Bipolar Induction Electric Machine

Abstract

A bipolar induction electric machine is provided, comprising: a stator arrangement comprising a plurality of circumferentially arranged stator modules, each stator module comprising a plurality of axially arranged and spaced apart stator pole elements mated with concentrated armature windings and terminating in an inwardly facing curved stator pole face; and a rotor arrangement rotatably and concentrically housed within the stator arrangement, the rotor arrangement comprising a plurality of axially arranged rotor modules, each rotor module comprising at least one circumferentially arranged curved bipolar member comprising a pair of curved rotor pole elements axially displaced on either side of a fixed concentric field exciter coil housed within the stator arrangement. The curved rotor pole elements are concentrically arranged with respect to the stator pole faces to define uniform air gaps therebetween, thus resulting in a plurality of axially segmented multi-pole magnetic flux circuits.

Description

[Technical field]

[0001] The present invention relates to a bipolar induction synchronous electric machine with multiple axially segmented magnetic flux circuits. In particular, the machine has a stator arrangement with a circumferential array of stator modules, each having a plurality of axially arranged magnetic pole elements, and a corresponding rotor arrangement with a plurality of axially arranged rotor modules, each having at least one set of bipolar shaped field poles that induce a correspondingly shaped electromotive force waveform (in the case of an electric alternator) or back electromotive force (in the case of a motor). [Background technology]

[0002] Electric machines generally comprise two main components: a stator, which is the part of the machine that remains stationary during operation, and a rotor, which is the part of the machine that rotates during operation. At a high level, an electric machine may be either an electric motor (although a linear machine has parts that move in a straight line) in which electricity is supplied to the machine to spin the rotor and generate rotational mechanical force, or an electric alternator in which the rotor is rotated to generate electricity in the form of an electromotive force waveform. The interchangeability between motors and alternators is well known, and thus the term "electric machine" is used herein to refer to either a motor or an alternator.

[0003] Thus, there are many different types of electric machines. The two main parts of an electric machine can be described in mechanical or electrical terms. Mechanically speaking, as previously mentioned, the rotor is the rotating part and the stator is the stationary part of the machine. Electrically speaking, there is an armature, which is the generating component and the magnetic field is the magnetic field component of the electric machine. The armature may be in either the rotor or the stator, but in this case the armature is in the stator. The magnetic field can be provided by either electromagnets or permanent magnets attached to either the rotor or the stator, but in this case the rotor provides the magnetic field.

[0004] With regard to alternators, there are two types: AC alternators, which convert mechanical energy into alternating current (AC) electricity. AC alternators may take the form of induction alternators or synchronous alternators. In the former, the stator flux induces a current in the rotor. A prime mover then drives the rotor above synchronous speed, which causes the opposing rotor flux to induce a current in the stator coils, thus sending power back to the grid. In the latter, i.e., synchronous alternators, the current for the magnetic field is provided by a separate DC current source. The present invention can best be described as a synchronous machine, and will be described primarily in relation to synchronous alternators (in the main embodiment of the invention). For completeness, a DC alternator is one that converts mechanical energy into direct current (DC) electrical energy. DC alternators generally have a commutator with split rings that generate DC current instead of AC current, and it is a specific object of the present invention not to use a commutator or split rings.

[0005] As for electric motors, these machines convert electrical energy into mechanical energy, where a magnetic field interacts with a current carrying conductor to produce a rotational force (or a linear force, for linear motors). Again, there are two main types: AC motors and DC motors.

[0006] AC motors convert AC current into mechanical energy and generally comprise an outer fixed stator with coils that are supplied with alternating current to generate a rotating magnetic field, and an inner rotor attached to an output shaft on which the torque is exerted by the rotating magnetic field. Two main types of AC motors are distinguished by the type of rotor used. The first type is the induction (asynchronous) motor, in which the rotor magnetic field is generated by an induced current. The rotor rotates slightly slower (or faster) than the stator magnetic field to supply the induced current. The second type is the synchronous motor, which does not rely on induction and can therefore rotate exactly at the supply frequency. In this case, the rotor's magnetic field is generated by a direct current delivered through slip rings and thus exciting the rotor windings, or by permanent magnets attached to the rotor.

[0007] DC motors, such as brushed DC electric motors, use internal commutation, stationary permanent magnets, and rotating electromagnets to generate torque directly from the DC electrical power supplied to the motor. Brushes and springs carry the electrical current from the commutator to rotating wire windings on a rotor inside the motor. Brushless DC motors use rotating permanent magnets in the rotor and stationary electromagnets on the motor housing.

[0008] In yet another machine type, permanent magnet machines have permanent magnets in the rotor that set up the magnetic field. The magnetic fields produced by modern permanent magnets, such as neodymium magnets, are relatively strong, which means that permanent magnet machines tend to have better torque / volume and torque / weight ratios than machines with rotor coils in continuous operation. The permanent magnets in permanent magnet machines already introduce significant reluctance, so the reluctance of the air gap and coils is less important. This allows a great deal of freedom in designing permanent magnet machines.

[0009] Particular mention should be made of a homopolar induction alternator 10 of the type shown in Figure 1, which is based on unidirectional flux induction. In this configuration, a one-piece HIA rotor 12 at the bottom of Figure 1 comprises a central shaft 14 having a pair of spaced-apart, offset (or staggered as shown by dashed outline 15) toothed rotor elements 16, 18. A field winding 20, typically a copper ring / coil, in a stator core 22 (adjacent to a stator yoke 24) of a surrounding stator 25 induces magnetic flux through the poles of each toothed rotor element 16, 18, e.g., the toothed poles of the first rotor element 16 may have a magnetic polarity of north and, conversely, the toothed poles of the second rotor element 18 may have a magnetic polarity of south. The armature winding 26 thus experiences alternating polarities as the rotor 12 rotates within the stator 25, producing a pulsating DC magnetic flux. The lack of rotating windings means it is an inherently more reliable machine 10, and is therefore the primary choice for aerospace, missile and gas turbine applications. These alternators 10 typically have a high frequency due to the high pole count for light weight. In addition to the high frequency, the output voltage is far from an ideal sinusoidal waveform. Machines with two or four poles can have a more sinusoidal waveform, but suffer from slot harmonics and are too heavy for many applications.

[0010] Rotation of the toothed rotor components 16, 18 creates a variable permeability between itself and the stator 25, producing a voltage in the stator windings 26 according to Faraday's Law. Because the magnetic flux density resulting from the variable permeability never reverses, it has a relatively large DC component resulting in a DC flux flowing in the magnetic circuit. Sufficient iron must be provided to support this flux, and thus the machine 10 is inherently heavier than wound rotor machines which have no DC component. Thus, the inherent trade-off is weight versus greater reliability.

[0011] Finally, both switched reluctance motors and variable reluctance motors are synchronous motors similar to brushless permanent magnet motors, except that the rotor is made from laminated "soft" magnetic material shaped to form salient poles. Reluctance varies with rotor position. The rotor tends to align with the magnetic flux lines. The coils are digitally commutated (switched on and off) in the proper sequence at the desired speed. In synchronous reluctance motors, a sine wave is used to drive the coils. Because of the double salience, this design suffers from torque ripple, structural resonance, and acoustic noise.

[0012] To address the shortcomings of typical machines as discussed above, the primary and overlapping objectives of the present invention are to: - to provide a bipolar induction synchronous electric machine comprising a plurality of axially segmented magnetic flux circuits; - to provide a machine having a stator arrangement comprising a circumferential arrangement of stator modules, each having a plurality of axially arranged magnetic pole elements, and a corresponding rotor arrangement having a number of axially arranged rotor modules, each having at least one set of bipolar shaped field poles, each of which induces a corresponding shaped electromotive force waveform (in the case of an electric alternator) or back electromotive force (in the case of a motor), To provide an armature arrangement having an armature core with AC poles to provide and ensure flux reversal and thus overcome the large DC component of conventional homopolar induction alternators; - providing a magnetless synchronous machine without slip rings, commutator or rotor windings; providing a slotless stator, thus eliminating slot harmonics; - providing a synchronous motor or alternator with concentrated coils located on the outer part of the machine for better cooling; To provide a synchronous motor or alternator with concentrated coils that can be easily manufactured without special tools or skills, as is the case for conventional motors and alternators; - to provide a synchronous motor and alternator having a simple laminated silicon steel stator; - to provide a synchronous motor and alternator having simple laminated silicon steel rotor poles; - to provide synchronous motors and alternators with simple cast or machined steel rotor poles; - to provide a synchronous motor and alternator having sufficient gaps between alternating rotor poles to minimize flux leakage, the poles defining a unitary, untruncated whole; To provide a synchronous motor and alternator having a segmented magnetic circuit to reduce back iron mass, the number of segments being independent of the number of poles; and - To provide a synchronous motor and alternator that is substantially cogging-free; It is.

