electric motor

Abstract

The stator includes a plurality of stator poles with electrical windings for the plurality of stator poles. The mover includes a plurality of mover poles. The mover is movable relative to the stator and mates with the stator to define a nominal gap between the stator poles and the mover poles. The mover poles include a magnetically permeable pole material. The mover also includes an array of frequency programmable flux channels (FPFCs). Each FPFC includes a conductive loop surrounding a corresponding mover pole. The stator and mover are arranged such that, upon starting, the electrical windings on the stator induce an excitation current in at least one of the frequency programmable flux channels.

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates to electric motors and the operation of such motors. [Background technology]

[0002] There are two ways that electric motor performance can be characterized: by its torque / force and by its power output. Power output for a rotary motor is the product of the torque generated by the motor and the angular velocity of the output shaft. For a linear motor, power output is the product of linear force and speed. Traditionally, the two main ways to directly improve motor performance are (1) increasing the motor size and (2) strengthening the magnetic field itself generated by the motor. While the final size of the motor limits the specific applications for which it can be used, increasing the magnetic field and therefore the electromagnetic force is key to improving motor performance and further expanding the applications of motor technology. Summary of the Invention

[0003] Aspects of the present disclosure feature motors with frequency programmable flux channels (FPFCs) positioned around passive poles to redirect the magnetic flux generated during operation in a manner that increases the component of the magnetically induced driving force aligned with the direction of motion (to provide effective torque and / or linear force).

[0004] One exemplary embodiment of the subject matter described in this disclosure is an electric machine having: a stator including a plurality of stator poles with electrical windings for the plurality of stator poles; a mover including a plurality of mover poles; the mover being movable relative to the stator and mating with the stator to define a nominal gap between the stator poles and the mover poles; the mover poles including a magnetically permeable pole material; and the mover also including an array of frequency programmable flux channels (FPFCs), each including a conductive loop surrounding a corresponding mover pole.

[0005] One exemplary embodiment of the subject matter described in this disclosure is an electric machine having: a stator configured to generate a controlled magnetic field; a mover configured to move relative to the stator in response to the controlled magnetic field; the mover mating with the stator to define a nominal gap between a surface of the mover and a surface of the stator; the mover including a magnetically permeable pole material; and the mover including a variable magnetomotive force source controllable by the controlled magnetic field generated by the stator.

[0006] One exemplary embodiment of the subject matter described in this disclosure is a motor control method comprising: providing a pulse of magnetizing current for a specified duration to a stator coil of a stator pole when the stator is aligned with the mover pole across a nominal gap; the magnetizing current charges the magnetic field of the mover pole by inductive coupling; providing a load current pulse for a specified duration to the stator coil when the mover pole is positioned between adjacent stator poles; the load current pulse stiffens the magnetic field at the mover pole; and the load current pulse has a greater number of pulses per time duration than the magnetizing current pulses.

[0007] One exemplary embodiment of the subject matter described in this disclosure is a motor control method having the following features: the mover poles of an electric machine are hard-magnetically imparted by currents around the mover poles, which are induced by currents flowing in the stator coils, and movement of the mover relative to the stator is caused by electromotive forces generated by the currents flowing in the stator coils and the currents flowing around the mover poles.

[0008] One exemplary embodiment of the subject matter described in this disclosure is a method for starting a three-phase electric motor, comprising: passing a DC current through a stator winding associated with a stator phase for a particular duration; and subsequently passing a DC current in a pulsed manner in the opposite direction through the stator winding associated with that phase for a second duration.

[0009] One exemplary embodiment of the subject matter described in this disclosure is a method of driving an electric motor, the method comprising: first increasing the average magnetic flux of an electric mover by a waveform excitation from a stator;

[0010] The above implementations may include any, all, or none of the following features.

[0011] The stator and armature are arranged such that, upon start-up, the electrical windings of the stator excite a current in at least one of the frequency-programmable flux channels.

[0012] The stator and armature are arranged so that, at start-up, the electrical windings on the stator magnetize at least one of the armature poles.

[0013] The excitation current of an FPFC is generated by the electrical windings of the stator during operation.

[0014] The conductive loop comprises a material that is more conductive than the armature core material.

[0015] The conductive loop comprises a material that has a lower magnetic permeability than the armature core material.

[0016] Each FPFC does not overlap with adjacent FPFCs.

[0017] The conductive loop has a substantially uniform inductance, which may be a radial inductance.

[0018] The conductive loop has at least one turn of shorted conductive material.

[0019] The conductive loop has a shorted Litz wire.

[0020] The thickness of the individual conductors in the conductive loop is small enough for full skin effect penetration at the drive frequency. The drive frequency can be between 0 and 20 Hz. The drive frequency can range from 100 to 2000 Hz, or greater than 20,000 Hz.

[0021] The conductive loop includes a rectifier in series with each end of the conductive loop. The rectifier may include a diode. The diode may be a pn junction diode. The diode may be a Schottky diode. The Schottky diode may be a silicon carbide diode. The diode may be a gas diode. The diode may be a Zener diode.

