# US 2013/0154397 A1 · High efficiency magnetic core electrical machines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154397 A1 - Document ID: US20130154397A1 - Status: Published application - Kind: A1 - Application number: 13/330,075 - Filed: 2011-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: John T. Sullivan - Inventors: John T. SULLIVAN - Web page: https://patentgrep.com/patent/US20130154397A1 ## CPC - H02K 21/00: Synchronous motors having permanent magnets; Synchronous generators having permanent magnets - H02K 1/14: Stator cores with salient poles - H02K 1/141: {consisting of C-shaped cores} - H02K 1/145: {having an annular coil, e.g. of the claw-pole type} - H02K 1/148: {Sectional cores (H02K1/141 takes precedence)} - H02K 3/522: {for generally annular cores with salient poles} - H02K 21/028: {by modifying the magnetic circuit within the field or the armature, e.g. by using shunts, by adjusting the magnets position, by vectorial combination of field or armature sections} - H02K 21/12: with stationary armatures and rotating magnets - H02K 21/14: with magnets rotating within the armatures - H02K 21/22: with magnets rotating around the armatures, e.g. flywheel magnetos - H02K 21/24: with magnets axially facing the armatures, e.g. hub-type cycle dynamos - H02K 21/44: with armature windings wound upon the magnets - H02K 41/031: {of the permanent magnet type} - H02K 2201/06: Magnetic cores, or permanent magnets characterised by their skew - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A high efficiency magnetic core electrical machine includes magnet and coil assemblies that may be axially stacked to form modules. The magnet sub-assemblies include magnet locators on which multiple permanent magnets are arranged, and the coil sub-assembly includes a pair of bobbin holders supporting multiple bobbins and magnetic cores that extend through the bobbins and through openings in the bobbin holders to form magnetic poles that face the permanent magnets. The permanent magnets and magnetic poles may be arranged in various zero-cogging configurations, including one in which the permanent magnets on opposite sides of the coil assembly are skewed relative to each other to cause cogging force cancellation. In addition, a power matching circuit may be used to optimize the output power of the electrical machine to rotor speed when the electrical machine is used as a generator. ## Claims ### Claim 1 A high efficiency magnetic core electrical machine, comprising: a permanent magnet sub-assembly including a plurality of permanent magnets of opposite polarity arrayed axially and circumferentially around the permanent magnet sub-assembly; a three-dimensional pole structure sub-assembly including at least one soft magnetic flux return ring, a plurality of soft magnetic arms extending axially from the flux return ring, and at least two pole arms extending radially from each of said axially extending arms, each pole arm being axially spaced to face axially spaced sets of said permanent magnets as at least one of said permanent magnet sub-assembly and said pole structure sub-assembly are rotated relative to the other of said permanent magnet sub-assembly and said pole structure sub-assembly, wherein electrical windings are positioned on said pole structure sub-assembly to interact inductively with changing magnetic flux in said pole structure sub-assembly, and wherein said relative rotation of said permanent magnet and pole structure sub-assemblies causes permanent magnets of opposite polarity to face axially and circumferentially adjacent ones of said pole arms such that magnetic flux flows through and converges in said pole arms, said axially extending arms, and said flux return ring to thereby interact inductively with said windings. ### Claim 2 (depends on 1) An electrical machine as claimed in claim 1, wherein said flux return ring, said axially-extending arms, and said pole arms are arranged in a plurality of individual pole structure modules, each said module including an arc shaped section of said flux return ring, at least one axially-extending arm, and at least two said radially-extending pole arms. ### Claim 3 (depends on 2) An electrical machine as claimed in claim 2, wherein said axially-extending arm extends above and below said arc shaped section, and said module includes three said pole arms, one of which extends arc shaped ring and two of which extend from ends of said axially-extending arms to form an E-shaped structure. ### Claim 4 (depends on 3) An electrical machine as claimed in claim 3, wherein said pole arms extend radially inwardly. ### Claim 5 (depends on 3) An electrical machine as claimed in claim 3, wherein a number of said arc-shaped sections is three, one of said arc-shaped sections extending from a middle of said axially extending arm and two of said arc-shaped sections extending from ends of said axially-extending arm to form three said flux return rings. ### Claim 6 (depends on 2) An electrical machine as claimed in claim 2, wherein arc-shaped sections of adjacent said modules are joined together by a mortise and tenon connection. ### Claim 7 (depends on 6) An electrical machine as claimed in claim 6, further comprising a mortise or tenon on each end of said axially extending arms to enable connection of multiple said flux return rings. ### Claim 8 (depends on 6) An electrical