WO2018109237A1

WO2018109237A1 - Rotary electrical machine

Info

Publication number: WO2018109237A1
Application number: PCT/ES2016/070877
Authority: WO
Inventors: Enrique ANDRADES LAGO; Javier ANDRADES LAGO
Original assignee: Andrades Lago Enrique; Andrades Lago Javier
Priority date: 2016-12-12
Filing date: 2016-12-12
Publication date: 2018-06-21

Abstract

A rotary electrical machine comprises a stator (500) and one or more rotors (100), each rotor (100) being formed by a non-magnetisable segment (101) and one or more magnetisable segments (102) inserted into a plurality of coils (200) of the stator (500). Each magnetisable segment covers an arc of circumference about the axis of rotation of the rotor (100) of less than 360°. The field generated inside the coils (200) can thus be utilised, increasing the torque and the output of the machine.

Description

ROTARY ELECTRIC MACHINE

DESCRIPTION Object of the invention

The present invention relates to the field of machinery for conversion between electrical and mechanical energy, and more specifically to a rotating electric machine capable of operating as a motor and as a generator.

Background of the invention

The most exploited rotary electric machines in the world context are the synchronous machine and the induction motor. Induction motors are a type of alternating current motor in which the current necessary to produce rotor torque is generated by electromagnetic induction by means of stator winding. This avoids the typical electrical connections of universal, direct current or synchronous motors. The most common induction motors are three-phase motors, typically squirrel cage or winding. When a spatial and temporal offset is applied to said coils, a rotating magnetic field is induced on the rotor. For example, US 6177,750 B1 and US 6,566,778 B1 present a sample of the wide variety of rotor and stator designs existing in induction motors. However, they all suffer from a low torque that considerably limits the resulting performance.

Synchronous machines allow this limitation to be overcome by synchronizing the rotation speed of the shaft with the electric frequency, both being mutually dependent on both its operation as a motor (conversion of electrical energy into mechanical energy) and as a generator (conversion of mechanical energy into electrical energy ). However, it is more common to use them as generators by not presenting starting torque, which requires using different starting and acceleration methods until the synchronization speed is reached. An example of such starting methods is presented in US 5,488,286 A. Its use is also known for reactive power control in a network, thanks to the possibility of varying the reactive power that absorbs or yields to the network, keeping the active power developed at a constant level.

In a first example, US 6,100,620 A presents a synchronous rotary electric machine that implements step functions for the electric phase difference between rotor and stator teeth, allowing the device to operate at high frequency. In a second example, US 6, 140,719 A features a synchronous machine that incorporates a high temperature superconductor rotor with thermal reserve to absorb the resulting energy in case of failure.

However, despite the variety of known synchronous machines, they still have a number of limitations:

- They require brushes to excite the rotor, forcing the use of permanent magnets for high powers. Additionally, this implies an increase in manufacturing difficulty and a reduction in system reliability.

- Since permanent magnets cannot modify their magnetic field density, torque control and operating speed are limited.

- The stator and rotor arrangement forces the use of coils that are shorter than their radius, limiting the generated field density.

- The rotor is displaced axially from the center of the coil, which limits the induced electromotive force.

- Synchronous machines operate as magnets tending to be oriented within a magnetic field. Since there is an element rotating inside the coil, said coil cannot be fully utilized, negatively affecting the torque and the induced electromotive force.

In short, there is still a need in the state of the art for a rotating electric machine that optimizes the reliability of the system, as well as its torque and induced electromotive force.

Description of the invention The present invention solves the problems described above by means of a rotating electric machine comprising at least one stator and a rotating rotor with respect to the stator, where the stator comprises a plurality of coils each wound forming an arcuate or curved tubular body. The rotor is a circumferential ring-shaped body and is arranged inside the coils and is rotatable through the inside of the coils.

With this configuration, it is possible to maximize the induced electromotive force and the efficiency and reliability of the system.

For this, the rotor comprises a heterogeneous crown with a non-magnetizable section that serves as support for one or more magnetizable sections. While the non-magnetizable section may close on itself, covering the entire arc of the rotor circumference around the axis of rotation, the magnetizable section extends an arc of circumference less than 360 ° around said axis. That is, the magnetizable section (or sections) do not close on themselves around the axis.

Preferably, the magnetizable section extends in an arc of circumference greater than the length of one of the reels and less than the entire circumference minus the length of said reels. Note that in this context the length of the coil is understood as the circumference arc in which the coil extends, or in other words to the projection of said coil on the circumference defined by the rotation of the magnetizable section of the rotor.

