MXPA06004856A - Stator coil arrangement for an axial airgap electric device including low-loss materials - Google Patents

Abstract

A dynamoelectric, rotating electric machine includes a stator assembly that includes stacked stator coil windings. The machine is preferably a polyphase, axial airgap device. Improved slot filling results from the stacked stator coil configuration. Device performance capability is thereby increased. The stator assembly of the electric device has a magnetic core made from low loss, high frequency material. A high pole count permits the electrical device to operate at high commutating frequencies, with high efficiency, high power density and improved performance characteristics. Low-loss materials incorporated by the device include amorphous metals, nanocrystalline metals, optimized Si-Fe alloys, grain-oriented Fe-based materials or non-grain-oriented Fe-based materials.

Description

STATOR COIL ARRANGEMENT FOR AN AXIAL ELECTRICAL ENERGY DEVICE THAT INCLUDES LOW LOST MATERIALS BACKGROUND OF THE INVENTION Field of the Invention The invention relates to a rotating, dynamo-electric machine; and more particularly, a rotary, dynamoelectric, axial air gap machine comprising a rotor assembly and a stator assembly including a stator stator coil arrangement.

Description of the Invention The industry of electric motors and generators is continually seeking ways to provide rotating, dynamo-electric machines with increased energy densities and efficiencies. As used herein, the term "engine" refers to all classes of motor and generating machines which convert to rotational motion electrical energy and vice versa. Such machines include devices that can alternatively operate as motors, generators and regenerative motors. The term "regenerative motor" is used herein to refer to a device that can be operated either as an electric motor or as a generator. A wide variety of engines are known, including the types of permanent magnet, coiled field, induction, variable reluctance, switched reluctance, and brush and brushless. These can be energized directly from a source of direct or alternating current provided by the network of the electrical installation, batteries or other alternative source. Alternatively, these may be supplied with current having the required waveform that is synthesized using the electronic drive circuit set. The rotational energy derived from any mechanical source can drive a generator. The generator output can be directly connected to a load, or conditioned using the set of electronic power circuits. Optionally, a given machine is connected to a mechanical source that functions either as a source or mechanical energy dissipator during different periods in its operation. The machine in this way can act as a regenerative motor, for example, by connecting through the set of power conditioning circuits, capable of performing the operation in four quadrants. Rotary machines ordinarily include a stationary component known as a stator and a rotating component known as a rotor. The adjacent faces of the rotor and stator are separated by a small air gap traversed by the magnetic flux that connects the rotor and the stator. It will be understood by those skilled in the art that a rotating machine may comprise multiple mechanically connected rotors and multiple stators. Virtually all machines - Rotators are conventionally classifiable either as radial or axial air gap types. A type of which the -rotor and -the stator - fluj -o- magnetic -or p-asante is directed predominantly perpendicular to the axis of rotation of the rotor. In an axial air gap device, the rotor and the stator are axially separated and the flow crossing is predominantly parallel to the rotational axis. Except for certain specialized types, - motors and generators generally use soft magnetic materials of one or more types. - "Soft magnetic material" means one that is. easily and efficiently magnetized and demagnetized. . The energy that is inevitably dissipated in a magnetic material during • each magnetization cycle is called loss of -histéresis or loss-core. The magnitude of the hysteresis loss is a function of the excitation amplitude and the frequency. A soft magnetic material also shows • high permeability and low coercivity. The engines and '25 generators - also include a magnetomotive force source, which can be provided either by one or more permanent magnets or by additional soft magnetic material circularly surrounded by windings carrying current. By "permanent magnet material", also called "hard magnetic material", is meant a magnetic material that has a high magnetic coercivity and strongly retains its magnetization and resists being demagnetized. Depending on the type of motor, soft permanent magnetic materials can be placed either on the rotor or on the stator. Up to now, the preponderance of currently produced engines uses as a soft magnetic material various grades of electric or motor steels, which are iron alloys with one or more alloying elements, including especially silicon, phosphorus, carbon and aluminum. Most commonly, silicon is a predominant alloying element. While it is generally believed that motors and generators that have rotors built with advanced permanent magnet material and stators that have cores made with soft, low loss, advanced materials, such as amorphous metal, have the potential to provide substantially more efficiencies high and energy densities compared to conventional radial air gap motors and generators, there has been little success in constructing such machines either of axial or radial air gap type. Previous attempts to incorporate amorphous material into conventional radial or axial air gap machines have been largely unsuccessful commercially. The first designs involved mainly the replacement of the stator and / or the rotor with windings or amorphous metal circular laminations, typically cut with teeth through the internal or external surface. Amorphous metal has unique magnetic and mechanical properties that make it difficult or impossible to directly replace ordinary steels in conventionally designed engines. A number of applications in current technology, including widely diverse areas such as high speed machine tools, aerospace drives and motors, and compressor drives, require electric motors operable at high speeds (for example, high rpm), many times greater than 15,000 ,000 rpm, and in some cases up to 100,000 rpm. High-speed electric machines are almost always manufactured with low pole counts, so that magnetic materials in electric machines operating at higher frequencies do not experience excessive core losses that contribute to inefficient motor design. This is mainly due to the fact that the soft material used in the vast majority of current engines is a silicon-iron alloy (Si-Fe). It is well known that the losses resulting from the change of a magnetic field at frequencies greater than about 400 Hz in conventional Si-Fe-based materials causes the material to heat up, sometimes to a point where the device can not be cooled by means acceptable To date, it has proven very difficult to provide easily manufactured electrical devices at low cost, which take advantage of low loss materials. Previous attempts to incorporate low loss materials into conventional machines have generally failed, as early designs typically relied on merely replacing the new soft magnetic materials, such as amorphous metal, with conventional alloys, such as silicon-iron, magnetic cores of machine. The resulting electrical machines have sometimes provided increased efficiencies with less loss, but generally suffer from an unacceptable reduction in energy efficiency, and are significantly increased in cost, associated with the handling and formation of the amorphous metal. As a result, they have not achieved commercial success or market penetration. For example, U.S. Patent No. 4,578,610 discloses a highly efficient motor having a stator constructed by simply winding a strip of amorphous metal tape, wherein the amorphous strip is rolled and then grooved, and a suitable stator winding is then placed inside the slots. U.S. Patent No. 4,187,441 discloses a high energy density machine having laminated, spirally wound magnetic cores, made of amorphous metal strip having slots for receiving stator windings. The patent further discloses the use of a laser beam to cut the grooves in the amorphous metal strip. A problem that is especially significant in high slot count devices is the amount of slot space that can not be filled with windings, because the insulation must be sandwiched between the stator windings and the stator core. The thickness of the insulation is relatively fixed, being determined by the operating voltage of the electrical device. Therefore, there is an upper limit on the percentage of the total slot area that may be intended for the stator winding windings. This value is ordinarily less than 50% when known stator coil winding techniques are employed in. the manufacture of pole-level electric devices, conventionally configured. The limit on the usable area of the slot in turn limits the current density that determines the magnetomotive force (ampere-turns) that can be generated. As a result, the output power and operation of the electrical device are also limited. Accordingly, there remains a need in the art for highly efficient electrical devices, which take full advantage of the specific characteristics associated with the low loss material, thereby eliminating many of the disadvantages associated with conventional machines. Ideally, an improved machine could provide higher conversion efficiency between the form of mechanical and electrical energy. Improved efficiency in generating machines powered by fossil fuels could concomitantly reduce air pollution. The machine could be smaller, lighter, and satisfy more demanding requirements of torque, energy and speed. The cooling requirements could be reduced. Motors that operate from the required power could operate for a longer time for a given charge cycle. For certain applications, axial air gap machines are better suited, due to their size and shape and their particular mechanical attributes. Similar orations in the properties of the machine are sought for axial and radial air gap devices.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a dynamoelectric electric machine comprising a rotor assembly and a stator assembly, which includes a back-up or reinforcement iron section and a number of sections of stator teeth, together with the stacked windings. of stator phase. A slot between each adjacent pair of tooth sections accommodates a plurality of windings - stator phase stacks. Preferably two such windings are present in each slot. The rotor assembly is supported for rotation about an axis and includes a plurality of poles. The electrical device can have any pole and slot counts in the low to high range. The rotor assembly is accommodated and positioned for magnetic interaction with the stator assembly. Preferably, the stator comprises a generally toroidal structure employing laminated layers composed of at least one low core loss material selected from the core consisting of nanocrystalline amorphous metals and optimized iron-based alloy. However, other soft magnetic materials may also be used in the construction of all or part of the stator assembly. The use of advanced soft magnetic materials, low core loss, provides significant flexibility in design, by enabling a wide range of pole counts and switching frequencies, while also maintaining high operating efficiency, high density of energy, and a wide range of possible operating speeds. Examples of electrical machines that can be produced and operated in accordance with the invention include, but are not limited to, electric motors, generators and regenerative motors. One or more of the electrical devices could be a component in a composite device or system. An example of such a composite device is a compressor comprising one or more electric motors, where one or more electric motors can be integral with a fan. The machine is preferably of an axial air gap configuration, but can also be a radial air gap device. The invention further provides a method for constructing a dynamoelectric machine, comprising: (i) the provision of at least one stator assembly comprising a supporting or reinforcing iron section and a plurality of sections of teeth, the stator assembly having a slot between each adjacent pair of the tooth sections and a plurality of stator phase stacked windings, each winding circularly surrounding one or more of the tooth sections; and (ii) the provision of at least one rotor assembly supported for rotation about an axis and the inclusion of a plurality of poles, the rotor assembly is accommodated and arranged for magnetic interaction with at least one stator assembly. Preferably, two phase windings are stacked in each of the slots and the windings consist of equal numbers of ascending coils and descending coils. A dynamo-electric machine system comprises a dynamo-electric machine of the aforementioned type and an electronic energy means for interconnecting and controlling the machine. The electronic means of energy are operably connected to the machine. The new winding of the stator coil and the new stacking techniques provided in one aspect of the present invention result in stator slot filling, greatly increased, which is a measure of the percentage of the winding of the coil of the stator in the slot, relative to the total volume of the slot. As a result, the preferred electrical devices of the present invention provide increased performance, energy and efficiency. The stator assembly of the present device preferably has a magnetic core made of high frequency material, of low loss. More preferably, the magnetic core of the stator is made of amorphous metals, nanocrystalline metals, optimized silicon-iron alloys, iron-based materials of oriented grain or iron-based materials of non-oriented grain. The introduction of amorphous metals, nanocrystalline metals, optimized silicon-iron alloys, grain-oriented iron-based materials or non-oriented grain-based iron materials within electrical devices makes it possible for the device frequency to be increased to above 400 Hz only with a relatively small increase in core loss, compared to the large increase shown in conventional machines, thereby producing a highly efficient electrical device capable of providing increased power. The invention further provides a highly efficient electrical device with a high pole count, capable of providing increased energy density and a torque-speed moment curve that extends at the highest speed, while retaining improved efficiency.