[0022] The conductive loop includes a discrete capacitor in series across the conductive loop, which may be connected in parallel with a diode.

[0023] The conductive loop includes a logic circuit in series across the conductive loop, and the logic circuit may include a transistor, which may include a field effect transistor, a dual gate field effect transistor, or a bipolar junction transistor.

[0024] The conductive loop is a first conductive loop, and each frequency programmable magnetic flux channel further includes a second conductive loop, a corresponding armature pole, and an additional armature pole adjacent to the first armature pole. The second conductive loop can include a material having a higher conductivity than the armature core material. The second conductive loop can include a material having a lower magnetic permeability than the armature core material. The inductance of the first conductive loop can have a substantially uniform first inductance, and the second conductive loop can have a substantially uniform second inductance. The substantially uniform second inductance can be a radial inductance. The substantially uniform second inductance can be substantially equal to the substantially uniform first inductance. The second conductive loop can have at least one turn of shorted conductive material. The second conductive loop can include shorted Litz wire. The thickness of the individual conductors in the second conductive loop can be sufficiently small for full skin effect penetration at the drive frequency. The second conductive loop can encompass an additional third mover pole adjacent to the first mover pole. The second conductive loop can include a logic circuit in series with both ends of the second conductive loop. The logic circuit can include a transistor. The transistor can include a field effect transistor, a dual gate field effect transistor, or a bipolar junction transistor. The second conductive loop can include a rectifier in series with both ends of the conductive loop. The rectifier can include a diode. The diode can be a pn junction diode. The diode can be a Schottky diode. The Schottky diode can be a silicon carbide diode. The diode can be a Zener diode. The diode can be a gas diode. The second conductive loop can include a discrete capacitor in series with both ends of the conductive loop. The capacitor can be connected in parallel with the diode.

[0025] The mover surrounds the stator in the circumferential direction.

[0026] The stator surrounds the mover in the circumferential direction.

[0027] The mover and stator are separated by an axial gap.

[0028] The electric machine is a motor.

[0029] Each of the mover poles includes a material with non-zero remanence.

[0030] The controller is configured to supply a pulse of magnetizing current of a specific duration to the stator coil of a stator pole when the stator pole is aligned with the mover pole across the nominal gap. The magnetizing current charges the magnetic field of the mover pole by inductive coupling. The controller is further configured to supply a load current pulse of a specific duration to the stator coil when the mover pole is located between the adjacent stator poles. The load current pulse strengthens the magnetic field in the mover pole. The load current pulse has a greater number of pulses per time duration than the magnetizing current pulses.

[0031] The mover further includes a permanent magnetic channel. A permanent magnetic channel can be disposed at each mover pole. A permanent magnetic channel can be disposed between the FPFC and the stator. A permanent magnetic channel can be disposed within a back yoke of the mover. The permanent magnetic channel can include ferrite. The permanent magnetic channel can include SmFeN. The permanent magnetic channel can include N35. The permanent magnetic channel can include N45.

[0032] The mover includes a plurality of permanent magnetic spokes extending from a central axis of the mover, the spokes being capable of being positioned between the FPFCs.

[0033] The magnetizing current is supplied as a single pulse of current over a specific time period. The single pulse of current may include a half-sine wave. The single pulse of current may include a half-square wave. The single pulse of current may include a half-trapezoidal wave. By supplying the above magnetizing current, the mover poles can be strongly coupled to the stator poles.

[0034] The load current pulses are supplied as multiple current pulses over a specific time period as the mover rotates from the first pole to the second pole. The multiple current pulses can include half-sine waves. The multiple current pulses can include half-square waves. The multiple current pulses can include half-trapezoidal waves. The multiple current pulses can include full-sine waves. The multiple current pulses can include full-square waves. The multiple current pulses can include full-trapezoidal waves. The multiple current pulses are independent of the mover speed. The multiple current pulses are applied at 5 to 10 Hz.

[0035] Maintain mover flux within a desired range during peak load conditions. The desired range can vary between 50-100%. The desired range can vary between 65-100%. The desired range can vary between 80-100%.

[0036] The stator includes a permanent magnet channel. The control method further includes adjusting a strength of apparent magnetism in the permanent magnet channel. The permanent magnet channel can include ferrite.

[0037] The mover includes permanent magnet spokes, and the control method further includes adjusting the apparent magnetic strength in the permanent magnet spokes.

[0038] The variable magnetomotive force source also includes an array of frequency programmable flux channels (FPFCs), each including a conductive loop surrounding a corresponding mover pole, and upon start-up, the magnetizing current of the frequency programmable flux channels is generated by the controlled magnetic field of the stator.

[0039] The electrical mover rotates in synchronization with the waveform.

[0040] Increasing the average magnetic flux involves supplying a magnetizing current to the stator coil of the stator pole when the stator pole is aligned with the mover pole across the nominal gap, the magnetizing current strengthening the magnetic field at the mover pole.