That is, with the minimum and maximum dimension described for the arc of the magnetizable section it is guaranteed that, when passing through a coil, the magnetizable section cannot be completely covered by said coil; as well as that, in certain instants of the rotation, the magnetizable section is outside (is longer) of said coil in its entirety. In the case of using coils of different lengths, the above definition is preferably applied to the coil of greater length.

Note that, preferably, the coils have a smaller radius than length, allowing to optimize the induced electromotive force, understanding by length the dimension that follows the direction of rotation of the rotor, and by radius the largest dimension of the section perpendicular to said direction of rotation. As for the materials in which the rotor is implemented, the magnetizable section preferably comprises a ferromagnetic material, while the non-magnetizable section preferably comprises a paramagnetic material or a diamagnetic material. Also preferably, the rotor comprises a first gear teeth in an inner face and / or a second gear teeth in an outer face for the transmission of mechanical energy between said rotor and a transmission shaft. In the case of understanding said first gear on the inner face, the machine preferably comprises a plurality of internal gears distributed angularly and equidistant around the axis of rotation. Said plurality of gears connects the first gear with the drive shaft, said gears preferably alternating with the stator coils, that is, each gear is disposed between the space between two consecutive coils. Note that, depending on the preferred embodiment, the teeth can be fully implemented on the non-magnetizable section, either on the magnetizable or non-magnetizable section. That is, in the second case the magnetizable section with the built-in teeth, also magnetizable, would cover an arc less than 360 °. The rest of the arc up to 360 ° is composed of non-magnetizable material, with an equally non-magnetizable teeth.

Note also that the position of the transmission shaft that allows to introduce or extract the mechanical energy does not have to coincide with the axis of rotation of the rotor, being able to be implemented on any of the gears of the system, or on an external element. Also, in a preferred option, the mechanical energy can be extracted by a second non-magnetizable external crown, concentric to the rotor.

The described configuration allows the combination of multiple rotors on the same axis of rotation, as well as the serial connection of multiple motors. That is, of According to a preferred option, the machine comprises a plurality of rotors mechanically connected to the same drive shaft, multiple rotors can be introduced in the same set of coils or in different sets of coils depending on the particular implementation of the machine. The plurality of rotors are preferably connected by a plurality of external gears angularly distributed around said transmission shaft.

The rotary electric machine can operate both as a motor and as a generator. Preferably, operating as a motor, it also comprises control means that switch the plurality of coils sequentially to induce a rotating magnetic field on the rotor, converting electrical energy into mechanical energy. Also preferably, operating as a generator, the machine is connected to rotating means that cause the rotor to move (such as blades in a wind generator or any other rotating element of the power generation systems known in the state of the art) , said rotor movement being converted into electrical energy through the electromotive force induced in the stator.

The rotary electric machine described maintains the basic advantages of synchronous machines with respect to induction motors, that is, the high torque and performance. Additionally, the described machine has the following advantages over said synchronous machines:

- The excitation of the rotor does not need brushes, so it is easier and cheaper to manufacture, also improving the reliability of the system.

- Also derived from being able to excite without brushes, the efficiency of the motor speed and torque control is improved, increasing the overall efficiency and the operating range.

- From a geometric point of view, an optimal coil (I understand that the one that generates the highest magnetic field density) has a radius much smaller than its length. In traditional machines known in the state of the art this situation is reversed, allowing the present invention to generate denser magnetic fields from the same current. This fact translates into greater torque and lower consumption. - The machine of the present invention operates at the point of highest magnetic field density, which occurs in the center of the coils. Torque and induced electromotive force are optimized.

- When operating by traction instead of rotation, the whole winding of the stator is used, again improving the torque and the induced electromotive force.

These and other advantages of the invention will be apparent in light of the detailed description thereof.

Description of the figures

In order to help a better understanding of the features of the invention according to a preferred example of practical realization thereof, and to complement this description, the following figures are attached as an integral part thereof, the character of which is illustrative and non-limiting:

Figure 1 schematically shows a rotor with internal teeth according to a particular embodiment of the machine of the invention.

Figure 2 shows a rotor with internal and external teeth according to another particular embodiment of the machine of the invention.

Figure 3 illustrates the connection of the rotor to the drive shaft, in this central case, and the coils according to particular embodiments thereof.

Figure 4 schematically shows the stator and rotor assembly, according to particular embodiments thereof.