machine as claimed in claim 6, further comprising interfitting curved surfaces on each end of said axially extending arms, said axially extending arms being joined by pins that extend through bores communicating bores in the axially extending arms of adjacent said modules to enable connection of multiple said flux return rings. ### Claim 9 (depends on 2) An electrical machine as claimed in claim 2, wherein said pole arms include at least one radially inwardly extending pole arm and at least one radially outwardly extending pole arm, and wherein said electrical machine permanent magnets are arranged on an inner cylinder to face said inwardly extending pole arms and on an outer cylinder to face said outwardly extending pole arms. ### Claim 10 (depends on 8) An electrical machine as claimed in claim 8, wherein each said module include three said radially extending pole arms, three said outwardly extending pole arms, and three said arc shaped sections extending on each side of said axially-extending arm to form three said flux return rings. ### Claim 11 (depends on 1) An electrical machine as claimed in claim 1, wherein said windings are wound around coil bobbins fitted onto said pole arms. ### Claim 12 (depends on 1) An electrical machine as claimed in claim 1, wherein said pole arms are flared to increase a surface area that faces said permanent magnets. ### Claim 13 A high efficiency magnetic core electrical machine, comprising: a permanent magnet sub-assembly including a plurality of permanent magnets of opposite polarity arrayed around the permanent sub-assembly; a pole structure sub-assembly including poles that face different said permanent magnets as said pole structure sub-assembly moves relative to said permanent magnet sub-assembly to thereby cause reversals of flux carried by said pole structure sub-assembly, wherein said pole structure sub-assembly includes a plurality of auxiliary permanent magnets that are freely movable relative to said pole structure sub-assembly to follow said flux reversals and thereby boost magnetic flux flowing through said pole structure sub-assembly in each direction as said permanent magnets of opposite polarity move past respective said poles. ### Claim 14 (depends on 13) An electrical machine as claimed in claim 13, wherein said pole structure sub-assembly includes a flux return ring and said auxiliary permanent magnets are annular dipole magnets mounted for rotation within said flux return ring. ### Claim 15 (depends on 14) An electrical machine as claimed in claim 14, wherein a number of said permanent magnets of said permanent magnet sub-assembly is greater than a number of said poles to provide an anti-cogging effect. ### Claim 16 (depends on 13) An electrical machine as claimed in claim 13, wherein said auxiliary permanent magnets are situated at ends of radially outwardly extending pole arms. ### Claim 17 (depends on 13) An electrical machine as claimed in claim 13, wherein said pole structure sub-assembly includes an outer flux return ring, and said auxiliary permanent magnets are arranged in radially aligned pairs extending between said permanent magnet sub-assembly and said outer flux return ring. ### Claim 18 (depends on 17) An electrical machine as claimed in claim 17, wherein coil windings are situated between individual auxiliary permanent magnets in each of said radially aligned pairs. ### Claim 19 (depends on 18) An electrical machine as claimed in claim 18, wherein said permanent magnet sub-assembly is a cylinder on an outside of said pole structure sub-assembly. ### Claim 20 (depends on 13) An electrical machine as claimed in claim 13, wherein said electrical machine is a linear electrical machine and said auxiliary permanent magnets are annular dipole magnets mounted for rotation. ### Claim 21 (depends on 20) An electrical machine as claimed in claim 20, wherein said permanent magnet sub-assembly includes a linear support member on which a row of said permanent magnets are fixed, said auxiliary permanent magnets are arranged in parallel with said linear member in at least two rows, and a flux return member is provided on an opposite side of said auxiliary permanent magnets from said linear support member. ### Claim 22 (depends on 21) An electrical machine as claimed in claim 21, wherein said flux return member is also provided with a row of permanent magnets. ### Claim 23 (depends on 21) An electrical machine as claimed in claim 21, wherein coil windings are positioned between respective pairs of auxiliary permanent magnets, one in at least two of said rows. ### Claim 24 A mono coil electrical machine, comprising: a magnetic pole structure comprising two sets of radially extending pole arms circumferentially arranged around opposite ends of a cylindrical soft magnetic member with a space between said two sets of radially extending pole arms; a single coil supporting structure extending around said cylindrical soft magnetic member in said space between said two sets of radially extending pole arms, and at least one coil wound around said coil supporting structure; and two cylindrical housing halves, each supporting a set of permanent magnets of opposite polarities interleaved on an inner surface, said magnets extending around said magnetic pole structure such that individual poles pass each of said magnets when said magnetic pole structure or said two cylindrical