SU1443106A1 - Electromechanical three-phase frequency converter - Google Patents

Abstract

The invention relates to a converter technique and m. used in power supply systems with variable frequency drive with alternating current. The aim of the invention is to increase efficiency and increase service life. The transducer contains two mechanical needle reciprocating reciprocator (PVPD), containing

Description

zs

  t

 23 312932

t).

i

(L

with:

4i 4

00

O5

electrically conductive fluid with high electrical resistivity. On the same shaft with a PVPD, an additional inverter is installed in the collector's nida and contact rings 36-38, with which the brushes 43-45 are in contact, Parts of the same copper rings 49-51 with which the co-axle actuators 33 and 47, PVPD through mechanical contact gear, built on contact runners x 16, 17 and brushes

18, 19., connected to the thyristors 20, 21. The current through the thyristors 20, 21 flows alternately through a pause in time sufficient to transfer the brushes 33 and 47 from one part of the ring to the other. Due to the conversion, in the form of a converter and a splitter of the number of needle-type phases and electrodes, the area of the electrodes can be increased and, therefore, the switching current density and power can be reduced. 7 il.

t

The invention relates to a converter technique, namely, electromechanical converters of direct current to alternating current, and can be used in power supply systems of loads with alternating three-phase current, adjustable in frequency.

The purpose of the invention is to increase the efficiency and increase the service life.

FIG. 1 is a schematic diagram of a frequency converter in FIG. 2 shows the construction of the collector J in FIG. 3 - electrically conductive plate with steel needles; in fig. 4 — part of an electrically conductive cube with holes; in fig. 5 - electrode needles in the cube hole in FIG. 6 shows the electrical circuit of the frequency converters in FIG. 7, the shape of the curved currents in the phases.

The converter contains a two-stroke crank mechanism 1 mounted on the same shaft with a low-power DC motor 2 in the bearing assemblies 3 and 4. The connecting rods 5 and 6 of the mechanism are connected through hinges 7 and 8 to the rods 9 and 10, which are mounted in the guides II and 12. At the ends of the pins 9 and 10, electrically conductive rectangular plates 13 and 14 are fixed in isolation from them, in which vertically tapered steel needles 15 are mounted (Fig. 3). The needles are fastened with wide ends to the plates either using electric welding or their installation in the holes.

five

five

0

five

0

five

0

plates are poured with liquid metal. Plates with needles form a cathode electrode. Needle electrodes were selected by the cathode in order to reduce needle needleability during electrolysis. The number of needles on the plate can reach several hundred or even thousands of pieces, depending on the power of the converter. Copper runners 16 and 17 are attached to the rods, electrically connected to the plates 13 and 14, with the runners mechanically contact the brush nodes 18 and 19, which are connected to the anodes of the thyristors 20 and 21, the cathodes of which are combined and connected to the negative terminal of the direct current source. Under the plates 13 and 14 are containers 22 and 23 of a dielectric material (plastic). The containers have plastic covers 24 and 25 with rubber gaskets 26 and 27. Holes are made in the covers for the steel needles of the cathode electrode. The containers are arranged in such a way that in the maximum raised position of the pins and plastic the lower ends of the needles do not come out of the collar. The containers are filled with an electrically conductive liquid with high electrical resistivity, which can be used as fresh water. The liquid through the tank circulates as follows.

In tanks 22 and 23, fluid is continuously supplied through hoses from the reserve tank, and from the drain holes restricting the upper level of the liquid, it returns back to the reserve; capacity using a pumping system. Cubes 28 and 29 of electrically conductive material, such as aluminum or graphite, are installed in the containers in the liquid. They are fixed to the container bodies with plastic inserts 30 and 31. In the cubes there are cone-shaped through holes 32, which are placed coaxially with the needles of the cathode electrodes. The largest diameter has the upper edge of the holes, and the sizes of the holes are somewhat larger than the sizes of the needles.

ten

switch 58 and both are connected via resistor 59 by conductor 60 to the power supply output terminal. Two other terminals of the switch contacts are connected to the control terminals of thyristors 20 and 21, Needle barriers are marked as contacts 61 and 62 (Fig. 6).