Figure 5 shows a second view of the same stator and rotor assembly.

Figure 6 exemplifies a machine with multiple concentric crowns according to a preferred embodiment of the invention. Figures 7 to 10 present two states of interaction between a linear magnetizable body and a coil, described only to illustrate the physical principles that act on the coils of the equivalent rotary machine.

Figure 11 shows a rotary machine with two crowns in which the transmission shaft is implemented in an external gear, according to a particular embodiment of the invention. Figure 12 shows a rotary machine with a crown in which the drive shaft is implemented in an external gear, in accordance with a particular embodiment of the invention.

Figure 13 illustrates a rotary machine with two crowns in which the outer crown acts as a drive shaft, in accordance with a particular embodiment of the invention.

Preferred Embodiment of the Invention

In this text, the term "comprises" and its derivations (such as "understanding", etc.) should not be understood in an exclusive sense, that is, these terms should not be construed as excluding the possibility that what is described and defined can include more elements, stages, etc.

Figure 1 presents a first preferred embodiment of the rotor 100 of the invention which, as seen, is in the form of a circumferential ring. In the embodiment of Figure 1, the cross section of the rotor is rectangular in shape, although it could have another shape suitable for its function. The rotor of figure (1) has an inner face and an outer face, so that the inner and / or the outer face can have a gear teeth. Specifically in Figure 1, the internal face of the rotor has a first gear teeth 103.

The rotor 100 comprises a non-magnetizable section 101 that extends throughout the complete circumference of the rotor around the axis of rotation of the rotor 100, and in which the gear teeth 103 is formed. The magnetizable section 102 extends in an arc of circumference, that is, it does not cover the entire complete circumference, and it is mounted on the outside on the non-magnetizable section 101, that is, the non-magnetizable section 101 and the magnetizable section 102 are superimposed. In the particular case of Figure 1, the magnetizable section 102 covers an arc of circumference of 270 °, although said arc may vary in other implementations. Also, other preferred embodiments may have polyphase configurations in which multiple magnetizable sections 102 alternate with multiple portions of the non-magnetizable section 101.

Figure 2 shows a second preferred embodiment of the rotor 100, in this case combining the first gear teeth 103 of the inner face with a second gear teeth 104 on the outer face. Note that, again, both teeth are implemented with a non-magnetizable material, being integrated in the non-magnetizable section 101 of the rotor 100.

Figure 3 shows the coils 200 in which the rotor 100 is inserted. Said coils are distributed angularly and preferably equidistant from each other, around the axis of rotation of the rotor 100. It can be seen that each coil 200 is a tubular body arched or curved, that is, the thread with which the coil is formed is wound to form the tubular configuration, whose curvature is coincident with the curvature of the rotor. The cross section of the coil cavity is rectangular and substantially coincident with the cross section of the rotor.

Unlike in the traditional cases known in the state of the art, the rotor 100 is arranged inside said coils 200, in order to maximize the efficiency of the machine. Since the magnetizable section 102 of the rotor 100 covers an arc of 270 °, the maximum length of a coil 200 covers a maximum arc of 90 °. Note that with said length of the coil 200 it also acts as a lower dimension of the arc covered by the magnetizable section 102. Note also that the number, size and shape of the coils may vary in other preferred embodiments of the invention. In particular, in case of using a coil 200 of greater length, the rotary machine would remain functional, although the arc in which there will be traction will be smaller.

Additionally, the machine incorporates internal gears 300 that connect the first gear teeth 103 with a drive shaft 400 in this embodiment coinciding with the rotation axis of the rotor. The gears 300 have a cylindrical shape with the perimeter face provided with gear teeth, and so that the gears 300 are arranged such that the axis of rotation of each gear 300 is parallel to the rotation axis of the rotor. The internal gears 300 are angularly distributed around said drive shaft 400, alternating with the coils 200, that is, each gear 103 is disposed between the space between two consecutive coils. The drive shaft 400 has its own gear positioned in the center of the machine and engaged with the rest of the gears 300, so that the rotation of the rotor 100 causes the rotation of the drive shaft 400. In the embodiment of Figure 3, the drive shaft 400 could also be placed in the position of the rotation shaft of any of the gears 300.

However, the rotary electric machine can be implemented with any other mechanical system known in the state of the art that allows to transmit the rotation between rotor 100 and transmission shaft 400. Note also that other preferred implementations of the invention may comprise multiple connected rotors 100 to the same transmission shaft 400.