housing halves rotate, wherein a number of said pole arms extending from a respective end of said magnetic pole structure is one half a number of said permanent magnets on a respective said housing half such that said pole arms on one end of said magnetic pole structure all simultaneously face permanent magnets of a same polarity and at the same time said pole arms on a second end of said magnetic pole structure all simultaneously face permanent magnets of a polarity opposite to said same polarity to cause magnetic flux to flow through said coil in a first direction, and wherein as said magnetic pole structure and said housing halves relatively rotate, permanent magnets on each housing half alternately pass corresponding said poles to cause magnetic flux flowing through said coil to repeatedly reverse polarity and generate an alternating current in said coil. ### Claim 25 (depends on 24) A mono coil electrical machine as claimed in claim 24, wherein said radially extending pole arms are arranged to cause cooling air circulation as said magnetic pole structure rotates. ### Claim 26 (depends on 24) A mono coil electrical machine as claimed in claim 24, wherein a first set of said permanent magnets is arranged on an inner cylindrical surface of each said housing half to face ends of said pole arms, and a second set of said permanent magnets is arranged on an end surface of each said housing half to face sides of said pole arms. ### Claim 27 (depends on 24) A mono coil electrical machine as claimed in claim 24, further comprising a second magnetic pole structure, a second coil, and a second set of housing halves stacked to form a two phase electrical machine. ### Claim 28 (depends on 24) A mono coil electrical machine as claimed in claim 24, wherein a plurality of said magnetic pole structures and mono coils are axially stacked to form a multiple phase electrical machine. ### Claim 29 A spherical mono coil electrical machine, comprising: a spherical magnetic pole structure comprising two sets of arc-shaped pole sections, each arc-shaped pole section forming a curved-triangular section of a sphere-shape having vertices that terminate in a hub at a respective axial end of said pole structure and a base midway between said axial ends of the sphere-shape, said slices further inner sides that extend along an axis of the sphere-shape, with slices of the first set forming a first hemisphere, slices of the second set forming a second hemisphere, and slides of the first and second hemispheres being connected by a cylindrical soft magnetic member around which is an annular space; a single coil supporting structure extending around said cylindrical soft magnetic member in said space between said two sets of arc-shaped pole sections, with at least one coil wound around said coil supporting structure; and two hemispherical housing halves, each supporting a set of permanent magnets of opposite polarities interleaved on an inner surface, said magnets extending around said magnetic pole structure such that individual poles pass each of said magnets when said magnetic pole structure or said two cylindrical housing halves rotate, wherein a number of said arc-shaped pole sections on a respective hemisphere of said pole structure is one half a number of said permanent magnets on a respective first said hemispherical housing half such that said arc-shaped pole sections on said respective hemisphere all simultaneously face permanent magnets of a same polarity and at the same time said arc-shaped pole sections on a second said hemisphere of said magnetic pole structure all simultaneously face permanent magnets of a polarity opposite to said same polarity to cause magnetic flux to flow through said connecting member in a first direction, and wherein as said spherical magnetic pole structure and said hemispherical housing halves relatively rotate, permanent magnets on each hemispherical housing half alternately pass corresponding said arc-shaped pole sections to cause magnetic flux flowing through said connecting member, and therefore through said coil, to repeatedly reverse polarity and generate an alternating current in said coil. ### Claim 30 (depends on 24) A spherical mono coil electrical machine as claimed in claim 24, wherein said single coil supporting structure includes a passage for receiving a liquid coolant. ### Claim 31 (depends on 24) A spherical mono coil electrical machine as claimed in claim 24, wherein said hemispherical housing halves are made up of arc-shaped sections corresponding in number and shape to said permanent magnets supported by said hemispherical housing halves, spaces between said sections providing ventilation. ### Claim 32 (depends on 32) A spherical mono coil electrical machine as claimed in claim 32, wherein ends of said arc-shaped sections of a first of said hemispherical housing halves terminate in an annular flange that mates with a corresponding annular flange on a second of said hemispherical housing halves to join said hemispherical housing halves. ### Claim 33 (depends on 32) A spherical mono coil electrical machine as claimed in claim 32, wherein said annular flanges extend continuously around a perimeter of said hemispherical housing halves to serve as a flux return path between said arc-shaped hemispherical housing half sections. ### Claim 34 A mono coil electrical machine, comprising: a central