Instead of mechanical switches, made on stops. 55 and 56 and switches xx 57 and 58; contactless systems can be used, for example, built on reed switches.

(Fig. 5). The cubes form the anode element 15 optoelectronic elements. The electrode is electrically connected and connected to the brush assembly 33 of the additional inverter by wire 34. The secondary inverter comprises a rotor consisting of a collector 35 and slip rings 36-38 mounted on the same shaft in the sub-supports 39 and 40. The rotor shaft of the additional inverter is connected with crankshaft shaft

A standing magnet of a given length can be attached to the rod, and the reed switch can be mounted on a fixed rack. .

The converter works as follows: 20 W.

When voltage is applied to the drive motor 2, it drives the shaft of the crank drive mechanism into rotation. At the same time, the moving return gear mechanism on the two gear 25 forward rods 9 and 10 moving

wheels 41 and 42 with a gear ratio of three to one, with the larger wheel 41 mounted on the shaft of the additional inverter. The stator of the additional inverter is formed by three brush assemblies 43-45 mechanically contacting the rings 36-38 and connected to the three phases of the load 46, as well as two brush assemblies 33 and 47 mechanically contacting the collector 35. As the load 46 can serve as a three-phase stator an asynchronous motor winding Collector (Fig. 2) is made in the form of a dielectric disk 48, on the rim of which at an angle of 120 geometrically grad, to each other three identical parts of copper rings 49-51 with air gaps between them are installed. Each part of the copper ring is connected with conductors 52-54 to contact rings 36 and 38. Brush assemblies 33 and 47 are diametrically opposed, with brush 47 connected to the positive power source. The rods 9 and 10 are fitted with stops 55 and 46 of spring material, which, when moving

50 additional inverter as follows. At the moment of the time interval between the exit of any group of needles from the liquid- and the closure of the contacts of the opposite switch (the besttones of the rods upwards in a certain position can press the buttons of the 55-pause, the next brush 33 or the target switches 57 and 58, set 47 moves from one part of copper to new fixed stands. One of the contact terminals of the switch 57 is connected to the contact terminal of the collector ring to another part of the ring. For example, when the collector disk is rotated clockwise (Fig. 2

switch 58 and both are connected through resistor 59 by conductor 60 to the positive terminal of the power source. Two other terminals of the switch contacts are connected to the control electrodes of the thyristors 20 and 21, Needle barriers are indicated by contacts 61 and 62 (Fig. 6).

Instead of mechanical switches, made on stops. 55 and 56 and switches xx 57 and 58; contactless systems can be used, for example, built on reed switches.

A standing magnet of a given length can be attached to the rod, and the reed switch can be mounted on a fixed rack. .

The converter works as follows.

When voltage is applied to the drive motor 2, it drives the shaft of the crank drive mechanism into rotation. At the same time moving back

Plates 13 and 14 with needles 15 are placed, and the rotor of an additional inverter is rotated through a reducer. Moving around. alternately upward stops in a certain position, press the buttons of the switches, close their contacts. In the usual position, the contacts of the switches are open and the control current from the power source through the resistor 59 to the thyristor control electrodes is not flowing. The mutual arrangement of the stops 55 and 56 and the switches 57 and 58 is chosen so that pressing or pressing the button only occurs when the needles of the opposite plate come out of the liquid, breaking the electrical contact and rise above its level to a certain height. On the very same day

the needles of the other plate are deep in the holes of the cube in the liquid and vice versa.

