DESC:FIELD OF THE INVENTION

The present invention relates to permanent motor rotors. Specifically, the permanent magnet rotors used in permanent magnet motors as prime movers for electric vehicles.

BACKGROUND OF THE INVENTION

The torque of an electric motor may experience a ripple effect (i.e., a torque ripple) due to the particular construction of the electric motor. The torque ripple may be disadvantageous in the electric motor. The most significant source of torque ripple is slotting effect brought about by burying the magnet inside the rotor. The interaction between the rotor slots and the stator slots (the winding slots) generates significant torque ripple.

Present technologies available uses skewing to reduce torque ripple. Skewing is primarily used in the industry to lower cogging and ripple torque. This technique however lowers machine torque and adds manufacturing complexity and costs.

The rotor field in a permanent magnet machine is obtained by virtue of its structure, unlike other machines such as induction, switched or synchronous reluctance machines, in which the field is generated by a stator current supplied by a source. As a result, permanent magnet machines exhibit superior efficiency as compared to other such machines.

US8174158B2 discloses the various embodiments are directed to a permanent magnet machine (“PM machine”), and more specifically an internal permanent magnet machine (“IPM machine”) that includes rotor magnets configured asymmetrically with respect to the rotor periphery, thereby producing an averaging effect similar to that achieved through traditional skewing of the rotor magnets. In alternate embodiments, the span, placement and/or shape of the magnets may vary from one pole to the next.
US8922086B2 discloses a synchronous electric machine having a fixed stator, a multi-phase stator winding and having a rotor which has poles, excited in a predefined sequence, over its circumference, the number of poles being changeable as a function of the intensity and the direction of a field current in at least one field coil of the rotor. For improving the efficiency of the machine and for reducing the number of field coils and the entire coil cross section it is provided that the rotor has a laminated core, laminated in the axial direction, which has grooves on the circumference for accommodating the at least one field coil and that the at least one field coil is situated on the circumference of the rotor with a step size which corresponds to the pole pitch of the lower number of poles.

US5818140A discloses a synchronous reluctance electrical motor, including a stator having an even number of slots per pair of poles equal to ns, a rotor of the transverse lamination type having an even number nr of equivalent slots per pair of poles, and an air gap separating the stator from the rotor, wherein, in order to minimize the torque ripple, between the number ns of the stator slots and the number nr of the rotor equivalent slots the following relationships are satisfied: ns -nr ?0, +2, -2; nr >6; ns ?m·nr, m being an integer, and preferably also the following relationship: ns -nr =±4 . The rotor of this motor may have insulating layers open to the air gap and/or insulating layers closed towards the air gap by iron ribs suitable for being magnetically saturated; other iron ribs may traverse some insulating layers in intermediate positions thereof. Preferably the rotor layers are designed with constant permeance, in order to avoid producing harmonics capable of interacting with harmonics produced by the stator windings.

US20170357043A1 discloses a motor drive system and method for controlling an electric motor. The motor drive system includes a plurality of phase lines switchably connected to the electric motor, a plurality of controllable switches, and a controller. The controller is communicatively coupled to the plurality of controllable switches and configured to receive a signal indicative of a rotor speed and a rotor position from the rotor sensor. The controller generates a value expressing a back-electromotive force (back-EMF) as a function of the rotor position with respect to a rotating frame of reference. Based on the rotor position, the controller determines a plurality of phase currents that reduce a torque ripple of the electric motor to approximately zero. The controller actuates the controllable switches to supply the electric motor with the plurality of phase currents.

EP3086450A1 discloses a rotor 30 for a synchronous reluctance machine wherein a torque ripple behaviour of the machine is optimized by altering the geometry of insulating barriers 4 of the rotor 30. A q-axis pitch angle 12 is used as a design variable instead of setting its value equal to the rest of the rotor slot pitches or binding its value to the stator slot pitch. The resulting rotor 30 has a non-regular slot pitch across the q-axis and substantially regular slot pitch otherwise. Synchronous reluctance machines that employ rotor discs 1 and rotor assemblies in accordance with the present invention may exhibit low torque ripple without sacrificing high torque values.

OBJECT OF THE INVENTION

The prime object of the present invention is to remove the drawbacks the above mentioned prior arts have.

The object of the present invention is to provide a novel single layer permanent magnet rotor having design features so to reduce torque ripple.