BRIEF DESCRIPTION OF THE FIGURES The invention will be more fully understood and the additional advantages will become apparent when reference is made to the following detailed description of the preferred embodiments of the invention, and the accompanying figures, in which like reference numerals denote similar elements. throughout the various views and in which: Figures IA and IB illustrate top and side views, respectively, of a stator structure of the invention, showing the stator core with machined stator slots and the iron of back; Figure 2 illustrates a section of a stator structure of the invention, wound with the stator windings; Figures 3A and 3B illustrate top and side views, respectively, of a rotor structure of the invention, showing the location and polarity of the rotor magnets; Figure 4 illustrates an arrangement of the stators and the rotor therebetween for an electrical device of axial air gap type of the invention; Figure 5 illustrates a low slit count stator structure wound using conventional winding techniques; Figure 6 illustrates a high slot count stator structure wound using conventional winding techniques; Figure 7 illustrates a rolled stator structure according to the present invention; Figure 8 illustrates another rolled stator structure according to the present invention; Figure 9 illustrates a stator structure for a four-phase machine wound according to the present invention; Figure 10 illustrates primary magnetic flux paths for an upward coil of a rolled stator structure according to the present invention; Figure 11 illustrates secondary magnetic flux paths for an upward coil of a rolled stator structure according to the present invention; Figure 12 illustrates the primary magnetic flux paths of a down coil of a wound electrical device according to the present invention; and Figure 13 illustrates a rolled stator structure according to the present invention, which includes a cooling system.

DESCRIPTION OF THE INVENTION Preferred embodiments of the present invention will be explained in greater detail hereinafter, with reference to the appended figures. The present invention involves the design and manufacture of an electrical device, such as a brushless motor, having a wound stator core, made of low loss material and employing stator stator windings. Preferably, the stator core includes amorphous metals, nanocrystalline metals, optimized silicon-iron alloys, iron-based materials, grain-oriented materials, or iron-based materials of non-oriented grain.

General Device Structure The commonly assigned United States Provisional Application, Serial No. 60 / 444,271 ("Application 271") and United States Patent Application Serial No. 10 / 769,094 ("Application 094" ) which are both incorporated by reference herein, in their entirety, provide an electrical device having a rotor assembly and a stator accommodated in an axial air gap configuration, but with a winding configuration side by side. The stator includes an iron or backing section or reinforcement and a plurality of stator tooth sections, preferably made using high frequency, low loss materials. Figures 1 illustrate in top view (Figure IA) and in side view (Figure IB) a stator assembly 20 according to an aspect of the application? 094, which shows a unitary structure including sections 25 of stator teeth depending on the backing iron 23. The slot spaces 24 between the adjacent tooth sections are pointed to receive the stator windings 22 wound around the sections of tooth 25 using a conventional side-by-side winding arrangement, as shown in Figure 2. Preferably, one or more stators are formed from low loss materials, such as amorphous metal, nanocrystalline metal or optimized iron-based alloy. Alternatively, grain-oriented or non-grain oriented iron based material can be used. The backing iron and the tooth sections can be formed either as a described unitary structure, in which the tooth sections 25 are integrally dependent on the back-up iron section 23, or as separate components secured together by any appropriate means . For example, the constituent parts can be joined using an adhesive, clamp, weld or other methods known in the art. A wide variety of adhesive agents may be suitable, including those composed of epoxy materials, varnishes, anaerobic adhesives, cyanoacrylates, and vulcanized silicone materials at room temperature (RTV). The adhesives desirably have a low viscosity, low shrinkage, low elastic modulus, high peel strength, high operating temperature capacity, and high dielectric strength. The stator construction described by Figures 1A-1B is useful in the practice of the present invention, as are other forms of stator construction provided by the above-mentioned applications? 271 and? 094, and still others that incorporate the materials of low loss and are compatible with the stacked winding configuration described hereinafter. The present invention also provides the new stator winding windings and the stacking techniques for the application, preferably in electrical devices with axial air gap. Instead of the side by side arrangement conventionally used in motor windings, the present machine employs stacked windings. The embodiments wherein the stator comprises separate teeth and back-up iron sections can be wound with the stator windings before or after the components are assembled. The windings can also be formed as separate assemblies and then slid into position on the free end of the tooth sections 25. The stator 20 and its windings 22 can be placed in a stator carrier (not shown) and encapsulated with a dielectric material appropriate organic The present dynamoelectric magneal further includes a rotor assembly having a plurality of circumferentially spaced permanent magnets, accommodated in an axial configuration relative to the stator assembly. The present machine may comprise one or more rotor assemblies and one or more stator assemblies. Accordingly, the terms "one rotor" and "one stator" as used herein with reference to electrical machines mean a number of rotor and stator assemblies in the range of one to three as or more. In one aspect of the invention, there is provided a method for constructing and winding a stator assembly, such as that described by Figures 1-2 and others described herein. A metallic core is initially formed by spirally winding the high frequency, low loss strip material in a toroid. This toroid has the shape of a circular cylindrical shell, generally straight, which has an internal diameter and an external diameter when viewed in the axial direction. The annular end surface region 21 extending radially from the internal diameter "d" to the outer diameter "D", and circumferentially around the entire toroid formed, defines a surface area. The metallic core has an axial extension defining a height of the toroid "H". After winding, the core is machined to provide grooves 24 having outer width "w" which are generally radially directed. The depth of grooves 24 extends radially only partially through to the height of the toroid, which defines the teeth and grooves that have a slot height "T". The grooves reduce the total surface area of the metal core. The portion of the annular region left after slot removal is the total area (TA), also referred to as the amorphous metal area (AMA) for the modalities in which the low loss, high frequency material is a amorphous metal. Because the slots 24 extend completely from the inner diameter d to the outer diameter D, the circumference of the stator core in the internal and external diameters in the grooved portion of the toroid are not continuous. The removal of the material from the spaces of the groove produces a plurality of teeth 25. There is an equal number of teeth and grooves. The circumferentially continuous material that remains below the depth of the groove can function as the back-iron section 23, which provides a closure for flow in the tooth sections 25. In preferred embodiments, the narrowest part of a tooth it is not less than 2.5 mm (0.1 inch) for purposes of training capacity and mechanical integration. The slots 24 are wound with the stator windings 22, conductors, according to a pre-selected winding scheme for a given electrical device design.

