WO2024130206A1 - High efficiency multi-phase generator with enhanced rotor configuration - Google Patents

Abstract

A multi-phase generator has a stator or stator assembly in which permanent magnets are retained by the rotor such that substantial interference with magnetic field transition between two adjacent permanent magnets is reduced or even entirely eliminated, which in turn improves efficiency and power output.

Description

HIGH EFFICIENCY MULTI-PHASE GENERATOR WITH ENHANCED ROTOR CONFIGURATION

[0001] This application claims priority to our US Provisional Patent Application with the serial number 63/387,890, which was filed December 16, 2022 and which is incorporated by reference herein.

Field of the Invention

[0002] The field of the invention is multi-phase generators, especially as it relates to multiphase generators with an improved rotor configuration that reduces substantial interference from rotor laminations on the magnetic fields of the permanent magnets to thereby improve efficiency.

Background of the Invention

[0003] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0004] All publications and patent applications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0005] Multi-phase generators have become increasingly common in recent years and can now be found in numerous applications at a variety of power production levels. Among other design options, many multi-phase generators use permanent magnets in a rotor and a plurality of coils in the stator, and the particular use often drives specific design considerations. For example, where the power generator uses a low-speed rotor as described, for example in KR 10-1315870, multiple coil bundles are disposed in multiple rings that are circumferentially arranged about the periphery of a stator. While desirable in at least some use cases, assembly is often complex and tends to require elaborate wiring schemes. [0006] In another example, significantly higher rotational speeds can be realized in the split rotor multi-phase generator as described in US 9,444,294 where first and second rotors are used with respective stators to so generate electrical power. However, and regardless of the rotational speed, the output from the coils in the stator of multi-phase generators is in most cases not a clean sine wave but has a more jagged wave form that is indicative of magnetic fields inhomogeneity and/or distortion at the stator, ultimately resulting in loss of power production and efficiency.

[0007] Thus, even though various multi-phase generators based on rotors having permanent magnets are known in the art, all or almost all of them suffer from several drawbacks. Therefore, there remains a need for improved multi-phase generators.

Summary of The Invention

[0008] The inventive subject matter is directed to various devices, configurations, and methods for multi-phase generators with improved efficiency and power output that include a stator or stator assembly in which permanent magnets are retained by the rotor using a manner such that substantial interference with magnetic field transition between two adjacent permanent magnets is reduced or even entirely eliminated.

[0009] In one aspect of the inventive subject matter, the inventors contemplate a rotor laminate that comprises a disc having a central rotational axis and an outer perimeter encircling the rotational axis and a plurality of registration elements circumferentially arranged about the outer perimeter and configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other. In such device, the registration elements are configured such that the registration elements retain the plurality of permanent magnets without substantial interference with magnetic field lines of adjacent magnets having opposite polarity.

[0010] For example, the disc may comprise a ferromagnetic metal or metal alloy that conducts magnetic field lines, while in another example the disc comprises a polymeric material that includes a metal, a metal alloy, or a carbon allotrope that conducts magnetic field lines. In a yet further example, the disc comprises a non-magnetic material that does not conduct magnetic field lines, and the non-magnetic material is coupled to the outer perimeter and/or the registration elements. In typical embodiments, the plurality of registration elements will be configured to retain between 4 and 32 permanent magnets. [0011] In some embodiments, the plurality of permanent magnets, when retained by the registration elements, will radially extend to a radial height, and the plurality of registration elements will radially extend no more than 25% of the radial height. In further embodiments, the plurality of permanent magnets, when retained by the registration elements, will radially extend to a radial height, and the plurality of registration elements will radially extend more than 25% of the radial height. In such case, the plurality of registration elements will preferably comprise a material that does not conduct a magnetic field.

[0012] It is still further contemplated embodiments, the disc may have a thickness of between 1 mm and 10 mm, and/or may have a central opening configured to receive and rotationally retain a rotor axis. Where desired, the disc may also have a plurality of cutouts between the central rotational axis and the perimeter, wherein the cutouts are typically arranged in radial symmetry about the central rotational axis.

[0013] In another aspect of the inventive subject matter, the inventors contemplate a permanent magnet multi-phase rotor that includes a plurality of rotor laminates as presented herein in a stacked arrangement such that the registration elements of one laminate is in alignment with the registration elements of an adjacent laminate. Most typically, a plurality of permanent magnets will be radially retained by the registration elements and circumferentially arranged about the perimeter with alternate polarity. Moreover, it is generally contemplated that a first and a second end plate terminate respective ends of the stacked arrangement, wherein each end plate has a plurality of endplate retaining structures that retain the plurality of permanent magnets.