[0013] The specific objects of the present invention are as follows: providing a three-phase synchronous motor or alternator having a sinusoidal electromotive force waveform; To provide a two-phase synchronous motor with a triangular or double trapezoidal electromotive force driven by a simple square wave with high quality, ripple-free torque and high efficiency; To provide a two-phase alternator with a triangular or double trapezoidal electromotive force, each phase being fully rectified and connected in series to provide a ripple-free high quality DC output; - providing a two-phase motor having a square back EMF waveform driven by said two-phase alternator; - providing a two-phase motor having a square back EMF waveform driven by a triangular wave drive; - Providing two-phase or three-phase synchronous motors and alternators with simple sensor coils with concentrated windings for infinite resolution speed and position sensing; and - providing two-phase synchronous motors and alternators with parallelogram poles for inducing triangular or double trapezoidal electromotive force waveforms; It is. Summary of the Invention

[0014] According to a first aspect of the present invention, a stator arrangement comprising a plurality of circumferentially arranged stator modules, each stator module comprising a plurality of axially arranged and spaced apart stator pole elements mated with converging armature windings and terminating in inwardly facing curved (or arcuate, sector-shaped) stator pole faces; a rotor arrangement rotatably and concentrically housed within the stator arrangement, the rotor arrangement comprising a plurality of axially arranged rotor modules, each rotor module comprising at least one circumferentially arranged curved (or arcuate, sector-shaped) bipolar member comprising a pair of curved rotor pole elements axially displaced on either side of a fixed concentric field exciter coil housed within the stator arrangement; Equipped with the curved rotor pole elements are concentrically arranged with respect to the stator pole faces to define uniform air gaps between the curved rotor pole elements, thus resulting in an axially segmented multi-pole magnetic flux circuit, and the axial dimension of each rotor pole element varies during rotation of the rotor arrangement to vary the overlap between the rotor pole element and the stator pole faces, thus inducing a predetermined electromotive force waveform in the armature windings of the stator pole elements; A bipolar induction electric machine is provided.

[0015] In one embodiment, the axially disposed and spaced apart stator pole elements are joined by a common stator yoke (or core, or back iron), each stator pole element extends or projects radially inward toward a center of the bipolar induction electric machine, each stator pole element includes a (projecting or protruding) stator stem (or leg) for accommodating a concentrated armature winding, the stator pole elements terminate at their distal ends in stator poles defining curved stator pole faces, such that the circumferentially disposed multiple stator pole elements define a substantially cylindrical stator pole face, and fixed concentric field exciter coils are accommodated between adjacent stator poles of adjacent axially disposed and spaced apart stator pole elements.

[0016] In one embodiment, the stator arrangement comprises a plurality of axially arranged polygonal stator frame modules joined together to define an enclosed stator body, each stator frame module comprising a plurality of stator frame module components corresponding to the number of circumferentially arranged stator modules, each stator frame module component defining an opening or slot for accommodating a stator pole element.

[0017] In one embodiment, a circumferential gap may be defined between circumferentially arranged stator modules to accommodate a pickup sensor coil core element for determining position / velocity. The sensor coil is wound around a core having two ends, with each end positioned within the space between the two stator modules.

[0018] In one embodiment, the rotor arrangement includes a rotatable shaft supporting a plurality of axially arranged rotor modules, each bipolar member of each rotor module connected to the shaft via a support arm arrangement, each bipolar member having a corresponding pair of spaced apart stator pole faces such that each rotor pole element is aligned with a corresponding concentric stator pole element.

[0019] In one embodiment, each rotor pole element comprises: a substantially linear inner edge spaced from a corresponding inner edge of adjacent rotor pole elements which in combination define the bipolar members, the spacing corresponding to a spacing between adjacent stator pole faces of adjacent stator pole elements; a shaped outer edge that is shaped to define a shaped curved rotor pole face between the inner edge and the outer edge, the curved rotor pole face and a corresponding curved stator pole face of a corresponding stator pole element defining a uniform air gap between the curved rotor pole face and the corresponding curved stator pole face; Equipped with A fixed concentric field exciter coil surrounds the center of each rotor module to excite the bipolar members, and the shaped rotor pole faces provide variable area overlap with adjacent stator pole faces during rotation, thereby varying the magnetic flux through the stator pole elements, thereby inducing a correspondingly shaped electromotive force waveform in the armature windings of the stator pole elements.

[0020] In one embodiment, each axially disposed rotor module is separately excited by a dedicated concentric field exciter coil, with each rotor module having its own north and south poles axially disposed to define a bipolar member.

[0021] In one embodiment, the ends of the bipolar members of one rotor module of one polarity are axially staggered so as to be circumferentially adjacent the ends of the adjacent bipolar members of an adjacent rotor module of the opposite polarity when viewed axially from the end of the shaft.

[0022] Two-stage, two-pole rotor device In a first embodiment, for a two-pole machine, each rotor module comprises one curved bipolar member defining a 180 degree (mechanical and electrical) arc, and a counterweight arrangement is provided to balance the rotating shaft.

[0023] 2-stage 4-pole rotor device In a second embodiment, for a four-pole machine, each rotor module comprises two diametrically arranged (and therefore essentially balanced) curved bipolar members, each curved bipolar member defining a 90 degree (mechanical) arc with corresponding sector gaps defined between the curved bipolar members.

[0024] In this second embodiment, adjacent rotor modules are offset by 180 degrees (electrically) such that the curved bipolar members of one rotor module are interleaved with the curved bipolar members of an adjacent rotor module to occupy (or at least partially occupy) a sector gap defined in the adjacent rotor module. In particular, the interleaved curved rotor pole elements of adjacent rotor modules have adjacent poles of opposite polarity to generate bipolar induction.

[0025] In a first version of this second embodiment, the shaped outer edges of the rotor pole elements are curved to ultimately define a sinusoidal electromotive force.

[0026] In a second version of this second embodiment, the shaped outer edges of the rotor pole elements are triangular so as to ultimately define a triangular emf.

[0027] In a third version of this second embodiment, the shaped outer edges of the rotor pole elements are parallelograms so as to ultimately define a double trapezoidal emf.

[0028] In a fourth version of this second embodiment, the shaped outer edges of the rotor pole elements are full sinusoidal so as to ultimately define a double sine wave emf.

[0029] 8-pole rotor device In a third embodiment, each rotor module comprises four circumferentially disposed, equally spaced curved bipolar members each defining a 45 degree mechanical arc (from the end of the shaft when viewed axially), with four corresponding sector gaps defined between adjacent curved bipolar members.

[0030] In a third embodiment, adjacent rotor modules are mechanically circumferentially offset by 45 degrees such that the curved bipolar members of one rotor module are interleaved with the curved bipolar members of an adjacent rotor module to occupy (or at least partially occupy) a sector gap defined in the adjacent rotor module.

[0031] In a first version of the third embodiment, the shaped outer edges of the rotor pole elements are curved to ultimately define a sinusoidal emf, or are triangular to ultimately define a triangular emf, or are parallelograms to ultimately define a double trapezoidal emf, or are full sinusoids to ultimately define a double sinusoidal emf.

[0032] In all three embodiments, the curved rotor pole elements may be either cast rotor elements, manufactured rotor pole elements or laminated rotor pole elements, or any combination.

[0033] In one version, permanent magnets may be mounted within the bipolar member in place of the concentric field exciter coils. In another version, permanent magnets may be mounted within the bipolar member in addition to the field exciter coils.

[0034] Stator Unit In one embodiment, each stator module includes a pair of end stator pole elements associated with an endmost rotor pole element and at least one intermediate stator pole element associated with an intermediate rotor pole element, the armature windings around the intermediate stator pole elements receiving alternating magnetic flux / EMF due to bipolar induction to provide a predetermined EMF waveform.