Another object of the present invention is to provide a novel single layer permanent magnet rotor which eliminates the need for rotor skewing.

Yet another object of the present invention is to provide a novel single layer permanent magnet rotor which reduces torque ripple using novel barrier shape and conventional symmetrical windings.

Yet another object of the present invention is to provide a novel single layer permanent magnet rotor which reduces torque ripple by maintaining uniform air-gap and reduces torque ripple by novel rotor barrier profile.

SUMMARY OF THE INVENTION

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and featurs described above, further aspects, embodiments and features will become apparent by reference to the drawings and the following detailed description.

The embodiment of the present invention provides a rotor for a permanent magnet motor, comprising a magnetic component and a rotor body containing said magnetic component, characterized in that the torque ripple effect is reduced using novel barrier shape and conventional symmetrical windings.

Another embodiment of the present invention provides a rotor for a permanent magnet motor wherein the rotor has a symmetrical pole profile which reduces the torque ripple without any penalty on torque output.

Another embodiment of the present invention provides a rotor for a permanent magnet motor wherein the rotor uses uniform air-gap and reduces torque ripple by novel rotor barrier profile.

Yet another embodiment of the present invention provides a rotor for a permanent magnet motor, wherein the need for the rotor skewing is eliminated by the design feature of the rotor.

Yet another embodiment of the present invention provides a rotor for a permanent magnet motor, wherein the rotor has a single layer.

Yet another embodiment of the present invention provides a rotor for a permanent magnet motor, wherein the rotor has a permanent magnet.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and featurs described above, further aspects, embodiments and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrative exemplary embodiments and together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:

Figure 1 discloses a design feature of novel single layer permanent magnet rotor.

It should be appreciated by those skilled in the art that any block diagrams represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow chart, flow diagrams, state transition diagram, pseudo code, and the like readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION OF THE DRAWINGS

The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments: on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

It is also to be understood that various arrangements may be devised that although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.

In addition, the description of “first”, “second”, “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number f technical features indicated. Thus features defining “first” and “second” may include at least one of the features, either explicitly or implicitly.

It should be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.

Unless otherwise defines, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g. those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The foregoing detailed description of the system implemented is better understood when read in conjunction with the attached drawings. For better understanding, each component is represented by a specific number which is further illustrated as a reference number for the components used with the figure.

Unless otherwise defines, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g. those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Figure 1 discloses a design feature of novel single layer permanent magnet rotor. The torque ripple effect is reduced using novel barrier shape and conventional symmetrical windings. The rotor has a symmetrical pole profile which reduces the torque ripple without any penalty on torque output. The rotor uses uniform air-gap and reduces torque ripple by novel rotor barrier profile. The need for the rotor skewing is eliminated by the design feature of the rotor. The above rotor in reference has a single layer and also has a permanent magnet.

The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art can choose suitable manufacturing and design details.

It should be understood, however that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, as apparent from the discussion herein, it is appreciated that throughout the description, discussion utilizing terms such as “receiving” or “determining”, or “retrieving” or “controlling” or the like refer to the action and processes of an control unit or similar electronic device, that manipulates and transforms data represented as physical (electronic) quantities within the control unit’s registers and memories into other data similarly represented as physical quantities within the control unit memories or registers or other such information storage, transmission or display devices.

Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. It will be appreciated that several of the above-described and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

The claims, as originally presented and as they may be amended encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teaching described herein, including those that re presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
,CLAIMS:We claim:

1. A rotor for a permanent magnet motor, comprising:
- a magnetic component; and
- a rotor body containing said magnetic component, characterized in that the torque ripple effect is reduced using novel barrier shape and conventional symmetrical windings.

2. A rotor for a permanent magnet motor as claimed in claim 1, wherein the rotor has a symmetrical pole profile which reduces the torque ripple without any penalty on torque output.

3. A rotor for a permanent magnet motor as claimed in claim 1, wherein the rotor uses uniform air-gap and reduces torque ripple by novel rotor barrier profile.

4. A rotor for a permanent magnet motor as claimed in claim 1, wherein the need for the rotor skewing is eliminated by the design feature of the rotor.

5. A rotor for a permanent magnet motor as claimed in claim 1, wherein the rotor has a single layer.

6. A rotor for a permanent magnet motor as claimed in claim 1, wherein the rotor has a permanent magnet.