Stator Coil Stacking and Winding Techniques In particular, one aspect of the present invention provides the techniques of winding and stacking the stator coil, which increases the winding of the stator winding coil of electrical devices. Although applicable to radial air gap devices, the present stacked coil configuration is easily implemented in the manufacture of stators for axial air gap machines using modular coils, which can be slid over tooth sections that are not tapered in the direction axial In the preferred embodiments, the techniques of the invention are applied to electrical devices with axial air gap, high pole count, with a ratio of groove to phase per pole (SPP) of 0.5, where there is typically a discrete coil per stator tooth. However, the methods of the present invention are also applicable to electrical devices of axial gap air with winding schemes having SPP values different from 0.5. A conventional coil configuration for an axial three-phase air gap machine is illustrated in Figure 5, which shows a low slot count device, and in Figure 6 for a high slot count device. The successive teeth around the circumference of the stator are wound with the windings of the stator phase in a sequence of A-B-C-A-B-C ..., where the letters represent the three electric phases. Each stator slot thus contains the two-phase windings. The illustration of Figure 5 shows a winding or coiling scheme wherein a single stator winding coil, for example coils 24a and 24b, fits over each of the stator teeth, and the coil typically extends over the coil. most of the axial length of the stator teeth. As illustrated in Figures 5 and 6, stator coils 24a, 24b are in a side-by-side arrangement in the stator slots. The stator windings 24a and 24b of the adjacent stator teeth 40a and 40b, respectively, each typically occupy about 1/2 of the slot width and substantially the full slot depth that is available after it is made is carried out the authorization for sufficient insulation. However, the space available in practice is also reduced by the realistically necessary free space to insert or wind the bobbin. Figure 5 illustrates that the sequencing of materials proceeding circumferentially around the stator is as follows: 1. first staple tooth 40a; 2. insulation 42; 3. first winding 24a of the coil (the first tooth 40a of the stator is circularly surrounded); 4. insulation 42; 5. second coil winding 24b (second stator tooth 40b is circularly surrounded); 6. isolation 42; and 7. second tooth 40b of the stator. The same sequence is found in the structure of Figure 6. In both, the previous pattern is repeated around the circumference of the stator. A stacked coil configuration can be wound onto a stator for a radial air gap device which is conventionally formed of punched laminations that are stacked to register, for example, by needle winding. The geometric area of stator slots that is not picked up by the windings is ordinarily occupied with encapsulation, varnish, insulation and the like, and is considered waste area. The difference between the total area of the waste area is called the useful area. For an electrical device that has 54 slots of 4 mm width and an SPP ratio of 0.5, the percentage of useful space allocated to the conductor windings varies from approximately 35% ± 10%, when the coil winding and stacking techniques are employed. of the stator, and the machine is optimized for the highest practical energy density (for example, energy per unit volume, typically expressed in units of W / cm3). These percentage values are given under the assumption of a constant fundamental frequency, and a constant amperage-turns applied to each stator tooth. With the same calculation, and under the same assumption, a different percentage of approximately 50% ± 10% is found to optimize the torque moment per mass unit of the active material. The filling of the slot can reach up to approximately 65% of the available volume for a low-counting pole electrical device wound with a conventional slot winding / filling scheme. The introduction of low loss materials within electrical devices allows the design of electrical devices with high pole count, high slot count and high frequency with SPP = 0.5. However, the minimum thickness of the insulation layers 42 is determined by the operating voltage of the electrical device and as a result relatively fixed. The use of groove insulation, for example as illustrated in Figures 5-6, is established practice in the techniques of electrical machines. While stator windings are usually made with insulated wire, additional insulation such as Kraft paper or dielectric polymer film is ordinarily placed on the bottom and sides of the stator slots, to exhibit abrasion or chipping of the windings due to contact with the stator, especially during the winding or positioning of the stator winding coils. Interphase isolation is also conventional. Dielectric failure at a damaged site can result in a hot spot or overheating and burnout of the windings. In extreme cases, the failure can produce a shock or fire hazard. In practice, high frequency machines often operate at higher voltages, which requires a thicker insulation 42. Higher voltages, especially at high frequency, often result in a corona effect, which is a catastrophic break in the insulation material in the presence of a strong field, which is believed to ionize its constituent atoms, causing the insulator to come back highly driver. Therefore, extra isolation is necessary for high frequency devices, even further limiting the slot width available for the windings. The use of conventional coil arrangements and techniques, for example, as illustrated in Figure 6, as well as approximately 46% of the slot area, is not available. The filling of the stator winding coil of axial air gap high-count electrical devices can be greatly increased through the use of stator coil winding and stacking techniques of the present invention. In the embodiment of the present invention illustrated in Figure 7, the filling of the stator slot exceeds 59% for an electrical device at 4000 rpm with 54 slots of 4 mm in width. The slot filling could only be 46% if a conventional filling scheme were used in the same geometric slot volume. A geometric device with an increased slot fill greater than 59% could show a gain in operation of up to 28%, which is advantageous in the industry. The increase in possible slot filling provides more conductive area, which can be used to reduce winding resistance and thus ohmic losses. In addition, the larger conductor area allows the effective current density to be increased without otherwise changing the motor configuration. The higher current, in turn, allows a given design to be operated with power and torque increased of the machine. Electrical machines constructed in accordance with the present invention employ stacked windings. By "stacked windings" is meant a winding or winding configuration in which a plurality of stator phase windings are placed in a sequence in layers from the root of the tooth and extending to a level near the face of the tooth. The interphase isolation is preferably placed between the adjacent winding windings. The windings circularly surround one or more of the stator teeth sections. As used in this, the term "tooth root" refers to a site at the bottom of a tooth groove at the boundary or abutment of the tooth with the backing iron. Although configurations with three or more windings stacked in each slot can be employed in the present machine, the benefits of stacked coils are ordinarily achievable with only two stacked windings. For example, Figure 7 describes a preferred configuration for a stator 20 for a three phase axial air gap machine. As seen in Figure 7, the stator slots are divided vertically, as illustrated instead of horizontally, as in the conventional arrangement of Figures 5-6. Each stator slot includes two windings, one up coil 50 and one down coil 52. Each coil occupies substantially the full available slot width, but only about half the available slot depth. As used herein with respect to the winding configuration of the stator coil, "down" and "up" refer to the location of the stator windings respectively beginning at the root of the tooth, and approximately at the intermediate level of the groove, and extending to near the free end of the distal tooth of the backing iron. The respective coils 50 and 52 are wound around the teeth 40 and 44 of the adjacent stator, and are stacked one on top of the other, as further illustrated in Figure 7. Each phase of the three-phase system includes a plurality of ascending coils 50 and descending coils 52. The stator coils are stacked in an alternating, sequential ascending / descending pattern. In the mode described by Figure 7, the windings are placed in a pattern (A: descending-B: ascending) (C: descending-B: ascending) (C: descending-A: ascending) (B: descending-A: ascending) (B: descending-C: ascending) (A: descending-C: ascending) (A: descending-B ascending) (A: descending-B: ascending) ..., where the letters A, B and C represent the three electric phases and the representative nomenclature (A: descending-B: ascending) designates a slot that has a downward coil connected to phase A and an upward coil connected to phase B. The arrows in Figure 7 represent the direction of current flow in the extreme turns that they connect the turns on the respective sides of each tooth. Other sequences are also possible. For example, Figure 8 describes a structure that has a sequence (A: descending-C: ascending) (A: descending-A: ascending) (Brdescending-A: ascending) (B: descending-B: ascending) (C: descending-B: ascending) (C: descending-C: ascending) (Ardescent-C: ascending) ... The arrows again represent the direction of current flow in the extreme turns. The layers of insulation or dielectric material are interposed between the stator coils and the stator teeth in two different orientations. Conventionally the orientation of the insulation layer 42 covers the side walls and the bottom of the grooves, while the insulation layer 48 interfaces is oriented perpendicular to the conventional orientation, and is thus substantially parallel to the bottom of the groove. This configuration allows a higher slot filling of the stator slot windings. As a result of the implementation of the techniques of the present invention, the designer of the device can achieve increased energy or increased efficiency through increased stator slot filling. A variety of similar stator configurations are also useful for polyphase devices with a different number of phases of three. For example, a possible sequence for a four-phase device is described by Figure 9 and is denoted by (Ardescent-D: ascending) (A: descending-A: ascending) (B: descending-A: ascending) (B: descending-B: ascending) (C: descending-B: ascending) (C: descending-C: ascending) (D: descending-C: ascending) (D: descending-D: ascending) (A: descending-D: ascending ) ..., with the current flow of the final or extreme turn as shown by the arrows. Part of the reduction in the volume of insulation provided by the present configuration arises from simple geometric considerations. Comparing the arrangement of the insulation in the prior art device of Figure 6 and the present machine described in Figure 7, both configurations require substantially the same insulation on the groove and bottom walls, but different intermediate insulation to the windings of adjacent phase. In the configuration of Figure 6, the intermediate insulation is vertical and has a volume given approximately by T- (D-d) -s, where "s" is the nominal insulation thickness. On the other hand, the horizontal intermediate insulation observed in Figure 7 has an approximate volume w- (D-d) -s. Since the height T of the teeth is generally twice or more the width w of the groove in the preferred designs, the volume of the insulation interfaces is shortened by half by the present configuration. However, manufacturing considerations play an additional, and in general still more significant, role in improving the utilization of the slot provided by the present stacked package configuration. A Kraft paper commonly used for groove insulation in engine construction is 0.15 mm (6 mils) thick. However, an additional side space, often as much as 0.75 mm (30 mils), is necessary to provide your next clearance for the winding operation with the side-by-side coils used in the device of Figure 6. That amount substantially impacts the realistically available area, especially for narrow slots typical in high slot count designs. Although additional free space is required just during the effective phase coil, this can be generally recovered after this. By way of contrast, such extra space is not necessary to wind the present stacked coils. Further, after the down coil is wound up, any residual space associated with the insulation can often be substantially removed by compression before the up coil is wound up. Ordinarily, a highly conductive, inexpensive wire, such as copper or aluminum wire is preferred-for stator windings, but materials and shapes can also be used, including other metals and alloys and superconductors. The wire can have any cross section, but round and square wires are more common. In certain high frequency applications, strand wires or Litz wire may be advantageous. A preferred winding scheme involves one coil per tooth 25. Each coil ordinarily comprises multiple turns of conductive wire. However, any winding arrangement known in the art is applicable. The windings can be formed on the site around the teeth, or these can be separately prepared as a fitting and slid over the ends of the teeth. The stator assembly 20, together with the stator windings, can be placed in a stator carrier (not shown). Preferably, the stator assembly is encapsulated within the stator carrier using an appropriate organic dielectric material, such as one that does not induce excessive stress in the magnetic material of the stator. While the stator carrier is preferably non-magnetic, there is no restriction on the conductivity of the stator carrier material. Factors that can influence the choice of stator carrier material include the required properties of mechanical strength and thermal properties. Any suitable material capable of adequately supporting the stator assembly can be used as a stator carrier. In a specific embodiment, the stator carrier is formed from aluminum.