The movements of the rods are synchronized with the angle of rotation of the rotor shaft of the additional inverter as follows. At the moment of the time interval between the exit of any group of needles from the liquid- and the closure of the contacts of the opposite switch (dead time, the next brush 33 or 47 passes from one part of the copper

cova pause, the next brush 33 or 47 moves from one part of the copper

collector rings to another part of the ring. For example, when rotating the collector disk clockwise (figure 2)

the brush 47 moves from the part of the ring 51 to the part of the ring 50. For one turn of the collector, the brushes 33 and 47 six times pass through the air gaps from one part of the ring to another. This corresponds to the six outputs of the needles of the plate 13 and 14 from the liquid. If we consider that for one revolution of the shaft of the push-pull crank of the no-connecting-rod mechanism there are two alternate exits of the needles of plates 13 and 14 from the liquid, then six alternate exits of the groups of needles correspond to three revolutions of the shaft of the mechanism, per one revolution of the collector shaft. To this end, the gearbox connecting these shafts has a gear ratio of three to one,

When the supply voltage is applied from the source, the control current flows to the control electrode of the thyristor, in the control circuit of which there is a switch with closed contacts, i.e. That switch, on the button which presses the stop. This includes the contacts of the switch 57 (Fig. I), the button which presses the stop 55. The contacts of the switch 58 are open. At the moment of switching on the contacts of the switch 57, the control current begins to flow from the DC source through the resistor 59 to the control electrode of the thyristor 20, which causes it to open. At this time, the brushes 33 and 47 occupy a position on the portions of the copper rings, for example 49 and 50 (Fig. 2 and 6). Through the thyristor 20, the current flows through the circuit: plus source, brush 47, part of ring 30, slip ring 36, brush 45, two phases of the load, for example, phase A and C, brush 43, contact ring 38, part of ring 49, a brush 33, an anode electrode in a vnde cube 29, an electrically conducting fluid, needles 15, an electrically conductive plate 14, a copper runner 17, a brush, 19, a thyristor 20, minus the source (Figs. 1 and 6). As the needles dip into the liquid in the cube holes, the resistance of the liquid contact decreases and the current in the circuit increases, reaching the maximum value in the lowest position of the stem 10. Then, as the stem starts to rise, the needles move out of the holes and the current begins to drop. The conical shape of the holes and the plugs contributes more

0 5 o Q

0

a smooth change in the resistance of the liquid contact, especially in the area where the needles exit from the holes, which prevents a jump in the resistance in this area and the possibility of sparking in the presence of an energetic character of the power circuit. In addition, it is necessary to take into account that in the area where the needles exit the holes, the resistance of the liquid contact increases significantly, which leads to a sharp increase in heat generation from the flowing electric current, and the liquid layer in the gap between the needle and the hole is insignificant, because of which the heat exchange is low. This can lead to a very rapid evaporation at the site of contact, its disturbance and, as a result, sparking. With a conical shape of the hole and needle, the layer of liquid in the area of the upper edge of the hole is enlarged, besides, when the needle is extended, a fresh portion of the liquid is fed into the expanding hole with a twisted speed, intensively cooling the edges of the needle and the hole and preventing it from forming. Simultaneously with the insertion of the needles of the plate 14 from the liquid, the needles of the plate 13 begin to enter the liquid in the tank 22, the current does not flow through them, since the stop 56 has not yet reached the button of the switch 58 and has not closed its contacts. Therefore, the control current is not supplied to the thyristor 21 and it is in the locked state. Then, the needles of the plate 14 are released from the liquid, a threshold in the power circuit. Since the electrical resistivity of the electrolyte is high, then at the time of the removal of a needle, the needles from the contact resistance fluid reach several tens of thousands, and the current through the needle drops to a few milliamperes. Such a high contact resistance at the time of an opener needle is also achieved due to the influence of the force of the surface tension liquid, which carries the layer of liquid adjacent to the needle's end behind it, forming between the end of the moving needle and the bone surface, which extends several millimeters and simultaneously tapers fluid, further increasing the contact resistance at separation. Then this column of fluid breaks somewhere around

