SU1436245A1 - Three-phase voltage inverter - Google Patents

Description

(21) 4230533 / 24-07

(22) 04/14/87

(46) U7.11.88. Bul No. 41

(71) Leningrad Institute of Railway Engineers

im.akad.VNObraztsova

(72) K.Yu.Vurak, T.K.Aleksandrova and N.P. Lebedeva

(53) 621.314.572 (088.8)

(56) Japanese Application K 51-30251, cl. H 02 M 7/515, 1U76.

USSR Author's Certificate No. 131920U, cl. H 02 M 7/515, 1985.

(54) THREE-PHASE VOLTAGE INVERTER

(57) The invention relates to converter equipment. The goal is to increase the reliability of the inverter in the starting and braking modes of operation by additional charging of the switching capacitors. The device contains a bridge of main thyristors

1-6. The primary windings 30-32 tr-rrv of current 33-35 are included in phases A, B, C of the inverter load, and the secondary windings 36-38 are included in the diagonal of the subglobal bridges on the 39-50 diodes. The outputs of the latter are connected to a separate DC network, to which a charging capacitor 53 is connected. The AC output pins of the switching thyristors bridge T6-21 are connected via the switching capacitors 25-27 and the chokes 60-62 are connected to the AC outputs of the thyristors bridge 1-6. The connection thyristors 56-58 are connected to the junction points of the capacitors 25-27 and the chokes 60-62. The negative input terminal is connected to the negative terminal of single-phase bridges on diodes 39.50, which allows uninterrupted automatic charging of the capacitors 25-27. 3 il.

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The invention relates to power converter technology, namely to bridge thyristor inverters operating in a traction drive with collector motors.

In the starting: and braking modes of the traction electric drive, corresponding to small values of the voltage in the DC link and large. values of the load current, it is necessary to ensure reliable switching of the inverter, while maintaining the permissible dimensions of the switching devices.

The purpose of the invention is to increase the reliability of the inverter in the start-up and torpedo modes of operation by means of additional podnard commutating capacitors.

Figure 1 shows a circuit diagram of a three-phase voltage inverter; Fig. 2 shows a circuit for driving pulses of charge-retarding thyristors; FIG. 3 is a diagram of control pulses for all inverter thyristors.

The three-phase voltage inverter (FIG. 1) contains a three-phase main thyristor bridge 1-6, shunted by reverse diodes 7-12, and a filter capacitor 13 connected to the inverter DC terminals 14 and 15, a three-phase switching thyristor bridge 16-21, of which the thyristors of 19, 21 and 17 of the cathode arms of the inverter are connected to the main negative bus 15 by their cathodes. The middle point 22 (23,24) of each phase pair of switching thyristors 16,19 (18,21 and 20,17) through its switching circuit containing a capacitor 25 (26,27), is connected to the middle point 28 (29,30) a phase pair of main thyristors 1.4 (3.6 and 5.2), which through the primary winding 30 (31.32) of the phase transformer 33 (34.35) of the current is connected to its phase A (B, C) of the load. Secondary winding 36 (37,

38) each of the transformers 33 (34,35) of current is included. Into the diagonal of the alternating current of its single-phase subcharger bridge on diodes 39-42 (43-46, 47-50), of the same name. the direct current of each of which is connected by a common charging reserve 51 and 52, to which a charging capacitor 53 is connected, and to a complex charging reserve

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One end of the end (point 54) is connected to a back-charging choke 55. In addition, the Inverter contains charging thyristors 56-58 and a control block 59 (FIG. 2).

In the switching circuit (points 22 and 28.23 and 29, 24 and 30) of each phase A, B, C in series with the capacitor 25 (26,27) is connected to the midpoint 28 (29,30) of the main thyristors 1,4 (3 , 6 and 5.2) of its phase A (B, C). And its other end 63 (64.65), connected to the switching capacitor 25 (26.27) of its phase A (B, C), is connected to the cathode of the phase charge charging thyristor 56 (57.58).

The anodes of recharge thyristors 56-58 of all phases A, B.C are connected, forming a common additional pin 66, to which the anodes of commuting thyristors 16,18,20 of all the anode shoulders of inverters are connected, the second end 67 of the recharge drossel 55 and the cathode (point 68 ) an additional diode 69, the anode of which is connected to the positive terminal 14 of the inverter, and a negative charge charge

52 connected with pin 15. Recharge control electrodes

thyristors 56-58 are connected to shaper 70 of control signals for charging thyristors (Fig. 2) of control system 59.

Shaper 70 of the control signals (Fig. 2) of the thyristor charge generator 56-58 consists of three NOT logic elements, which are standard microcircuits of the KM 155 Jffl2 series. .

The control unit 59 provides control signals for the opening of the main thyristors 1-6 and the switching thyristors 16-21 according to the pulse diagram shown in FIG. In this control system, a 150-degree control law is used with a duration of control signals of main thyristors 1-6 150 al-degrees. and switching thyristors 16-21 120 el.grad.

The inverter works as follows.

