EA002726B1 - Traction motor and drive system - Google Patents

Abstract

1. A 3-phase traction motor comprising a winding, characterized in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 2. A motor as claimed in claim 1, which is an asynchronous motor. 3. A motor as claimed in claim 1, which is a synchronous motor. 4. A drive system for a locomotive or motor coach, comprising a motor as claimed in claim 1, 2 or 3 and a regulator device connected thereto. 5. A system as claimed in claim 4, wherein said regulator device is a semiconductor ac/ac converter. 6. A drive system for a locomotive or motor coach, comprising a transformer having a winding, a thyristor bridge supplied by the transformer, and a dc/ac converter supplied by the thyristor bridge and arranged to supply power to a traction motor, characterized in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 7. A drive system for a locomotive or motor coach, comprising a rotating converter having a winding and arranged to supply power to a traction motor, characterized in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface, and solid insulation between said semiconducting layers. 8. A system as claimed in claim 7, wherein the rotating converter comprises a single machine having both motor and generator functions. 9. A system as claimed in claim 8, wherein the rotating converter is a phase converter. 10. A system as claimed in claim 7, 8 or 9, wherein the rotating converter supplies a regulator device. 11. A system as claimed in claim 7, 8 or 9, wherein the rotating converter supplies a rectifier bridge which supplies a dc/ac converter. 12. A system as claimed in claim 7, 8 or 9, wherein the rotating converter supplies an ac/ac frequency converter. 13. A motor or system as claimed in any preceding claim, characterized in that at least one of said layers has substantially the same coefficient of thermal expansion as the solid insulation. 14. A motor or system as claimed in any preceding claim, characterized in that the flux paths in the core of a magnetic circuit in the motor, transformer or rotating converter consists of laminated sheet plate and/or rough forged iron and/or cast iron and or powder-based iron. 15. A motor or system as claimed in any preceding claim, characterized in that the innermost semiconducting layer (32) which surrounds at least one conductor (31) is at substantially the same potential as the conductor(s) (31). 16. A motor or system as claimed in any preceding claim, characterized in that the outer semiconducting layer (34) is connected to a selected potential. 17. A motor or system as claimed in claim 16, characterized in that the selected potential is earth potential. 18. A motor or system as claimed in any preceding claim, characterized in that a current-carrying conductor of the winding comprises a plurality of strands, only a few of the strands not being insulated from each other. 19. A motor or system as claimed in any preceding claim, characterized in that said winding(s) and also permanently insulated connection conductors for high tension current between the system units are produced using a cable (6) with solid insulation for high voltage and comprising at least two semiconducting layers (32, 34), and also strands (36) which may be insulated or uninsulated. 20. A motor or system as claimed in claim 19, characterized in that the high-voltage cables (6) have a conductor area of between 10 and 3000 mm<2> and have an outer cable diameter of between 6 and 250 nm. 21. A motor or system as claimed in any preceding claim, characterized in that said winding is designed to carry a rated voltage of at least 10 kV.

Description

The present invention relates to a traction motor and drive system, for example, for railway locomotives and buses, in which the traction motor and / or other electrical machines included in the system are equipped with a magnetic circuit containing a magnetic core and at least one winding.

Prior art

The magnetic circuit in electric machines usually contains a lamellar core, for example, from sheet steel, surrounded and fixed by a welded structure. To provide ventilation and cooling, the core is often divided into packages with radial and / or axial ventilation channels. In the case of large machines, the plates have punched holes in the segments that are attached to the frame of the machine, while the lamellar core is held as one piece by pressing fingers and pressure rings. The winding of the magnetic circuit is located in the grooves of the core, and the grooves, in general, have a cross-section in the shape of a rectangle or trapezium.

In multiphase electrical machines, the windings are made as either single-layer or double-layer windings. When single-layer windings are used, there is only one side of the coil per slot, whereas when using double-layer windings, there are two sides of the coil per slot. By coil side is meant one or more conductors combined vertically or horizontally and provided with common insulation of the coil, i.e. insulation, which must withstand the rated voltage of the machine relative to the ground.