the middle part and there is a final interruption of the contact between the needle and the liquid. Since the contact resistance is very high at the time the needle is detached from the liquid, the power commuted by the needle is insignificant and no sparking occurs. To further increase the resistance at the needle exit from the liquid, the level of the liquid should be at the top of the cubes. After the needles of the plate 14 leave the bone, the current in the power circuit does not flow, since the thyristor 21 is still locked. At this moment of a dead time, for example, the collector brush 33 moves from a part of the ring 49 to a part of the ring 51. Then the upwardly moving stop 56 presses the switch button 58, closing its contacts. In this case, the control current is supplied to the control electrode of the thyristor 21, which is opened. From the power source, the power current begins to flow along the circuit: plus source, brush 47, part of ring 50, ring 36, brush 45, two phases of the load, for example, phases A and B, brush 44, ring 37, part of ring 51 brush 33, anodic cube electrode 28, liquid, needles 15 of plate 13, copper runner 16, brush 18, thyristor 21, minus power source.

When the collector rotates clockwise, the sequence of transition of the brushes from one part of the ring to another is as follows: 33-49 and 47-50; 33-51 and 47-50; 33-51 and 47-49, 33-50 and 47-49i 33-50 and 47-51; 33-49 and 47- 51, etc. Six transitions of both brushes from one part of the ring to another form one period of current in each phase of the load. FIG. 7 shows the currents in the phases of the load, shifted by 120 e. hail.

An electrode system with needles serving as a resistive current switch (selector), thyristors provide an increase in the current modulation depth, and an additional inverter converts current pulses to three-phase alternating current.

By changing the rpm of the driving motor of direct current 2, it is possible to change the revolutions of the crank drive shaft mechanism and the additional inverter within wide limits. At the same time, the frequency of the three-phase inverted current also varies widely.

from 0 5 o

" with

five

0

five

Claims (1)

Invention Formula An electromechanical three-phase frequency converter containing stator and rotor parts with anodic and cathode electrodes and an electrically conductive fluid between them, a driving motor mounted on the same shaft with the rotor part, an additional mechanical inverter with contact rings located on its rotor connected to the same frequency m rings installed evenly with gaps between them on the dielectric disk and forming a collector, and on the stator - brush nodes, two of which are mechanically They contact the collector and are installed diametrically opposite, one of which is connected to one of the electrodes, and the other to one of the outputs of the DC source, the other brush assemblies contact the rings, the mechanical gearbox connecting the shafts of the drive motor and the additional inverter, characterized in that, in order to increase efficiency and increase service life, the motor shaft is connected to the rotary part of the converter through a crank-connecting rod mechanism with vertical reciprocating rods which are electrically insulated from them electrically conductive plates with vertical steel needles of conical shape fixed to them, forming the first electrode and connected to a copper contact runner m mounted on rods with which two brush assemblies contact, connected to the same power terminals of two thyristors, opposite The power outputs of which are connected to another output of the current source, the stator part of the transformer is made in the form of a capacitor made of a dielectric material, completely The electrically conductive fluid and installed under the needles plates, in the tank are placed cubes of electrically conductive material, each of which is located under the corresponding plate and has conical-shaped holes placed under the needles coaxially with them, the cubes are electrically connected to each other, forming a second electrode, a collector additional inverter a contains three parts of the rings. disk circumferentially angled 120 geometrically} deg, one to the other and connected to three contact rings that are connected to the three-phase load through brush nodes, stops are mounted on the rods, at points of their upper position o o o o o o o o oh oh oh oh oh oh oh oh 0 g) ° ® о «- о о oh oh oh oh oh oh oh limit switches are firmly fixed, the contacts of each of which are included in the circuit between the power supply source and the corresponding thyristor control, and the gearbox has a gear ratio of one to three.  I  ff WITH fs uu 45 Phie. 6 1Л7 17 NV