Claims:1. A rotor apparatus for an electrical machine, the apparatus comprising:
a. a rotor back iron (101) with one or more integrated holes (101a), wherein the rotor back iron (101) is fitted on a shaft of the electric machine;
b. a plurality rotor pole segments (102), wherein each rotor pole segment (102) is integrated with one or more holes (102a and 102b), wherein the rotor pole segment is placed on the rotor back iron; and
c. a plurality of rotor magnets (103), wherein each rotor magnet(103) is integrated with one or more holes (103a), wherein each rotor magnet (103) is disposed in-between each rotor pole segment (102) and the rotor back iron (101) for providing magnetic flux around the peripheral surface, wherein the rotor pole segments (102) and the rotor magnets (103)are adjacently connected and press fitted on the rotor back iron (101)to minimize the leakage flux during operating conditions, wherein the rotor pole segments (102) and the rotor magnets (103) are aligned in the particular direction to the rotor back iron (101) through the position of holes (101a, 102a, 102b and 103a) thereby, the rotor pole segments (102) and the rotor magnets (103) are fastened to the rotor back iron (101) through a plurality of screws (104).

2. The apparatus as claimed in claim 1, wherein the rotor back iron (101) and the rotor pole segments (103) are made of lamination steel.

3. The apparatus as claimed in claim 1, wherein the rotor pole segments (102) and the rotor magnets (103) are integrated as a single segment and press fitted on the rotor back iron (101) by riveting therein through the screws (104).

4. The apparatus as claimed in claim 1, wherein the rotor pole segments (102) are detachable (102c, 102d and 102e).

5. The apparatus as claimed in claim 1, wherein the lamination sheets of rotor pole segment (102) is integrated by the process of welding at one or more places (102f), wherein the top surface of rotor back iron (101) is further welded at one or more places (101b).

6. The apparatus as claimed in claim 1, wherein the lamination pack of rotor back iron (101) is integrated by the process of welding and the holes (101a, 102a, 102b and 103a) with counter bore are made on the top surface of the rotor back iron.

