges of the switching capacitor 12, is adjusted, for example, depending on the load current, in order to maintain the voltage Uj at the level required to reliably lock the thyristors of the converter, but does not depend on the duration of the intervals t and t, i.e. . introducing and removing the load current into the windings 6 of the transformer, which allows selecting the capacitor 12 less in power. The exclusion of the recharged drosel additionally reduces the mass and dimensional parameters and energy losses in the converter.

Claims (1)

Invention Formula An rectifier-inverter converter containing a power transformer, the secondary winding of which is made of two serially connected sections, each of which is bridged by a capacitor and connected to the output terminals for connecting the load through a rectifying thyristor bridge, to the anode group of the arms of the transition thyristor anode, also a switching node including a switching capacitor and a thyristor, characterized in that, in order to increase the reliability of operation by increasing the time switching off forcibly lockable thyristors .. To reduce mass-dimensional parameters and increase efficiency, four switching thyristors are additionally introduced into the switching node, with the switching capacitor connected to the cathode of the first and anodes of the second and third switching thyristors by a single terminal, and the second switching terminal to the cathode of the fourth switching thyristor and the anode of the fifth commuting thyristor, the cathode connected to the cathode; a group of shoulders of a rectifying thyristor; bridge, with an anode group of shoulders, which connects the anodes of the first and; fourth commuting thyristors, and the cathodes of the second and third commuting thyristors are connected to the corresponding extreme leads of the secondary winding of the power transformer, to the common point of connection of these sections of which The cathode of the transient thyristor is connected.