[0014] Most typically, but not necessarily, the rotor will have at least 6 rotor laminates in the stacked arrangement. It is further contemplated that the disc may comprise a ferromagnetic metal or metal alloy that conducts magnetic field lines. In other embodiments, the disc may also comprise a polymeric material that includes a metal, a metal alloy, or a carbon allotrope that conducts magnetic field lines. Alternatively, the disc may also comprise a non-magnetic material that does not conduct magnetic field lines, and the non-magnetic material is coupled to the outer perimeter and/or the registration elements. Most typically, between 4 and 32 permanent magnets will be radially retained by the registration elements.

[0015] In still further contemplated embodiments, the first and second end plates will comprise a material that does conduct a magnetic field (e.g., the first and second end plates comprise a ferrous steel). Where desired, the endplate retaining structures in the first and second end plates may comprise one or more openings that enclose respective end portions of the permanent magnets. Additionally, it is contemplated that a void space between adjacent magnets will remain unfilled.

[0016] In still further aspects of the inventive subject matter, the inventors contemplate a permanent magnet multi-phase rotor that comprises a monolithic rotor disc having a plurality of registration elements circumferentially arranged about the outer perimeter and being configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other. A plurality of permanent magnets is then radially retained by the registration elements and circumferentially arranged about the perimeter with alternate polarity. Most typically, a first and a second end plate may be coupled to respective ends of the monolithic rotor, wherein each end plate has a plurality of endplate retaining structure that retain the plurality of permanent magnets.

[0017] For example, the monolithic rotor may be machined or pressed/sintered from a single material that conducts magnetic field lines (e.g., ferromagnetic metal or metal alloy that conducts magnetic field lines) and/or may comprise a polymeric material that includes a metal or a metal alloy, or a carbon allotrope that conducts magnetic field lines. Alternatively, the monolithic rotor may also comprise a non-magnetic material that does not conduct magnetic field lines, wherein the non-magnetic material is coupled to the outer perimeter and/or the registration elements.

[0018] As noted before, between 4 and 32 permanent magnets may be radially retained by the registration elements, and/or the first and second end plates may comprise a material that does not conduct a magnetic field (e.g., a series 300 steel). In further embodiments, the endplate retaining structures in the first and second end plates may comprise openings that enclose respective end portions of the permanent magnets, and/or a void space between adjacent magnets may remain unfilled.

[0019] Consequently, the inventors also contemplate an electrical generator that includes a rotor as presented herein, and a stator circumferentially enclosing the rotor, wherein the rotor and stator are configured as a multi-phase generator (that may, for example, comprise between 4 and 32 permanent magnets). As will be readily appreciated, contemplated generators may also comprise a second rotor as presented herein, wherein the generator is configured such that the rotor and the second rotor may rotate in opposite directions. In most common embodiments, the generator will be configured such that the stator is fixed. However, in other embodiments, the generator may also be configured such that the stator rotates in an opposite direction relative to the rotation of the rotor.

[0020] Preferably, but not necessarily, contemplated generators will be configured as a 9- phase, 18-phase, 36-phase, or 72-phase generator. Moreover, the generator will typically be configured such that the rotor rotates at between 200 and 5,000 rpm during normal power generation and/or to generate between about 5-500 kW power. Furthermore, the inventors contemplate a power generator unit that includes the generator as presented herein, wherein the power generator unit is preferably actuated by a renewable power source.

[0021] In yet another aspect of the inventive subject matter, the inventors further contemplate a method of improving efficiency of a permanent magnet multi-phase generator having a stator and a rotor containing a plurality of permanent magnets. Most typically, such method will include a step of coupling a plurality of permanent magnets in a circumferential arrangement to the rotor in alternate polarity, wherein the plurality of magnets are retained in a radially fixed position relative to each other by a plurality of registration elements such that a gap is formed between two adjacent magnets. It is further preferred that the gap radially extends from the rotor or registration element to respective distal ends of the adjacent magnets and that the gap contains a material that does not conduct a magnetic field or air to thereby eliminate substantial interference with magnetic field transition. In another step of contemplated methods, the plurality of magnets are retained by a plurality of respective retaining structures at the ends of the rotor.