[0041] When the mover pole is positioned between the adjacent stator poles, a load current pulse is supplied to the stator coil. The load current pulse generates a driving force in the mover. The number of load current pulses is greater than the number of magnetizing current pulses.

[0042] The mover poles of the electric machine are soft-magnetically modified, which may involve changing the excitation waveform produced by the current flowing in the stator to allow magnetic damping in the mover poles or adjusting control circuits in the mover poles.

[0043] The hard magnetized armature poles respond to a sinusoidal drive frequency.

[0044] The direct current flows for 9 milliseconds, and the reverse direct current pulses for 1 millisecond.

[0045] The ratio of the duration of the DC current to the duration of the reverse current of the pulse waveform is 1:1 to 100:1. The ratio of the duration of the DC current to the duration of the reverse current of the pulse waveform can be 5:1 to 15:1. The ratio of the duration of the DC current to the duration of the reverse current of the pulse waveform can be 9:1.

[0046] The armature rotates in response to DC current flow and reverse DC current pulses, followed by AC current flow through the phases of the stator winding.

[0047] The term "electric motor" as used herein also includes generators that generate electrical power from mechanical power.

[0048] "Nominal gap" refers to the gap between the surfaces of the stator (or active magnetic element) and the mover (or passive magnetic element) that move relative to one another, across which magnetic flux extends during motor operation to induce a force on the mover (or passive magnetic element). The term "active magnetic element" refers to the portion of the motor that contains an electrical winding for each magnetically permeable structure in which magnetic flux is generated by current flowing through the electrical winding; the purpose of the winding typically includes directly inputting or extracting power from the electric machine. The poles of an "active magnetic element" are referred to as "active poles." Each electrical winding typically maintains a fixed relationship with its corresponding active pole. A wound stator is an example of an active magnetic element. The term "passive magnetic element" refers to the portion of the motor that experiences a driving force induced by magnetic flux generated by the active magnetic element that crosses the nominal gap to reach the passive magnetic element. The poles of a "passive magnetic element" are referred to as "passive poles." A rotor without windings is an example of a passive magnetic element. The nominal gap may be, for example, radial in a radial gap motor or axial in an axial gap motor, and may be filled with air or other gas or liquid, such as a refrigerant.

[0049] A "flux barrier" refers to a structure that provides at least one conductive path for the flow of current induced by a changing magnetic field. Generally, eddy currents are induced in the flux barrier, causing destructive interference of the resulting magnetic field, effectively blocking changes in magnetic flux during motor operation. This can result in a repulsive force that acts to increase the driving force on the passive pole. Specifically, a flux barrier is one that allows zero magnetic flux to pass through. Examples of flux barriers are described in U.S. Patent Application No. 16 / 534,217, filed August 7, 2019, which claims priority to U.S. Provisional Application No. 62 / 715,386, filed August 7, 2018, the disclosure of which is incorporated herein by reference.

[0050] A "frequency programmable magnetic flux channel" (FPFC) refers to a structure that provides at least one conductive path, at least near a pole portion of at least one mover pole where the inductance of the conductive path is substantially uniform. In some embodiments, the conductive path completely surrounds at least one mover pole. In some cases, it may also surround a stator pole. In some cases, the conductive loops may not overlap. Generally, a current is induced in the conductive path that opposes changes in magnetic flux density in the corresponding pole. This creates a reflective or oppressive magnetic field that allows the FPFC to controllably attenuate changes in magnetic flux during operation, which may create a repulsive force that acts to increase the driving force induced in the passive pole. Specifically, unlike a flux barrier, an FPFC can allow zero or non-zero magnetic flux to pass depending on the control frequency received from the stator winding.

[0051] "Flux pinning" refers to the inhibition of topological movement of magnetic flux locations, i.e., forcing magnetic flux to be routed to designated locations, typically on the teeth of the mover or the teeth of the stator.

[0052] "Conductivity" refers to the property of a material to conduct electricity. With respect to a structure, such as a wire, in which current flow is restricted to a primary direction, conductivity refers to conduction in this primary direction.

[0053] By "electrically isolated from one another," we mean that the ohmic resistance to potential across the flux barriers is at least 1 / 10 of the ohmic resistance between the flux barriers. When we say "isolated from one another" outside the ferromagnetic material, this does not preclude electrical communication through the ferromagnetic material of the layers. In fact, in many cases, the flux barriers are electrically connected to one another through the ferromagnetic material.

[0054] "Conductive" means that the material or structure is at least as conductive as amorphous carbon at typical motor operating voltages, or has an electrical conductivity greater than 1000 S / m. Examples of conductive materials include silver, copper, aluminum, nickel, iron, and electrical steel (grain-oriented and other electrical steels). Examples of non-conductive materials include unfilled resins, air, wood, and cotton. The term "insulator material" refers to a material that is non-conductive or non-electrically conductive.

[0055] By "finite width" it is meant that the layer has opposite ends, eg, the layer does not extend the entire circumference of the mover (or the entire length of the linear passive magnetic element).

[0056] Similarly, "finite thickness" means that the layer extends to a limited depth, eg, does not extend completely through the mover.

