Three-phase asynchronous motor with passive rotor

Abstract

The present invention relates to a three-phase asynchronous motor having a passive rotor and a stator, comprising a laminated core having slots, wherein the slots can accommodate a plurality of molded winding coils made of solid copper material using hairpin technology, the rotor is designed as a copper rotor, and the winding head of the stator can preferably be realized by layer-by-layer additive coating and locally selective solidification of a conductive material, particularly copper material. According to the present invention, the three-phase asynchronous motor has distributed pitch-free hairpin windings with a number of strand windings in the range of 100 or more, with 10 to 16 hairpins installed in each slot, and can achieve a limiting efficiency factor of IE4 or higher, particularly IE5 or higher, in accordance with IEC-60034-02, in a speed range of at least up to 2000 rpm.

Description

Summary of the Invention

[0001] According to the preamble of claim 1, the present invention relates to a three-phase asynchronous motor having a passive rotor and a stator, comprising a laminated core having slots, the slots being capable of accommodating a plurality of formed winding coils (Formspulen) made of solid copper material using hairpin technology, the rotor being designed as a copper rotor, and furthermore the winding heads of the stator can preferably be realized by layer-by-layer additional coating and local selective solidification of a conductive material, particularly a copper material.

[0002] A method for manufacturing a stator for an electromechanical machine, particularly an electric motor or a generator, using the so-called hairpin technology belongs to the state of the art.

[0003] Hairpins can replace windings manufactured using old winding methods such as, for example, needle windings. Hairpins can in particular be manufactured by appropriately shaping a solid metal conductor, particularly a solid copper wire.

[0004] Thus, in hairpin technology, plug-in coils are used which are inserted into the stator slots of the stator lamination core. In this regard, so-called U-shaped plug-in coils are already known. Alternatively, pins of so-called I-pin technology are used.

[0005] In recent years, the use of hairpin technology has been increasing in the automotive industry in order to increase the drive efficiency of electric vehicles.

[0006] In this industrial field, asynchronous motors, which are usually designed as three-phase asynchronous machines, are still the dominant type compared to others. The advantage over other types of electric motors is the absence of a commutator and brushes. An asynchronous motor is composed of an outer fixed stator and a rotating rotor. When operating such an asynchronous motor in a three-phase network, the number of copper windings in the stator is 3 or a multiple of 3, and the phase shift of the current in the corresponding adjacent windings is 120°.

[0007] Regarding the rotors of three-phase asynchronous motors, the designs of short-circuit or squirrel-cage rotors and slip-ring rotors are distinguished.

[0008] In addition to its robust design, asynchronous motors offer another advantage: their operating principle eliminates the need for expensive permanent magnets. Asynchronous motors can be easily operated via voltage-frequency control; complex sensor technology is not required.

[0009] The efficiency of an asynchronous motor is measured by its efficiency factor. For global standardization, the International Efficiency Code (IE Code) was introduced. The quantitative description and technical background of the IE Code are part of the international standard IEC 60034-30-1:201. In Germany, the derivation must comply with DIN EN 60034-30-1VDE 0530-30-1:2014-12.

[0010] This standard defines four or five efficiency classes, each specifying the corresponding minimum efficiency factor for a given rated output.

[0011] According to this standard, the required efficiency factor increases as the IE grade rises. Therefore, for energy-efficient asynchronous machines, IE4 grade is considered state-of-the-art.

[0012] In line with the goal of achieving full climate neutrality in Europe by 2050, significant improvements in energy efficiency must be achieved, particularly in industrial consumer use sectors. Approximately 70% of the electrical energy consumed is attributable to its use in electrically driven devices, such as pumps, fans, compressed air generators, cooling compressors, and conveyor systems.

[0013] For the reasons stated above, it is becoming increasingly important not only to improve the efficiency factor of electric drive systems in vehicles, but also to pursue high efficiency factors in various types of electric drive systems.

[0014] Based on the above, the object of the present invention is to provide an advanced three-phase asynchronous motor for industrial applications that achieves energy efficiency levels that have not been previously achievable with conventional machines, according to their respective performance classes.