[0022] Preferably, but not necessarily, the rotor has a mass density in a portion proximal to a rotational axis that is lower than the mass density in a portion distal to the rotational axis to thereby provide improved conservation of angular momentum as compared to a rotor with uniform mass density. Moreover, in at least some embodiments, the rotor is coupled to a first prime mover and that the stator is coupled to a second prime mover, wherein the rotor and the stator rotate in opposite directions. It is still further contemplated that the permanent magnet multi-phase generator in such methods is configured such that the rotor rotates at between 200 and 5,000 rpm during normal power generation, and/or that the permanent magnet multi-phase generator is configured as a 9-phase, 18-phase, 36-phase, or 72-phase generator. [0023] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

Brief Description of The Drawing

[0024] Prior Art FIG.1A-1C are exemplary rotor configurations for a multi-phase generator in which multiple permanent magnets are embedded in alternating polarity, and in which the permanent magnets are retained in specific retaining structures.

[0025] FIG.2 is a perspective view of an exemplary rotor lamination.

[0026] FIG.3 is a perspective view of a plurality of rotor laminates in stacked configuration with one endplate.

[0027] FIG.4 is a perspective view of a plurality of rotor laminates in stacked configuration with several permanent magnets coupled to the registration elements.

[0028] FIG.5 is a perspective view of a laminate stack placed between a pair of end plates.

[0029] FIG.6 is a schematic plan view of an exemplary stator.

[0030] FIG.7 is a schematic plan view of an exemplary stator end plate.

[0031] FIG.8 is a schematic illustration of an exemplary assembled generator.

[0032] FIG.9 is an exemplary oscillograph of a power output for a rotor with laminations as shown in FIG. IB.

[0033] FIG.10 is an exemplary oscillograph of a power output for a rotor with laminations as shown in FIG.2.

[0034] FIG.11A is an exemplary schematic illustration of a ‘dirty’ output wave from a rotor with interference.

[0035] FIG.11B is a schematic illustration of a ‘clean’ output wave (theoretical ideal sine wave). [0036] FIG.11C is an exemplary schematic illustration of a dirty power wave with a ‘clean’ power wave with multiple intersections and areas under the curve.

Detailed Description

[0037] The inventors have discovered various devices, configurations, and methods for multiphase generators that include a rotor having a retention structure for the permanent magnets in which magnetic interference is reduced, or even entirely eliminated. Advantageously, such rotors were demonstrated to exhibit more homogenous polarity transitions in the area between adjacent magnets and to generate an output current with a significantly improved sinewave shape, thereby improving efficiency and power output.

[0038] More particularly, and as exemplarily shown in Prior Art FIG.1A, the permanent magnets are retained in the rotor within respective slots formed in the rotor or are retained by retention structures that partially cover the permanent magnets as shown in Prior Art FIG. IB. Likewise, Prior Art FIG.1C depicts a rotor configuration in which the magnets are embedded in the periphery of the rotor. Notably, the inventors have now discovered that the presence of a material 110 that conducts magnetic field lines proximal to the outer edge of a permanent magnet as is the case in Prior Art FIGS.1 A-1C can lead to significant magnetic interference at the boundary of magnetic field of adjacent magnets. Such interference was shown to produce non-homogenous and even multiple polarity transitions in the area between adjacent magnets, resulting in magnetic force irregularities that reduce efficiency, distort power output wave form, and ultimately power production.

[0039] The term “substantial interference” when used in conjunction with a magnetic field or magnetic field lines refers to a deviation of a magnetic field or magnetic field lines from a theoretical magnetic field or magnetic field lines that would be expected with one or more magnets in a configuration in which the magnet or magnets are disposed in air or vacuum. Such deviation can be identified and/or quantified in a variety of manners, such as by use of a magnetometer or by current analysis of an induction coil that moves relative to the magnetic field or magnetic field lines. For example, where magnets are radially arranged with alternating polarity on a rotor, and where the rotor rotates in a stator that comprises a plurality of induction coils (as in a conventional permanent magnet generator), the current output of an induction coil exposed to the theoretical magnetic field or magnetic field lines would have the shape of a perfect sine wave. In case of substantial interference, the current output of the induction coil would have a wave shape that does not conform to the perfect sine wave but may be jagged, have multiple peaks, exhibit local asymmetry about the peak, and/or have a reduced amplitude as is shown in more detail below.

[0040] It was previously thought that a retention structure (e.g., covering ring, brackets, or T- shaped extension between magnets) for the magnets or even embedding the magnets in cutouts in the rotor was needed due to the considerable centrifugal forces as the rotor can spin at considerable frequency e.g., 200 to 5,000 rpm, and even higher). In contrast, the inventors now recognized that the magnets can be securely retained in the rotor where the rotor comprises a plurality of registration elements circumferentially arranged about the outer perimeter that are configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other. The relatively strong magnetic forces exerted by the permanent magnets (typically at least 200-250 pound pulling force), especially in conjunction with respective end plates that exert additional compressive forces to retain the magnets, have proven to effectively retain the permanent magnets without the need for retaining structures as shown in Part Art FIGS.1 A-1C. Advantageously, the registration elements have a radial height that is sufficiently small such as to not interfere with the magnetic field lines in the gap between and at the outer edges of the magnets.