Two-layer windings are usually performed as rhombic windings, while single-layer windings in this context can be performed as rhombic or flat windings. In rhombic windings, there is only one (perhaps two) coil width, whereas flat windings perform as concentric windings, i.e. with widely adjustable coil width. By coil width is meant the distance, measured in an arc, between the two sides of a coil belonging to one coil.

Usually all large machines are made using a two-layer winding and coils of the same size. Each coil is placed so that its one side is located in one layer and the other side in another layer. This means that all the coils intersect with each other in the frontal part of the coil. If there are more than two layers, these intersections complicate the work of winding, and the frontal part of the coil is less satisfactory.

Before it became possible to use a normal frequency (50 Hz or 60 Hz) for traction motors, the first system with an AC voltage electrified voltage low frequency (15-16 _^2/3 or 25 Hz). The traction motor used for such a long time in such systems was a single-phase sequential collector motor, also known as a single-phase traction motor. It works almost the same as a DC motor, except that both fields and the rotor current are reversed every half period, since it is powered by alternating current. In order for switching to occur without the formation of harmful sparking in the collector, low frequency and low speed motors had to be chosen.

The main advantage of AC systems over DC systems is that AC voltage can be converted (although at present DC voltage can be converted using so-called interrupters). Thus, it is possible to maintain a relatively high voltage in the contact wire relative to the voltage with which the motor operates. Due to the high voltage in the contact wire, the current becomes smaller, thus enabling better energy transfer and lower losses in the power system. Power supply stations can be located at a greater distance (30-120 km).

The most widely used current traction motor is a three-phase asynchronous motor due to its simplicity and reliability. It is powered by a three-phase current with adjustable voltage and frequency, produced by power semiconductor circuits, from the mains voltage (DC system) or from the secondary voltage of the transformer (AC system).

Machines of the above type with a conventional stator winding cannot be connected to a high-voltage network, for example, with a voltage of 15 kV without the use of a transformer for lowering the voltage. The use of an engine thus connected to the high-voltage network through a transformer causes a number of disadvantages in comparison with the case if the engine could be connected directly to the high-voltage network. Among others, the following disadvantages can be noted:

- transformer roads, increases transport costs and requires space;

- transformer reduces the efficiency of the system;

- transformer consumes reactive power;

- An ordinary transformer contains oil, causing associated risks.

Description of the invention

The present invention is to obtain an engine and drive system for it to work on an electrified railway or the like, which solves part of the problems inherent in known systems in this field.

The present invention provides an engine according to claim 1 and a drive system according to claim 6 or 7.

Thus, the invention is based on a special method of designing electrical machines, motors, generators, transformers, etc., in which electrical windings are produced using insulation that is different from oil and preferably dry and made in a special way. This allows either to exclude the use of a transformer and / or to design transformers without the inherent disadvantages of conventional transformers, which were indicated above.

The invention, of course, may also include such special machines in combination with conventional machines.

Thus, machines of the type to which the invention pertains may be a transformer or a traction motor, which, in such a case, does not require any transformer. Of course, alternatives can be combined.

The drive system and components according to the invention can adapt to power supply systems of various railway systems and, with suitable modifications, are designed for rail systems with external power supply or with their own power supply system, for railways with different voltage levels and different frequencies and for alternating systems current, and for DC systems, as well as for synchronous motors, and for asynchronous motors.

In cases where a transformer is considered necessary, it is an object of the present invention that the transformer will be manufactured using wires of the same type and appropriate method as for other electric machines included in the drive system.

The advantage obtained when achieving the above objectives is to exclude an intermediate transformer filled with oil, the reactance of which would otherwise consume reactive power.

To achieve this result, the magnetic circuit and its conductors, in at least one of the electric machines included in the vehicle, are made so that they have a twisted permanently insulated wire, the outer surface of which is connected to a chosen potential, such as ground.