When the supply voltage is applied to the terminals 14 and 15 (Fig. 1) of the inverter, a charge occurs up to the voltage U-Uj of the filter capacitor 13 through the circuit output 14 - the capacitor 13 - output 15, and the charging capacitor 53 along the output 14 - diode 69 - point

68 - point 67 - recharge choke 55 - point 54 - capacitor 53, pin 52 - pin 15. At the same time, choke 55 limits the rate of rise of current di / dt in the charge circuit of the capacitor 53. Thus, when the supply voltage is applied to the 14 and 15 of the inverter almost immediately charge the capacitor 53 to the voltage

When the inverter operates on A, B, C loads, the primary windings 30-32 of the current transformers 33-35 flow around the load current. The currents of the secondary windings 36-38 are rectified by recharge diode bridges 39-42, 43-46 and 47-50, with the result that at the terminals 51 and 52 there is a constant rectified voltage that discharges the charging capacitor 53 to a voltage equal to - with

Next, we consider the operation of the inverter on the example of a single phase, for example, phase A. Suppose that from block 59 (Fig. 2) control pulses are applied to the main thyristors 1 and 6 and to the switching thyristor 19 (Fig. 3). Two current paths are created. The first circuit is the output 14 of the power supply - thyristor 1 - phase A and B of the inverter load - thyristor 6 - output 15 of the power supply. The second circuit is the charge circuit of the switching capacitor 25: pin 14 - thyristor 1 - point 28 - choke 60 - point 63 - capacitor 25 - point 22 - switching thyristor 19 - pin 15 of the power supply. The choke 60 at the same time limits the rate of current rise through the thyristors 1 and 19. As a result of the charge of the capacitor 25, a positive potential is established on its right side, and a negative potential is established on the left. At the end of the charge of the capacitor 25, the thyristor 19 is closed, since the charge current of the capacitor 25 has decreased to zero, and thus the capacitor 25 is ready for subsequent switching,

In the starting or braking modes, as well as during short-term voltage drops in the inverter power network, when the input voltage of the inverter is below the threshold value, and the inverter current exceeds the threshold value, the switching capacity of the capacitor 25 is not sufficient for reliable switching.

436245 tori. To do this, it is necessary to recharge the capacitor 25 in advance, which is ensured by switching on the control unit 59 to simultaneously open the main thyristor 1 and the switching thyristor 19 (in phase A) and also the recharge thyristor 56. Signal to turn on the recharge thyristor

10 56 is identical to the signal for switching on the switching thyristor 19. As a result, a charge circuit of capacitor 25 from the charge source is created, i.e. from the bottom of the bottom of the condensate

15 of the capacitor 53, namely, the point 54 of the capacitor 53 - the charging choke 55 - the point 67 - the point 68 - the output 66 - the charging thyristor.56 - the point 63 - the capacitor 25 - the point 22 20 switching thyristor 19 - the output 15 - Vgod 52 - capacitor 53. This is possible because, due to the passage of current through the load of the inverter at pins 51 and 52, charging

25, an additional voltage appears that is accumulated on the capacitor 53, and the latter, under the described conditions, charges the capacitor 25. At the same time, the pressure value on the capacitor 25 becomes greater than the value. 25, thereby ensuring reliable switching of the phase thyristors.

Similarly, recharging of the capacitor 25 occurs at its opposite polarity, indicated in Fig. 1 in brackets, when the cathode arm of Phase A is operating. At the same time, control pulses (Fig. 2) are supplied to control thyristor 16 and main thyristor 4 (Fig. 3). A charge circuit is created. capacitor 53 - point 54 - choke 55 - point 67 - point 68 - switching thyristor 16 point 22 - capacitor 25 - point 63 - choke 60 - point 28 - main thyristor - output 15 - output 52 - capacitor 53.

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Thus, the switching of the switching capacitor takes place automatically and smoothly, since an additional DC voltage is constantly present at the sub-terminals of 51 and 52 diode bridges. And it will be maintained until the load terminates the electromagnetic processes, i.e. while the load is flowing around the current.

This applies equally to the starting and operating modes, as well as to the braking modes (resistor braking mode and braking with regeneration into the network).

Claims (1)

Thus, the proposed scheme from the first Moment of connecting it to the power supply is provided with the possibility of additional charging of the switching capacitors 25-27 regardless of the possible state of the power source in subsequent operating modes of the inverter, which ensures reliable switching of the inverter. A three-phase voltage inverter containing a filter capacitor connected to the input terminals and a three-phase main thyristor bridge, shunted by reverse diodes, the alternating current leads of which are connected to the output terminals through the primary windings of phase current transformers, the three-phase switching bridge of the thyristors, the cathode group of which is connected to the negative input pins, and pins j5 Signals are neither inclusive sub- subsection d-Criceparow, for example, Siyoen / YuV on the dongle of coimdate mupusmopse The current through the switching capacitors is connected to the cathodes of the corresponding recharge thyristors, the anodes of which are combined and connected via a recharge throttle to the positive terminal of parallel connected single phase diode bridges shunted by the recharge capacitor, the diagonal of the alternating current of each of which is connected to the secondary winding of the corresponding phase transformer, characterized in that, in order to increase the reliability of the inverters in the starting and braking modes of operation, by additional the charges of commuting capacitors, it is equipped with three commutating throttles and an additional diode connected between the positive input terminal and the anode group of the commutating thyristor bridge, combined with the charge thyristor anodes, between the cathodes of which and the AC terminals of the main thyristor bridge the corresponding additional chokes are included The negative input terminal is connected to the negative one of the single-phase diode bridges. one} ABOUT) i Jl 56 W /// L ll; khhchm 17 KH // X1 3 LX4XW4 U / L 3 K / H / U1 TO/// kXXXXX YuOOOO XX1 . .  I -TO 90 t 7ff 360 50 650 720 810 Rig.Z LXXXVVi HLAC W /// L (H CIU Y /// A kXXXXXI Y (: Uhh TO LXXXNXN K /// And kXXXXN U7 // L r //// j CALL KXXXXXN GchHHHHCH . .  I -TO