[0035] The armature windings around the end stator pole elements each experience a single directional magnetic flux due to unipolar induction, and the two halves presented by the end stator pole elements having armature windings of opposite polarity are connected in series to define an emf of corresponding shape (thus effectively corresponding to bipolar induction). [Brief description of the drawings]

[0036] These and other aspects of the invention will become apparent from the following description of an example taken in conjunction with the accompanying drawings. [Figure 1] 1 shows a cross-sectional side view of a known homopolar induction alternator and a perspective view of a rotor used in the alternator; [Diagram 2] 1 shows a perspective view of a section through a field exciter coil of a three-phase, two-stage, four-pole machine of one embodiment of the present invention. [Diagram 3] 3 shows a perspective view of a quarter section of the three-phase, two-stage, four-pole machine shown in FIG. [Figure 4] FIG. 4 shows a side cross-sectional view of the machine shown in FIGS. 2 and 3. [Diagram 5] FIG. 5 shows an end view of the middle segment of the machine shown in FIGS. [Figure 6] FIG. 5 shows an end view of the end segment of the machine shown in FIGS. 2-4. [Figure 7] FIG. 7 shows a perspective view of a rotor device comprising a plurality, in this case two axially arranged rotor modules, each comprising a pair of circumferentially arranged curved bipolar members, for use in the machine shown in FIGS. 2 to 6, comprising cast rotor elements. [Figure 8] 8A-8D show side and end views of one of the rotor modules shown in FIG. 7. [Figure 9] FIG. 8 shows a perspective view of a stator arrangement used in the machine shown in FIGS. 2 to 6 to accommodate the rotor arrangement shown in FIG. 7, the stator arrangement comprising a plurality of circumferentially arranged stator modules, in this case six stator modules, each stator module comprising a plurality of spaced apart axially arranged stator pole elements. [Figure 10] 10 shows a parts assembly of the stator arrangement shown in FIG. 9. [Figure 11] 11 shows a perspective view of one of the stator frame modules shown in FIGS. 9 and 10, and a perspective view of a phase armature module for insertion into the stator frame module shown in FIG. [Figure 12] 12 shows a detailed cross-sectional side view of the phase armature module shown in FIGS. 9 to 11 and a corresponding cross-sectional view taken along line AA. [Figure 13] FIG. 1 shows a schematic end view of another version of the armature phase module, in particular a segmented armature phase module. [Figure 14] 1 illustrates various possible voids that may be used in the present invention. [Figure 15] 3 shows various further possible rotor pole element shapes; [Figure 16] 1 shows a cross-sectional side view of a four pole, four stage machine according to a further embodiment of the invention; [Figure 17] 1 shows a cross-sectional side view of a four pole, eight stage, two phase machine according to a further embodiment of the invention; [Figure 18] FIG. 18 shows a perspective view of the fully assembled eight-stage machine shown in FIG. [Figure 19] 17 shows a perspective view of one of the stator frame modules which may be joined together to define a fully assembled stator arrangement shown in FIG. 18 for the machine shown in FIG. 17, and a perspective view of a phase armature module for insertion into the stator frame module shown in FIG. 18. [Figure 20] 20 illustrates a plurality of the stator frame modules of FIG. 19 joined together, with one phase armature module shown inserted. [Figure 21] 18 shows a middle segment of the machine shown in FIG. 17 taken along line CC in FIG. [Figure 22] 18 shows a middle segment of the machine shown in FIG. 17 taken along line BB in FIG. [Figure 23]FIG. 18 shows a schematic end view of another version of an armature phase module, in particular a segmented armature phase module, for defining a three-phase machine of the type shown in FIG. 17. [Figure 24] FIG. 2 shows a perspective view of a rotor arrangement with stacked rotor elements according to a first version. [Diagram 25] FIG. 2 shows a perspective view of a rotor arrangement with stacked rotor elements according to a first version. [Figure 26] 1 shows a perspective view of a rotor arrangement with stacked rotor elements according to another version. [Figure 27] 1 shows a perspective view of a rotor arrangement with stacked rotor elements according to yet another version. [Figure 28] 4 shows a perspective view of a rotor arrangement with stacked rotor elements according to a further version. [Figure 29] 4 shows a perspective view of a rotor arrangement with stacked rotor elements according to a further version. [Diagram 30] 4 shows a perspective view of a rotor arrangement with stacked rotor elements according to a further version. [Diagram 31] FIG. 1 shows a cross-sectional view of a modified rotor module in which permanent magnets are embedded to provide the required magnetic field excitation. [Diagram 32] A perspective view of an 8-pole rotor module is shown. [Diagram 33] 33 shows an 8-pole, 4-stage rotor assembly comprising four of the rotor modules shown in FIG. 32 adjacent to one another. [Diagram 34] Various stator assemblies of various sizes, i.e. small diameter stators, are shown. [Diagram 35] Various stator assemblies of various sizes, i.e., medium diameter stators, are shown. [Diagram 36] Various stator assemblies of various sizes, i.e. large diameter stators, are shown. [Figure 37] FIG. 7 shows a winding diagram of the three-phase machine shown in FIGS. [Figure 38] 1 illustrates a two-phase, four-pole, 16-stage DC wind turbine stator according to another embodiment of the present invention. [Figure 39] FIG. 39 illustrates a winding diagram for the DC wind turbine stator shown in FIG. 38. [Diagram 40] FIG. 2 shows a winding diagram of a two-phase motor driven by a triangular wave driver. [Diagram 41] FIG. 1 shows a winding diagram for a two-phase motor driven by a square wave driver. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Referring initially to FIGS. 2-8, at a high level, the bipolar induction electric machine 30 comprises a stator arrangement 32 and a rotor arrangement 34 rotatably and concentrically housed within the stator arrangement 32.

[0038] As best shown in Figures 2, 3, 5 and 6, the stator arrangement 32 includes a plurality of circumferentially arranged stator modules 36, in this case six stator modules 36. As best shown in Figures 3 and 4, each stator module 36 includes a plurality of axially arranged and spaced apart stator pole elements 38 that are fitted with concentrated armature windings 40 and terminate in inwardly facing curved (or arcuate, sector-shaped) stator pole faces 42.

[0039] 4 and 7, the rotor arrangement 34 comprises a plurality of axially arranged rotor modules 50, each of which comprises at least one (but in this case two) circumferentially arranged curved (or arcuate, sector-shaped) bipolar members 52. Each bipolar member 52 comprises a pair of curved rotor pole elements 54 that are axially displaced (as best shown in FIG. 4) on either side of a fixed concentric field exciter coil 56 housed within the stator arrangement 32.

[0040] 4, the curved rotor pole elements 54 are concentrically disposed with respect to the stator pole face 42 to define uniform air gaps 58 therebetween, thus providing axially arranged, multiple toroidal sector magnetic flux circuits having alternating multi-pole paths through the intermediate stator elements. Importantly, the axial dimension of each rotor pole element 54 varies during rotation of the rotor arrangement 34 to vary the overlap between the rotor pole element 54 and the stator pole face 42, thus inducing a predetermined emf waveform in the armature winding 40 of the stator pole element 38.

[0041] Focusing initially on the stator arrangement 32, and referring also to Figures 9-12, axially arranged, spaced apart stator pole elements 38 are joined by a common stator yoke 60 (also referred to as a core or backing), with each stator pole element 38 extending or projecting radially inward towards the center of the machine 30.

[0042] Each stator pole element 38 includes a protruding or projecting stator stem or leg 62 for housing the concentrated armature windings 40. The stator pole elements 38 terminate in stator poles 64, the distal ends of which define the curved stator pole face 42. As a result, the circumferentially arranged plurality of stator pole elements 38 define a substantially cylindrical stator pole face 42, with the fixed field exciter coils 56 housed between adjacent stator poles 64 of adjacent axially spaced apart stator pole elements 38. Thus, in this embodiment, there are three stator pole elements 38 when viewed from the side (e.g., as in FIG. 4 ), and thus two field coils 56 (one per rotor module 50).

[0043] As shown in Figures 4 and 12, a step is shown between the stator stem 62 and the stator poles 64, but this is not necessary (other than to provide more space for the copper of the stator coils (at the expense of higher flux density in the stem 62)), i.e., they may have the same width.