disc having a plurality of flux reversal structures mounted on a periphery of said disc; an annular permanent magnet sub-assembly comprising a plurality of soft magnetic structures to which are affixed axially aligned pairs of permanent magnets, such that adjacent ones of said permanent magnets alternate in polarity both axially and around a circumference of said permanent magnet sub-assembly; and at least one coil positioned to intercept magnetic fields generated by said permanent magnets, wherein a number of said flux reversal structures is one half a number of said axially aligned pairs of permanent magnets, and wherein as said central disc and annular permanent magnet sub-assembly relatively rotate, top and bottom ends of said flux reversal structures face different axially aligned pairs of said permanent magnets, causing magnet flux flowing between said top and bottom ends to reverse, thereby causing changes in magnetic fields that intercept said coil to induce a current. ### Claim 35 (depends on 34) A mono coil electrical machine as claimed in claim 34, wherein said annular permanent magnet sub-assembly includes a plurality of c-shaped soft magnetic structures having radially extending arms, ends of said arms supporting said permanent magnets, and said coil extending around said permanent magnet sub-assembly in spaces between the arms of the c-shaped soft magnetic structures. ### Claim 36 (depends on 34) A mono coil electrical machine as claimed in claim 34, wherein said annular permanent magnet sub-assembly comprises a continuous flux return member having a c-shaped cross section forming an annular space that extends around said sub-assembly, said coil being received in said annular space. ### Claim 37 (depends on 34) A mono coil electrical machine as claimed in claim 34, wherein said flux reversal structures each includes a pair of bracket arms for securing said flux reversal structures to said central disc. ### Claim 38 (depends on 37) A mono coil electrical machine as claimed in claim 37, wherein said flux reversal structures each further includes upper and lower pole arms extending radially outwardly from said central disc to face said permanent magnets. ### Claim 39 (depends on 37) A mono coil electrical machine as claimed in claim 37, wherein said flux reversal structure each includes an axially extending face, one end of which faces first said permanent magnets of said axially aligned pairs of permanent magnets and a second end of which faces second said permanent magnets of said axially aligned pairs. ### Claim 40 (depends on 37) A mono coil electrical machine as claimed in claim 37, which is stacked with at least one additional said mono coil electrical machine to form a multiple phase electrical machine. ### Claim 41 (depends on 34) A mono coil electrical machine as claimed in claim 34, wherein said permanent magnet sub-assembly includes a plurality of permanent magnet/coil modules, each including an individual coil. ### Claim 42 (depends on 41) A mono coil electrical machine as claimed in claim 41, wherein said permanent magnet/coil modules each includes a pair of soft magnetic holders and a permanent dipole magnet extending between the holders, said dipole magnet extending through a coil holder around which said individual coil is wound. ### Claim 43 (depends on 42) A mono coil electrical machine as claimed in claim 42, wherein said holders each includes a recess shaped to receive and securely hold an end of said dipole magnet. ### Claim 44 (depends on 41) A mono coil electrical machine as claimed in claim 41, wherein permanent magnet/coil modules each includes a pair of pole structures having poles that extend towards said flux reversal structures and a pair of pockets for respectively receiving permanent magnets of opposite polarity, said modules further including a common flux return plate for retaining said permanent magnets within said pockets. ### Claim 45 (depends on 34) A mono coil electrical machine as claimed in claim 34, wherein said permanent magnet sub-assembly includes a plurality of horseshoe magnets. ### Claim 46 (depends on 45) A mono coil electrical machine as claimed in claim 45, wherein said at least one coil is a single coil extending around said permanent magnet sub-assembly in spaces between arms of said horseshoe magnets. ### Claim 47 (depends on 45) A mono coil electrical machine as claimed in claim 45, wherein said at least one coil includes an individual coil surrounding one arm of each of said horseshoe magnets. ### Claim 48 A linear electrical machine, comprising: an armature including at least one flux reversal structures; rows of permanent magnets of opposite polarity, said flux reversal structure extending between said rows of permanent magnets; and at least one coil positioned to sense changes in a magnetic field resulting from said flux reversals, wherein one side of said flux reversal structure faces a permanent of first polarity and an opposite side of said flux reversal structure faces a permanent magnet of opposite polarity, and wherein as said flux reversal structure moves relative to said rows of permanent magnets, said ends of said flux reversal structure face permanent magnets of alternating polarity to cause repeated reversal of magnetic flux in said flux reversal structure, thereby inducing an alternating current in said coil. ### Claim 49 (depends