SU1302406A1 - Device for forced commutation of converter thyristors - Google Patents

Abstract

This invention relates to a converter technique and can be used in adjustable rectifiers and inverters. The aim of the invention is to improve technical and energy performance. The device contains a three-phase bridge of switching thyristors (CT) 27–32 and a bridge of charge thyristors 33–36. The AC output of a bridge CT 27–32 is connected to switching .LC circuits 37–42, which are connected via charge thyristors 43 , 46 and separation diodes 44, 45 to the power source (PI) 19. The DC outputs of the bridge CT 27–32 are connected to the PI 19 through diodes 25, 26. The PI 19 includes a filter capacitor (FC) 24. When switching thyristors converter 1 voltage of the corresponding capacitor LC circuits 37 - 42 is limited at the level of FC 24, 1 hp f-ly, 3 ill. a (Q oo tN3 4 o o:

Description

The invention relates to converter equipment and can be used to force the switching of thyristors in controlled rectifiers and inverters 5, in particular in autonomous inverters, for example, AC electric locomotives with asynchronous traction motors.

The aim of the invention is to enhance; technical and economic indicators by more efficiently limiting industrial stresses.

Fig. 1 is a schematic diagram of the device for forcing the switching of the thyristors of the converter; Fig. 2 shows the control pulse diagrams of the respective elements, the operation of the device, as well as the curves of the current and voltage pulses on the switching capacitors; Fig. 3 is a functional diagram of one of the possible variants of the control signal generator of the device for switching the thyristors of the converter.

The device for forced switching (Fig. 1) is connected to the thyristor converter 1, consisting of 2-7 J main thyristors, 8-13 reverse thyristors, 14-16 load, diodes, 17 and 18, with their own buses. The power supply source 19 of the forced switching device is made in the form of a thyristor bridge 20-23 and filter capacitor 24 and connected via diodes 25 and 26 to the DC terminals of a three-phase switching thyristor bridge 27-32. The forced switching device also contains a charge thyristor bridge 33- 36, switching circuit LC, consisting of chokes 37-39 and capacitors 40-42, charge thyristor 43p separation diodes 44 and 45, charge thyristor 46, switching transformer with two Primary windings 47 and 48 with two secondary W windings 49 and 50, discharge diodes 5 оды 52, return diodes. 53 and 54, an anodic group of distribution thyristors 55, consisting of tiris-. tori 56-58, a cathode group of distribution thyristors 59, consisting of thyristors 60-62, limiting thyristors 63 and 64, and driver 65 of control signals. The cathodes of diodes 51 and 53 are connected to common points of thyristor anodes connected.

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27-29 and to the anode of the diode 25, the anodes of the diodes 52 and 54 are connected to the cathodes of the thyristors 30-32 and to the cathode of the diode 26.

Switching LC circuits are connected to one output; .. ohm connected to the AC output pins of the switching thyristor bridge 27-32 and other terminals to the anode of the separation diode 44, to the cathode of the separation diode 45 and to the common connection point of the separation diodes 44 and 45. Anodes the charge thyristors 33r34 and 43 and the cathode of diode 25 are connected to the positive bus of source 19, the cathodes of charge thyristors 35j36 and 46 and the anode of diode 26 are connected to the negative terminal of the power supply 19. The primary windings 47 and 48 of the switching transformer are connected to the cathode and anode of various diodes 44 and 45 and to the knowledge and cathode of the discharge diodes 51 and 52, The secondary windings 49 and 50 of the switching transformer are connected to the end of 4 primary 1x windings 47 and 48 and to the cathode and anode of return diodes 54 and 3, the Anodic group of distribution thyristors 55 is connected by cathodes to the corresponding terminals of the thyristor converter 1 and the anodes to the cathode of separation diode 45,

The cathode group of distribution thyristors under the key is € 1t with anodes to the terminals of the tyrne transmers of the converter 1 and the cathodes to the anode of the separation diode 44, the outputs of the control signal generator 65 are connected to the thyristors 27-36, 43, 46, 56-62J62 and 64, Ogre. Thyristors 63 and 64 are connected by an anode and a cathode to common circuits connections of chokes 37 and 39 with capacitors 40 and 42 and other leads to 1 voltage of power supply 19, Ano; 5 charge thyristors 33 and 34 and charge thyristor cathodes 35 and 35 36 are connected to the buses of the power source 19. The cathode of the thyristor 34 and the anode of the thyristor 35 are connected (2din to the conclusion of the commenting throttle 38s, the cathode of the thyristor 33 and the anode of the thyristor 36 to the conclusions of the chokes 27 and 39,

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Consider the operation of a device for receiving / dutating switching on the example of switching thyristors of an autonomous voltage inverter converter.

