RU1098495C - Series inverter - Google Patents

Abstract

1. A SERIAL INVERTER containing two capacitors connected to the first input terminals, each of which is bridged in series with the 11th thyristor and inductor and connected by a second plate, through a counter diode to another input terminal, two serial circuits in each phase, consisting of an additional throttle and diode, connected in accordance with the thyristor, and connected to the second plates of the capacitors. as well as a load circuit and a pulse-width thyristor pulse control unit, characterized in that, in order to expand the functional capabilities by providing frequency control and obtaining a multiphase output voltage. a multiphase rectifier bridge is introduced; connected opposite to the input terminals and connected by the alternating current outputs for the purpose of loading, as well as by 1 (phase two additional 1 thyristors, two additional capacitors and two transformers are introduced, the primary winding of each of which is connected in series with the diode of the corresponding series circuit and, with it, is shunted by an additional thyristor, and all 11 sequential circuits are connected in parallel and the secondary windings of the transformer | amp; amp; are connected in series with the corresponding diodes of the rectifier bridge are shunted with additional capacitors from the shoulders 2. Invert | 3 according to item 1. on power supply SK and so on) with an output voltage of 10, the transformer is equipped with up to 11 light output voltage, including about 1 corresponding glechr Fighting mitogy bridge. 00 ate

Description

The invention relates to the field of converting direct current into alternating current of variable frequency and amplitude with a different number of phases by means of thyristor inverters with serial switching and can be used to control the speed of AC motors and for power supply systems with a number of phases. excellent O1, .6 | bald.

A serial inverter with two power sources is known, which contains LC-KOHtyp switching elements, key elements, bridge-type connections for connecting key elements to the power source. The disadvantages of this inverter are: unbalanced mode of operation, partially pulsed regulation of the output voltage, restrictions on the magnitude of the load resistance.

Also known is the Ambient motor inverter, containing: 94 cc. Of four LC-KOHrypa with thyristors. connected via power supply diodes, and four key elements in the load circuit. The inverter provides a symmetrical mode of conversion, but it is complex and does not allow regulation of the output 1 strand, the load of the inverter must be inductive.

The closest technical solution to the proposed one is a sequential inverter containing the first and second cells, in each of which a capacitor is connected to the corresponding power supply. and in parallel with it, the first choke and thyristor are connected in series with each other, to which two differently connected diodes are connected, the first diode connected in opposite to the thyristor is directly connected to another lithium bus; the second diode is connected in accordance with the e thyristor and in series with the second inductor, a load circuit and a pulse-width thyristor control unit; ; . /. G.;;; ;. ;.; .:

The inverter is stable over the entire range of variation of the load from infinity to zero. The output parameter is adjustable by pulse width method.

However, this inverter does not provide alternating voltage (current) with a frequency lower. What is the inversion frequency of its own, and when executed at low operating frequencies it has unsatisfactory overall weight and weight indicators.

The aim of the invention is to expand the functionality of the inverter by enabling

control the frequency and obtain a multiphase output voltage.

To achieve this goal in a serial inverter containing

two capacitors connected by the first plates to the corresponding input terminals, each of which is shunted by a thyristor and a choke connected in series and connected by a second plate through a counter diode to another input terminal, two consecutive chains in each phase, consisting of a choke and a diode connected according to C5 by the thyristor and connected to the second capacitor plates, as well as the load circuit and the pulse-width thyristor control unit, a multiphase rectifier bridge connected

0 is towards the input terminals and connected to the AC terminals with a load circuit. In addition, two additional thyristors, two additional capacitors and two trans5 transformers are introduced for each phase, the primary winding of each of which is sequentially connected to the diode of the corresponding series circuit and shunted with it by the additional thyristor , and all

0 consecutive circuits are connected in parallel, and the secondary windings of the transformer are connected in series with the corresponding diodes of the rectifier bridge, whose shoulders are shunted

5 additional capacitors.

With a single-phase output voltage, each transformer is equipped with an additional secondary winding included in the corresponding arm of the external bridge.

The inverter allows you to convert the DC voltage to an alternating voltage of adjustable frequency and amplitude with a different number of phases due to the separate regulation of the current in the windings of the additional transformers by appropriate control of additional thyristors using the start pulses coming from the unit

0 pulse width thyristor control.

In FIG. 1 shows a diagram of a three-phase version of the device: figure 2 - diagram

single-phase device, in Fig.Z. 4 - time diagrams of voltages U and currents I

elements of inverters.

The inverters (Figs. 1 and 2) contain thyristors 1. 2, capacitors connected to the input terminals 3. 4. inductors are connected in series with the thyristors 5. b and counter diodes 7, 8 are series circuits consisting of diodes 9-14 and additional chokes 15-20. Additional thyristors 21-26 bypass the diodes 9-14 and the primary windings of 27-32 transformers connected in series with them. The inverter also contains a power supply 33, a pulse-width control unit 34, and a multiphase rectifier: a bridge on diodes 35-40 connected in turn, with secondary windings 41-46 of transformers in series with the diodes. and the vivods of the AC bridge are connected to the load circuit, additional capacitors 47-52. In Figure 2, D01 additional secondary windings 53. 54 transformers are connected similarly to the main ones. Letters indicate the connection points of the primary windings of the transformers.