[0041] One exemplary rotor lamination is depicted in FIG.2. Here, a rotor laminate 200 has a plurality of registration elements 210 circumferentially arranged about the outer perimeter 202 and the registration elements 210 are configured to radially retain a plurality of permanent magnets (not shown). A central opening 220 is formed concentrically with the central rotational axis and is sized and dimensioned to accommodate a rotor axis (not shown). Cutouts 230 are arranged in radial symmetry about the central rotational axis to reduce overall weight of the laminate. Through holes 232 are used to align and secure multiple laminates to each other and to allow for compression of the laminates and respective endplates to so generate further retaining forces on the magnets.

[0042] FIG.3 depicts a plurality of rotor laminates 300 in a stacked configuration in which the registration elements cooperate to form a structure that retains a plurality of radially spaced magnets (not shown). Note that the upper end plate 340 is secured to the laminate stack via bolts or screws 350 that extend across the through holes. FIG.4 depicts the laminate stack of FIG. 3 in an inverted position with rotor axis 470 inserted and with a number of magnets 460 having alternate polarity positioned and retained in the stack (not all magnets shown). As can be readily seen from FIG.4, the magnets are retained in the laminate stack but also contact the endplate to an extent sufficient to allow compression and retention of the magnets. FIG.5 is another exemplary view of a laminate stack placed between a pair of end plates, with through holes, cutouts, and central opening aligned to so form a rotor (magnets not shown).

[0043] Upon complete assembly of the rotor using the laminations, magnets, and end plates, the rotor can then be placed in a stator, and an exemplary stator is schematically depicted in FIG.6. As will be readily appreciated, the stator will upon assembly retain a plurality of coils surrounding the radially spaced protrusions as is well known in the art (note the widened terminal ends of the protrusions and near homogenous thickness). In this context, it should also be appreciated that the rotational symmetry of the rotor laminations/rotor assembly and the stator will allow for homogenous magnetic field line geometries. To enable a fixed position of the stator relative to the ground, stator endplates as exemplarily shown in FIG.7 can be used that have corresponding through holes to so allow for assembly. The rotor axis in this example extends though the rotor and end plates and the stator end plates and is rotationally fixed in a bearing. As can be readily seen from FIG.7, the stator is in fixed relationship to the stator end plates via bolts, and the generator can be mounted to a surface or bracket (not shown) via end the plates, and FIG.8 depicts an exemplary assembled generator. Of course, it should be recognized that the assembled generator may be built with an open architecture or in a conventional moor/generator enclosure.

[0044] With respect to the specific dimensions of the rotor laminate it should be appreciated that the exact sizes may vary considerably depending on the particular use and desired power output of the generator. Therefore, it should be recognized that the thickness of a lamination can be between 1 mm and 5 mm, or between 5 mm and 1 cm, or between 1 cm and 10 cm, and even thicker. Likewise, the diameter (as measured to the outer perimeter) of the rotor may vary considerably but will typically be between about 5 and 25 cm, or between 25 and 50 cm, or between 50 cm and 150 cm, and even larger. Therefore, the number and size of the registration elements will also change depending on the size of the rotor lamination and number of magnets required.

[0045] Most typically, contemplated rotors will have a plurality of permanent magnets, and it is generally contemplated that the number of magnets will be at least 4, at least 6, at least 8, at least 12, at least 16, at least, 32, at least 64, and even more. However, in most typical embodiments, the number of permanent magnets will be between 4 and 32. As will be readily appreciated, suitable magnets will especially include rare earth-based permanent magnets such as neodymium-based magnets (e.g., alloys from neodymium, iron and/or boron), samariumcobalt magnets, and alnico magnets (from aluminum, nickel, and cobalt, optionally containing copper, titanium and/or iron). In most of the embodiments presented herein, the magnetic strength of the magnet, alone or in combination with the compressive force of the endplates, will be sufficient to retain the magnet to the rotor. However, it should be noted that the magnets may be further coupled to the rotor using an adhesive or resin (e.g., epoxy). In yet further contemplated aspects, it should be appreciated that while exemplary embodiments presented herein use permanent magnets, such magnets can also be replaced by excited coils to so generate a magnetic field as is known in the art.