Inductance of the Ascending Coils and Descending Stator Coils The ideal "L" inductance of a coil is calculated as: L = N2-P (1) where L = self-conductance of the coil, N = number of turns per coil, P = magnetic circuit permeance. The permeance "P" is defined as: P = μ0-μr-A / l (2) where μr = relative permeability of the magnetic circuit, μ0 = air permeability, A = cross section of the magnetic circuit, 1 = path length of the magnetic circuit. Equation 2 is very difficult to calculate accurately for otherwise simpler coil geometries. While N can be maintained equal for the ascending and descending coils of the invention, a designer of the device has to perform approximations for A, 1, and μr, which are not only specified for an open magnetic circuit, and especially not for a circuit with a complicated geometry. Each of the present coil windings of the stator has an associated inductance dependent on the geometry. In particular, a qualitative consideration of Equation (2) indicates that the difference in marginal flow patterns differentiates the inductance of the ascending and descending coils. For the rising coil, the effective area A of the magnetic flux of the coil includes the core area of the stator for the length of the tooth. Progressing towards the backing iron, the magnetic flux area of the coil is the cross-sectional area of the backing iron, and then to a second tooth with its respective core area, and finally the approximate area of the air gap. The length 1 of the circuit is approximately the aggregate of the core length, the distance covered from tooth to tooth through the backup iron in two directions, the length of the adjacent teeth, and then the approximate length of the magnetic flux through of air, as illustrated in Figure 10. There are also other magnetic flux trajectories as illustrated in Figure 11, which travel through stator cores farther and farther, however, these have less impact on the computations of inductance The value of μr in the air gap can be approximated as the value in the free space, for example 1.0. Any practical soft magnetic material has μr at least at 103, and often substantially higher, so that the permeance is dominated by the air gap. Hence, a practical calculation can take into account the magnetic path through the air only. As a result, Equation (2) for the rising coil is approximated by: L = DN2- 1 (3) For the falling coil, the effective area of the air gap is increased by a factor f that is significantly greater than 1.0. This is due to the propensity of part of the total magnetic flux to cross the width of the groove, as illustrated in Figure 12. For similar reasons, the effective length of the air gap is decreased by a factor g of less than 1.0. As a result, the Equation (2) for the downward coil is approximated by: L = μ0-N2- (A-f) / (1-g) (4) As a result, the down coil ordinarily has a much greater inductance than the up coil. The inductance in a circuit carrying alternating current produces reactance, and the reactance combined with the resistance produces the impedance. An electric current will flow "circularly" within a phase for any electrical device that has coils wound in parallel, if there is any difference in the impedance between the coils. These "circulating currents" are very harmful for the operation of a device. These do not work in a useful way and are detrimental to the output energy of the device, while at the same time adding ohmic losses to the machine. In one aspect, the present invention provides a solution to the problem of circulating currents, where the relative number of turns N of the coil - up and the down coil are modified. The desired values of N for the coils can be determined mathematically by adjusting the inductances of the rising and falling coils to be equal. However, the change in the number of turns per coil modifies the relative resistances of the ascending and descending coils and the counter-EMF constant (electromotive force) per ascending and descending coil. Since full impedance is of interest, a difference in resistance also causes sequential circulating currents. The difference in resistance can be compensated by the use of different sizes of wire. The difference in the counter-EMF constant can also be a cause of the circulating currents, but this can not be corrected when changing the wire size. In a preferred embodiment of the invention, the problem of the circulating currents is rather solved by coiling in series each rising coil to a corresponding downward coil. The series winding of the descending coils with the ascending coils, in a one-one coupling base, substantially reduces or eliminates unwanted circulating currents. While the series connection is usually sufficient by itself, the previous adjustment of the wire size and the number of turns can be used.

Low Loss Stator Materials The incorporation of the amorphous, nanocrystalline or optimized iron-based alloy material, or the oriented grain-oriented or non-oriented grain-based material in the preferred embodiments of the present electric magneut, makes it possible for the frequency of Switching of the machine is increased above 400 Hz only with a relatively small increase in core loss, compared to the unacceptably large increase that could be observed in conventional machines. The use of low loss materials in the stator core consequently allows the development of high frequency, high pole count electrical devices, capable of providing increased energy density, and improved efficiency. In addition, decreases in stator core loss also allow a motor to be operated well beyond a conventional base speed without the need to reduce the normal capacity of the torque and energy frequently needed by the thermal limits in conventionally designed machines. . Preferably, the stator assembly comprises laminated layers composed of at least one material selected from the group consisting of amorphous, nanocrystalline or optimized iron-based alloy.

Amorphous metals Amorphous metals exist in many different compositions suitable for use in the present engine. The metallic glasses are typically formed from a molten alloy of the required composition, which is rapidly quenched from the melt, for example by cooling at a rate of at least about 106 ° C / second. These do not show long interval atomic order and have X-ray diffraction patterns that show only diffuse haloes. Similar to those observed for inorganic oxide glasses. A number of compositions having suitable magnetic properties are described in U.S. Patent No. RE32,925 to Chen et al. The amorphous metal is typically supplied in the form of extended lengths of thin ribbon (e.g., a thickness of at most about 50 μm) in widths of 20 cm or more. A useful process for forming metal strips of indefinite length is described by U.S. Patent No. 4,142,571 to Narasimhan. An exemplary amorphous material suitable for use in the present invention is METGLAS® 2605 SAI, sold by Metglas, Inc., Conway, SC in ribbon form of indefinite length, and up to about 20 cm in width and 20-25 μm of thickness (see http: // www .meglas.com / products / page5_l_2_4. htm). Other amorphous materials with the required properties can also be used. Amorphous metals have a number of characteristics that must be taken into account in the manufacture and use of magnetic implements. Contrary to most soft magnetic materials, amorphous metals (also known as metallic glasses) are hard and brittle, especially after the heat treatment typically used to optimize their soft magnetic properties. As a result, many of the mechanical operations ordinarily used to process conventional soft magnetic materials, for engines, are difficult or impossible to perform on amorphous metals. The stamping, punching or cutting of the material thus produced generally results in unacceptable wear of the tool, and is virtually impossible on fragile heat-treated material. Conventional drilling and welding, which are often performed with conventional steels, are also usually excluded. In addition, amorphous metals exhibit a lower saturation flux density (or induction) than conventional Si-Fe alloys. The lower flow density ordinarily results in lower energy densities in engines designed according to conventional methods. Amorphous metals have lower thermal conductivities than Si-Fe alloys. Since thermal conductivity determines how heat can be easily conducted through a material from a hot location to a cold location, a lower value of thermal conductivity needs careful engine design to ensure proper disposal of waste heat arising from core losses in magnetic materials, ohmic losses in windings, friction, aerodynamic drag and other sources loss. Improper disposal of the waste heat, in turn, could cause the engine temperature to rise unacceptably. It is likely that excessive temperature causes premature failure of electrical insulation or other engine components. In some cases, over-temperature could cause a shock hazard or trigger a catastrophic fire or other serious danger to health and safety. Amorphous metals also show a higher magnetostriction coefficient than certain conventional materials. A material with a lower magnetostriction coefficient undergoes smaller dimensional change under the influence of a magnetic field, which in turn could probably reduce the audible noise coming from a machine, as well as make the material more susceptible to the degradation of its properties magnetic as the result of induced stresses during the manufacture or operation of the machine. Despite these challenges, an aspect of the present invention provides an engine that successfully incorporates advanced soft magnetic materials and allows the operation of the motor with high frequency excitation, for example, a switching frequency greater than about 400 Hz. The construction techniques for the manufacture of the engine are also provided. As a result of the configuration and use of advanced materials, especially amorphous metals, the present invention successfully provides a motor that operates at high frequencies (defined as switching frequencies greater than about 400 Hz) with a high pole count. Amorphous metals show much lower hysteresis losses at high frequencies, which result in much lower core losses. Compared to Si-Fe alloys, amorphous metals have much lower electrical conductivity and are typically much thinner than ordinary Si-Fe alloys, which are often 200 μm thick or more. These two characteristics promote the lower parasitic current core losses. The invention successfully provides an engine that benefits from one or more of these favorable attributes and with these operates efficiently at high frequencies, using a configuration that allows the advantageous qualities of the amorphous metal to be exploited, such as the lower core loss, while that the challenges faced in previous attempts to use advanced materials are avoided.