Figures 4 and 5 present two views of a preferred embodiment of the structure or crankcase that acts as a stator 500 and supports the rest of the rotating machine elements. The stator comprises a base 501 with a central opening 502 that allows the transmission shaft 400 to pass. The stator 500 also comprises a plurality of fixing elements 503 that fix the position of the internal gears 300, allowing said internal gears 300 to rotate on themselves but not around the drive shaft 400. The position of the coils 200 in the stator 500 also remains fixed during the entire operation of the machine, the stator 500 being able to incorporate any support element and any additional electrical connection necessary. The rotary machine can operate in both motor mode and generator mode. In motor mode, the movement of the rotor 100 is motivated by the interaction of the magnetic field generated by the coils 200 and the magnetization of the magnetizable material itself 102. Given the geometry of the machine, in any position of the rotor 100 the magnetizable section 102 is always partially inserted into a first coil 200 or is about to be introduced therein. In addition, a second coil 200 houses said magnetizable section 102 along its entire length. In this way, by supplying the second coil 200 with electric current, the magnetizable section 102 is magnetized and is attracted by the magnetic field generated by the first coil 200.

Throughout the 360 ° rotation of the rotor, the feeding of the coils 200 is switched by the control means to give rise to this situation, that is, a first coil 200 that divides the material and a second coil 200 that magnetizes it . Note that once the magnetizable section 102 is sufficiently inserted in the first coil 200, there is a magnetic coupling sufficient to be magnetized by it, so that magnetization of the first coil 200 is no longer essential. Depending on the order of switching of the coils 200, the motor may operate in one direction of rotation or another interchangeably.

In generator mode, the machine generates electrical energy from mechanical work applied to the axis of the machine. The operation is the inverse to the motor mode, with the difference that the rotor 100 rotates faster than it would with the voltage level to which the coils 200 are fed, so that the electromotive force induced in the stator 500 makes that the current circulates in the opposite direction to the operation as motor.

The described configuration can be extended to multiple concentric crowns around the same transmission shaft 400, as exemplified in Figure 6 with a two-crown rotor. Both crowns follow the previously described structure, with a non-magnetizable section 101 that closes on itself and that supports a magnetizable section 102 that covers an arc of circumference less than 360 °. Each crown is introduced into a group of coils 200, although in particular implementations the number or arrangement of coils could change 200 between both crowns. The inner crown is connected to the drive shaft 400 through the internal gears 300, in contact with the first gear teeth 103 of its inner face. Also, the inner crown is connected to the outer crown through a plurality of external gears 301, in contact with the second gear teeth 104 of its outer face. In this particular case, the outer crown is only toothed on its inner face, although in other embodiments it could comprise external teeth connected to successive crowns.

To facilitate the understanding of the operation of the machine, consider the equivalent linear problem as shown in Figures 7 to 10, in which we replace the heterogeneous crown with a linear ferromagnetic body 102 inserted in a coil 200. Note that the linear displacement of the Ferromagnetic body 102 is equivalent to the rotational displacement of the crown. In that case, the intensity profile of the magnetic field B along the axis of the coil 200 is a plateau, rapidly decaying out of the length of the coil.

The force F that moves the mechanism is born from the interaction between the magnetic field B generated by the coil 200 and the magnetization M proper of the magnetizable body 102. For such force F to exist, it is not enough that such fields exist, but that the end of the magnetizable body 102 must be partially inserted in the coil 200. Let us therefore consider a first situation in which the magnetizable body 102 is fully inserted in the coil 200, as seen in Figure 7. In that case there would be no force , since the ends of the magnetizable body 102 are not affected by any magnetic field. On the contrary, in a second situation, illustrated in Figure 8, in which the magnetizable body 102 is partially inserted in the coil 200, at the end of the magnetizable body 102 a force is generated with the same direction and direction as the vectors of fields B and M.

Finally, when the magnetizable body 102 is not magnetically coupled to the coil 200, field M would not exist, and therefore no tensile force would be generated, as shown in Figure 9. However, by including a previous coil 200 which excites the magnetizable body 102 and generates the field M, yes it it generates the tensile force since the end of the magnetizable body 102 is at the edge of the coil 200 which is where the domain of the magnetic field B begins. Therefore, the use of multiple coils 200 allows for force to exist since the body magnetizable 102 enters the coil 200, thus taking advantage of the entire length of said coil 200.