[0057] "Current skin depth" refers to the depth below the surface of a conductor through which currents, particularly eddy currents induced by a changing magnetic field at a particular frequency, flow. For a given material, the skin depth can be calculated using the following formula:

number

[0058] "Magnetic permeability" generally refers to the ability of a material to support the creation of a magnetic field. The magnetic permeability of a material can be determined according to ASTM A772. For a substance to be "magnetically permeable," it must have a magnetic permeability of at least 1.3 x 10 -6 This means that the magnetic field has a permeability of 1000 H / m.

[0059] "Permeable range" refers to the frequency range in which the decrease in permeability compared to the permeability at 60 Hz does not exceed 10 dB when measured under static frequency conditions (for example, when permeability measurements are performed at a given frequency measured over at least five periods of an applied magnetic field).

[0060] Several configurations described in this disclosure include a frequency programmable flux channel (FPFC) for increasing the performance of electric motors, e.g., at high torque and power density. The flux barrier has dynamic (or transient) diamagnetic properties. By using an FPFC in a motor, a substantial gain in torque can be achieved by changing the magnetic field by redirecting the radial (or normal) force along this tangential direction, thereby shifting the magnetic flux direction significantly closer to the tangential direction. In other words, whereas the dominant force vector in a conventional motor design is naturally radial, the average force vector during operation becomes significantly more tangential.

[0061] The magnetic permeability of an FPFC can be controlled by adjusting the magnetic frequency of the current induced in the FPFC, for example by pulsing current through the electrical windings of the active poles. In this way, an electric motor can significantly change its magnetic properties at different magnetic frequencies, such that at low frequencies the FPFC becomes ferromagnetic in nature, and at medium to high operating frequencies the permeability of the flux barrier is reduced below that of air, making the FPFC diamagnetic in nature.

[0062] Some embodiments described herein can also form a high-reactance circuit in which the magnetic field is substantially reflected rather than transmitted through the electromagnetic circuit, thereby reducing or eliminating magnetic flux fringing. Unlike traditional permanent magnet (PM) motors, motors that use FPFCs in their design have less magnetic flux transmitted through the FPFC, thereby avoiding demagnetization (retentive force) and excessive heat during operation. Furthermore, because FPFCs can generate a magnetic field according to the frequency imparted by the stator windings during operation, they can behave similarly to PM motors under certain conditions, allowing for the use of lower-energy permanent magnetic materials or even the elimination of permanent magnetic materials altogether.

[0063] Aspects of the present disclosure can be applied to various types of motors to improve their performance. The motors can be radial gap motors, axial gap motors, or linear motors. The motors can be, for example, switched reluctance motors (SRMs), induction motors (IMs), or permanent magnet motors (PMs).

[0064] Various embodiments disclosed herein can provide particularly high motor performance with substantial torque / force and power density, and can be used to propel vehicles or even in stationary systems to provide a substantially smooth and efficient output shaft power. This design concept allows for more effective torque and power increase by increasing the motor's saliency ratio, avoiding some of the traditional tradeoffs that sacrifice one for the other. The motor also allows for higher system efficiency during cyclic operation by avoiding magnetic braking, which can occur under passive conditions with permanent magnet motors.

[0065] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the following description and drawings, taken in conjunction with the claims. [Brief explanation of the drawings]