[0044] 9 to 11 , the stator arrangement 32 comprises a plurality of axially arranged polygonal (in this case hexagonal) stator frame modules 70 joined together to define an enclosed stator body 72. Each stator frame module 70 includes a number of stator frame module components 74 corresponding to the number of circumferentially arranged stator modules 36, in this version there are six stator frame module components 74, one for each circumferentially arranged stator module 36.

[0045] The number of circumferentially arranged stator modules 36 depends on the number of phases desired, and the machine 30 in the figures is described as being a three-phase machine, which will be explained in more detail below with reference to the structure of the rotor arrangement 34 (and the winding diagram for a three-phase machine in FIG. 37).

[0046] Each stator frame module component 74 defines an opening or slot 76 for receiving a stator pole element 38, as best shown in Figure 9. The stator frame modules 70 are joined together with bolts 77 that extend through openings defined in lugs 78 provided at the ends of (or the interfaces between) adjacent stator frame module components 74. Although not shown, these lugs 78 are also used to attach field coil formers having appropriate "ears" with holes.

[0047] As best shown in Figure 11, a number of axially spaced stator elements 38 may be joined together to form a phase armature module 80. The phase armature module 80 thus extends longitudinally along the length of the machine 30, as best shown in Figures 9 and 10. Advantageously, this allows the armature module 80 to be mounted externally (i.e., externally) to the stator arrangement 32. The armature module 80 essentially defines a comb-like structure, with each leg of the comb corresponding to a stator pole 64, as previously described.

[0048] Retainer plates 82 are provided to secure the stator elements 38 together to define the armature modules 80. In this regard, the machine 30 may be referred to as a slotless machine and therefore does not experience or exhibit slot harmonics. A slot is, from the standpoint of the electric machine, a slot only if it is part of a magnetic flux changing circuit. The gaps between the stator poles are not slots because they do not form part of a magnetic circuit, but rather do not disturb or impede the magnetic flux at any instant during rotation of the rotor arrangement 34 (when the machine 30 is operating).

[0049] 13 shows a schematic end view of another version of an armature phase module 80'. In particular, this figure shows a segmented armature phase module 80' (as compared to the integral phase module 80 shown in FIG. 12). The armature phase module 80' comprises a plurality of radially segmented stator poles 64' and stator yokes 60' surrounded by an armature winding 40, but which are circumferentially arranged such that their curved stator pole faces 42' still define a substantially cylindrical stator pole face 42'.

[0050] As best shown in FIG. 5, circumferential gaps 90 are defined between the circumferentially arranged stator modules 36 to accommodate pickup sensor coil core elements to determine position / velocity. A sensor coil 92 (shown in FIG. 3) is wrapped around a core having two ends, each end disposed within the space between two stator modules 36. These gaps 90 do not change the electromotive force waveform induced in the armature winding 40 of the stator pole elements 38; the electromotive force waveform may vary in amplitude at different gaps, but is not truncated or distorted or modified in any deleterious way. In particular, because the stator pole arc is less than 180 degrees electrically (as a result of the gaps 90 for the sensor coil cores), the electromotive force waveform amplitude will be lower, but will have the same shape as the intended waveform. Thus, the output electromotive force (or amperes, or volt-amperes, or power) will be lower than if the stator pole arc were a full 180 degree electrical arc. However, the integrity or quality of the induced electromotive force waveform is not degraded.

[0051] In one version, these gaps 90 can receive or accommodate stacked units similar to the armature modules 80, but much narrower, with an armature winding that can be used as a sensor to indicate the position and speed of the machine by providing an analog signal in the shape of an electromotive force waveform. This pickup or sensor coil acts exactly like the armature modules 80, but has a much weaker electromotive force. However, this signal is not affected by the variations in the main armature module 80, and is therefore ideally suited for signal pickup or sensor. In some cases, the armature modules 80 may be too wide to leave space between each other for pickup coils. In such cases, it is sufficient for pickup coils to be installed only in one intermediate segment, or alternatively in both end segments. These particular armature modules will be narrower than the rest, thereby providing less electromotive force than the rest. However, when in series with the intermediate coils, the overall result will be a sine wave (since sine waves of different amplitudes, when combined, provide another sine wave).

[0052] In comparison to the conventional homopolar induction alternator 10 described above with reference to FIG. 1, the armature module 80 of the present invention undergoes pole reversal and therefore does not suffer from the significantly larger DC component of the homopolar induction alternator 10.

[0053] 7 and 8, the rotor arrangement 34 includes a rotatable shaft 100 for supporting axially arranged rotor modules 50. Each bipolar member 52 of each rotor module 50 is connected to the shaft 100 via a support arm arrangement 102 and an associated central hub 103 so as to extend substantially perpendicular to the shaft 100. As best shown in FIG. 4, each bipolar member 52 has a corresponding pair of spaced apart stator pole faces 42 such that each rotor pole element 54 is aligned with a corresponding concentric stator pole element 38.

[0054] In one embodiment, each rotor pole element 54 includes a substantially linear inner edge 104 spaced apart from a corresponding inner edge 104 of an adjacent rotor pole element 54 that in combination defines the bipolar member 52. This spacing corresponds to the spacing between adjacent stator pole faces 42 of adjacent stator pole elements 38, with intermediate salient pole grooves 106 defined between the inner edges 104 of adjacent rotor pole elements 54.

[0055] 7 and 8, the straight inner edges 104 of the rotor pole elements 54, although strictly speaking circular or arcuate, are flat edges or faces that are parallel to one another. In other words, each edge 104 forms a plane perpendicular to the shaft. This comment applies to all following references to "straight inner edges" of the rotor pole elements.

[0056] Each rotor pole element 54 further includes an outer edge 108 shaped to define a curved rotor pole face 110 shaped between the inner edge 104 and the outer edge 108, the curved rotor pole face 110 and the corresponding curved stator pole face 42 of the corresponding stator pole element 38 defining a uniform air gap 58 therebetween.

[0057] Alternatively, the stator pole faces 42 may be molded in place of the rotor pole faces 110, but a molded curved, arcuate rotor pole face 110 is preferred because the pole faces 110 have a smaller area and therefore less weight for the rotor arrangement 34. Also, it is relatively easy to wind rectangular stator poles (i.e., in this case, the stator stems or legs 62).

[0058] A concentric field exciter coil 56 surrounds the center of each rotor module 50 to excite or polarize the bipolar members, and the shaped rotor pole faces 110 provide variable area overlap with adjacent stator pole faces 42 during rotation, thereby varying the magnetic flux through the stator pole elements 38 and inducing an electromotive force waveform of a corresponding shape in the armature windings 40 of the stator pole elements 38.

[0059] In one embodiment, as best shown in FIG. 4 , each axially arranged rotor module 50 is separately excited by a dedicated concentric field exciter coil 56, with each rotor module 50 having its own north and south poles axially arranged to define a bipolar member 52.

[0060] As best shown in Figures 5 and 7, the rotor modules 50 are rotationally offset relative to one another such that the ends of the bipolar members 52 of one rotor module 50 of one polarity are axially staggered to be circumferentially adjacent the ends of the adjacent bipolar members 52 of an adjacent rotor module 50 of the opposite polarity, when viewed axially from the end of the shaft (as best shown in Figure 5).

[0061] In one embodiment, as best shown in FIG. 4, each stator module 36 includes a pair of end stator pole elements 38 associated with an endmost rotor pole element 54 and at least one intermediate stator pole element associated with an intermediate rotor pole element 54. The armature windings 40 around the intermediate stator pole elements 38 experience alternating magnetic flux / EMF due to bipolar induction, providing a predetermined EMF waveform, as described above and in more detail below. Each armature winding 40 around the end stator pole elements 38 experiences a single directional magnetic flux due to unipolar induction, with the two halves provided by the end stator pole elements 38 having armature windings 40 of opposite polarity connected in series to define an EMF of a corresponding shape (thus effectively corresponding to bipolar induction).