The main and significant difference between the known technology and the variant corresponding to the invention, therefore, is that the latter includes at least one machine, which, due to the nature of its magnetic circuit, can be directly connected through breakers and insulators to the high-voltage network 10-800 kV. The magnetic circuit thus contains one or more lamellar cores with a winding consisting of twisted wire having one or more permanently insulated conductors having a semiconducting layer both on the conductor and outside the insulation, with the outer semiconducting layer connected to ground potential.

To solve the problems arising from the direct connection of electrical machines, both rotating and static machines, to all types of high-voltage power grids, at least one machine in the drive system according to the invention has a number of features mentioned above, which clearly differ from the known technology . Additional features and other embodiments of the invention are defined in the dependent claims and are described below.

The above features and other characteristics of the drive system and at least one of the electrical machines included in it according to the invention include the following:

- the winding for the magnetic circuit is made of wire having one or more permanently insulated conductors with two semiconducting layers, one of which surrounds the conductors and one forms a sheath. Some typical conductors of this type are insulated with cross-linked polyethylene or ethylene-propylene rubber. For this purpose, the conductors can also be developed both in terms of the veins in the conductor and the nature of the outer shell;

- wires with a circular cross section are preferred, but wires with some other cross sections may be used to obtain, for example, greater packing density;

- such wire allows the development of a lamellar core in the part concerning the grooves and teeth in a new and optimal way according to the invention;

- the winding is preferably made with a stepped insulation for the best use of a lamellar core;

- the winding is preferably made as a multi-layer concentric winding from a wire, which, thus, helps to reduce the number of intersections at the ends of the coils;

- the design of the groove may correspond to the cross-section of the winding wire in such a way that the grooves are made in the form of a series of cylindrical holes extending axially and / or radially inside of each other and have a narrow portion extending between the layers of the armature winding;

- the design of the groove can be adjusted to the cross-section of the corresponding wire and the stepped winding insulation. Step insulation allows the magnetic core to have teeth with substantially constant width regardless of radial extent;

- the further improvement noted above in the part concerning the outer shell led to the fact that the outer shell was cut off at the corresponding points along the conductor length, and the partial length of each slice was connected directly to the ground potential.

The use of a wire of the type described above allows you to maintain the entire length of the outer semiconducting sheath of the winding, as well as other parts of the drive system, with ground potential. An important advantage is that the electric field is close to zero within the region of the coil end outside the outer semiconducting layer. When the potential of the outer layer is equal to the ground potential, there is no need to control the electric field. This means that the field concentration will not occur either in the core, in the areas of the ends of the coils, or in the transition between them.

A mixture of isolated and / or uninsulated tightly compressed or transposed veins gives small scattering losses.

The high voltage wire used in the winding of the magnetic circuit consists of an inner core / conductor with many wires, at least one semiconducting layer, the innermost surrounded by an insulating layer, which, in turn, is surrounded by an outer semiconducting layer having an outer diameter within 6250 mm, while the cross-sectional area of the conductor lies in the range of 10-3000 mm ² .

If at least one of the machines of the installation according to the invention is designed in this way, the start-up and control of the engine (s) used in the locomotive or motor carriage can be carried out in ways that are known per se.

According to a particularly preferred embodiment of the invention, at least two of these layers, preferably all three, have the same coefficient of thermal expansion. The indisputable benefit obtained in this way is that during thermal motion in the winding, the occurrence of defects, cracks, etc. is excluded.

Since the isolation system, which is accordingly constant, is designed so that, in terms of thermal effects and electricity, it is designed for voltages above 10 kV, the system can be connected to high-voltage networks without any intermediate step-down transformer, thereby achieving the above advantages.

The above and other preferred embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings

The invention will be described in more detail in the following description of a preferred embodiment of the design of the magnetic circuit of an electrical machine with reference to the accompanying drawings, in which FIG. 1 shows a schematic end view of the stator sector of an electric machine in an installation according to the invention;

FIG. 2 is a view with graduated withdrawals of the terminal part of the wire used in the stator winding corresponding to FIG. one; and FIG. 3-5 are drive systems with traction motors corresponding to different embodiments of the invention.