[0066] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an electric drive system. [Figure 2A] FIG. 1 is a schematic diagram illustrating a motor controller with power switching. [Figure 2B] FIG. 1 is a schematic diagram illustrating an example power switch for an electrical winding. [Figure 2C] FIG. 1 is a schematic diagram illustrating a motor controller with power switching. [Figures 3A-3D] Figure 3A is a schematic diagram of a stator pole aligned with a mover pole with an FPFC, Figure 3B is a schematic diagram of a mover pole charged in the aligned state, Figure 3C is a schematic diagram of a stator pole not aligned with a mover pole with an FPFC, and Figure 3D is a schematic diagram of a mover hard magnetization in the not aligned state. [Figures 4A-4C] FIG. 1 illustrates an example passive frequency programmable flux channel (FPFC) that can be used in aspects of the present disclosure. [Figure 5A] FIG. 5 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 4. [Figure 5B] FIG. 5 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 4. [Figure 5C] 5 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 4. [Figure 5D] 5 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 4. [Figures 6A-6C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 7A] FIG. 7 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 6. [Figure 7B] FIG. 7 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 6. [Figure 7C] FIG. 7 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 6. [Figure 7D] FIG. 7 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 6. [Figures 8A-8C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 9A] FIG. 9 is a perspective view of a portion of an electric motor that uses the passive FPFC shown in FIG. 8 attached to the back side of the permanent magnet of the mover. [Figure 9B] FIG. 9 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 8 attached to the back side of the permanent magnet of the mover. [Figure 9C] FIG. 9 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 8 attached to the back side of the permanent magnet of the mover. [Figure 9D] FIG. 9 is a perspective cross-sectional view of a portion of an electric motor that uses the passive FPFC shown in FIG. 8 attached to the back side of the permanent magnet of the mover. [Figures 10A-10C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 11A] FIG. 11 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 10. [Figure 11B] FIG. 11 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 10. [Figure 11C] 11 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 10. [Figure 11D] 11 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 10. [Figures 12A-12C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 13A] FIG. 13 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 12. [Figure 13B] FIG. 13 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 12. [Figure 13C] 13 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 12. [Figure 13D] 13 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 12. [Figures 14A-14C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 15A] FIG. 15 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 14. [Figure 15B] FIG. 15 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 14. [Figure 15C] FIG. 15 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 14. [Figure 15D] FIG. 15 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 14. [Figures 16A-16B] Fig. 16A is a perspective view of a mover provided with the passive FPFC shown in Fig. 14. Fig. 16B is a plan cross-sectional view of the mover shown in Fig. 16A. [Figure 17A] FIG. 1 is a perspective view of an electric motor in which an example passive FPFC is attached to the back side of the permanent magnet in the mover. [Figure 17B] FIG. 17B is a plan view of a portion of the electric motor shown in FIG. 17A. [Figure 17C] FIG. 17B is a cross-sectional plan view of a portion of the electric motor shown in FIG. 17A. [Figure 17D] FIG. 17B is a perspective cross-sectional view of a portion of the electric motor shown in FIG. 17A. [Figure 18] FIG. 1 is a perspective view of an example electrical mover provided with an example passive FPFC. [Figures 19A-19C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 20A] FIG. 20 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 19. [Figure 20B] FIG. 20 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 19. [Figure 20C]FIG. 20 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 19. [Figures 21A-21C] FIG. 1 illustrates an example passive FPFC that can be used in aspects of the present disclosure. [Figure 22A] FIG. 22 is a perspective view of a portion of an electric motor using the passive FPFC shown in FIG. 21. [Figure 22B] FIG. 22 is a plan view of a portion of an electric motor using the passive FPFC shown in FIG. 21. [Figure 22C] FIG. 22 is a plan cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 21. [Figure 22D] 22 is a perspective cross-sectional view of a portion of an electric motor using the passive FPFC shown in FIG. 21. [Figures 23A-23C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 24A] FIG. 24 is a perspective view of a portion of an electric motor using the commutated FPFC shown in FIG. 23. [Figure 24B] FIG. 24 is a plan view of a portion of an electric motor using the commutated FPFC shown in FIG. 23. [Figure 24C] FIG. 24 is a plan cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 23. [Figure 24D] FIG. 24 is a perspective cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 23. [Figures 25A-25C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 26A] FIG. 26 is a perspective view of a portion of an electric motor using the commutated FPFC shown in FIG. 25. [Figure 26B] FIG. 26 is a plan view of a portion of an electric motor using the commutated FPFC shown in FIG. 25. [Figure 26C] FIG. 26 is a plan cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 25. [Figure 26D] FIG. 26 is a perspective cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 25. [Figures 27A-27C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 28A] FIG. 28 is a perspective view of a portion of an electric motor using the commutated FPFC shown in FIG. 27. [Figure 28B] FIG. 28 is a plan view of a portion of an electric motor using the commutated FPFC shown in FIG. 27. [Figure 28C] FIG. 28 is a plan cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 27. [Figure 28D] FIG. 28 is a perspective cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 27. [Figures 29A-29C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 30A] FIG. 30 is a perspective view of a portion of an electric motor using the commutated FPFC shown in FIG. 29. [Figure 30B] FIG. 30 is a plan view of a portion of an electric motor using the commutated FPFC shown in FIG. 29. [Figure 30C] FIG. 30 is a plan cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 29. [Figure 31A] FIG. 1 is a perspective view of an electric motor with an example commutated FPFC mounted on the back side of the permanent magnet in the mover. [Figure 31B] FIG. 31B is a plan view of a portion of the electric motor shown in FIG. 31A. [Figure 31C] FIG. 31B is a cross-sectional plan view of a portion of the electric motor shown in FIG. 31A. [Figures 32A-32C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 33A] FIG. 33 is a perspective view of a portion of an electric motor using the commutated FPFC shown in FIG. 32. [Figure 33B] FIG. 33 is a plan view of a portion of an electric motor using the commutated FPFC shown in FIG. 32. [Figure 33C] FIG. 33 is a plan cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 32. [Figure 33D] FIG. 33 is a perspective cross-sectional view of a portion of an electric motor using the commutated FPFC shown in FIG. 32. [Figures 34A-34C] FIG. 1 illustrates an example rectified FPFC that can be used in aspects of the present disclosure. [Figure 35A] FIG. 35 is a perspective view of a portion of an electric motor using the FPFC shown in FIG. 34. [Figure 35B] FIG. 35 is a plan view of a portion of an electric motor using the FPFC shown in FIG. 34. [Figure 35C] FIG. 35 is a plan cross-sectional view of a portion of an electric motor using the FPFC shown in FIG. 34. [Figure 35D] FIG. 35 is a perspective cross-sectional view of a portion of an electric motor using the FPFC shown in FIG. 34. [Figure 35E] FIG. 35 is a perspective view of an example motor using the FPFC shown in FIG. 34. [Figure 35F] FIG. 35F is a longitudinal cross-sectional view of the example motor shown in FIG. 35E. [Figure 35G] FIG. 35F is a perspective cross-sectional view of the example motor shown in FIG. 35E. [Figure 36A-36B] Figure 36A is a perspective view of an example axial gap motor that can be used in multiple aspects of the present disclosure. Figure 36B is a side view of the example axial gap motor shown in Figure 36A. [Figure 36C-36D] Figure 36C is a perspective view of a mover used in the motor shown in Figure 36A. Figure 36D is a perspective view of a stator used in the motor shown in Figure 36A. [Figure 37A] FIG. 1 is a perspective view of an example distributed winding electric motor that can be used in aspects of the present disclosure. [Figure 37B] FIG. 37B is a side view of the example electric motor shown in FIG. 37A. [Figure 37C] FIG. 37B is a perspective view of the stator of the electric motor shown in FIG. 37A. [Figure 37D] FIG. 37B is a cross-sectional plan view of the example motor shown in FIG. 37A. [Figure 37E] FIG. 37B is a perspective cross-sectional view of the example motor shown in FIG. 37A. [Figure 38A-38B] 1A and 1B are perspective and plan views of an example distributed winding motor that can be used in aspects of the present disclosure. [Figure 39A] FIG. 1 is a perspective view of an example of a linear motor in which a commutated FPFC is provided on the "mover." [Figure 39B] FIG. 39B is a longitudinal side view of the example linear motor shown in FIG. 39A. [Figure 39C] FIG. 39B is a longitudinal cross-sectional view of the example linear motor shown in FIG. 39A. [Figure 39D] FIG. 39B is a perspective view of the stator of the example linear motor shown in FIG. 39A. [Figure 39E] FIG. 39B is a perspective view of the "mover" of the example linear motor shown in FIG. 39A. [Figure 40A] FIG. 1 is a perspective view of an example linear motor in which a commutated FPFC is provided in the "mover" and stator. [Figure 40B] FIG. 40B is a longitudinal side view of the example linear motor shown in FIG. 40A. [Figure 40C] FIG. 40B is a longitudinal cross-sectional view of the example linear motor shown in FIG. 40A. [Figure 40D] FIG. 40B is a perspective view of the stator of the example linear motor shown in FIG. 40A. [Figure 41A-41B] Figure 41A is a hysteresis graph for a "soft" magnetic material. Figure 41B is a hysteresis graph for a "hard" magnetic material. [Figure 42] 1 is a schematic diagram of an electric motor with markings for alignment of the mover and stator; [Figure 43A-43B] Figure 43A is a graph showing torque on the mover versus its relative position to the stator, and Figure 43B is a graph showing current in the FPFC during rotation of the mover. [Figure 44A] 10 is a group of graphs showing drive waveforms in a state in which a mover is constrained. [Figure 44B] 10 is a graph showing a transition from a state in which the mover is constrained to a state in which the mover is moving. DETAILED DESCRIPTION OF THE INVENTION