[0015] A solution to the object of the present invention is provided by a three-phase asynchronous motor having a passive rotor and a stator, as described in claim 1, and the dependent claims include at least suitable embodiments and further developments.

[0016] Therefore, the starting point is a three-phase asynchronous motor, which is known in itself and has a passive rotor and a stator.

[0017] The stator has a laminated core with slots, which can accommodate multiple molded winding coils made of solid copper material using hairpin technology.

[0018] The rotor is designed as a copper rotor.

[0019] Furthermore, the stator winding head is preferably realized by the additional layering and localized selective solidification of a conductive material, particularly a copper material.

[0020] According to the present invention, the motor has distributed pitch-free hairpin windings with a number of strand windings in the range of 100 or more, with 10 to 16 hairpins installed in each slot, and can achieve a limiting efficiency factor of IE5 or higher in accordance with IEC-60034-02 in a speed range of at least up to 2000 rpm.

[0021] The dimensions of the hairpin windings and winding heads are set to minimize strand resistance and reduce stator heat loss for each motor power class.

[0022] This utilizes the finding that at least one-third of the heat loss in such motors is attributable to the stator design.

[0023] The motor according to the present invention is also characterized by a low pole number design having 2 pole pairs.

[0024] The number of slots of the motor is in the range of 60 to 120, preferably 60 to 96.

[0025] The hairpin has a rectangular cross-section, and the corresponding slots are the same.

[0026] The winding of the motor according to the present invention is composed only of hairpin plug-in coils having a maximum slot filling factor.

[0027] The air gap between the stator and the rotor laminated core is in the range of 0.30 mm or less, which is about 25% smaller than that of a conventional IE4 asynchronous motor.

[0028] Furthermore, by reducing slip, the losses in the rotor winding are reduced.

[0029] Preferably, in order to realize a rotor short-circuit cage, copper is used instead of aluminum. The strand winding of the motor is designed as a star connection, and all the conductors of the strand are connected in series.

[0030] The stator winding is designed as a wave winding, and each strand winding surrounds the stator several times in the circumferential direction and terminates at the star point.

[0031] By additional techniques, the winding head can be designed to be mechanically self-supporting, and the winding head connector has an indefinite step width.

[0032] Therefore, the present invention practices the knowledge of the main loss mechanisms and leads to an optimized design of the asynchronous machine. As a result of using a winding without pitch, the winding factor measuring the coupling between the stator and the rotor windings exceeds 95%.

[0033] The improved coupling reduces the magnetization current, thereby decreasing copper losses in the stator windings. Compared to pitched windings, the winding coefficient is effectively less than 90%.

[0034] The numerous holes, ranging from 5 to 5, and the resulting numerous status holes reduce the overfelder scattering number (Oberfelder-Streuziffer) to less than 0.75%. As a result, harmonic losses in the rotor are minimized. The numerous holes offer an advantage over conventional pitches in that the winding coefficient reduction is smaller.

[0035] The number of status lots in the machine according to the present invention is substantially 50% more than that of a so-called standard motor.

[0036] By combining the star connection described above with a high winding coefficient exceeding 95% for distributed windings used according to the present invention, the number of windings is minimized compared to commonly used delta connections.

[0037] By minimizing the number of windings, the cross-sectional area of ​​the copper is maximized, allowing the copper fill density to be maximized to over 70%. Copper loss in status lots is inversely proportional to the copper fill density.

[0038] Standard motors have a copper filling ratio of approximately 35%, which results in twice the copper loss in the stator compared to the solution according to the present invention.

[0039] Based on a minimum number of windings and the series connection of all conductors within the aforementioned strands, solid copper rods can be used instead of conventional circular conductors.

[0040] This improves the copper filling density on the one hand, and improves the thermal coupling between the stator windings and the laminated core on the other hand. As a result, the winding temperature decreases and losses in the stator are reduced.