Suppose that the thyristors 2s4 and 6 of the converter are turned on at time t, and the load current is closed along the following circuits: plus the input voltage, elements 1,2,14,15 and 16, minus the input voltage; plus input voltage, elements 1,4,16 15 and 6, minus input voltage. Suppose that capacitors 40 - 42 are charged at time t with the polarity indicated in FIG. 1 (with a plus on the right side). At time t, the switching thyristor 27, the switching thyristor 56 to the thyristor 11, and the capacitor 40 begins to discharge in a circuit: elements 40,44,45,56,2,17, 27,37 and 40, the load current is displaced from the thyristor 2 of the converter 1,

At time t, the current of the oscillating LC KOHTypa from the throttles 37 and the capacitor 40 becomes equal to the load current, and the thyristor 2 is locked. The excess current of this LC circuit, which is a part of the switching current pulse exceeding the switched load current, is closed along the circuit: elements 40,44,45, 47,51,27,37 and 40, creating on the primary winding of the switching trans - JQ 1. This opens the reverse of the transformer 47, the voltage drop, plus of which is applied through the distribution thyristor 56 to the cathode of the lockable thyristor 2, and the minus through diodes 51 and 17 - to the anode of the thyristor 2. When the EMF of the secondary winding 49 of the switching transformer is reached, exceeding for example The source 19 on the filter capacitor 24 opens the return diode p4, and the current of the winding 49 closes the circuit: elements 49,51,25,24,26,54,49. Thus, for the duration of the flow of current across the primary winding 47, a reverse voltage of a rectangular shape is applied to the lockable thyristor 2 with an amplitude equal to the charge voltage of the filter capacitor 24 divided by the transformation ratio of the switching transformer and its locking properties are restored

The load current 14 of the switched phase flows through the circuit: plus the power source of the converter 1, elements 17,27,37,40,44,45,56,14,15 and 6, minus the power source of the converter 1. At the time of 35

40

45

rice Op 51 of the inverter and the load current is switched from the LC circuit 39.42 to the load. In this case, in a conventional circuit, the capacitor 42 is recharged for a time interval t, .. t by a falling load current (current and voltage curves are shown by a dashed line) to a voltage much higher than the input voltage of the converter I, along the circuit: the power source of the converter 1 , diode 17, elements 29,39,42,56,14,15 and 6, minus the power source of the converter 1. As the current decreases in the circuit: the power source of the converter 1, elements 17, 29, 39, 42,56,14, 1 S and 6 current in the circuit: elements 14,15,6 and

11 increases, and at time t

but,

50

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The GOK in the LC circuit 41,42 becomes equal to 1mA zero, and in the reverse thyristor circuit, fopa 11 increases to the load current, in the proposed scheme, in contrast to the known one in the time interval t. ,,

about

... t (the current and voltage curves are shown by a solid line) opens the limiting thyristor, and at the time when the voltage of the capacitor 42 becomes equal to the voltage of the power supply 19, the portion of the current t, turns on the switching thyristor 28, and the load current from LC circuit 37, 40 transfer 1-5 TC to LC circuit 38, 41. At time fj, the current of the first LC circuit 37.40 drops to zero, and then the excess of the second LC circuit closes along the circuit: elements 41.45 , 47.51, 28.38, 41. At time t, the switching thyristor 29 is turned on and the load current from the LC circuit 38.41 is transferred to the LC circuit 39.42. The excess current is closed along the circuit: elements 42,47,51,29,41 and 42. At the time tg, the excess current becomes equal to the load current, and diode 5 is closed. Further, if the voltage of the capacitor 42 is less than the input voltage of the power supply source 19, the capacitor of the load circuit is dispensed over the time interval t.,. ,,. t up to the voltage of the power source of the converter 1 along the circuit: plus the power source of the converter 1 elements 17,29,41,42,56,14,15 and 6, minus the power source of the converter 1.

At time t, the voltage of the capacitor 42 becomes equal to the input voltage of the converter.