Nanocrystalline Metals Nanocrystalline materials are polycrystalline materials with average grain sizes of approximately 100 nanometers or less. The attributes of nanocrystalline metals compared to conventional coarse-grained metals generally include increased strength and hardness, increased diffusivity, improved ductility and firmness, reduced density, reduced modulus, higher electrical resistance, increased specific heat, coefficients of thermal expansion higher, lower thermal conductivity, and superior soft magnetic properties. The nanocrystalline metals also have somewhat higher saturation induction, in general than most amorphous iron-based materials. The nanocrystalline metals can be formed by a number of techniques. A preferred method comprises initially emptying the required composition as an indefinite-length metal glass strip, using techniques such as those taught hereinabove, and forming the ribbon into a desired configuration such as a rolled shape. After this, the initially amorphous material is heat treated to form a nanocrystalline microstructure therein. This microstructure is characterized by the presence of high grains density having average size less than about 100 nm, preferably less than about 50 nm, and more preferably about 10 to 20 nm. The grains preferably occupy at least 50% of the volume of the iron-based alloy. These preferred materials have low core loss and low magnetostriction. The latter property also makes the material less vulnerable to the degradation of magnetic properties by the stresses resulting from the manufacture and / or operation of a device comprising the component. The heat treatment necessary to produce the nanocrystalline structure in a given alloy should be carried out at a higher temperature and for a longer time than would be necessary for a heat treatment designed to preserve a substantially complete microstructure therein. crystalline Preferably, the nanocrystalline metal is an iron-based material. However, the nanocrystalline metal could also be based on or include other ferromagnetic materials, such as cobalt or niguel. Representative nanocrystalline alloys suitable for use in the construction of magnetic elements for the present device are known, for example, the alloys described in U.S. Patent No. 4,881,989 to Yoshizawa and U.S. Patent No. 5,935,347 to Suzuki et al. Such materials are available from Hitachi Metals, Vacuumschmelze GmbH and Alps Electric. An exemplary nanocrystalline metal with low loss properties is Hitachi Finemet FT-3M. Another exemplary nanocrystalline metal with low loss properties is • Vacuumschmelze Vitroperm 500 Z.

Optimized Iron-Based Alloys These machines can also be built with low loss, optimized iron-based crystalline alloy material. Preferably, such material is in the form of a strip having a thickness of less than about 125 μm, much thinner than steels conventionally used in engines, having thicknesses of 200 μm or more, and sometimes as much as 400 μm or more . Oriented grain or unoriented grain materials can be used. As used herein, an oriented material is one in which the major crystallographic axes of the constituent crystallite grains are not randomly oriented, but are predominantly correlated along one or more preferred directions. As a result of the above microstructure, an oriented strip material responds differently to magnetic excitation along different directions, while an unoriented material responds isotropically, for example, substantially with the same response to excitation along any direction in the plane of the strip. The oriented grain material is preferably oriented in the present motor with its easy direction of magnetization substantially coincident with the predominant direction of the magnetic flux. As used herein, conventional Si-Fe refers to silicon-iron alloys with a silicon content of about 3.5% or less of silicon by weight. The limit of 3.5% by weight of silicon is imposed by the industry due to the poor properties of the metallic work material of the Si-Fe alloys, with higher silicon contents. The core losses of the conventional Si-Fe alloy grades resulting from an operation to a magnetic field with frequencies greater than about 400 Hz are substantially higher than those of the low loss material. For example, in some cases, the conventional Si-Fe losses can be as much as 10 times those of the amorphous metal adequate to the frequencies and flow levels found in the machines operating under the frequency and flow levels of the present machines. As a result, in many embodiments the conventional material under high frequency operation could be heated to a point where a conventional machine could not be employed by any acceptable means. However, some grades of silicon-iron alloys, referred to herein as optimized Si-Fe, are directly applicable to the production of a high-frequency machine. The iron-based optimized alloys useful in the practice of the present invention include silicon-iron alloy grades comprising more than 3.5% by weight of silicon, and preferably more than 4%. The non-oriented grain-based iron material used in the construction of machines according to the invention preferably consists essentially of an iron-silicon alloy in an amount in the range of about 4 to 7.5% by weight of silicon. These preferred alloys have more silicon than conventional Si-Fe alloys. Also useful are Fe-Si-Al alloys such as Sendust. The most preferred non-oriented optimized alloys have a composition consisting essentially of iron with about 6.5 ± 1% by weight of silicon. More preferably, alloys having approximately 6.5% silicon show near zero values of the saturation magnetostriction, making them less susceptible to the damaging degradation of the magnetic property due to stresses encountered during the construction or operation of a device containing the material . The aim of the optimization is to obtain an alloy with improved magnetic properties, including reduced magnetostriction and especially, lower core losses. These beneficial qualities are obtainable in certain alloys with increased silicon content, made by the appropriate manufacturing methods. In some cases, these optimized grades of Si-Fe alloy are characterized by magnetic core and saturation losses similar to those of the amorphous metal. However, alloys containing more than about 4% by weight of silicon are difficult to produce by conventional means due to their fragility due to the short interval arrangement. In particular, the conventional lamination techniques used to produce conventional Si-Fe are generally capable of making optimized Si-Fe. However, other known techniques are used to produce optimized Si-Fe. For example, a suitable form of Fe-6.5Si alloy is supplied as magnetic strips of 50 and 100 μm thickness by JFE Steel Corporation, Tokyo, Japan (see also http: // www. Jfe-steel .co.jp / in / products / electrical / supercore / index.html). The Fe-6.5% Si produced through the rapid solidification process, as described in U.S. Patent No. 4,865,657 to Das et al. and U.S. Patent No. 4,265,682 to Tsuya et al., may also be used. Rapid solidification processing is also known to prepare Sendust and related Fe-Si-Al alloys.

Loss Behavior of Preferred Soft Magnetic Materials A greater contribution to improved losses in preferred materials for the present stator results from significantly reduced hysteresis losses. As is known in the art, hysteresis losses result from the motion of the wall-prevented domain during the magnetization of all soft magnetic materials. Such losses are generally higher in conventional magnetic materials used, such as conventional grain-oriented Si-Fe alloys, and non-oriented electric and electric steels, in the improved materials preferably used in the present machines. The high losses, in turn, can contribute to the overheating of the core. More specifically, it is found that the core loss of soft magnetic materials can generally be expressed by the following modified Steinmetz equation: L = af-Bb + c-fd-Be (5) where: L is the loss in W / kg, f is the frequency in kHz, B is the magnetic flux density in Tesla peak, ya, b, c, d and e are all specific empirical loss coefficients for any particular soft magnetic material. Each of the loss coefficients prior to a, b, c, d and e, can generally be obtained from a manufacturer of a given soft magnetic material. Especially preferred for use in the present stator structure are magnetic materials of low core loss characterized by a core loss smaller than "L" where L is given by a form of Equation (5), in which L = 12-f-B1"5 + 30-f2" 3-B2"3.