[0062] Before describing some specific embodiments, FIG. 14 is described. As mentioned above, and best shown in FIG. 4, the curved rotor pole elements 54 are arranged concentrically with respect to the stator pole face 42 to define uniform air gaps 58 between them, thus resulting in multiple axially segmented multi-pole flux circuits. In this case, the air gap 58 is a cylindrical air gap 58.1 between the bipolar element 52.1 and the stator pole element 38.1, as shown diagrammatically in FIG. 14a, defining a closed flux path 112.1. In the prior art, this is sometimes referred to as a "radial flux" or "transverse flux" machine. However, as shown in FIG. 14, other air gap arrangements, namely: - the geometry of the flat or planar air gap 58.2 between the bipolar elements 52.2 and the stator pole elements 38.2, as shown in FIG. 24b, to define a closed flux path 112.2, which may be referred to as a prior art "axial flux" machine; a conical air gap 58.3 between the bipolar element 52.3 and the stator pole element 38.3 to define a closed magnetic flux path 112.3, as shown in FIG. 14c, or - a mixed air gap 58.4 between the bipolar element 52.4 and the stator pole element 38.4 to define a closed magnetic flux path 112.4, as shown in Figure 14d, It is expected.

[0063] In any case, what FIG. 14 aims to convey is that a toroidal flux circuit can be divided into two parts by introducing two air gaps, one part being stationary and the other part being rotating (or linearly movable in the case of a linear machine).

[0064] Thus, the machine 30 described above, with particular reference to Figures 2-10, is a two rotor (i.e., two rotor modules 50), four pole (i.e., four rotor pole elements 54 per rotor module 50) machine. Thus, as described above, each rotor module 50 comprises two diametrically arranged curved bipolar members 52, each of which defines a mechanical 90 degree arc when viewed axially from the end, with corresponding sector gaps 116 (as shown in Figure 8) defined between the curved bipolar members 52. As will be appreciated, two rotor modules 50 also imply two field coils 56 (as shown in Figure 3).

[0065] In this embodiment, adjacent rotor modules 50 are offset by 180 degrees (electrically) such that the curved bipolar members 52 of one rotor module 50 are interleaved with the curved bipolar members 52 of an adjacent rotor module 50 to occupy (or at least partially occupy) a sector gap 116 defined in the adjacent rotor modules 50 (as best shown in FIG. 5). In particular, to generate bipolar induction (as best shown in FIG. 4), the interleaved curved rotor pole elements 54 of adjacent rotor modules 50 have adjacent poles of opposite polarity.

[0066] In a first version of this embodiment, as best shown in Figures 7 and 8, the shaped outer edges 108 of the rotor pole elements 54 are curved to ultimately define a sinusoidal EMF. Other shapes are envisioned and possible. For example, Figure 15a shows a four-pole configuration 120 in which the shaped outer edges 122 of the rotor pole elements 54.1 of each rotor module 50.1 are triangular to ultimately define a triangular EMF. Figure 15b shows a four-pole configuration 124 in which the shaped outer edges 126 of the rotor pole elements 54.2 of each rotor module 50.2 are parallelograms to ultimately define a triangular or double trapezoidal (truncated triangular) EMF. In yet another version, Figure 15c shows a four-pole configuration 128 in which the shaped outer edges 130 of the rotor pole elements 54.3 of each rotor module 50.3 are full sinusoids to ultimately define a double sinusoidal EMF.

[0067] In yet another embodiment, not shown, a two-pole rotor arrangement may be provided, where each rotor module 50 includes a curved bipolar member 52 (instead of the two shown in FIG. 7) that defines a 180 degree arc, and a counterweight arrangement is provided to balance the rotating shaft.

[0068] Depending on the number N of rotor modules 50, the machine may be referred to as an N-stage machine, i.e., two rotor modules 50 (as shown in FIG. 4, for example) correspond to a two-stage machine, three rotor modules correspond to a three-stage machine, etc. The corresponding number of stator pole elements 38 is N+1. The minimum configuration for this class of machines is two stages. It is preferable to have an even number of stages because with an even number of stages, the stator end coils introduce harmonics into the emf waveform.

[0069] Thus, FIG. 16 shows a four pole, four stage machine 140. However, this machine 140 is substantially similar in construction and operation to the machine 30 shown in FIG. 4 in particular, except for the additional axially disposed rotor module 50 supporting a pair of bipolar members 52, and the additional axially spaced stator pole elements 38. The remaining components are substantially as previously described and therefore will not be described again in greater detail. The number of circumferentially disposed stator modules 36 depends on the number of phases. Again, the outer edges of the rotor pole elements 54 can have a variety of shapes including curved to ultimately define a sinusoidal emf, triangular to ultimately define a triangular emf, parallelogram to ultimately define a triangular or double trapezoidal emf (depending on the inter-pole and inter-stator pole clearances as will be described in more detail below), or full sinusoidal to ultimately define a double sinusoidal emf.

[0070] 17-22 show various views of a four pole, two phase, eight stage machine 150. This machine 150 is however substantially similar in construction and operation to the machine 30 shown in FIG. 4 in particular (although it is a two phase machine, i.e. two stator modules per pole (in the three phase machine of FIG. 4, two poles are shared by three stator modules)). As clearly shown and expected, there are eight axially arranged rotor modules 50 supporting a pair of bipolar members 52, and nine axially spaced apart stator pole elements 38. The remaining components are substantially as previously described and therefore will not be described again in greater detail.

[0071] Again, the outer edges of the rotor pole elements 54 of this machine 150 can have a variety of shapes including curved to ultimately define a sinusoidal emf, triangular to ultimately define a triangular emf, parallelogram to ultimately define a triangular or double trapezoidal emf, or full sine wave to ultimately define a double sinusoidal emf.

[0072] As best shown in Figures 18-22, the machine 150 has eight circumferentially arranged stator modules 36. As best shown in Figures 19 and 20, the stator arrangement 32 comprises a plurality of axially arranged polygonal (in this case octagonal) stator frame modules 70' joined together to define an enclosed stator body. Each stator frame module 70' includes a number of stator frame module components 74 corresponding to the number of circumferentially arranged stator modules 36, in this version there are eight stator frame module components 74, one for each circumferentially arranged stator module 36. Each stator frame module component 74 defines an opening or slot 76' for receiving a stator pole element 38, as best shown in Figure 20.

[0073] As best shown in Figure 19, as already described above, a plurality of axially arranged spaced apart stator elements 38 may be joined together to form a phase armature module 80. The phase armature module 80 thus extends longitudinally along the length of the machine 30, as best shown in Figures 18 and 20. Advantageously, this allows the armature module 80 to be mounted externally (i.e., externally) to the stator arrangement 32. The armature module 80 essentially defines a comb-like structure, with each leg of the comb corresponding to a stator pole 64, as previously described.

[0074] 17 illustrates several additional structural features that also apply to machines 30 and 140. These features include a coil bobbin 152 for housing the armature winding 40 and an armature support 154 for supporting the armature module 80. Additional features include covers 156 at both ends, bearing arrangements 158, and cooling fans 160 (and associated cooling air intakes 162) at both ends. The other end of the shaft 60 is housed by bearing arrangements 164. The rotor diameter is indicated by dimension line 166 and the axial pitch of the field poles 54 is indicated by dimension line 168.

[0075] 22 and 23 show circumferential gaps 90 of the type previously described between circumferentially arranged stator modules 36 for accommodating pickup sensor coil core elements for determining position / velocity.

[0076] Figure 23 itself is similar to Figure 13 in that it illustrates a segmented armature phase module 80' (as compared to the integral phase module 80 shown in Figure 21). The armature phase module 80' comprises a plurality of radially segmented stator poles 64' and stator yokes 60' surrounded by the armature windings 40, but which are circumferentially arranged such that their curved stator pole faces 42' still define a substantially cylindrical stator pole face 42'.

[0077] In the various versions discussed above, the rotor pole elements 54 are cast elements. Figures 24-30 show various views of a two stage, four pole rotor arrangement with laminated rotor pole elements. Again, the outer edges of the laminated rotor pole elements in these views are curved to ultimately define a sinusoidal emf, although other shapes as previously discussed may also be provided, i.e. triangular to ultimately define a triangular emf, trapezoidal to ultimately define a triangular or double trapezoidal emf, or fully sinusoidal to ultimately define a double sinusoidal emf.

[0078] 24 and 25, rotor arrangement 170 includes a pole arm support plate 172 to which a shaft 174 can be secured. The shaft 174 has a base flange 176 that can be secured to the support plate 172 with bolts 178 (and associated nuts 179). The rotor arrangement 170 includes a pair of axially arranged rotor modules 180, 181, each of which includes two circumferentially arranged curved (or arcuate, sector-shaped) laminated bipolar members 182. Each bipolar member 182 includes a pair of curved rotor pole elements 184, each of which includes a substantially linear inner edge 186 spaced from a corresponding inner edge 186 of an adjacent rotor pole element 184 that in combination defines the bipolar member 182. Each rotor pole element 184 further includes an outer edge 188 that is shaped to define a curved rotor pole face 190 shaped between the inner edge 186 and the outer edge 188 .