Description of preferred embodiments of the invention

In the embodiment shown in FIG. 1 shows a schematic view from the end of the stator 1 sector of an electric machine of a rotating type included in the installation according to the invention, the rotor 2 of the machine is also shown. The stator 1 is formed of a lamellar core. FIG. 1 shows the sector of the machine corresponding to one pole division. The row of teeth 4 recedes radially inward from the yoke 3 of the core in the direction of the rotor 2, while the teeth are separated by grooves 5 in which the stator winding is located. The wires 6 forming this stator winding are high-voltage wires, which can be of essentially the same type as the wires used for power distribution, for example, wires with sheath of cross-linked polyethylene. One difference is that the outer sheath, which provides mechanical protection, and the metal shield, usually surrounding such wires for power distribution, are excluded, and the wire for the presented application contains only a conductor and at least one semiconducting layer on each side of the insulating layer. Thus, the semiconducting layer lies open on the surface of the wire.

The wires 6 are schematically shown in FIG. 1, with only the conductive part of each wire portion or coil side shown. As can be seen, each groove 5 has a varying cross section with alternating wide portions 7 and constricted portions 8. The wide portions 7 have a substantially circular configuration and surround the wire. Narrow parts 8 are used to fix the position of each wire in the radial direction. The cross section of the groove 5 also tapers radially inward. This is because the voltage in the parts of the wire is the lower, the closer they are to the radially inner part of the stator 1. Thus, a thinner wire can in this case be used inwards, while a thicker wire is needed outwards. In the example shown, wires of three different sizes are used, which are arranged in three sections of the corresponding dimensions 51, 52, 53

five.

The above description of the magnetic circuit for a rotating electrical machine made of wire 6 also applies to static electrical machines, such as transformers, stabilizer windings, etc. The following important advantages are obtained both from the point of view of construction and from a production point of view:

- transformer windings can be created without taking into account any propagation of the electric field, and the problematic transposition of parts according to known technology is thus not necessary;

- the transformer core can be designed without taking into account any propagation of the electric field;

- oil is not required for the electrical insulation of the wire and the winding, and instead the wire and the winding may be surrounded by air or a non-combustible or slow burning fluid;

- in many applications, special bushings are not required, as in the case of transformers filled with oil, for electrical communication between the external connections of the transformer and the coils / windings located inside;

- the absence of oil significantly reduces the risk of fire and explosion in the transformer according to the invention;

- a transformer may be more resistant than a conventional transformer, which increases its ability to withstand short circuits;

- the transformer is less noisy, cleaner and requires less maintenance; and

- the production and testing technology required for a dry transformer with the magnetic circuit described above is much simpler than that required for conventional transformers / stabilizers.

FIG. 2 is a view, with stepped seals, of a terminal part of a high-voltage wire for use in an electric machine included in an installation according to the present invention. High-voltage wire 6 contains one or more conductors 31, each of which contains a certain number of cores 36, which together form a circular cross-section, for example, of copper (Cu). These conductors 31 are located in the center of the high-voltage wire 6 and are surrounded, in the shown embodiment of the invention, by separate insulation 35. However, as for separate insulation 35, it can be eliminated on one of the conductors 31. In the present embodiment of the invention, the conductors 31 are jointly surrounded by the first semiconducting layer 32. Around this first semiconducting layer 32 is an insulating layer 33, for example, cross-linked polyethylene insulation, which, in turn, is surrounded by the second semiconducting layer 34. Thus Braz, high-voltage wire need not include any metallic screen or outer sheath type that normally surrounds such a cable for power distribution. Since the traction equipment often becomes very warm, the insulating layer 33 may contain heat-resistant polymers, for example, silicone rubber or polymers based on organic fluorine compounds. Semiconducting layers 32, 34 may contain a material similar to that of an insulating layer, but with conductive particles, such as black carbon particles, carbon black, or metal particles embedded in it. In general, it has been found that a particular insulating material has similar mechanical properties when it does not contain or contains some carbon particles.