Rotor Structure In a further aspect of the present invention there is provided an electric permanent magnet, without the brush, axial air gap device, wherein a rotor structure is positioned adjacent to the stator body on a common axis. Figures 3A and 3B illustrate a top and side view, respectively, of an axial rotor 30 suitable for the present machine. Figure 3A illustrates a plurality of magnets 32 having alternating polarity positioned around the rotor. The magnets have alternating polarity and are placed circumferentially securely around the rotor with substantially equal spacing. The different parameters of the rotor magnets, such as size, position, angle, inclination, shape and the like, are selected to achieve the desired operation. Figure 3B illustrates a side view of the rotor, taken along line A of Figure 3A. Alternatively, the permanent magnet rotor assembly can take any form that secures the magnets for rotation in proximity to the faces of the stator teeth. For example, the magnets of the rotor 32 can be adjusted inside, or mounted on, a rotor carrier. The rotor assembly can include any number of magnets of the rotor 32. In some embodiments, the rotor magnets extend through the thickness of the rotor, while in others, they do not. The magnets can be spaced such that there is little or no circumferential space between the alternating magnets. It is preferable that the spacing between the magnets be selected to have an optimum value, which also minimizes the occurrence of roughing of the torque. An optimum spacing is derived by first dividing the area of the low stator metal by the number of stator slots, to obtain the area of each single metal core tooth. The optimal spacing between the magnets will then be such that the total area of each magnet equals 175 ± 20% of the area of a core tooth. Figure 4 illustrates a side view of one embodiment of the electrical device, including two stators placed in an axial type arrangement on either side of, and along a common central axis with a simple rotor, which serves both stators 20. In a specific embodiment, an electrical device that includes amorphous metal stators on either side of a single rotor, is found to exhibit a high energy density. Such a configuration beneficially reduces the axial thrust on the rotor, since the attraction between the rotor and the respective stators is oppositely directed and substantially displaced. Although the rotor magnets have been described as permanent magnets, alternative embodiments of the present machine employ other types of magnetic material or electromagnets. For example, an induction machine can employ laminated soft magnetic material, while a switched reluctance machine can have a solid iron rotor. Rotor Materials Any type of permanent magnet can be used in the present rotor. Rare-earth metal alloy magnets-transition such as samarium-cobalt magnets, other rare cobalt-earth magnets, or rare earth-transition metal-metalloid magnets, for example, NdFeB magnets are especially suitable. Alternatively, the structure of the rotor magnet comprises any other sintered permanent magnet material, bonded with plastic or ceramic. Preferably, the magnets have a high product of maximum BH energy, high coercivity, and high saturation magnetization, together with a normal linear demagnetization curve of the second quadrant. More preferably, rare earth-transition metal alloy magnets are used, oriented and sintered, since their higher energy product increases the flow and therefore the torque, while allowing the volume of the permanent magnet material expensive be minimized. Preferably, the rotor arrangement comprises a disc rotor or axial type assembly that includes circumferentially spaced, high energy product permanent magnets, such as rare earth-transition metal magnets (e.g., SmCo) or rare earth magnets. metalloid-transition metal (for example, NdFeB and NdFeCoB), each having opposite ends defining the north and south poles. As best seen in Figures 3A and 3B, the rotor 30 and its magnets 32 are supported for rotation about an axis of the motor, for example, on an axis 34 or any other suitable arrangement, such that the poles of the magnets they are accessible along a predetermined path adjacent to one or more stator assemblies. Ordinarily, the shaft is supported by bearings of any suitable type known for rotating machines. The area of the magnet on the rotor has an external diameter and an internal diameter. In a preferred embodiment, for an axial air gap type rotor, the external diameter and the internal diameter of the magnets 32 are substantially identical to those of the stator assemblies 20. If the outer diameter of the magnets 32 is greater than that of the sections 21 of stator teeth, then the outer portion of the rotor does not contribute appreciably to the operation. If the outer diameter of the rotor is smaller than that of the stator teeth sections 21, the result is a reduction in the operation of the electrical device. In any case, some of the hard or soft magnetic material present in the machine increases the cost and weight, but without improving the operation. In some cases, the extra material even decreases the operation of the machine.

Slot Proportions by Phase by Pole The slot value per phase per pole (SPP) of an electric machine is determined by dividing the number of stator slots by the number of phases in the stator winding, and the number of DC poles ( SPP = slots / phases / poles). In the present description, a pole refers to the non-time-varying magnetic field, also referred to herein as a DC field, which interacts with a changing magnetic field, for example, one that varies in magnitude and direction with the time and position. In the preferred embodiments, the permanent magnets mounted by the rotor provide the DC field, and therefore the number of non-time-varying magnetic poles, referred to herein as DC poles. In other embodiments, the DC electromagnet can provide the DC field of the rotor. The electromagnets of the stator windings provide the changing magnetic field. A slot refers to the spacing between the alternating teeth of the stator of the present machine. The techniques of the present invention are applicable to electrical devices with any SPP value. Beneficially, the design of the present machine provides considerable flexibility in the selection of an optimal SPP ratio. Conventional machines are often designed to have an SPP ratio of 1 to 3 to obtain acceptable functionality and acceptable noise levels, and to provide smoother output due to the better distribution of the winding. However, designs with a lower SPP value, for example, 0.5, have been sought to reduce the effect of extreme or final turns. The final turns are the portions of the cable in the stator coil that connect the windings between the slots. Although such a connection, of course, is required, the final turns do not contribute to the torque and output of the machine. In that sense these are undesirable, because they increase the amount of wire required, and contribute to the ohmic losses for the machine, while not providing benefit. Therefore, one goal of the engine designer is to minimize the final turns and provide a motor with manageable noise and wear. On the other hand, preferred implementations of the present engine allow a reduced SPP ratio, together with desirably low noise, wear, and electronic power wave described in more detail below. This benefit is obtained by operating with a high pole and slot count. These options were not feasible in the previous magics, due to the required increase in switching frequency which is unacceptable without the use of advanced low loss stators materials. For some applications, it is advantageous to build an engine with a fractional SPP value, since such an engine can employ preformed coils positioned around a single stator tooth. In different embodiments of the present machine, the SPP ratio is an integral ratio, such as 0.25, 0.33 or 0.5. For example, the four-phase modality of Figure 9 has SPP = 0.33. SPP values of 1.0, or even greater than 1.0, are also possible. Preferably, the SPP values are in the range of about 0.25 to 4.0. However, more preferred embodiments of the present machine are beneficially designed with an SPP ratio of 1 or less, and still more preferably of 0.5 or less. It is possible to wire multiple slots within a common magnetic section, whereby an SPP value greater than 0.5 is provided. This is the result of a number of stator slots greater than the rotor poles, resulting in a distributed winding. An SPP value less than or equal to 0.5 indicates that there are no distributed windings. An industry convention is to include windings distributed in the stator. Ordinarily, prior art machines designed with distributed windings have many slots per pole, resulting in the lowest frequency operation. As a result, in conventional machines that have SPP of 0.5 or less, and that operate at low frequency, there will also be a low pole count and high and difficult to control wear. On the other hand, the use of advanced magnetic materials in the present magma allows the switching frequency to be high, so that SPP values can be kept low, while the wear is still reduced to a minimum and without reducing the speed of the machine. However, while the methods of the present invention are applicable to an electrical device with SPP values below 0.5 (eg, 0.25), such a configuration is sometimes made less desirable by practical considerations, including increased reactance of the machine at the highest switching frequency required, somewhat increased leakage flow from the rotor magnets, and the mechanical support necessary to accommodate the rotor magnets are smaller and numerous. A low SPP value is often less advantageous for other important parameters of the electrical device. On the other hand, the increase in the SPP value effectively increases the machine's pole space. For example, the multiple stator slots can be wired in a common magnetic section, which corresponds to a slot value per phase per pole (SPP) greater than 0.5 Although the present machine can be designed with a single phase device, or a polyphase device, with any number of phases and a coarse number of windings on each of the stators, a three-phase machine with three-phase windings, is preferred according to the industrial convention, since it provides an efficient utilization of the hard and soft magnetic materials together with good energy density. Modes with SPP ratios of 0.5 are particularly suitable for three-phase applications. For example, in a three-phase machine, with SPP = 0.5, the number of rotor poles is two thirds the number of stator slots, with the number of slots being a multiple of the phase number. While the machine is usually wired in a three-phase Y-configuration according to industrial convention, a delta configuration can also be employed. In a preferred embodiment provided by the present invention, the stator winding configuration of stacked coils is especially applicable to an electrical device with an SPP value optimally equal to 0.5.