[0079] The bipolar members 182 of rotor module 180 are attached to an assembly 192 that includes a central hub 194 that is also secured to the pole arm support plate 172 by bolts 178. The bipolar members 182 of rotor module 181 fit directly to the pole arm support plate 172 using bolts 196 and associated nuts 198 that extend through holders 197.

[0080] 26, rotor apparatus 200 includes a shaft 202 with a number of arms 204 extending therefrom to support ends of curved laminated bipolar members 206. Again, each bipolar member 206 includes a pair of curved rotor pole elements 208, each rotor pole element 208 including a substantially linear inner edge 210 spaced apart from a corresponding inner edge 210 of an adjacent rotor pole element 208 that in combination define the bipolar member 206. Each rotor pole element 208 further includes an outer edge 212 shaped to define a curved rotor pole face 214 shaped between the inner edge 210 and the outer edge 212. This version of the lamination has a compound curvature, i.e., is curved in two planes.

[0081] FIG. 27 shows two views of a laminated bipolar member 216. Each bipolar member 216 includes a pair of curved rotor pole elements 218, each with a substantially straight inner edge 220 spaced apart from a corresponding inner edge 220 of an adjacent rotor pole element 218 that in combination defines the bipolar member 216. Each rotor pole element 218 further includes an outer edge 222 shaped to define a curved rotor pole face 224 shaped between the inner edge 220 and the outer edge 222. This version of the lamination has a simple bend (as opposed to the complex curvature of FIG. 26). In this version, more laminate material is used, but this is offset by a shorter support arm (from the shaft) as the salience is necessarily deeper due to the straight groove bottom. Furthermore, this version is relatively simple and easy to manufacture.

[0082] 28-30, rotor arrangement 230 includes a shaft 232 from which a damper ring 234 extends. Each bipolar member 236 (and damper ring) is retained by a bolt 237 that threads onto shaft 232, as best seen in FIG. 30. Again, each bipolar member 236 includes a pair of curved rotor pole elements 238, each including a substantially linear inner edge 240 spaced apart from a corresponding inner edge 240 of an adjacent rotor pole element 238 that in combination defines the bipolar member 236. Each rotor pole element 238 further includes an outer edge 242 shaped to define a curved rotor pole face 244 shaped between the inner edge 230 and the outer edge 232.

[0083] Regarding the features of the damper ring 235, conventional alternators (larger units for power production) usually have a set of rods (or simply a squirrel cage as used in induction motors) sunk into the face of the poles. These dampers are necessary in that for a changing load, the magnetic flux fluctuations in the stator coils cause the rotor core to fluctuate. This is undesirable as it results in "hunting", where the rotor vibrates in twist. The damper ring 235 is relatively simple and does not require slots as all the magnetic flux flows through the damper ring.

[0084] 31 shows a cross-sectional view of a modified rotor module 250 in which permanent magnets 252 are embedded within bipolar members 254 to provide the necessary magnetic field excitation. This arrangement can be used in place of or in conjunction with the fixed concentric field exciter coils 56 described above. A magnet retainer 256 is provided to prevent the magnets 252 from flying away due to centrifugal acceleration.

[0085] All previous figures have shown four pole rotor arrangements. However, an eight pole rotor arrangement 260 can be used, as shown in Figures 32 and 33. In this embodiment, each rotor module 262 includes four circumferentially disposed and equally spaced curved bipolar members 264, each of which defines a 45 degree mechanical arc (when viewed axially, from the end of the shaft), and there are four corresponding sector gaps 266 defined between adjacent curved bipolar members 264.

[0086] In this embodiment, as shown in FIG. 33, adjacent rotor modules 262 are mechanically circumferentially offset by 45 degrees such that the curved bipolar members 264 of one rotor module 262 are interleaved with the curved bipolar members 264 of the adjacent rotor module 262 (so as to occupy (or at least partially occupy) a sector gap 266 defined in the adjacent rotor modules 262).

[0087] Each bipolar member 264 includes a pair of spaced apart rotor pole elements 268, each of which includes a substantially linear inner edge 270 spaced apart from a corresponding inner edge 270 of an adjacent rotor pole element 268 that in combination define the bipolar member 264. Each rotor pole element 268 further includes an outer edge 272 shaped to define a curved rotor pole face 274 shaped between the inner edge 270 and the outer edge 272.

[0088] In this illustrated version, the shaped outer edge 272 is a parallelogram to ultimately define a double trapezoidal EMF. As previously mentioned, other contemplated shapes include a curve to ultimately define a sinusoidal EMF, a triangle to ultimately define a triangular EMF, or a full sine wave to ultimately define a double sinusoidal EMF.

[0089] Again, although the rotor pole elements 268 are shown as cast rotor pole elements, they may also be laminated rotor pole elements.

[0090] Although not shown, other rotor arrangements are possible. In one such example, three bipolar members may be provided, in which case a two-phase machine with six armature-stator modules may be constructed, or a single-phase machine with three armature-stator modules, in which case each bipolar member is mechanically spaced 120° apart, but mechanically spaced in a 60° arc, to provide space for the interleaved 60° poles of the adjacent rotor modules.

[0091] Figures 34-36 show various stator assemblies of various sizes: small diameter stator 280 in Figure 34, medium diameter stator 290 in Figure 35, and large diameter stator 300 in Figure 36. The three figures are at different scales to fit the document format. However, the pole elements 282, 292, 302 have equal axial lengths and therefore the magnetic flux circuit paths are approximately the same length for all three assemblies 280, 290, 300.

[0092] The small diameter stator 280 in FIG. 34 is sized to have the smallest possible rotor diameter if the coil bobbins 284 are not clashed, as best seen in front view. The other two stators 290, 300 have larger shafts, while keeping the height of the phase modules 296, 306 the same. This means that it is possible to manufacture an annular type of ultra-light motor as shown (with a large hole or spoke in the middle, suitable for many applications such as aircraft, marine thrusters, turboalternators, etc.). The laminations of the small diameter stator 280 are stacked in a row and show machined holes (or the laminations are stepped but of varying height), while the laminations of the larger units 290, 300 are all the same, but stacked to form a circular arc (all laminations are the same size and final machining to a smooth bore is minimal). The stator laminations 286 are stacked in a circular arc, and therefore the stator support frame may be cylindrical with appropriate slots to accommodate the stator pole elements 282.

[0093] Figures 34, 35 and 36 show the inherent design flexibility of the present technology: the axial division of the magnetic circuit can result in a very light machine, and the number of poles is independent and can be chosen as any desired number (as stated in one of the objects of the present invention).

[0094] Figure 37 shows a winding diagram 310 for the three-phase machine shown in Figures 2-6. Shown are each of the six stator modules 36 around the shaft 100, as well as the armature windings 40 around each stator stem 62. The ends of the armature windings 40 are shown at 312, which may ultimately be connected to form either a three-phase delta connection 314 or a three-phase star connection 316. Although like phases are shown wired in series, parallel connections are also possible.

[0095] FIG. 38 shows a two-phase, four-pole, sixteen-stage wind turbine stator 320 according to another embodiment of the present invention. This stator 320 is particularly suitable for so-called direct drive wind turbine alternators in that the alternator can have a low pole count but be axially segmented with a large diameter. It therefore represents a high power density machine with a very high quality current waveform output, as will be described in more detail below. This particular stator 320 comprises eight circumferentially arranged stator modules 322, with each phase armature module 324 comprising sixteen axially arranged spaced apart stator pole elements 326. These components have already been described and will not be described again.

[0096] FIG. 39 shows a winding diagram for the DC wind turbine stator 320 shown in FIG. 38 (but which may be used for other two-phase alternator DC output devices contemplated by the present invention, with appropriate modifications). Each of the eight stator modules 322 around the shaft 328 is shown, as well as the armature windings 330 around each stator stem 332. The ends of the armature windings 330 are shown at 334 and 336, and the output is rectified to form a rectified DC output, shown as a rectified double trapezoidal waveform 338 in series. Rectification is performed using passive semiconductors such as diodes. The double trapezoidal waveform 338 serves very conveniently for switching commutation, since switching can be performed when the current is zero at the crossover and the zero dwell is long enough for effective current-free switching.