On Fig.3-a shows the timing diagrams of the voltages U and currents i of the elements of the inverter of FIG. 1: a - voltage U on the capacitors 3.4; b - voltage U n3 thyristors 1.2; V-current i through the chokes of 5.6 and a torus M t, 2; g-current I through condensers 3.4, d - current Gcherez of the coil 15-20: e-current G through diodes 9-14 and primary windings of 27-32 transformers.

4, a-c, time diagrams of currents I and voltages U of a bridge circuit are given;

a - current I through the secondary windings of 41.46 transformers and diodes 35.40;

b - current i through the secondary windings of 43.44 transformers and diodes 37, 38;

voltage and one phase at the inverter output.

The inverter operates as follows.

Before starting the inverter, the capacitor 3 and 4 (Fig. 1) are charged from the power supply 33 to its voltage (for example, due to the leakage currents of the diodes 7 and 8, if these currents are much larger than the leakage currents of the thyristors 1 and 2). Capacitors 47-52 are charged to a voltage equal to half the voltage of source 33. The voltages at the output terminals of the inverter are zero.

At time ti (Fig. 36), the triggering pulses coming from the control unit 34 (Fig. 1) simultaneously turn on thyristors 1 and 2 and the capacitors 3 and 4 are recharged through thyristors 1 and 2 and chokes 5 and 6. Oscillating circuits formed by the indicated capacitors and throttles have a high quality factor and natural frequency, several times higher than the operating frequency of the inverter, therefore, by the end of the first half-cycle of the natural frequency of the circuits (time t2 in Fig. 3a), the capacitors are charged to the voltage of the initial value but Counterface sign.

During this half-cycle, over a period of time 5 ri t2-ti, a sinusoidal current pulse, shown in FIG. 1, flows in the inverter circuits (Fig. 1). Sv, g. At time t2 (Fig. Over), the current in the circuits drops to zero, the thyristors t and 2 (Fig. 1)

0 turn off, and starts the recharging of capacitors 3 and 4 to source 33, capacitor 3, reactors 15-20, diodes 9-14, primary windings of 27-32 transformers, capacitor 4 of a sinusoidal field of 5 volt current (Fig. 3d and 3d) of duration G2 t4-t2 (Fig. Over). In the absence of a triggering pulse of Additional Thyristors 21-26 (Fig. 1) from the block 34, the currents of the primary windings 2t, 28, 29, 30, 31, 32 of the transformers are transformed in their secondary windings 41, 42, 43, 44, 45, 46 ; with the symmetry of the diode bridge circuit, these currents cannot change the voltages at the capacitors 47, 48, 49, 50, 51, 52, the output voltages

At 5 terminals, the inverters are Zero, and the transforming energy is returned to the power source 33. At time t3, the voltage across capacitors 3 and 4 (Fig. 1), as well as thyristors 1 and 2, becomes equal

0 to zero (t3-t2 is the time allowed to restore the blocking properties of the thyristors), capacitors 3 and 4 begin to charge with the voltage of the original polarity. To the moment when the voltage

5 on the capacitors 3 and 4 reaches the voltage value of the power supply 33, in the interconnections 5,16,17,18., 19, 20 there is still some excess reactive energy, which also returns to the source 33

0 feed per circuit; Inductors 15,16,17,18,19,20, windings 27, 28, 29, 30, 31, 32 of the transformers, diodes 7 and 8. At the time ts, the currents in the inverter circuits cease and the circuit returns to its original state.

5 When triggering pulses are supplied from the control unit 34 to additional thyristors 21, 22; 23, 24, 25, 26 at time ts (Fig. See), the primary windings 27, 28, 29, 30, 31, 32 of the transformers are shunted by additional thyristors, as a result of which the currents in the primary windings, and therefore in the secondary windings 41 , 42, 43, 44, 45, 46 transformers flows only: during the time period tz-t2.

5 Since the additional thyristors 21, 22, 23. 24, 25. 26 are controlled independently of each other, an imbalance is caused by a change in the duration Gz of the current flow in the windings of the individual transformers

voltages at capacitors 47.48,49,50, 51, 52. For example, if thyristors 21 and 25 are turned on before thyristors 22 and 24, voltages at capacitors 47 and 51 will decrease, and at capacitors 5 € and 51 will increase, at In this case, between 8b1 input 4 terminals of viHBepTOpa, voltages appear, the magnitude and change law of which can be controlled by changing the switching moment of each of the additional thyristors 21.22, 2 $. 24.25, 26,

A single-phase inverter operates as described ;. Its circuit is distinguished only by the presence of two transformers, each of which has a file secondary windings 41.54 and 42.53, respectively.

With a large 0% ratio of the inversion frequency to the output frequency of the device (as a rule, the ratio is at least two orders of magnitude), the inverter provides an output sinusoidal voltage with sufficiently small ripple with an invert output frequency. The inverter has high unreliability and durability, the power factor on the supply side is 1, the efficiency is 0.9 (with an inverter power of 5 - 15 kW).

(56) Copyright certificate of the USSR Mg 982510, cl. H 02 M 7 / 515.1978.

USSR author's certificate No. 982511. cl, N 02 M 7 / 515.1978.

Copyright certificate of the USSR I 1011016, cl. H 02 M 7 / 515.1980.

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