[0046] With respect to suitable materials for the rotor laminations, it should be appreciated that a large variety of materials are deemed appropriate for use herein so long as such materials are magnetically conductive. For example, appropriate rotor lamination materials include various ferromagnetic metals or metal alloys that conducts magnetic field lines. However, in further embodiments, the lamination may also comprise, or be entirely manufactured from a polymeric material that includes a metal, a metal alloy, or a carbon allotrope that conducts magnetic field lines. Such materials may be especially advantageous where a lower weight of the rotor is desired. Additionally, contemplated laminations and rotors may also comprise a non-magnetic material that does not conduct magnetic field lines. In such case, it is typically preferred that the non-magnetic material is coupled to the outer perimeter and/or the registration elements extending radially outwards from the perimeter.

[0047] Regardless of the particular choice of material for the rotor lamination or rotor, it is generally preferred that the registration elements are configured such that the registration elements retain (at least relative to other magnets, and preferably also radially relative to the perimeter) the plurality of permanent magnets without interference with magnetic field lines of adjacent magnets having opposite polarity. Therefore, in at least some embodiments, the registration elements will not significantly extend in a radial direction from the perimeter of the lamination or rotor. For example, where the permanent magnets are inserted and retained between respective registration elements, it is typically preferred that the registration elements radially extend to a radial height that extends no more than 60%, or no more than 50%, or no more than 40%, or no more than 30%, or no more than 25%, or no more than 20%, or no more than 15%, or no more than 10% of the radial height of the permanent magnets. It should be appreciated that such relatively shallow registration elements will advantageously not interfere with the magnetic field lines between adjacent magnets of opposite polarity at the outer edges and faces of the installed magnets.

[0048] However, it should also be appreciated that taller registration elements, and even conventional retention structures could be used where such structures are non-magnetic or do not conduct magnetic field lines. For example, such materials may include aluminum, copper, titanium, and their alloys (bronze), stainless steel, as well as various polymer materials.

[0049] In still further contemplated aspects of the inventive subject matter it should be noted that the rotor lamination may include a number of cutouts to reduce the overall weight of the rotor. Most typically, such cutouts will be symmetrical with regard to their position to avoid imbalances during rotation, and the number and/or shape of the cutouts will depend on the desired degree of weight reduction. However, preferred cutouts will be circular for ease of manufacture. Furthermore, while a central rotor axis is generally preferred, multiple axes that form a bundle or other geometries are also deemed suitable for use herein.

[0050] With respect to the endplates, it is generally contemplated that the endplates have a diameter that exceed that of the lamination or rotor. Therefore, the endplates will have a radius that is at least 2%, or at least 5%, or at least 10%, or at least 15%, or at least 20% larger than the radius of the outer perimeter of the rotor lamination or rotor. Thus, in some embodiments, the end plate will not extend beyond the distal ends of the magnets or may be co-extensive with the distal ends of the magnets. In other embodiments, the end plate will extend beyond the distal ends of the magnets (and in such case the stator may also be positioned between the end plates.

[0051] Most typically, the rotor endplates will be made from a material that is ferrous steel, non-magnetic or does not conduct magnetic field lines. For example, such materials may include aluminum, copper, titanium, and their alloys (bronze), stainless steel, as well as various polymer materials. Still further, it is contemplated that the endplates have a thickness and/or are manufactured from a material that has sufficient resilience to allow compression of the endplates to so assist in retention of the magnets to the rotor. Likewise, and especially where the endplates are made from a ferrous material, such endplates will not only add to the clamping/bonding forces exerted on the magnets, but may also provide magnetic shielding. [0052] Furthermore, it should be appreciated that while the above considerations were with regard to multiple rotor laminations that are stacked to form a rotor, the rotor in alternative embodiments may also be a monolithic rotor that is manufactured from a single piece of material. Similar to the embodiments noted above, the monolithic rotor will have a plurality of registration elements circumferentially arranged about the outer perimeter and configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other and also be bracketed by respective non-magnetic endplates to help retain the permanent magnets.

[0053] As will be readily appreciated, the monolithic rotor may be manufactured in a variety of manners and the specific mode of manufacture will at least in part determine the type of production. However, and among other options, preferred methods of manufacture include machining from single work pieces, pressing and/or sintering material that conduct magnetic field lines, etc. Most typically, the monolithic rotor will be made of or comprise a ferromagnetic metal or metal alloy that conducts magnetic field lines or a polymeric material that includes a metal or a metal alloy, or a carbon allotrope that conducts magnetic field lines.