Note that the extraction shaft 400 does not have to be located on the rotation axis of the rotor 100. For example, Figure 1 1 shows a rotary machine in which the transmission shaft 400 is implemented on one of the external gears 301 communicating the first and second rotor 100. Note that in this case, for simplicity, the coils have not been represented nor have the magnetizable and non-magnetizable parts of the rotor been differentiated. In a second example, presented in Figure 12, the machine comprises a single rotor 100, the transmission shaft 400 being integrated in an external gear 301. In this case, said external gear 301 does not operate as a connection between crowns, but is an element for extracting or introducing mechanical energy into the system, depending on whether it operates as a motor or as a generator. Finally, Figure 13 presents a preferred embodiment in which a non-magnetizable external crown acts as a whole as a transmission shaft 400. That is, the external crown does not participate in the conversion of electrical to mechanical energy nor does it have associated coils, but rather It is used to extract mechanical energy from the system.

In view of this description and figures, the person skilled in the art may understand that the invention has been described according to some preferred embodiments thereof, but that multiple variations can be introduced in said preferred embodiments, without departing from the object of the invention such and as claimed.

Claims

1. Rotary electric machine comprising at least one stator (500) and a rotating rotor (100) with respect to the stator (500), said stator (500) comprising a plurality of coils (200) angularly distributed around an axis of rotation of the at least one rotor (100), where each coil (200) is wound forming a tubular body, and where the rotor (100) is a circumferential ring-shaped body and is disposed inside the coils (220), and where the rotor (100) comprises:

- a section of non-magnetizable material (101); Y

- at least one section of magnetizable material (102) extending in an arc of circumference less than 360 ° around the axis of rotation.

2. Machine according to claim 1 characterized in that the at least one rotor (100) comprises a plurality of magnetizable sections (102) angularly distributed around the axis of rotation of the rotor (100), covering the assembly of said plurality of sections magnetizable (102) an arc of circumference less than 360 ° around the axis of rotation.

3. Machine according to any of the preceding claims characterized in that the circumference arc covered by the at least one magnetizable section (102) is greater than a length of a coil (200) according to the direction of rotation of the rotor (100) , the magnetizable section (102) being kept at least partially out of said coil (200) regardless of its position.

4. Machine according to any of the preceding claims characterized in that the circumference arc covered by the sum of magnetizable sections (102) is less than 360 ° less the length of a coil (200) according to the direction of rotation of the rotor ( 100).

5. Machine according to any of the preceding claims characterized in that it comprises a transmission shaft (400) mechanically coupled with the rotor (100) so that the rotation of the rotor It produces the rotation of the transmission shaft. , and a plurality of internal gears (300) connecting a first gear teeth (103) of an internal face of the at least one rotor (100) with a transmission shaft (400) located on the axis of rotation of the rotor (100 ).

Machine according to claim 5 characterized in that the plurality of internal gears (300) and the plurality of coils (200) alternate angularly around the transmission shaft (400).

7. Machine according to any one of claims 1 to 4 characterized in that it comprises a drive shaft (400) offset with respect to the axis of rotation of the rotor (100).

8. Machine according to any of claims 1 to 4 characterized in that it comprises a non-magnetizable external crown for mechanical energy transmission.

Machine according to any of the preceding claims characterized in that it comprises a plurality of rotors (100) with the same axis of rotation.

Machine according to claim 8 characterized in that it comprises a plurality of external gears (301) that connect a second gear teeth (104) on an outer face of a first rotor (100) with the first gear teeth (103 ) of a second rotor (100).

1 Machine according to claims 8 and 9 characterized in that it comprises a plurality of external gears (301) that laterally connect the first rotor (100) to a third gear.

12. Machine according to any of the preceding claims characterized in that the length of each coil (200) following the direction of rotation of the rotor (200) is greater than the radius of said coil (200) in a section perpendicular to said direction of rotation

13. Machine according to any of the preceding claims characterized in that it comprises control means configured to switch the plurality of coils (200), converting an electric energy of the coils (200) of the stator (500) into mechanical energy of the rotor ( 100).

14. Machine according to any of claims 1 to 11 characterized in that it comprises rotating means configured to rotate the rotor (100) and induce an electromotive force that converts a mechanical energy of said rotor (100) into electrical energy in the coils (200) of the stator (500).

15. Machine according to any of the preceding claims characterized in that the at least one magnetizable section (102) comprises gear teeth.

16. Machine according to any of the preceding claims characterized in that the magnetizable material has a magnetic permeability greater than the magnetic permeability of the non-magnetizable material.