Design of high pole count, high frequency using low loss materials The present structure and method are applicable to electrical devices that have a pole count in the low to high range. However, the benefits of the present configuration of slot winding, stacking, are especially realized in the modalities where the use of materials of low loss in the stator allows the design of electrical devices of high pole count, which operate at high frequencies. In specific embodiments, the present invention provides an electrical axial gap with a high pole count, which operates at high frequencies, for example, a switching frequency greater than about 400 Hz. In some cases, the device is operable at a switching frequency in the range of about 500 Hz to 3 kHz or more. Designers have ordinarily avoided high pole counts for high-speed motors, since conventional stator core materials, such as Si-Fe, can not operate at the proportionally higher frequencies needed by the high pole count. In particular, known devices using Si-Fe can not be changed at magnetic frequencies significantly above 400 Hz, due to core losses resulting from the changing magnetic flux within the material. Above the limit, core losses cause the material to heat up to the point where the device can not be used by any acceptable means. Under certain conditions, the heating of Si-Fe material may even be severe enough, so that the machine can not be cooled in any way, and will self-destruct. However, it has been determined that the low loss characteristics of the amorphous, nanocrystalline and iron-based optimized, suitable metals allows much higher switching or switching ratios than those that are possible with conventional Si-Fe materials. While in a preferred embodiment the choice of the amorphous metal alloy, such as the METGLAS® 2605SA1 alloy, eliminates the limitation of the system due to heating at low frequency operation, the winding configuration and the complete configuration of the motor are also improved for take better advantage of the beneficial properties of the amorphous material. The ability to use much higher excitation frequencies allows the present machines to be designed with a much wider range of possible pole counts. The number of poles in the present device is a variable based on an allowable machine size (a physical constraint) and on the expected operating range. Subject to allowable agitation frequency limits, one pole may be increased until the magnetic flux leakage increases to an undesirable value, or the operation begins to decrease. There is also a mechanical limit presented by the construction of the stator on the number of poles of the rotor, since the stator slots must coincide with the magnets of the rotor. The mechanical and electromagnetic constraints in unison limit the number of slots that can be made in the stator. These effects, in turn, are in part a function of the size of the machine structure. Some limits may be established to determine an upper limit on the number of slots for a given stator structure that provides an adequate balance of copper and soft magnetic material. The adjustment of the balance can be used as a parameter in the production of well-functioning axial iron machines. The present invention provides motors that optimally have approximately 4 or 5 times the number of poles typical for current industrial machines of comparable physical size. As an example, for a typical industrial motor that has 6 to 8 poles, and that operates at speeds of approximately 800 to 3600 rpm, the switching frequency is approximately 100 to 400 Hz. The switching frequency (CF, in Hz) is the rotation speed multiplied by the number of pole pairs, where the pole pairs is the number of poles divided by two, and the rotation speed is in units of revolutions per second (CF = rpm / 60 x pole / 2). Also available in the industry are devices with 16 or more poles, but with speeds less than 1000 rpm, which still correspond to a frequency lower than 400 Hz. Alternatively, motors with a relatively low pole count (for example, less than 6 poles) are also available, and with speeds up to 30,000 rpm, which will still have a switching frequency of less than about 400 Hz. In representative embodiments, the present invention provide machines that have 96 poles, for 1250 rpm at 1000 Hz; 54 poles for 3600 rpm at 1080 Hz, 4 poles, for 30,000 rpm at 1000 Hz; and 2 poles, for 60,000 rpm at 1000 Hz. The high frequency machines of the invention can operate at frequencies of approximately 4 to 5 times higher than known axial air gap motors, made with conventional materials and designs. The machines provided are generally more efficient than the typical engines in the industry, when operated in the same speed range, and as a result provide greater speed options. The present configuration is particularly operative for the construction of motors having a very wide range of speed, energy and torque ratios, in a way that combines high energy efficiency, high energy density, ease of assembly , and the efficient use of soft and hard, expensive magnetic materials.

Thermal properties and efficiency One of the characteristics that limits the achievable output efficiency of the device in all electrical machines, including those that use conventional Si-Fe alloys and those that use soft magnetic materials with low core loss, improved, is the loss of energy to waste heat. This waste heat comes from a number of sources, but predominantly from ohmic losses, losses from film effect and proximity in the windings, rotor losses from eddy currents in the magnets and other rotor components, and the loss of core from the stator core. The "continuous power limit" of conventional machines is often determined by the maximum speed at which the machine can operate continuously, while still dissipating enough of the waste heat to prevent an unacceptable rise in temperature. The limit of continuous energy is a function of the current. In high-frequency, high-pole electrical devices, optimally applicable in the practice of the present invention, less waste heat is generated because the iron-based, amorphous, nanocrystalline, and optimized metal alloy has lower losses than the conventional Si-Fe. The designer can exploit the low loss characteristics of these materials by increasing the frequency, speed and energy or power, and then correctly balance and "barter" the low core loss versus the ohmic loss. In general, for the same energy of conventional machines, the high frequency, high pole electrical devices optimally applicable in the present invention show less loss and therefore at torques and higher speeds, and thus they can reach higher continuous speed limits than conventional machines. One advantage of the preferred machine in practicing one aspect of the present invention is the ability to maximize the efficiency of the device, while maintaining the cost effectiveness. As it is conditional, the efficiency of the device is defined as the output of useful energy divided by the energy input. The high frequency, high pole count, electric devices optimally applicable in the present invention operate simultaneously at higher switching frequencies, with high pole count, resulting in a more efficient device having low core and high losses. energy density. These exceed the standard high frequency limit in the industry of 400 Hz, beyond which there have been few until now, if any practical applications. The operation and increased efficiency of the preferred, high-pole, high-frequency electrical devices applicable to the present invention are not simply inherent characteristics of replacing conventional Si-Fe with amorphous metal. A number of designs with amorphous metal have been proposed, but have encountered malfunctions (including overheating and lower output power). It is believed that this failure has arisen largely as a result of merely applying new materials (eg amorphous metals) and production methods in ways that were designed for, and suitable for, a conventional material (SiFe containing 3.5% or less silicon by weight). The early failure of operation, combined with the perceived cost of amorphous metal processing in engines, led the industry to abandon research efforts. Currently preferred electrical devices operate the prior art malfunctions through the design of a rotating electrical machine that exploits the beneficial properties of the amorphous metal alloy, nanocrystalline, optimized, iron-based, or materials based on grain oriented iron or non-oriented grain. Construction methods compatible with the physical and mechanical characteristics of the various improved materials are also provided. These designs and methods provide machines that possess some or all of the various advantageous qualities, including operation at switching frequencies greater than 400 Hz, with a high pole count, at high efficiency and with a high energy density. While other conventional methods have sometimes been able to provide engines with at most one or two of the four qualities, among the modalities provided herein, are the high-frequency, high pole-count electrical devices, which show some , and preferably all, the four simultaneous qualities. While machines including those provided by the '094 application provide reduced magnetic losses when using low loss stators materials, the present machine provides yet another mechanism by which losses can be reduced and efficiency increased, namely through the use of an improved stacked coil winding configuration. As a result of the increased efficiency, the high-frequency, high pole count electrical devices, optimally applicable in the present invention, are also capable of achieving a larger continuous speed range. Conventional motors are limited in that they can provide either low torque for high speed (low energy) intervals, or high torque for low speed intervals. The high frequency, high pole count electrical devices optimally applicable in the present invention successfully provide high torque electric devices for high speed intervals.

Cooling the electrical device Cooling the winding of the stator coil can be a challenge in any design of the electrical device. Although machines constructed in accordance with the principles of the present invention generally provide a significant improvement in efficiency over prior art devices, they may also benefit from improved cooling for certain high demand requirements. In many practical machines, the dissipation of the ohmic heating in the windings is a main limitation on the performance of the machine in idle state. Conventional motors often employ convection cooling using air circulated by a rotary flow on the motor shaft, but heat transfer in this arrangement can only occur on the outer surfaces of the windings and other components. The alternating stacking of the coils of the stator phase according to the present invention allows the use of cooling medium placed within the stator slots. Sufficient space for such means can be provided in certain modalities, without causing serious reduction of the operation of the device. For example, the heat conductive devices or materials may be placed in channels between adjacent phase windings in some or all of the stator slots. Any suitable heat conducting means may be used, including not exclusively the passive devices described in U.S. Patent No. 6,259,347, which is incorporated herein in its entirety, by reference. Other heat conducting materials, heat pipes or the like, can also be used. Also suitable are active systems that provide a liquid or gaseous cooling fluid that circulates using some external mechanism. Figure 3 illustrates an embodiment of the present invention that includes an electrically isolated cooling channel 54 located between the windings of the stacked stator coils instead of the layer-like insulation 48, such as paper or polymeric film. In alternative embodiments, cooling channel 54 and one or more insulation layers 48 are present. In other additional embodiments, the cooling channel is simply an open channel without walls, necessitating the use of liquid or gaseous refrigerant with adequate dielectric strength to resist breakage. The use of the cooling means, including the circulation cooling or heat conduction means, greatly improves the efficiency of the heat removal from inside the windings.

Flexibility in wiring / winding design An additional advantage of certain embodiments of the present machine is the flexibility of using different winding configurations. In traditional stators designs, they limit the choices of coil design due to the aforementioned focus when using SPP ratios of 1.0 to 3.0, which require distributing the windings over multiple slots. It becomes difficult to have more than 2 or 3 winding options with distributed windings. The present invention provides the ability to take advantage of the design of SPP = 0.5, where there is typically only one discrete coil per stator core (including the tooth). However, the invention does not exclude other arrangements with SPP = 0.5. Multiple coils can be easily modified and reconnected to provide any voltage demanded by a given application, while maintaining the serial pairing of the ascending and descending coils. Thus, given an SPP ratio approaching 0.5 as in the device of this invention, there is significant flexibility for configurations of the stator winding. For example, the manufacturer can wind each stator separately from each other, or the manufacturer can provide separate stator windings within the same stator. This capability is one of the advantages of a system with an SPP equal to 0.5. Although there have been occasional industrial systems that employ SPP = 0.5, they are not as widespread and have found success only in niche applications. The present invention successfully provides a system with SPP equal to 0.5 which allows this flexibility in the winding. In this way, a given hardware (hardware) configuration can provide a wide range of solutions, simply by changing the stator coils or interconnection. In general, the coil is the easiest component to modify in an electromagnetic circuit. Economies and significant simplification are provided for the manufacturer, and need less standard designs, for the distributor, who can maintain a simpler inventory, or for the user, who can modify a given machine to accommodate changing usage requirements.