[0097] Furthermore, since the segmentation of the magnetic flux circuit is independent of the number of magnetic poles, the above wind turbine can be called a "direct drive wind turbine" (in that it has no gearbox) and at 4 seconds per revolution (for a 4 pole machine) the alternator works at 1 Hz. Thus, the commutation switching has a frequency of 1 Hz, which can actually be called a DC current (as opposed to the usual 50 or 60 Hz of the national grid). Of course, the machine may have more poles for higher frequency and / or voltage output.

[0098] 40 shows a winding diagram 340 of a two-phase motor driven by a triangle wave driver 341. Shown are each of eight stator modules 342 around a shaft 344, as well as the armature windings 346 around each stator stem.

[0099] 41 shows a winding diagram 350 for a two-phase motor driven by a square wave driver 351. Shown are each of eight stator modules 352 around a shaft 354, as well as the armature windings 356 around each stator stem.

[0100] The operation of a machine having curved / sinusoidal rotor pole elements (such as rotor pole element 54 in Figures 4 and 7) will now be described in more detail. The bipolar induction described above can be represented diagrammatically in Figure 1 as follows:

[0101] [Table 1]

[0102] Figure 1 shows an arrangement of sinusoidal poles 54 for a rotor with a stator pole face 42 (of the type shown in Figure 4) translating to the right at a position θ. The static poles are of alternating polarity and may be arranged in a number of ways such as the three examples above. For a sinusoidal electromotive force, the pole area should vary sinusoidally when traversed by a vertical line.

[0103] The field coil in the stator generates an electromotive force according to the BLV law, as shown in Graph 1 below.

[0104]

number

[0105] [Table 2]

[0106] Virtual magnetic pole h EThe height of varies sinusoidally as shown in Graph 2 below and can be defined as follows:

[0107]

number

[0108] [Table 3]

[0109] The virtual pole phase angle (advance offset) is a linear ratio and is only half the difference between the field pole and armature pole arcs.

[0110]

number

[0111] This is shown in the graph below, Graph 3.

[0112] [Table 4]

[0113] It can be seen that if the armature pole width matches that of the field poles, then the virtual and physical pole sizes and positions match, i.e., they are identical.

[0114] The electromotive force emf is calculated according to the virtual pole shape in that the effective length per coil turn lies on a sinusoidal curve of twice the height of the virtual pole. This is due to bipolar induction with respect to the intermediate stator elements and associated intermediate rotor elements as previously described. We now consider the end stator elements and associated endmost rotor elements which have unipolar induction as previously described. As previously described, when opposing stator coils are connected in series the combined result is equivalent to bipolar induction. The emf plot for the end coils is shown in the following figure, Figure 2.

[0115] [Table 5]

[0116] Using simple graphical tools, the emf can be plotted. If the common overlapping area of ​​the stator and rotor pole faces defines the flux linkage λ, then the sum of the intersection heights of the leading and trailing edges of the rectangular stator pole faces defines the emf by the following rule:

[0117] S pole leading edge: +l S (Correct) Trailing edge of S pole: -t S (negative) Leading edge on N pole: -l N (negative) Trailing edge of S pole: +t N (Correct)

[0118] When both the leading and trailing edges overlap the rotor pole face, the emf varies according to curve 1 in Figure 2, which is a sinusoid. However, when only one edge overlaps the rotor pole face, as in curve 2 in Figure 2, the emf varies and produces a sine wave whose amplitude is smaller, sqrt(3), when the armature pole width (or arc) is 1 / 3 of the field pole pitch. This pole width corresponds to a three-phase machine where the armature coil is continuous across one pole pitch. The resulting emf curve in Figure 2 is therefore a composition of two sinusoids, shown in bold.

[0119] The choice of reference point for angle θ is arbitrary, but in the above case is chosen as the trailing edge of the stator pole offset from when the stator pole is centered above the rotor poles.

[0120] In the figure below, graph 4, the electromotive force position θ moves from curve 1 to curve 2.

[0121] [Table 6]

[0122] Meanwhile, the opposite end coil (related to drawing 2) is shown in the following figure, graph 5.

[0123] [Table 7]

[0124] When the end coils are wound in the same direction as in Figure 3 below, the electromotive force in each coil can be represented in Graph 6 below.

[0125] [Table 8]

[0126] [Table 9]

[0127] With respect to graph 6 above, to achieve the stagger of the two curves (which stagger is half the difference in rotor and stator polar angles), the end pole elements of the rotor modules must be electrically phased 180 degrees. This means that the stator modules should preferably have an odd number of stator pole elements (i.e., stator legs), or for rotor arrangements, an even number of rotor modules (i.e., an even number of field exciter coils), as shown / confirmed in the figures and associated description. Machines with an odd number of stages introduce harmonics due to the end coils, and these harmonics become less pronounced as the number of stages increases.

[0128] The figure below, graph 7, is an oscilloscope trace of the prototype showing the end coil emf waveform.

[0129] [Table 10]

[0130] [Table 11]

[0131] The combined waveform of the end coils 1 and 3 is the same as the bipolar induction of the middle coil number 2.

[0132] The two figures below, graphs 9 and 10, show the yellow and blue tail waveforms, while the white line is the composite curve integrated by the oscilloscope.

[0133] [Table 12]

[0134] [Table 13]

[0135] The figure below, graph 11, shows an oscilloscope trace of the end coil.

[0136] [Table 14]

[0137] The figure below, graph 12, shows an oscilloscope trace of the opposite end coil.

[0138] [Table 15]

[0139] The figure below, graph 13, is an oscilloscope trace of two end coils connected in series.

[0140] [Table 16]

[0141] The operation of a machine having triangular rotor pole elements of the type shown in Figure 15a will now be described in more detail. The bipolar induction described above can be represented diagrammatically in graph 14 as follows:

[0142] [Table 17]

[0143] The back EMF is triangular, therefore in case of a motor it may be driven by a square waveform and in case of an alternator for DC current the two phases may be commutated as explained further below.As shown in the next figure, graph 15, it can be seen in the above figure that there is no gap in the armature poles, in fact there is a gap which makes the EMF waveform a truncated triangular (trapezoidal) waveform.

[0144] [Table 18]

[0145] Since there may be gaps between the armature poles, a trapezoidal shaped rotor pole face is more desirable. The armature pole pitch p is half the field pole pitch τf. This is an important geometric defining feature of the present invention. This reduces the zero crossing t, a desirable feature for switched power electronic drives. d This is desirable because it has a zero emf dwell at the poles. With parallelogram poles it is also possible to have gaps between the poles themselves as shown in the following figure, graph 16. This introduces chamfers at all corners of the trapezoidal waveform.

[0146] [Table 19]

[0147] The electromotive force waveform remains symmetrical about its half amplitude, as shown in the next figure, graph 17.

[0148] [Table 20]

[0149] The diagram above, graph 17, shows two phases modified. When the phases are connected in series, a DC current results. The dwell time is also shown. The DC current can be obtained by passive diodes, but if the dwell time is highly desirable due to the slow operation of the mosfet switches, a switching converter can be used.

[0150] Graphs 18, 19, and 20 below for double sine wave induction:

[0151] [Table 21]

[0152] [Table 22]

[0153] [Table 23]

[0154] It is worth mentioning that for ripple-free DC rectification, only double sine wave waveforms can have odd (even) phases. All other shapes such as triangles and trapezoids must have a pair of phases.

[0155] The figure below, graph 21, is a scan of a prototype three-phase alternator.

[0156] [Table 24]

[0157] One application of the present invention is a two-phase synchronous motor / generator. The generator has a triangular back-EMF waveform and two phases. Each phase is rectified with a full bridge rectifier and the rectified phases are connected in series to produce a uniform DC current.

[0158] There are two topologies for motors: triangular back-EMF and square-wave back-EMF. In a square-wave synchronous motor, the power electronics driver has current switching control with a triangular output. In a triangular-wave synchronous motor, the power electronics driver has current switching control with a square-wave output. With stator teeth having a skew of 1 / 2 pole pitch, there is no cogging. The poles may be shaped to have a sinusoidal or any other waveform.