[0054] Contemplated stators are preferably round, hexagonal, or have an otherwise axial- symmetrical configuration to so ascertain equal distribution of magnetic field lines. Therefore, in preferred aspects contemplated stators will not have an asymmetric portion used for mounting to a surface or other carrier. To that end, it is generally contemplated that the stator will be held in a fixed position to stator end plates using bolts, brackets, or other connectors. The stator endplates may then have any suitable geometry to allow mounting of the assembly to a surface or other carrier. As will be readily recognized, the geometry of the stator endplates will generally follow the design parameters of the stator and/or generator configuration. Thus, stator endplates may be, for example, polygonal or round. FIG.8 provides an exemplary schematic view of an assembled generator. With further regard to the stator, it should be recognized that the coils for the stator will typically follow well-known structure and assembly, and all known coil configurations for multi-phase generators are deemed suitable for use herein. In addition, with regard to the protrusions at the stator around which the coils are placed, it is generally preferred that the protrusions have substantially uniform thickness extending substantially entirely to the distal end of the protrusions.

[0055] Consequently, it should be recognized that the multi-phase generators presented herein will have a superior efficiency and performance, provide a smoother sine wave form as raw coil output, and that such generators can be produced in a fast and conceptually simple modular manner. Among other configurations, it is typically preferred that the generators will be set up to operate as a 9-phase, 18-phase, 36-phase, or 72-phase generator. Most preferably, contemplated generators will be able to produce a power output of between about 5-500 kW electric power per generator unit, which will typically operate at between 200 and 5,000 rpm during normal power generation. As such, particularly preferred prime movers will be regenerative energy sources such as wind power and hydroelectric power.

[0056] In still further contemplated aspects, the generator may be configured such that the stator is in a fixed position relative to the ground, or that the stator and the rotor may rotate in opposite directions. Additionally, it is contemplated that suitable generators may have more than one rotor (within one or more stators).

[0057] In view of the above, it should therefore be recognized that the efficiency of a permanent magnet multi-phase generator having a stator and a rotor containing a plurality of permanent magnets can be significantly improved by coupling a plurality of permanent magnets in a circumferential arrangement to the rotor in alternate polarity, wherein the plurality of magnets are retained in a radially fixed position relative to each other by a plurality of registration elements such that a gap is formed between two adjacent magnets. In such methods, the gap extends radially from the rotor or registration element to respective distal ends of the adj acent magnets and contains a material that does not conduct a magnetic field or air to thereby eliminate interference with magnetic field transition. The plurality of magnets are retained as described above by a plurality of respective retaining structures at the ends of the rotor, which may further cooperate with respective endplates to provide additional compressive forces.

Examples

[0058] The following examples provide an exemplary description of certain advantages and aspects of the devices and methods presented herein and are not intended to limit the scope of the inventive subject matter.

[0059] In one set of experiments, the inventor tested power output of two generators in which one conventional rotor had rotor laminates as shown in FIG. IB and in which another rotor had rotor laminates as shown in FIG.2. Table 1 provides exemplary results for power output of the rotor of FIG. IB, while Table 2 provides exemplary results for power output of the rotor of FIG.2. As can be seen from the Tables below, the new rotor laminates delivered a significantly higher power as compared to the conventional rotor laminates.

Table 1

Table 2

[0060] The inventor then investigated whether such dramatic increase in power output (and especially increase in voltage) could be due to a reduced interference by the rotor laminate with magnetic field lines. As any inhomogeneity and even polarity reversal in the distal space between the magnets will necessarily affect induction of current in the stator coils, the inventor measured the wave characteristics of the two rotors, and FIG.9 and FIG.10 depict sine wave shapes for the conventional rotor of FIG. IB (FIG.9) and the rotor according to the inventive subject matter as shown in FIG.2 (FIG.10). As can be clearly seen from the oscillographs, the induction current from the conventional rotor was significantly deviated from a sine wave, whereas the induction current of the inventive rotor was nearly identical to a theoretical ideal sine wave.

[0061] Therefore, the inventor contemplates that the interference of a rotor with magnetic field lines of adjacent magnets having opposite polarity can be quantitated by a metric that expresses the deviation of the measured output sine wave from an ideal sine wave. For example, such metric may use the area under the curve that is formed between segments above and below the ideal sine wave. Alternatively, or additionally, such metric may also include a count of intersections of the measured output sine wave with the ideal sine wave. FIG.11A illustrates another exemplary output wave (‘dirty wave’) from of a rotor with significant interference of the rotor with magnetic field lines of adjacent magnets having opposite polarity. In contrast FIG.11B depicts a theoretical ideal sine wave (‘clean wave’). FIG.11C shows an exemplary overlay of the dirty and clean waves. As can be readily seen from FIG.11C, multiple areas (‘AUC’) are apparent in which the dirty wave deviates from the clean wave. Moreover, multiple intersections (‘IS’) of the two waves are apparent.