[0041] By selecting a rectangular status rod in conjunction with a solid copper rod, maximum utilization of the motor volume is achieved, resulting in optimal filling with the active materials, iron and copper.

[0042] As a result, the magnetic flux density and current density are minimized, thus minimizing losses in iron and copper.

[0043] Accordingly, the motor according to the present invention is characterized by corrugated windings in the stator and a mechanically self-supporting winding head.

[0044] The winding head connector has the aforementioned variable step width in the range of m × q ± 1, where m = number of strands and q = number of holes. As described above, the variation in step width in the winding head connector helps to geometrically pack each stator winding head tightly.

[0045] The solid copper conductors used allow the winding head to stand on its own; in other words, no additional fastening elements are attached during assembly.

[0046] Forming the winding head is preferable by the additional coating of copper material layer by layer and localized selective solidification, but the winding head can also be formed from a solid copper rod, and the connection of hairpins to the elements of the winding head can be achieved, for example, by welding or soldering.

[0047] In contrast to standard motors, which typically use circular conductors on the winding side, have winding pitch, and require additional layers of insulation within the slots, the present invention achieves a remarkably high copper filling rate, well over 35% of that of a standard machine.

[0048] Similarly, the motor according to the present invention does not have the typical circular wire loop windings in the winding head found in standard motors.

[0049] According to a preferred embodiment of the present invention, the number of strand windings is in the lower range of the electromagnetically detectable spectrum. This maximizes the copper filling rate because a smaller number of strand windings reduces the proportion of insulating material in the status lot.

[0050] The slot support width of the status lot is very small, selected within a range of 1.5 mm or less. This is technically possible because it allows the hairpin to be inserted axially into the laminated core during assembly.

[0051] On the other hand, conventional circular wire solutions require a correspondingly larger slot opening to insert the wound wire.

[0052] The smaller slot width also reduces the actual air gap between the rotor and stator. This reduces stator current and decreases the losses incurred.

Claims

1. A three-phase asynchronous motor having a passive rotor and a stator, comprising a laminated core having slots, the slots capable of accommodating a plurality of molded winding coils made of solid copper material using hairpin technology, the rotor being designed as a copper rotor, and the winding head of the stator being preferably realized by layer-by-layer additive coating and locally selective solidification of a conductive material, particularly copper material. A three-phase asynchronous motor having distributed pitch-free hairpin windings with a number of strand windings in the range of 100 or more, 10 to 16 hairpins installed in each of the slots, and capable of achieving a limiting efficiency factor of IE4 or higher, particularly IE5 or higher, in accordance with IEC-60034-02, in a speed range of at least up to 2000 rpm.

2. The three-phase asynchronous motor according to claim 1, characterized in that the dimensions of the hairpin winding and the winding head are set with the aim of achieving the minimum strand resistance and reduced limit values ​​with respect to stator heat loss for each motor output class.

3. A three-phase asynchronous motor according to claim 1 or 2, characterized by a low pole number design having two pole pairs.

4. A three-phase asynchronous motor according to any one of the preceding claims, characterized in that the number of slots is in the range of 60 to 120, preferably 60 to 96.

5. A three-phase asynchronous motor according to any one of the preceding claims, characterized in that the hairpin has a rectangular cross-section.

6. The three-phase asynchronous motor according to any one of the preceding claims, characterized in that the winding consists only of hairpin plug-in coils having the maximum slot filling rate.

7. A three-phase asynchronous motor according to any one of the preceding claims, characterized in that the air gap between the stator and the rotor laminated core is in the range of 0.3 mm or less.

8. A three-phase asynchronous motor according to any one of the preceding claims, characterized in that the strand winding is designed as a star connection and all conductors of the strand are connected in series.

9. The three-phase asynchronous motor according to claim 8, characterized in that the stator winding is designed as a corrugated winding, and each strand winding surrounds the stator several times in the circumferential direction and terminates at the star point.

10. The three-phase asynchronous motor according to any one of the preceding claims, characterized in that the winding head is designed to be mechanically self-supporting, and the winding head connector has an indeterminate step width.

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