[0067] The present disclosure discloses an electric machine including a mover and a stator. The stator has a plurality of stator poles with electrical windings for the stator poles. The mover is movable relative to the stator and has a plurality of mover poles. The mover poles include a magnetically permeable pole material. The mover and stator together define a nominal gap between the stator poles and the mover poles. As described in detail throughout this disclosure, the mover includes an array of frequency programmable flux channels (FPFCs). Each FPFC includes a conductive loop with some resistance surrounding a corresponding mover pole. In some embodiments, the stator and mover are arranged such that, upon start-up, the stator electrical winding excites current in at least one of the FPFCs. In some embodiments, the stator and mover are arranged such that, upon start-up, the stator electrical winding magnetizes at least one of the mover poles. In other words, the FPFCs can act as a variable magnetomotive force source controlled by the stator. This power transfer is generally synchronous with the magnetic field generated by the stator. The inherent resistance of the conductive loop allows for frequency modulated operation through a resistive load.

[0068] The FPFC itself acts to reflect the stator's magnetic field away from the mover. Such a configuration can be used to protect the mover's permanent magnets from demagnetizing forces induced by the stator. As a result, lower permanent magnetic components can be used in the mover without reducing the torque or power capabilities of the electric machine. In this disclosure, "lower magnetic components" means that relatively lower-energy magnetic materials can be used than those found in conventional permanent magnet motors of comparable power and torque ratings, or that smaller amounts of high-energy materials can be used than those found in such permanent magnet motors. In fact, the above configurations can eliminate permanent magnetic materials entirely. In this disclosure, the energy of a magnetic material depends on the material's coercivity and remanence. Furthermore, the geometry and amount of material can play a significant role in determining the total magnetic energy and total magnetic flux density. For example, a small amount of neodymium magnet, such as NeFeB, can have the same total energy product effect as a larger amount of magnetic ferrite.