on 48) A linear mono coil electrical machine as claimed in claim 48, wherein said flux reversal structure two arms extending parallel to a direction of movement of said armature relative to said rows of permanent magnets, a connecting arm extending between said two parallel arms, and pairs of pole arms extending transversely from ends of said parallel arms, each pole arm in the pair of pole arms extending from one side of said flux reversal structure facing a respective permanent magnet of like polarity. ### Claim 50 (depends on 49) A linear mono coil electrical machine as claimed in claim 49, further comprising additional pole arms extending transversely to said pairs of pole arms, and additional rows of permanent magnets faced by said additional pole arms to form a three-dimensional linear actuator. ### Claim 51 (depends on 50) A linear mono coil electrical machine as claimed in claim 50, wherein a number of pole arms extending from each respective end of each of said parallel arms of said flux reversal structure is three, and a number of said rows of permanent magnets is six. ### Claim 52 (depends on 48) A linear mono coil electrical machine as claimed in claim 48, wherein a number of said flux reversal structures is at least two to provide multiple phases. ### Claim 53 (depends on 48) A linear mono coil electrical machine as claimed in claim 48, wherein said row of permanent magnet structures include a row of c-shaped magnets, and said coil extends around arms of a plurality of said c-shaped magnets. ### Claim 54 (depends on 48) A linear mono coil electrical machine as claimed in claim 48, wherein said flux reversal structure comprises a plurality of soft magnetic discs connected by cylindrical structures to form spaces between said discs, and said rows of permanent magnets include rows of semi-circular permanent magnets extending around said soft magnetic discs to cause flux reversals in said discs as said armature and rows of permanent magnets move relative to each other. ### Claim 55 (depends on 54) A linear mono coil electrical machine as claimed in claim 54, wherein said at least one coil includes a plurality of coils wrapped around said cylindrical structures in said spaces between said discs. ### Claim 56 (depends on 54) A linear mono coil electrical machine as claimed in claim 54, wherein said at least one coil includes a plurality of coils wrapped around a cylinder to which the permanent magnets are affixed. ### Claim 57 A mono coil electrical machine, comprising: a permanent magnet subassembly including a plurality of permanent magnets of opposite polarity; and at least one flux reversal structure that includes a cylindrical section, flanges extending in opposite directions from each end of the cylindrical section, and a coil wrapped around said cylindrical section, wherein respective said flanges face permanent magnets of opposite polarity, and wherein as said permanent magnet sub-assembly moves relative to said flux reversal structure, polarities of said permanent magnets that face said flanges alternates to cause flux reversals in said cylindrical section and induce an alternating current in said at least one coil. ### Claim 58 (depends on 57) A linear mono coil electrical machine as claimed in claim 57, wherein each of said flanges includes a plurality of openings, and wherein said electrical machine includes a plurality of said modules aligned by pins extending through said openings. ### Claim 59 (depends on 58) A linear mono coil electrical machine as claimed in claim 58, wherein said rows of permanent magnets are semi-circular permanent magnets joined together to form a structure that rotates within central openings of said plurality of flux reversal structures. ### Claim 60 An electrical machine, comprising: a first set of permanent magnets mounted on a cylindrical housing structure; a second set of permanent magnets mounted on a soft magnetic magnet holder, said cylindrical housing structure and said magnet holder being relatively movable; and at least one coil positioned to detect changes in a magnetic field that results from relative movement of said first and second sets of permanent magnets, wherein said soft magnetic magnet holder surrounds a shaft and includes radially extending spokes for supporting the magnets. ### Claim 61 (depends on 60) An electrical machine as claimed in claim 60, wherein said cylindrical housing structure and magnet holder are made of steel, and the at least one coil is on the outside of the housing to pick up a switching magnetic field in the housing. ### Claim 62 A low cogging mono coil electrical machine, wherein permanent magnets are mounted on opposite sides of a plurality of plates, said plurality of plates being parallel to each other and mounted on shaft so as to be out-of-phase in order to produce a sine wave in a pair of pickup coils extending around said shaft and permanent magnets between respective pairs of said plates. ### Claim 63 An electrical machine, comprising: a rotor comprising a pair of annular axially spaced discs on which are mounted permanent magnets of opposite polarity; a plurality of linear flux reversal members extending in parallel with an axis of said rotor such that ends of said flux reversal members face respective permanent magnets of opposite polarity on said axially spaced discs; and at least one pick-up coil, wherein said