Machine system and electronic energy control In yet another aspect, a dynamo-electric machine system is provided comprising an electrical axial air gap machine of the aforementioned type, and electronic energy means for interconnecting and controlling the machine. The system can function as a motor or generator or a combination thereof. The motor machines can be supplied with AC power, either directly or by DC power switching. Although mechanical switching has been widely used with brush-type machines, the availability of high-energy semiconductor devices has made it possible to design electronic brushless switching means that are used with many modern permanent magnet motors. In generation mode, a machine (unless mechanically switched) inherently produces AC. It is said that a large proportion of machines operate synchronously, which is why it is understood that the AC input and output energy has a congested frequency with the rotational frequency of the number of poles. Synchronous motors directly connected to a power grid, for example, the 50 or 60 Hz network commonly used by electrical installations or the 400 Hz network, frequently used in shipboard systems and aerospace systems, therefore operate at particular speeds, with variations obtainable only by changing the pole count. For synchronous generation, the rotational frequency of the main mover must be controlled to provide a stable frequency. In some cases, the inherent main mover produces a rotational frequency that is too high or too low to be accommodated by motors that have pole counts within practical limits for known machine designs. In such cases, the rotating machine can not be directly connected to a mechanical axis, so that a gearbox must frequently be used, despite the expected added complexity, and loss in efficiency. For example, wind turbines rotate so slowly that an excessively large pole count is required in a conventional motor. On the other hand, to obtain an adequate operation with the desired mechanical efficiency, typical gas turbine engines rotate so rapidly that even with a low pole count, the frequency generated is unacceptably high. The alternative for the applications of motors and generators is the conversion of active energy. The embodiments of the present electrical machine, including a stator assembly with stacked winding configurations of the aforementioned types, are beneficially employed with the conversion of active energy, especially in applications involving a wide speed range and / or energy requirements. fired. As used herein, the term "electronic energy component" is understood to mean the set of electronic circuits adapted to convert the electric power supplied as direct current (DC) or as alternating current (AC) of a frequency and form of Particular waveforms at the output of electrical power such as DC or AC, the output and the input differ in at least one of the voltage, frequency and waveform. The conversion is achieved by a set of conversion circuits of the electronic energy component. For a voltage transformation different from a simple AC power using an ordinary transformer that preserves the frequency and the simple bridge rectification of the AC to provide DC, the modern energy conversion ordinarily employs non-semiconductor devices. linear and other associated components that provide active control. As discussed hereinabove, in more detail, machines constructed in accordance with the present invention are operable as motors or generators over a much wider range of rotational speeds than conventional devices. In many cases, the gearbox required up to now in motor and generator applications, can be eliminated. However, the resulting benefits also generally require the use of operable electronic energy devices over a higher electronic frequency range than that used with conventional machines.

For motor applications of the dynamo-electric machine system, the machine is interconnected to an electrical source, such as the electric power grid, electrochemical batteries, fuel cells, solar cells or any other suitable source of electrical energy. A mechanical load of any type required can be connected to the machine shaft. In generation mode, the axis of the machine is mechanically connected to a main mover, and the system is connected to an electric charge, which can include any form of electrical device or store of electrical energy. The machine system can also be used as a regenerative engine system, for example as a system connected to the drive wheels of a vehicle, alternatively providing mechanical propulsion to the vehicle and converting the vehicle's kinetic energy back into electrical energy, stored in a battery to effect braking. The electronic energy means useful in the present axial air gap machine system should ordinarily include active control with sufficient dynamic range to accommodate the expected variations in mechanical and electrical load, while maintaining satisfactory electromechanical operation, regulation and control. . The means must function satisfactorily over the phase impedance range arising from the aforementioned changing permeance, during each revolution. Any form of energy conversion topology can be used including switching interruption regulators employing reinforcement, opposition and reverse converters and pulse width modulation. Preferably, the voltage and current are independently controllable in phase, and the control of the electronic power components can operate with or without direct detection of the position of the shaft. In addition, it is preferred that four-quadrant control be provided, allowing the machine to operate either for clockwise or counter-clockwise rotation and either in engine or generator mode. The current loop and speed loop loop control circuitry is preferably included whereby control can also be employed in the torque mode and the velocity mode. For stable operation, the electronic energy means should preferably have a control loop frequency range at least about 10 times as large as the intended switching frequency. For the present system, the operation of the rotating machine of up to about 2 kHz switching frequency thus requires a control loop frequency range of at least about 20 kHz. The controllers used in motor operations typically employ IGBT semiconductor switching elements. These devices show an increase in switching or interruption losses with frequency, so that it is ordinarily preferred to operate with switching frequencies of up to about 1000 Hz. The motor systems are thus advantageously designed with switching frequency in the range of about 600 to 1000 Hz, allowing the use of less expensive IGBTs while retaining the benefits (for example, increased energy density, resulting from the higher operating frequencies made possible by low loss materials. Suitable rectifier bridges allow operation at even higher switching frequencies Having thus described the invention in further complete detail, it will be understood that there is no need to adhere strictly to such details, but that various changes and modifications may suggest themselves to a person of experience in the technique, for exampleAlthough electric axial air gap machines have been generally described herein, other types of electric machines can be designed according to the principles described herein, such as radial air gap machines or linear machines. In addition, electrical machines could include a number of types of electrical machines other than permanent magnet machines, such as induction machines, synchronous machines, synchronous reluctance machines, switching reluctance machines and electromagnet machines. In addition, other rotor types and / or winding patterns of stators are within the scope of the present invention. It is therefore intended that such modifications be encompassed by the scope of the invention, as defined by the appended claims.

It is noted that in relation to this date, the best known method for carrying out the aforementioned invention is that which is clear from the present description of the invention.

Claims (18)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A multi-phase axial air dynamoelectric machine, characterized in that it comprises: (a) at least one stator assembly comprising a back-up iron section and a plurality of tooth sections, the stator assembly has a slot between each adjacent pair of teeth. tooth sections and a plurality of stator phase windings stacked, each winding circularly surrounding one or more of the tooth sections; and (b) at least one rotor assembly supported on rotation about an axis, and including a plurality of poles, the rotor assembly is accommodated and arranged for magnetic interaction with at least one stator assembly.

The machine according to claim 1, characterized in that the windings consist of equal numbers of ascending coils and descending coils, and each of the ascending coils is connected in series with one of the descending coils, and two of the coils in Stacked phase are present in each of the slots.

The machine according to claim 1, characterized in that the stator assembly comprises the magnetic material of low core loss comprising laminated layers composed of at least one material selected from a group consisting of amorphous metal, nanocrystalline metal, and optimized alloy in iron.

The machine according to claim 3, characterized in that the magnetic material of low core loss is distinguished by a smaller core loss of "L" when operated at an excitation frequency "f" at a peak induction level. "Bmax" where L is given by the formula L = 12-f-B1-5 + 30-f2"3-B2-3, the core loss, the excitation frequency and the peak induction level are measured in watts per kilogram, kiloherzio, and teslas, respectively

5. The magnetron according to claim 1, characterized in that the rotor assembly comprises a plurality of permanent rotor magnets placed with alternating polarity and securely positioned circumferentially around the rotor with spacing substantially the same

6. The machine according to claim 5, characterized in that the magnets are SmCo or FeNdB magnets.

7. The machine according to claim 1, characterized in that the ratio of groove to phase per pole is in the range of approximately 0.25 to 1.

8. The machine according to claim 7, characterized in that the phase-to-pole ratio is 0.50.

9. The machine according to claim 1, characterized in that it has at least 16 poles.

The machine according to claim 1, characterized in that it is adapted to run with a switching frequency in the range of approximately 500 Hz to 3 kHz.

The machine according to claim 1, characterized in that it comprises two stator assemblies and a rotor assembly placed between them.

12. The machine according to claim 1, characterized in that it further comprises the cooling means placed within the stator slots.

13. The machine according to claim 1, characterized in that the machine is an axial air gap device.

A method for constructing a dynamoelectric machine, characterized in that the method comprises: (a) providing at least one stator assembly comprising a back-up iron section and a plurality of tooth sections, the stator assembly having a slot between each adjacent pair of tooth sections, and a plurality of stator phase windings stacked, each winding circularly surrounds one or more of the tooth sections; and (b) the provision of at least one rotor assembly supported for rotation about one axis and including a plurality of poles, the rotor assembly is accommodated and arranged for magnetic interaction with at least one stator assembly.

The method according to claim 14, characterized in that two stacked phase windings are present in each of the slots, the windings consist of equal numbers of ascending coils and descending coils, and each of the ascending coils are connected in series with one of the descending coils.

16. The method of compliance with the claim 14, characterized in that the stator assembly comprises magnetic material of low core loss, comprising: laminated layers composed of at least one material selected from the group consisting of amorphous metal, nanocrystalline metal and optimized alloy based on iron.

17. The method according to claim 14, characterized in that the stator assembly is formed as a unitary structure by a process comprising the steps of: (a) spirally coiling a toroid of the laminated layers of magnetic material of low core loss, the toroid having an internal diameter, an external diameter and a toroid height; and (b) cutting a plurality of grooves extending in a substantially radial direction from the inner diameter to the outer diameter, and having a groove depth less than the height of the toroid.

18. The machine according to claim 1, characterized in that the additional system comprises electronic energy means for interconnecting and controlling the machine and for being operably connected to it.