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rice Op 51 of the inverter and the load current is switched from the LC circuit 39.42 to the load. In this case, in a conventional circuit, the capacitor 42 is recharged for a time interval t, .. t by a falling load current (current and voltage curves are shown by a dashed line) to a voltage much higher than the input voltage of the converter I, along the circuit: the power source of the converter 1 , diode 17, elements 29,39,42,56,14,15 and 6, minus the power source of the converter 1. As the current decreases in the circuit: the power source of the converter 1, elements 17, 29, 39, 42,56,14, 1 S and 6 current in the circuit: elements 14,15,6 and

11 increases, and at time t

but,

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The GOK in the LC circuit 41,42 becomes equal to 1mA zero, and in the reverse thyristor circuit, fopa 11 increases to the load current, in the proposed scheme, in contrast to the known one in the time interval t. ,,

about

... t (the current and voltage curves are shown by a solid line) opens the limiting thyristor, and at the time when the voltage of the capacitor 42 becomes equal to the voltage of the power supply source 19, part of the load current is closed along the circuit; converter power supply point, 1, elements 17,29,39,63,24,26 and 18 / minus power source of converter 1.. At the same time, part of the current is closed along the circuit: plus power supply source of converter 1, elements 17,29,39,42 , 56.14, 15, and 6, minus the power source of converter 1, Since the capacitance of the capacitor 24 is chosen to be much higher than the capacitance of the capacitor 42, the voltage of the capacitors 24 and 42 due to the energy stored in the reactor by the falling load current rises slightly, and therefore, the voltage of capacitor 42 is limited by the level of voltage of the condenser Ator 24, the value of which is maintained at a predetermined level thyristors 20-23. In this case, the load current 14 is closed along the circuit: elements 14, 15, 6, 11, and 14. At time tj, the current in the capacitors 42 and 24 drops to zero and is fully transferred to the circuit: elements 14, 15, 6, and p. Thyristor 56 and the diode 17 is locked, and the switching process is completed. Thus, the energy stored in the capacitor 42 is transferred to the filter capacitor 24, and the choice of the ratio of the capacitors 24 and 42 can limit the voltage on the capacitor 42 at any given level.

At time tg, the charge thyristors 33 and 34 are opened and the switching capacitors 40 and 41 are going through the circuits: plus source 19, elements 33,37,40,44,

(ABOUT

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military thyristor 9. Condenser 42 begins to discharge in a circuit: elements 42,39,32,18., 44.45 and 42, displacing the load current from the thyristor Excess current of capacitor 42 is closed in a circuit: elements 42 (39, 32,52, 48,44,45 and 42.

Plus, the voltage of the winding 48 is applied to the cathode of the lockable thyristor 6 along the circuit: plus the windings 48, elements 52 and 19, the cathode of the thyristor 6. Minus the voltage of the winding 48 is applied through the distribution thyristor 6 to the anode of the thyristor 6, At the moment H it switches on

a thyristor 31, and the load current is transferred from the LC circuit 39 ,, 42 to the LC circuit 385410 B moment t includes the switching thyristor

20 30 ,, and the load current is transferred from the LC circuit 38.41 to the LC circuit 37.40. In the time interval t ,,. T, a control pulse is applied to the limiting thyristor 64, and when the voltage

25 on the capacitor 40 becomes equal to the voltage of the filter capacitor 24 of the power supply source 19, part of the load current is closed in the circuit: plus the power supply of the converter 1

30 elements 2, 14, 15, 6, 4 1, 37, 30 and 18, minus the power supply of converter 1, Another part of the current is closed along the circuit:, plus the power supply of converter 1, elements 2

35 24.64,37,30 and 18, minus the power source of the converter 1; In this case, the load current is transferred to the circuit: elements 15s, 9,2, i4 and 15, At the moment of time the current in the LC circuit 37,38 spa

45 and 46, minus source 19; plus 40 gives to zero, and in the chain: elements 2,

source 19, elements 34,38,41,45 and 46, minus source 19,

Thus, the energy terminated by the load current is used to dose two other LC circuits. At time t, the dispensation process is over, and the circuit is prepared for the next switching with the opposite polarity.

Consider the switching of the thyristors of the cathode group of the converter 1; Suppose that by the time t the thyristors 5,6 and 4 of the converter I are turned on, and the capacitors 40 - 42 are charged with the polarity shown in FIG. I in brackets, At time t, for switching the thyristor 6, the thyristor 6I is switched on, the switching thyristor 32 and with a time delay about

military thyristor 9. Condenser 42 begins to discharge in a circuit: elements 42,39,32,18., 44,45 and 42, displacing the load current from thyristor 6. Excess current of capacitor 42 is closed in a circuit: elements 42 (39, 32, 52,48,44,45 and 42.