[0159] In a generator-motor combination, a square waveform generator can be used to synchronously drive a triangular waveform motor, or vice versa.

[0160] In the case of battery stored DC or rectified DC current, the motor can be operated by power electronics. A square back EMF waveform motor has a driver with a triangular waveform current switching output. A triangular back EMF waveform motor has a driver with a square waveform current switching output.

[0161] In general, for generators, a triangular or double trapezoidal waveform has a high quality ripple-free uniform DC current output. It is simple in construction. It has a simple winding with maximum copper utilization (minimum end turn length) since each tooth is wound individually. It has very high efficiency. The DC output can be easily chopped and inverted to clean AC current.

[0162] In general, with regard to motors, triangular back-EMF waveform motors have no cogging torque. It has high quality, pulsation-free, uniform torque. Its efficiency is better than high-end state-of-the-art 3-phase sinusoidal drive (field-oriented control, direct torque and other control algorithms) motors. It is simple in construction. It has simple windings with maximum copper utilization (minimum end turn length) since each tooth is wound individually.

[0163] When a hybrid drive having a prime mover, alternator and motor is used, for example in an electric vehicle drive where an IC engine drives an alternator which drives the motor of the present invention, complete control can be achieved by varying the relatively low currents in the exciter coils of the motor and / or alternator, resulting in a relatively inexpensive and simple power electronic drive. This is in contrast to the state of the art where the main armature currents must be handled by expensive and complex power electronics.

Claims

1. a stator arrangement comprising a plurality of circumferentially arranged stator modules, each stator module comprising a plurality of axially arranged spaced apart stator pole elements mated with converging armature windings and terminating in inwardly facing curved stator pole faces; a rotor arrangement rotatably and concentrically housed within the stator arrangement, the rotor arrangement comprising a plurality of axially arranged rotor modules, each rotor module comprising at least two circumferentially arranged, spaced apart, curved bipolar members, each of the bipolar members comprising a pair of axially viewed curved rotor pole elements axially displaced on either side of a fixed concentric field exciter coil housed within the stator arrangement; Equipped with the curved rotor pole elements are concentrically arranged with respect to the stator pole face to define uniform air gaps between the curved rotor pole elements, thus resulting in a plurality of axially segmented multi-pole magnetic flux circuits, and the axial dimension of each rotor pole element varies during rotation of the rotor arrangement to vary overlap between the rotor pole element and the stator pole face, thus inducing a predetermined electromotive force waveform in the armature winding of the stator pole element. Bipolar induction electric machine.

2. 2. The bipolar induction electric machine of claim 1, wherein the axially disposed spaced stator pole elements are joined by a common stator yoke, each stator pole element extending or projecting radially inward toward a center of the bipolar induction electric machine, each stator pole element including a stator stem for housing the concentrated armature windings, the stator pole elements terminating at their distal ends in stator poles defining the curved stator pole face, such that the circumferentially disposed plurality of stator pole elements define a substantially cylindrical stator pole face, and the fixed concentric field exciter coil is housed between adjacent stator poles of the adjacent axially disposed spaced stator pole elements.

3. 2. The bipolar induction electric machine of claim 1, wherein the stator arrangement comprises a plurality of axially arranged polygonal stator frame modules joined together to define an enclosed stator body, each stator frame module comprising a plurality of stator frame module components corresponding to a number of circumferentially arranged stator modules, each stator frame module component defining an opening or slot for accommodating a stator pole element.

4. 4. The bipolar induction electric machine of claim 3, wherein circumferential gaps are defined between the circumferentially disposed stator modules to accommodate pickup sensor coil core elements for determining position / velocity.

5. 2. The bipolar induction electric machine of claim 1, wherein the rotor arrangement includes a rotatable shaft supporting a plurality of axially disposed rotor modules, each bipolar member of each rotor module connected to the shaft via a support arm arrangement, each bipolar member having a corresponding pair of spaced apart stator pole faces such that each rotor pole element is aligned with a corresponding concentric stator pole element.

6. Each rotor pole element is said bipolar members in combination define substantially linear inner edges spaced from corresponding inner edges of adjacent rotor pole elements, the spacing corresponding to the spacing between adjacent stator pole faces of adjacent stator pole elements; a shaped outer edge that is shaped to define a shaped curved rotor pole face between the inner edge and the outer edge, the curved rotor pole face and the corresponding curved stator pole face of the corresponding stator pole element defining a uniform air gap between the curved rotor pole face and the corresponding curved stator pole face; Equipped with the fixed concentric field exciter coils surround the center of each rotor module to excite the bipolar members, and the shaped rotor pole faces provide variable area overlap with adjacent stator pole faces during rotation to vary magnetic flux through the stator pole elements, thereby inducing correspondingly shaped electromotive force waveforms in the armature windings of the stator pole elements.

6. The bipolar induction electric machine of claim 5.

7. 7. The bipolar induction electric machine of claim 6, wherein each axially disposed rotor module is separately excited by a dedicated concentric field exciter coil, each rotor module having unique north and south poles axially disposed to define the bipolar members.

8. 8. The bipolar induction electric machine of claim 7, wherein ends of the bipolar members of one rotor module of one polarity are axially interleaved so as to be circumferentially adjacent ends of adjacent bipolar members of an adjacent rotor module of the opposite polarity when viewed axially from the end of the shaft.

9. 2. The bipolar induction electric machine of claim 1, wherein for a two-pole machine, each rotor module comprises one curved bipolar member defining a 180 degree (mechanical and electrical) arc, and a counterweight arrangement is provided to balance the rotating shaft.

10. 2. The bipolar induction electric machine of claim 1, wherein for a four pole machine, each rotor module comprises two diametrically arranged curved bipolar members, each curved bipolar member defining a 90 degree (mechanical) arc with a corresponding sector gap defined therebetween.

11. 11. The bipolar induction electric machine of claim 10, wherein adjacent rotor modules are offset by 180 degrees (electrical) such that the curved bipolar members of one rotor module are interleaved with the curved bipolar members of an adjacent rotor module to occupy (or at least partially occupy) the sector gap defined in the adjacent rotor module, and in particular, the interleaved curved rotor pole elements of adjacent rotor modules have adjacent poles of opposite polarity to generate bipolar induction.

12. The bipolar induction electric machine of claim 11 , wherein the shaped outer edges of the rotor pole elements are curved to ultimately define a sinusoidal electromotive force.

13. The bipolar induction electric machine of claim 11 , wherein the shaped outer edges of the rotor pole elements are triangular to ultimately define a triangular emf.

14. The bipolar induction electric machine of claim 11 , wherein the shaped outer edges of the rotor pole elements are parallelograms to ultimately define a double trapezoidal emf.

15. The bipolar induction electric machine of claim 11 , wherein the shaped outer edges of the rotor pole elements are full sinusoidal to ultimately define a double sine wave electromotive force.

16. Each rotor module is 45 mm long (from the end of the shaft when viewed axially).

2. The bipolar induction electric machine of claim 1, comprising four circumferentially disposed, equally spaced curved bipolar members defining a mechanical arc of 10 degrees, with four corresponding sector gaps defined between adjacent curved bipolar members.

17. 17. The bipolar induction electric machine of claim 16, wherein adjacent rotor modules are mechanically offset circumferentially by 45 degrees such that the curved bipolar members of one rotor module are interleaved with the curved bipolar members of an adjacent rotor module to occupy (or at least partially occupy) the sector gap defined in the adjacent rotor module.

18. 18. The bipolar induction electric machine of claim 17, wherein the shaped outer edges of the rotor pole elements are curved to ultimately define a sinusoidal emf, or triangular to ultimately define a triangular emf, or parallelogrammatic to ultimately define a double trapezoidal emf, or full sinusoidal to ultimately define a double sinusoidal emf.

19. 2. The bipolar induction electric machine of claim 1, wherein each stator module includes a pair of end stator pole elements associated with an endmost rotor pole element and at least one intermediate stator pole element associated with an intermediate rotor pole element, the armature windings around the intermediate stator pole elements receiving alternating magnetic flux / EMF due to bipolar induction to provide the predetermined EMF waveform.

20. 20. The bipolar induction electric machine of claim 19, wherein the armature windings around the end stator pole elements each experience a single directional magnetic flux due to unipolar induction, and two halves presented by the end stator pole elements having armature windings of opposite polarity are connected in series to define an electromotive force of a corresponding shape.

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