[0062] Consequently, it should be appreciated that interference can be quantified in a format in which the number of intersections between the two waves (e.g., per wave period) are enumerated. For example, a rotor with low interference or substantially no interference will have less than 4 intersections, or less than 3 intersections, or less than 2 intersections, or no intersection. In contrast, a rotor with interference or strong interference will have at least 4 intersections, or at least 5 intersections, or at least 6 intersections, or at least 10 intersections, or even more.

[0063] Similarly, the area under the curve formed between the two waves (e.g., per wave period) in a rotor with low interference or substantially no interference will be less than 15%, or less than 10%, or less than 5%, or less than 3%, or even less, whereas a rotor with interference or strong interference will have an area under the curve of at least 15%, or at least 20%, or at least 22%, or at least 25%, or even higher. Of course, it should be appreciated that the quantification of interference may also be expressed in a combination of these two metrics (e.g., a rotor with low interference may have equal or less than 2 intersections and an AUC of equal or less than 10%).

[0064] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

[0065] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0066] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. As also used herein, and unless the context dictates otherwise, the term "coupled to" is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously.

[0067] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification or claims refer to at least one of something selected from the group consisting of A, B, C . . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.

Claims

CLAIMS What is claimed is:

1. A rotor laminate, comprising: a disc having a central rotational axis and an outer perimeter encircling the rotational axis; a plurality of registration elements circumferentially arranged about the outer perimeter and configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other; and wherein the registration elements are further configured such that the registration elements retain the plurality of permanent magnets without substantial interference with magnetic field lines of adjacent magnets having opposite polarity.

2. The rotor laminate of claim 1, wherein the disc comprises a ferromagnetic metal or metal alloy that conducts magnetic field lines.

3. The rotor laminate of claim 1, wherein the disc comprises a polymeric material that includes a metal, a metal alloy, or a carbon allotrope that conducts magnetic field lines.

4. The rotor laminate of claim 1, wherein the disc comprises a non-magnetic material that does not conduct magnetic field lines, and wherein the non-magnetic material is coupled to the outer perimeter and/or the registration elements.

5. The rotor laminate of claim 1, wherein the plurality of registration elements are configured to retain between 4 and 32 permanent magnets.

6. The rotor laminate of any one of claims 1-5, wherein the plurality of permanent magnets, when retained by the registration elements, radially extend to a radial height, and wherein the plurality of registration elements radially extend no more than 25% of the radial height.