[0069] In some embodiments, an FPFC comprises only conductive loops with inherent resistance, capacitance, and inductance values. While the conductive loops may inherently have these values, additional passive, discrete components (e.g., resistors, capacitors, and inductors) may be added to the conductive loops to achieve desired characteristics. Hereinafter, embodiments using only passive components are referred to as "passive FPFCs." In some embodiments, the FPFC or conductive loops have capacitance, and in some embodiments, this capacitance can be formed, inserted, and / or defined by specific portions of the FPFC or conductive loops. In other embodiments, the FPFC or conductive loops can have a resonant frequency. In some embodiments, the resonant frequency of the FPFC can be within the permeable range of the magnetically permeable poles or FPFC material.

[0070] During recharging (field strengthening), the magnetomotive force generated by a passive FPFC can reduce the torque moment it generates during operation. In other words, if the FPFC's magnetic field weakens, it may need to be recharged at specific intervals during operation to induce a magnetic force in the mover. Field weakening in an FPFC can occur in two ways. First, the magnetic field weakens over time due to the FPFC's intrinsic reactance. Second, a permanent magnetomotive force source (e.g., a permanent magnet) weakens under load. Recharge cycles designed to counteract this effect can reduce efficiency and generate torque ripple. To mitigate this problem, FPFCs can be equipped with a rectifier (hereafter referred to as a "rectified FPFC") to essentially "break" the circuit during recharge cycles, preventing current from crossing the magnetic flux in the corresponding mover pole (and thus preventing a reduction in the resulting torque moment). This configuration ensures that current only flows in one direction within the loop, allowing the commutated FPFC to maintain a desired magnetic flux during operation.

[0071] While maintaining a desired magnetic flux in the mover can be advantageous, there are also operating modes, such as high-speed, low-load conditions, where it is desirable to weaken the magnetic flux faster than is possible with inherent field weakening. Such operating modes can include inertial motion of the mover or flywheel operation of the mover when the electric machine is not operating as a generator. While such operating conditions can be accommodated by a commutated FPFC, logic circuitry in the FPFC can provide additional control and sensitivity in reducing the magnetic drag experienced by the system during such conditions. The logic circuitry can include active components such as field-effect transistors, dual-gate field-effect transistors, or bipolar junction transistors. Such circuitry can be directly controlled by brush connections, photosensitive diodes, or other wireless communication media. Hereinafter, such configurations will be referred to as "active FPFCs."

[0072] The disclosed embodiments provide systems, devices, and methods for using FPFCs to improve the performance of electric motors. Various designs / configurations of FPFCs for motors are presented and described. The FPFCs are configured to exhibit a diamagnetic effect that varies based on the current operating mode, allowing a variable magnetomotive force source in the mover to be actively controlled and actively regulated primarily by the magnetic field generated by the stator windings.

[0073] <Example of an electric drive system> 1 shows an electric drive system 100 including an electric motor 102 and a motor controller 107 coupled to the electric motor 102. The motor controller 107 is configured to operate the electric motor 102 to drive a load 104. The load 104 may be an additional gear train, such as a planetary gear set, or may be other motors that are coupled together to operate in parallel.

[0074] The electric motor 102 includes an output shaft 107 rotatable relative to a motor housing 105, which serves as a datum for rotation and other motion of the motor components. In use, the output shaft 107 may be coupled to a load 104, and the motor 102 may provide a rotational force to the load 104 when electrically activated by appropriate power and signals from a motor controller 107. The output shaft 107 may extend through the motor and be exposed at both ends, i.e., its rotational force may be delivered at both ends of the motor. The housing 105 may be rotationally symmetric about the axis of rotation of the output shaft, but may have any outer shape and generally may include means for securing the housing to another structure to prevent it from rotating during motor operation.

[0075] The electric motor 102 includes an active magnetic element 106, such as a stator, and a passive magnetic element 108, such as a mover. For purposes of explanation, the stator will hereinafter be taken to represent an active magnetic element and the mover will hereinafter be taken to represent a passive magnetic element.

[0076] The mover 106 is mounted relative to the stator 108, and may be located inside the stator 108, such as in an inner rotor radial gap motor, or may be located parallel to the stator, such as in an axial gap motor or linear motor. As will be explained more fully below, electrical activity in the stator 108, when properly controlled, drives the movement of the mover 106. The mover 106 is rotationally coupled to the output shaft 107, such that any rotational component of the mover motion is transferred to the output shaft 107, thereby rotating the output shaft 107. The stator 108 is fixed to the motor 102 so that the mover 106 moves around or parallel to the stator 108 during operation.