7. The apparatus as claimed in claim 1, wherein the rotor back iron (101) and the rotor pole segment (102) are further made of powdered alloy materials, wherein the powder alloy materials are in the form of solid and it possible to make the holes in the material.
, Description:[0001] Preamble to the Description
[0002] The following specification particularly describes the invention and the manner in which it is to be performed:
[0003] Description of the invention:
[0004] Technical field of the invention
[0005] The present invention relates toa rotor apparatus for an electrical machine, which does not create leakage of electric flux in the interior permanent magnet rotor during operating conditions.
[0006] Background of the invention
[0007] Permanent magnet motors are type of electric motors that include a stator and a rotor. The stator is a stationary part of the motor that may be in the form of a hollow cylinder. The rotor is a part of the motor that rotates and may be in the form of a cylinder having a central bore. The rotor may be mounted on a shaft that is received through the central bore. The shaft may be connected to a load, which is to be driven by the motor.
[0008] Generally, the permanent-magnet rotors that have been used in the electric motors include magnets that are mounted at the periphery of the rotor surface or buried inside the rotor iron. The buried magnet arrangement finds more merit as compared to surface mounted in terms of higher operating speed, high field weakening capability and magnet are less exposed for demagnetization. In these motors, the rotor is typically made of a magnetically conductive material such as iron. The use of magnetically conductive material allows the flux lines to flow without a reluctance and makes a closed path between rotor, air gap and stator, during operating conditions. The motor produces the flux lines and link across an air gap to the stator, during operating conditions. The magnets are arranged such that, the adjoining rows of magnets have opposite magnetic poles thereof. Further, the ability of the rotor to magnetize and generate a magnetic field may be determined by the rotor's magnetic permeability. The higher the permeability, the more easily the rotor may magnetize and generate its own magnetic field, which drives the rotation of the rotor within the stator.
[0009] An electrical machine with interior permanent magnet rotor has considerable leakage flux in the rotor iron material. The leakage flux mainly depends on the thickness of rotor iron bridge. A finite rotor bridge thickness is necessary to withstand. The rotor iron having finite thickness withstands the higher centrifugal force at very high running speed and increases the leakage flux thereby. The reduction of leakage is import in interior permanent magnet machine.
[0010] Generally, the lamination sheets are integrated by rivet holes and rivets. The iron bridge between adjacent magnet pole acts as an alternative flux path without the stator. This iron bridge should be as minimum as possible in order to have a low leakage flux. Whereas it should have sufficient thickness to withstand the large centrifugal force produces at a very high speed of rotation. Hence the optimum iron bridge thickness is maintained for the effective use of magnetic material. The magnetic flux starts from magnet of rotor and reaches stator and comes back to rotor. These fluxes are termed as useful flux. Some portion of the Permanent Magnet (PM) flux closes itself in rotor portion via iron bridges which are the leakage flux. The leakage flux path is shown in Figure 2 (Prior art).
[0011] In conventional IPM rotor permanent magnets are placed inside the magnet slot, are known from the prior art. The patent WO201122996A1 proposes a method to reduce the leakage flux by placing the composite material between magnet poles, which increases rotor assembly cost. In patent WO2005117235 proposes a method to reduce leakage flux by placing magnet in the cavity between two sheet packs and which needs additional locking pieces and arrangements. In patent US4510680 deals with the placement of non-magnetic material between the poles and integral rotor is achieved through bolted arrangements, in this arrangement requires a special non-magnetic structural member for making integral rotor.
[0012] Various types of conventional electrical machines that reduce leakage flux are known in the art. In conventional electrical machines, the interior permanent magnet rotor is connected using the drilled process. Typically, the electrical machines use the composite materials for fixing the interior permanent magnet rotor. The use of composite material creates complex mechanical arrangement and lead to leakage of electric flux in the interior permanent magnet rotor.
[0013] Hence, there is need of a rotor apparatus in the electric machine, which eliminates the leakage of electric flux in the interior permanent magnet rotor.
[0014] Summary of the invention:
[0015] The present invention overcomes the drawbacks in the prior art and provides a rotor apparatus for an electrical machine. In a preferred embodiment, the apparatus comprises of a rotor back iron with one or more integrated holes, wherein the rotor back iron is fitted on a shaft of the electric machine. A plurality rotor pole segments. Each rotor pole segment is integrated with one or more holes. The rotor pole segment is placed on the rotor back iron. A plurality of rotor magnets wherein each rotor magnet is integrated with one or more holes. Each rotor magnet is disposed in-between each rotor pole segment and the rotor back iron for providing magnetic flux around the peripheral surface, wherein the rotor pole segments and the rotor magnets are adjacently connected and the rotor magnets are fastened through the screws.
[0016] In preferred embodiment of the invention, the rotor back iron and the rotor pole segments are made of lamination steel.
[0017] In preferred embodiment of the invention,the rotor pole segments and the rotor magnets are integrated as a single segment andfastenedon the rotor back iron by the screws.
[0018] In preferred embodiment of the invention, the rotor pole segments are detachable.
[0019] The present invention provides a rotor apparatus for electric machine, which eliminates leakage of electric flux in the interior permanent magnet rotor during operating conditions and also prevents the wastage of raw materials during manufacturing process.The electrical machines use the composite materials for fixing the interior permanent magnet rotor in conventional apparatus. The proposed apparatus does not create complex mechanical arrangement using the composite materials.
[0020] The present invention provides a rotor apparatus which is simple, cost effective and easy to assemble and is suitable for the applications in all types of motor manufacturing industries.