ends of said flux reversal members face magnets of alternating polarity as said rotor and cylindrical housing rotate relative to each other, thereby causing flux reversals that induce currents in said pick-up coil. ### Claim 64 (depends on 63) An electrical machine as claimed in claim 63, wherein said linear flux reversal members are mounted in slots in a cylindrical housing, and said pick-up coil extends around said cylindrical housing. ### Claim 65 (depends on 64) An electrical machine as claimed in claim 64, wherein said rotor discs includes a plurality of spokes to which said permanent magnets are mounted. ### Claim 66 (depends on 63) An electrical machine as claimed in claim 63, wherein said pick-up coils includes a plurality of radially extending pick-up coils. ### Claim 67 (depends on 66) An electrical machine as claimed in claim 66, wherein said pick-up coils are aligned relative to said permanent magnets on said rotor by notches in said linear flux reversal members. ### Claim 68 An electrical machine, comprising: a stator including an outer housing member and a plurality of pole structures, each pole structure joined to the outer housing member by an interface that forms a self-aligning connection, and each pole structure including abase and at least one arm connected to the base and extending parallel to an axis of the electrical machine, said at least one arm including a pole face arranged to face permanent magnets of opposite polarity; a disc-shaped rotor having said permanent magnets of opposite polarity mounted around a periphery of the rotor; and at least one coil extending through an opening between the base and the at least one arm of each of the pole structures. ### Claim 69 (depends on 68) An electrical machine as claimed in claim 68, wherein the at least one coil is a mono coil. ### Claim 70 (depends on 68) An electrical machine as claimed in claim 68, wherein the self-aligning connection is a mortise and tenon joint. ### Claim 71 (depends on 68) An electrical machine as claimed in claim 68, wherein the self-aligning connection is a dovetail joint. ### Claim 72 (depends on 68) An electrical machine as claimed in claim 68, wherein each pole structure includes two arms extending parallel to the axis of the electrical machine in opposite directions, said pole face of respective arms arranged to simultaneously face opposite polarity ones of said permanent magnets. ### Claim 73 (depends on 68) An electrical machine as claimed in claim 68, wherein said outer housing is cylindrical and said pole structures are annular pole structures, and pairs of said annular pole structures include a plurality of said axially extending arms, said annular pole structures in a pair being joined to capture the at least one coil and form a single phase coil assembly, and said self-aligning connection enabling multiple said single phase coil assemblies to be aligned with said outer housing. ### Claim 74 (depends on 73) An electrical machine as claimed in claim 73, wherein said self-aligning connection includes axially extending ribs on said annular pole structures and axially extending grooves on an interior surface of said outer housing. ### Claim 75 (depends on 73) An electrical machine as claimed in claim 73, wherein said annular pole structures are joined to each other by a step interface. ### Claim 76 (depends on 68) An electrical machine as claimed in claim 68, wherein said self-aligning connection includes pins and openings. ### Claim 77 (depends on 68) An electrical machine as claimed in claim 68, wherein the outer housing member is annular and said pole structures are U-shaped members that are bolted to the outer housing member. ### Claim 78 (depends on 68) An electrical machine as claimed in claim 68, wherein said pole structures further include integrated permanent magnets. ### Claim 79 (depends on 68) An electrical machine as claimed in claim 68, wherein said arms are skewed with respect to said permanent magnets to reduce cogging. ### Claim 80 (depends on 68) An electrical machine as claimed in claim 68, wherein said at least one coil includes an outer insulating member that surrounds a plurality of conductors and a pressurized coolant fluid. ### Claim 81 (depends on 68) An electrical machine as claimed in claim 68, wherein said at least one coil includes an outer insulating member surrounding a tube-shaped conductor, said outer insulating member and said tube-shaped conductor both filled with pressurized coolant fluid. ### Claim 82 A control circuit for an electrical machine having at least two coils, comprising a switch and means for controlling the switch to switch between a series connection of the two coils at low speeds and a parallel connection of the two coils at high speeds. ### Claim 83 An electrical machine with skewed-stator anti-cogging features, comprising: a rotor having an axis of rotation and a plurality of permanent magnets arranged around a periphery of the rotor; and a stator having a plurality of pole structures, said pole structures facing said magnets and having principal axes, wherein said principal axes of said pole structures are skewed with respect to said axis of rotation of the rotor. ### Claim 84 (depends on 83) An electrical machine as claimed in claim 83, wherein said permanent magnets have principal axes that are also skewed with respect to said axis of rotation of the rotor.