Plus, the voltage of the winding 48 is applied to the cathode of the lockable thyristor 6 along the circuit: plus the windings 48, elements 52 and 19, the cathode of the thyristor 6. Minus the voltage of the winding 48 is applied through the distribution thyristor 6 to the anode of the thyristor 6, At the moment H the switching thyristor turns on 31, and the load current is transferred from the LC circuit 39 ,, 42 to the LC circuit 385410 B switching time thyristor

30 ,, and the load current is transferred from the LC circuit 38.41 to the LC circuit 37.40. In the time interval t ,,. T, a control pulse is applied to the limiting thyristor 64, and when the voltage

on the capacitor 40 it becomes equal to the voltage of the filter capacitor 24 of the power supply source 19, part of the load current is closed in the circuit: plus the power supply of the converter 1,

elements 2, 14, 15, 6, 4, 1, 37, 30 and 18, minus the power source of converter 1, Another part of the current is closed along the circuit:, plus the power source of converter 1, elements 25,

24,64,37,30 and 18, minus the power source of the converter 1; In this case, the load current is transferred to the circuit: elements 15s, 9,2, i4 and 15, At the moment of time the current in the LC circuit 37,38 drops to zero, and in the chain: elements 2,

, 9 and 2 increases to the current load,

At the time t, g is turned on, the thyristors are 35.36 and 43, and the condensate is connected.

ss 40 and 4-2 are charged along the chains plus source 19 elements 43,44, 41.j39 and 35, minus source 9; plus source 19, elements 43, 44, 45, 42, 39 and 36, minus source 19. At the time point, the dose current drops to zero, and the co-switching process of the mutation ends. Thus, when the thyristors of the cathodic group of the converter 1 are mutated 1, the voltage of the capacitor 40 is limited at the voltage level of the filter capacitor 24. It is known that the energy i, which is transmitted to the switching and filter capacitors, with the oscillating control, is determined by the inductance of the switching reactor. To reduce the inductance of the switching reactor, the natural frequency of the oscillating circuit of the first and third LC circuits can be selected higher than the second LC circuit. The voltage and current curves of the switching capacitors for this case are shown in FIG. 2. At the same time, the minimum inductance value of the switching reactor can be chosen from the condition of the maximum allowable speed of loading current, i.e.

L. ..-;

dl / dt

where dl / dt is the maximum allowed

direct current rise rate according to thyristor technical conditions. The characteristic impedance of the first and third circuits (i.e., capacitance C can be chosen from the condition that the amplitudes of the switching pulse of the first and third circuits are equal,

C 5: g

those.

-min

where C

2

L. Capacity and inductance of the second circuit.

If the natural frequency of the second oscillating circuit is significantly higher than the natural frequency of the first and third circuits, the inductance of the second circuit with the same amplitudes of the switching current pulses is also much higher, i.e.

H

 fMtf

Consequently, the charging of the second LC circuit from the power source 19 consumes a significant portion of the energy transmitted by the falling load currents of the first and third LC circuits. With such a choice of parameters of commuting LC-circuits, with some loss in size, an energy balance can be achieved.

The use of the proposed forced switching device is most effective when instead of one switching thyristor it is necessary, by the condition of permissible power loss, to turn on three switching thyristors in parallel. In this case, the number of commuting thyristors in the single-circuit and three-circuit circuits is the same. This mode can

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in the case of connecting the windings of the converter 1 into a triangle. In this case, the amplitude of the current pulses, its steepness and, accordingly, the loss in the switching thyristors in the growth and current settings, increases.

The control signal generating system 65, the device for forced switching (FIG. 3), consists of a frequency controller 66 and a control pulse distributor 67 made in the form of two control channels on the logic elements. Each channel of the pulse distributor consists of a amplifier of the body 68, one-shot 69-72, and amplifier-shapers 73-78.

The outputs of the controller 66 are connected to the inputs of the .forming amplifiers 68, the outputs of the shaping amplifiers 68 to the inputs of single-oscillators 69-72, and the outputs of the single-oscillators to the inputs of amplifying amplifiers 73-78. From the outputs of the shaping amplifiers 73-78, the control signals are fed to the control terminals of the thyristors 27-29, 63,33,34 and 46 in the first control channel and to the control outputs of the thyristors 31,30,64,35,36 and 43 in the second control channel.

The control signal shaping device i according to the control pulse pattern operates as follows.