[0021] It is to be understood that both the foregoing general description and the following details description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
[0022] Brief description of the drawings:
[0023] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0024] Figure 1shows a conventional rotor construction in the electrical machine.
[0025] Figure 2shows a leakage flux in conventional IPM rotor
[0026] Figure 3 shows a perspective view of the rotor apparatus for an electrical machine, according to one embodiment of the invention.
[0027] Figure 4 shows an exploded view of the rotor pole segments of rotor, according to one embodiment of the invention.
[0028] Figure 5 shows the leakage flux in present innovation with IPM rotor, according to one embodiment of the invention.
[0029] Figure 6 shows the welded rotor back iron and pole segment, according to one embodiment of the invention.
[0030] Figure 7 shows the rotor back iron and pole segment made of powdered alloy material, according to one embodiment of the invention.
[0031] Figure 8 illustrates the flux linkage comparison of conventional rotor arrangement and proposed rotor.
[0032] Figure 9 illustrates the net flux linkage comparison of conventional rotor arrangement and proposed rotor.
[0033] Detailed description of the invention:
[0034] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0035] The present invention provides a rotor apparatus for electric machines, which prevents the wastage of raw materials during manufacturing process and also eliminates leakage of electric flux in the interior permanent magnet rotor during operating conditions. The electrical machines use the composite materials for fixing the interior permanent magnet rotor. The apparatus does not create complex mechanical arrangement using the composite materials.
[0036] Figure 3 shows a perspective view of the rotor apparatus for an electrical machine, according to one embodiment of the invention. In a preferred embodiment, the rotor apparatus (100) includes a rotor back iron (101) with one or more integrated holes (101a),a plurality of rotor magnets (103)with one or moreintegrated holes(103a) and a plurality rotor pole segments (102)with one or more integrated holes (102a and 102b). The rotor back iron (101) is fitted on a shaft of the electrical machine. The rotor pole segment (102) is arranged on the rotor back iron (101). The rotor magnet (103) is disposed in-between the rotor pole segment (102) and the rotor back iron (101) for providing magnetic flux through said adjacent segments for linking around the peripheral surface. The rotor pole segments (102) and the rotor magnets (103) are aligned in the particular direction to the rotor back iron (101) through the position of holes (101a, 102a, 102band 103a) thereby. The rotor pole segments (102) and the rotor magnets (103) are fastened to the rotor back iron (101) through a plurality of screws (104) therein. The rotor back iron (101) and the rotor pole segments (102) are made of lamination steels. In the preferred embodiment, the rotor pole segments (102) and the rotor magnets (103) are integrated as a single segment and press fitted on the rotor back iron (101) by riveting therein through the screws (104).
[0037] Figure 4 shows an exploded view of the rotor pole segments of rotor, according to one embodiment of the invention. In a preferred embodiment, the rotor pole segment (102) is preferably made of lamination steel. The rotor pole segment (102) is detachable (102c, 102d and 102e) and is placed on the rotor magnet (103), wherein the rotor magnet (103) is placed on the rotor back iron (101). The rotor pole segment (102) is detachable (102c, 102d and 102e) and shall be arranged as shown. The rotor pole segment (102) is connected through a screw (104), which is fastened to hold the rotor magnet (103) and rotor back iron (101)firmly. In the preferred embodiment, the rotor pole segment (102) is made of multiple set of segments. The apparatus will avoid the process of drilling in rotor pole segment (102). This rotor pole segment (102) and the rotor magnet (103) is arranged over the rotor back iron (101) and integrated by the fixing screws (104) and is shown in Figure 4.
[0038] Figure 5shows the leakage flux in present innovation with IPM rotor, according to one embodiment of the invention.
[0039] Figure 6shows thewelded rotor back iron and pole segment, according to one embodiment of the invention. In a preferred embodiment, the rotor back iron and rotor pole segment (102) are welded each other. The number of lamination sheets of rotor pole segment (102) is integrated by the process of welding at one or more places (102f). Similarly, welding is done at the top surface of rotor back iron (101) at one or more places (101b). The complete rotor apparatus (100) is obtained by fixing rotor pole segment (102), the rotor magnet (103) and rotor back iron (101) with the help of screws (104).
[0040] Figure 7shows the rotor back iron and pole segment made of powdered alloy material, according to one embodiment of the invention. In a preferred embodiment, the powder alloy material is used instead of lamination sheet for making rotor pole segment (102) and rotor back iron (101). The powder alloy material is in the form of solid and it possible to make the hole in this material. The use of this material will reduce the complexity in making holes in lamination sheets. One or more holes with counter bore for screw fixing is made on the top surface of the rotor pole segment (102). Similarly, the drill is made on the top surface of the rotor back iron (101). The integrated rotor is assembled by arranging rotor pole segment (102), the rotor magnet (103) and rotor back iron (101) one above another and fixed with help of screws (104).
[0041] Figure 8 illustrates the flux linkage comparison of conventional rotor arrangement and proposed rotor.
[0042] Figure 9 illustrates the net flux linkage comparison of conventional rotor arrangement and proposed rotor. In a preferred embodiment, the proposed rotor arrangement has reduced flux leakage which results higher flux linkage with the proposed rotor as compared to the conventional rotor arrangement
[0043] The present invention provides a rotor apparatus for electric machine, which prevents the wastage of raw materials during manufacturing process and also eliminates leakage of electric flux in the interior permanent magnet rotor during operating conditions. The electrical machines use the composite materials for fixing the interior permanent magnet rotor. The apparatus does not create complex mechanical arrangement using the composite materials.
[0044] The present invention provides a rotor apparatus which is simple, cost effective and easy to assemble and is suitable for the applications in all types of motor manufacturing industries.