The use of electric machines equipped with magnetic circuits of the type described above, makes it possible to significantly simplify and increase the efficiency of both the power supply of the traction motors and the traction motors themselves. In operation of the railway with the AC voltage, the currently used supply voltages are typically 15 kV and 16 _^2/3 Hz, 11 kV, 25 Hz or 25 kV 50/60 Hz in the supply line 104 from which the current collector 112 feeds the locomotive one or more traction motors 114, as shown in FIG. 3-5

Known traction motors for AC voltage are usually driven by voltages up to 1 kV, and the locomotive must therefore be equipped with a transformer and speed control equipment, which thyristors comprise in modern locomotives.

Transformers used in well-known locomotives are filled with oil and have a number of mechanical and electrical deficiencies, and also cause problems regarding environmental pollution. Rotating machines and means used to transform and work in well-known locomotives have various problems, both mechanical and electrical, which may have a more or less satisfactory scale.

The above problems can be eliminated or minimized by designing magnetic circuits in at least one of the electrical machines of the system according to the present invention.

FIG. 3-5 depict a three-phase asynchronous motor 114 providing mechanical power for a locomotive and having a winding formed of a high-voltage cable shown in FIG. 2. Motor winding 114 has the advantages described above.

FIG. 3 depicts a drive system for a motor, comprising a transformer 122 and a thyristor converter bridge 123, connected via a smoothing circuit and a filter circuit 124 to a DC / DC converter 125 to a three-phase alternating current that powers the three-phase motor 114. The transformer 122 has a winding formed from a wire, shown in FIG. 2. Thus, this transformer has the advantages listed above, as well as it is lighter and less bulky than the well-known transformer filled with oil.

4a depicts a drive system comprising a rotary converter 130, comprising a motor M, fed directly from a current collector 112, and a generator C, which feeds a three-phase motor 114 through a regulating device 131. Branched connections 132a, 132b can be used to control the voltage applied to the motor 114 and a series of poles connected for coarse speed control.

FIG. 4b demonstrates an alternative system in which rotary converter 130, which preferably generates a multi-phase, for example six-phase, alternating current, is connected to a bridge rectifier circuit 133, which feeds the motor 114 through the converter 125 to three-phase alternating current.

FIG. 4c demonstrates another alternative system in which power is supplied from rotating transducer 130 to motor 114 through an ac frequency converter 134.

In the systems shown in FIG. 4a, 4b and 4c, either the motor M, or the generator C, or they both have a winding using the wire shown in FIG. 2. The engine and generator can be separate machines with a common shaft, or, alternatively, the rotary converter can contain a single unit, as described, for example, in German patents Nos. 372390, 386561 and 406371. The rotating converter can also be a phase converter , as described in James Napbysh Bethokoshobupep, pp. 254-255, E1ss1p5s11sg Weiley, 85th Yearbook, brochure 12/1987, pp. 388-389 or Biedeg. Technik run Teyshk, p. 395.

FIG. 5 shows a system in which a motor 114 is a high voltage motor that is powered by a regulating device 135 connected to a current collector 112. The regulating device is preferably a direct semiconductor converter of alternating current to alternating current. Because the motor 114 is powered by high voltage current, a transformer or other means of changing the voltage is not required, and the drive system has the advantage of being compact and light.

Although certain voltage values were mentioned above, they should be considered only as examples. Similarly, various combinations of conventional electric machines and electric machines equipped with a magnetic circuit according to the invention are possible. Thus, the invention should not be construed as being limited to the systems described with reference to the drawings, on the contrary, it covers all possible systems defined by the appended claims.

Although it is preferable that electrical insulation is performed by pressing, it is possible to perform an electrical insulation system consisting of layers of film or sheet material that are tightly wound and overlap each other. Both the semiconducting layers and the electrical insulation layer can be formed in this way. The insulation system can be made of a pure synthetic film with inner and outer semiconducting layers or parts made of a thin polymer film, such as polypropylene, polyethylene terephthalate, low density polyethylene or high density polyethylene with embedded conductive particles, such as soot particles or metal particles, and with an insulating layer or part between the semiconducting layers or parts.