An input reference signal Uj is output to the input of frequency controller 66. frequency From the output of the controller 66 dl. Each phase of the I converter generates two signals (for example, s). According to the diagram (Fig. 3) on the falling edge of these signals, the formers 68 form pulses arriving at the input of thyristors 27 and 45 32 and at the input of one-shot 69-72. Single-oscillators generate pulses with a duration equal to the time intervals t, ... t, t, ... t, t, ... tg, 11 ... tg, no to the rear edges of which 50 amplifiers-formers 73-78 form control pulses, arriving at thyristors 27-29,63,33,34 and 46 in the first control channel and to thyristors 31,30,64,35,36 and 43 in the second control channel.

thirty

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F o

rmula of invention

i. Device for forced switching thyristor converter.

containing a three-phase switching-thyristor power supply source, to the DC terminals of which there are connected the corresponding outputs of two discharge and two return diodes, two consistently-connected separation diodes, three switching LC circuits connected by one appropriate output and to the terminals AC three-phase bridge commuting thyristors and other findings to the corresponding conclusions of the separation diodes, two charge thyristor connected by one anode and cathode to the corresponding power supply lines and other cathodes and anode to the anode of the first and to the cathode of the second isolating diodes, a switching transformer connected by the corresponding leads of their primary windings to the common points of connection of the charge thyristors and the separating diodes, the corresponding leads of the secondary windings to the anodes and cathodes of discharge and return diodes and other conclusions of the primary windings, the anode and cathode group of distribution thyristors connected by anodes to the cathode of the second separating diode ode, cathodes to the anode of the first separating diode and other anodes and cathodes to the corresponding terminals of the thyristor converter, two

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thyristors, connected by an appropriate anode and cathode to the common DMD of junction points of the capacitors and reactors of the corresponding LC circuit forformer control signals connected to the control electrodes of the thyristors, in order to improve technical and energy indicators by more effectively limiting switching voltages S, it is additionally equipped with two: / m diodes connected respectively by a single cathode and anode to the power supply buses and another anode and cathode ohm - to the conclusions of a direct current of a three-phase commutating thyristor bridge, as well as four pairwise counter-connected anodes and cathodes with additional charge thyristors, the common connection points of the anodes and cathodes of which are connected to the positive and negative power supply buses, and their other anodes and the cathodes are attached: to the corresponding pins of the bc-chain; and other pins of the limiting thyristors are connected to the corresponding buses of the power source,

2, The device according to claim 1 (1, characterized by TeMj that the power source is designed as a thyristor bridge with an output filter capacitor,

to. “to & t: -9-eN - 5 -“ OlO

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Claims (2)

Claim 4. Device for forced switching of thyristors of a converter,] 302406 10 containing a power supply, a three-phase bridge of switching thyristors, to the terminals of 'direct current to which ··· are connected the corresponding conclusions of two discharge and two return diodes, two diodes connected in series, three switching LC circuits connected by one of the corresponding terminals to the alternating current terminals <d of the three-phase bridge of the switching thyristors and other terminals to the corresponding terminals of the dividing an ode, two charging thyristors connected by the same anode and cathode to the corresponding buses of the power supply and other cathodes and the anode to the anode of the first and to the cathode of the second isolation diodes, a switching transformer connected by the corresponding terminals of their primary windings to the common points of the connection of the charging thyristors and isolation diodes , the corresponding conclusions of the secondary windings - to the anodes 25 and the cathodes of the discharge and return diodes and to other conclusions of the primary windings, the anode and cathode group x thyristors connected by anodes to the cathode of the second isolation diode, cathodes to the anode of the first isolation diode and other anodes and cathodes to the respective terminals of the thyristor converter, two limiting thyristors connected by the corresponding anode and cathode to common connection points of the capacitors and reactors of the corresponding LC circuits, shaper control signals connected by leads to the control electrodes of the thyristors, characterized in that, in order to improve technical and energy indicators by more efficiently limiting switching voltages, it is additionally equipped with two diodes connected respectively by one cathode and) a 5 anode to the power supply buses and other anode and cathode - to the direct current terminals of the three-phase bridge of the switching thyristors, as well as four two-in-one connected 2Q anodes and cathodes with additional charging thyristors, the common connection points of the anodes and cathodes of which are connected to the positive and negative buses of the power source, and their other anodes and cat odes are connected to the corresponding terminals of the LC circuits, and the other terminals of the limiting thyristors are connected to the corresponding busbars of the power supply source. 2. The device according to π, 1, characterized in that the power source is made in the form of a thyristor bridge with a filter capacitor at the output. 13 024 06 t of tn ti5 tie tn tts tlt't tz a t4t5.tt t7 t8 t9 tto til t16117 t1Q FIG. 2 ‘302406