7. The rotor laminate of any one of claims 1-5, wherein the plurality of permanent magnets, when retained by the registration elements, radially extend to a radial height, and wherein the plurality of registration elements radially extend more than 25% of the radial height, and wherein the plurality of registration elements comprise a material that does not conduct a magnetic field. The rotor laminate of claim 1, wherein the disc has a thickness of between 1 mm and 10 mm. The rotor laminate of claim 1, wherein the disc has a central opening configured to receive and rotationally retain a rotor axis. The rotor laminate of claim 1, the disc has a plurality of cutouts between the central rotational axis and the perimeter, wherein the cutouts are arranged in radial symmetry about the central rotational axis. A permanent magnet multi-phase rotor, comprising: a plurality of rotor laminates according to claim 1 in a stacked arrangement such that the registration elements of one laminate is in alignment with the registration elements of an adjacent laminate; a plurality of permanent magnets radially retained by the registration elements and circumferentially arranged about the perimeter with alternate polarity; and a first and a second end plate terminating respective ends of the stacked arrangement, wherein each end plate has a plurality of endplate retaining structures that retain the plurality of permanent magnets. The rotor of claim 11, wherein at least 6 rotor laminates are in the stacked arrangement. The rotor of claim 11, wherein the disc comprises a ferromagnetic metal or metal alloy that conducts magnetic field lines. The rotor of claim 11, wherein the disc comprises a polymeric material that includes a metal, a metal alloy, or a carbon allotrope that conducts magnetic field lines. The rotor of claim 11, wherein the disc comprises a non-magnetic material that does not conduct magnetic field lines, and wherein the non-magnetic material is coupled to the outer perimeter and/or the registration elements. The rotor of any one of claims 11-15, wherein between 4 and 32 permanent magnets are radially retained by the registration elements. The rotor of any one of claims 11-15, wherein the first and second end plates comprise a ferrous material. The rotor of claim 17 where the first and second end plates comprise a series 300 steel or carbon steel. The rotor of any one of claims 11-15, wherein the endplate retaining structures in the first and second end plates comprise openings that enclose respective end portions of the permanent magnets. The rotor of any one of claims 11-15, wherein a void space between adjacent magnets remains unfilled. A permanent magnet multi-phase rotor, comprising: a monolithic rotor disc having a plurality of registration elements circumferentially arranged about the outer perimeter and configured to radially retain a plurality of permanent magnets in a radially fixed position relative to each other; a plurality of permanent magnets radially retained by the registration elements and circumferentially arranged about the perimeter with alternate polarity; and a first and a second end plate coupled to respective ends of the monolithic rotor, wherein each end plate has a plurality of endplate retaining structure that retain the plurality of permanent magnets. The rotor of claim 21, wherein the rotor is machined or pressed/sintered from a single material that conducts magnetic field lines. The rotor of claim 22, wherein the single material comprises a ferromagnetic metal or metal alloy that conducts magnetic field lines. The rotor of claim 22, wherein the single material comprises a polymeric material that includes a metal or a metal alloy, or a carbon allotrope that conducts magnetic field lines. The rotor of any one of claims 21-24, wherein the rotor comprises a non-magnetic material that does not conduct magnetic field lines, and wherein the non-magnetic material is coupled to the outer perimeter and/or the registration elements. The rotor of any one of claims 21-24, wherein between 4 and 32 permanent magnets are radially retained by the registration elements. The rotor of any one of claims 21-24, wherein the first and second end plates comprise a ferrous material. The rotor of claim 27 where the first and second end plates comprise a series 300 steel or carbon steel. The rotor of any one of claims 21-24, wherein the endplate retaining structures in the first and second end plates comprise openings that enclose respective end portions of the permanent magnets. The rotor of any one of claims 21-24, wherein a void space between adjacent magnets remains unfilled. An electrical generator, comprising a rotor of claim 1 or claim 21, and a stator circumferentially enclosing the rotor; and wherein the rotor and stator are configured as a multi-phase generator. The generator of claim 31, wherein the rotor comprises between 4 and 32 permanent magnets. The generator of claim 31, wherein the generator comprises a second rotor of any one of claims 11-30. The generator of claim 31, wherein the generator is configured such that the rotor and the second rotor rotate in opposite directions. The generator of claim 31, wherein the generator is configured such that the stator is fixed. The generator of claim 31, wherein the generator is configured such that the stator rotates in an opposite direction relative to the rotation of the rotor. The generator of any one of claims 31-36, wherein the generator is configured as a 9-phase, 18-phase, 36-phase, or 72-phase generator. The generator of any one of claims 31-36, wherein the generator is configured such that the rotor rotates at between 200 and 5,000 rpm during normal power generation. The generator of any one of claims 31-36, wherein the generator is configured to generate between about 5-500 kW power. A power generator unit comprising the generator of claim 31, wherein the power generator unit is actuated by a renewable power source. A method of improving efficiency of a permanent magnet multi-phase generator having a stator and a rotor containing a plurality of permanent magnets, comprising: coupling a plurality of permanent magnets in a circumferential arrangement to the rotor in alternate polarity; wherein the plurality of magnets are retained in a radially fixed position relative to each other by a plurality of registration elements such that a gap is formed between two adjacent magnets; wherein the gap radially extends from the rotor or registration element to respective distal ends of the adjacent magnets and wherein the gap contains a material that does not conduct a magnetic field or air to thereby eliminate substantial interference with magnetic field transition; and retaining the plurality of magnets by a plurality of respective retaining structures at the ends of the rotor. The method of claim 41, wherein the rotor has a mass density in a portion proximal to a rotational axis that is lower than the mass density in a portion distal to the rotational axis to thereby provide improved conservation of angular momentum as compared to a rotor with uniform mass density. The method of claim 41, wherein the rotor is coupled to a first prime mover and wherein the stator is coupled to a second prime mover, and wherein the rotor and the stator rotate in opposite directions. The method of any one of claims 41-43, wherein the permanent magnet multi-phase generator is configured such that the rotor rotates at between 200 and 5,000 rpm during normal power generation. The method of any one of claims 41-43, wherein the permanent magnet multi-phase generator is configured as a 9-phase, 18-phase, 36-phase, or 72-phase generator.