For the concept of imposing insulation, a sufficiently thin film will have butt gaps that are smaller than the so-called Paschen minima and, thus, liquid impregnation becomes unnecessary. Dry, wound, multi-layer thin film insulation also has good thermal performance.

Another example of an electrical insulation system is similar to conventional cellulose-based wire insulation, where cellulose-based or synthetic paper or non-woven paper is wound around the conductor. In this case, the semiconducting layers on both sides of the insulating layer can be made of cellulose paper or non-woven material made of fibers of an insulating material, and with embedded conductive particles. The insulating layer may be made of the same base material or another material may be used.

Another example of an insulating system is produced by combining a film and a fibrous insulating material, either in the form of layers or with overlapping. An example of such an insulating system is the commercially available so-called laminate of paper and polypropylene, but several other combinations of film and fiber portions are possible. Various impregnations can be used in these systems, such as mineral oil.

Claims (21)

1. A three-phase traction motor comprising a winding, characterized in that said winding comprises an insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface and strong insulation between said semiconducting layers. 2. The engine according to claim 1, characterized in that it is an asynchronous motor. 3. The engine according to claim 1, characterized in that it is a synchronous motor. 4. The drive system for a locomotive or bus, containing the engine according to paragraphs. 1, 2 or 3 and the control device connected to it. 5. The system according to claim 4, characterized in that said control device is a semiconductor AC to AC converter. 6. A drive system for a locomotive or bus, a carriage, comprising a transformer having a winding, a thyristor converter bridge, powered by a transformer, and an AC / DC converter fed by a thyristor converter bridge and adapted to supply power to the traction motor, characterized in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing a substantially equipotential surface and a strong olation between semiconducting layers. 7. A drive system for a locomotive or bus, comprising a rotary converter having a winding and adapted to supply power to the traction motor, characterized in that said winding includes insulation consisting of at least two semiconducting layers, each layer providing, essentially equipotential surface, and strong insulation between the semiconducting layers. 8. The system according to claim 7, characterized in that the rotating transducer contains a single machine having the functions of both an engine and a generator. 9. The system of claim 8, wherein the rotating transducer is a phase converter. 10. The system according to claims 7, 8 or 9, characterized in that the rotating converter feeds the control device. 11. The system according to claims 7, 8 or 9, characterized in that the rotating converter feeds the bridge rectifier circuit, which feeds the DC / AC converter. 12. The system according to claims 7, 8 or 9, characterized in that the rotating converter feeds the AC frequency converter. 13. The engine or system according to any one of the preceding paragraphs, characterized in that at least one of these layers has essentially the same coefficient of thermal expansion as that of strong insulation. 14. The engine or system according to any one of the preceding paragraphs, characterized in that the magnetic flux lines in the core of the magnetic circuit in the motor, transformer or rotary converter consist of a plate plate and / or raw wrought iron and / or cast iron and / or iron on powder base. 15. An engine or system according to any one of the preceding paragraphs, characterized in that the innermost semiconducting layer (32) that surrounds at least one conductor (31) has essentially the same potential as the conductor (s) ) (31). 16. An engine or system according to any one of the preceding paragraphs, characterized in that the outer semiconducting layer (34) is connected to the selected potential. 17. The engine or system according to clause 16, wherein the selected potential is the ground potential. 18. The engine or system according to any one of the preceding paragraphs, characterized in that the current-carrying conductor of the winding contains many cores and only a few of the cores are not isolated from each other. 19. The engine or system according to any one of the preceding paragraphs, characterized in that said winding (s) and also permanently insulated connecting conductors for high voltage current between the system units are made using wire (6) with strong insulation for high voltage and contain, according to at least two semiconducting layers (32, 34) and also conductors (36), which may or may not be insulated. 20. The engine or system according to claim 19, characterized in that the high-voltage wires (6) have a cross-sectional area of the conductor from 10 to 3000 mm ² and have an outer diameter of the wire from 6 to 250 nm. 21. The engine or system according to any one of the preceding paragraphs, characterized in that said winding is designed to carry a nominal voltage of at least 10 kV.