[0077] The stator 108 has a plurality of stator poles with electrical windings, and the mover 106 has a plurality of mover poles, for example, as shown in detail in FIGS. 5A-5D. The mover 106, together with the stator 108, defines a nominal air gap between the stator poles and the mover poles, for example, as shown in detail in FIGS. 5A-5D later in this application. The mover 106 is movable relative to the stator 108 along the direction of motion. As shown in FIG. 2A, the stator 108 has a plurality of windings 132 spaced apart around the periphery of the mover 106, and these windings 132 are independently operable. Adjacent windings 132 of the stator 108 are operable simultaneously as a winding set, and the stator 108 can have a plurality of such multi-winding sets spaced apart around the stator 108. The motor 102 may include a winding controller 130 that includes a set of switches 134 operable to activate windings 132 on the stator 108. The switches 134 may be semiconductor switches, e.g., transistors such as metal-oxide semiconductor field-effect transistors (MOSFETs). The winding controller 130 is coupled to the gates of the switches 134 and operable to send a respective control voltage to each switch 134. The control voltages may be direct current (DC) voltages. The winding controller 130 may be provided within the motor controller 107.

[0078] While only three switches are shown in FIG. 2A , it is understood that the motor controller 107 can have a switch for each stator pole or multiple switches to energize multiple coils. Adjacent pole pairs can be wired in series through a common switch; however, in such cases, the faster of two moving movers may instantaneously draw more power by generating a slightly larger back electromotive force (EMF) than the slower pole, further accelerating their relative speeds apart. High-frequency excitation can reduce the effects of low-frequency harmonic ripple during operation. To balance the relative speeds between multiple movers in a nested configuration, the switches 134 can be wired in parallel with parallel inductive load reactors. In certain embodiments with nested mover configurations, the individual movers in the system can be driven individually, reducing the load on a particular mover and thereby bypassing any harmonic frequencies from one mover to another. In other embodiments, the movers can be nested in pairs to locally balance the forces between the inner and outer rings.

[0079] FIG. 2B shows another example power switch 200 for an individual electrical winding 132. The power switch 200 may include an H-bridge circuit with the electrical winding 132 at the center of four switching elements 202a, 202b, 202c, and 202d in an H-shaped configuration. The switching elements 202a, 202b, 202c, and 202d may be bipolar transistors or FET transistors. Each switching element 202a, 202b, 202c, and 202d may be coupled to a respective diode D1, D2, D3, and D4. The diodes are called catch diodes and may be of the Schottky type. The top end of the bridge is connected to a power supply, e.g., a battery V bat The lower end is connected to a power supply such as a GND terminal, and the lower end is grounded. The gates of the switching elements can be coupled to a winding controller 130, which is operable to send a corresponding control voltage signal to each switching element. The control voltage signal can be a DC voltage signal or an AC (alternating current) voltage signal.

[0080] The switching elements can be individually controlled by the controller 130 and can be individually turned on and off. In some cases, when switching elements 202a and 202d are turned on, the left lead of the stator is connected to a power source and the right lead is connected to ground. Current begins to flow in the stator, energizing the electrical winding 132 in a forward direction. In some cases, when switching elements 202b and 202c are turned on, the right lead of the stator is connected to a power source and the left lead is connected to ground. Current begins to flow in the stator, energizing the electrical winding 132 in a reverse direction. That is, by controlling the switching elements, the electrical winding 132 can be energized / activated in either direction.

[0081] FIG. 2C is a schematic diagram of a motor controller with power switching. FIG. 2C is substantially similar to FIG. 2A, except for all differences described herein. As shown in FIG. 2C, each armature winding 132 phase (A, B, C) includes a switch between the positive power rail 148 and the respective winding 132, and a switch between each armature winding phase and the negative power rail 149. Voltages are supplied to both the positive rail 148 (positive voltage) and the negative rail (negative voltage), and these voltages are supplied substantially constant while the controller 130 controls switches 150 to transfer current between the winding 132 and the respective power rails (148, 149). In other embodiments, the controller and power switches can be connected and configured to operate from a current source.

[0082] A motor controller 107, such as winding controller 130, can be configured to sequentially operate switches 134, 150, or 200 for each pole energization duty cycle to generate magnetic flux across the air gap between the stator and mover poles, as described in detail throughout this disclosure. These switches can be controlled to sequentially energize the stator poles to generate localized attractive forces that pull on the mover poles. This sequential energization (or actuation) can cause the mover 106, output shaft 107, and load 104 to rotate.

[0083] As described in more detail below, various types and configurations of FPFCs can be implemented in the mover 106 and / or stator 108. The FPFCs can adjustably attenuate the magnetic flux passing through the mover 106 or stator 108.

[0084] In some examples, FPFCs are made of a single type of material, such as aluminum, copper, brass, silver, zinc, gold, pyrolytic graphite, bismuth, graphene, or carbon nanotubes. In some examples, ferromagnetic combinations of materials, such as copper-iron, nickel-iron, lead-iron, brass-iron, silver-iron, zinc-iron, gold-iron, bismuth-iron, aluminum-iron, pyrolytic graphite-iron, graphene-iron, carbon nanotube-iron, or AlNiCo (aluminum-nickel-cobalt) alloy, can be used as flux barriers. Such combinations often have higher electrical conductivity than the ferromagnetic material (e.g., iron) from which the mover poles are made. In some examples, FPFCs made of copper-iron, for example, have lower effective magnetic permeability than ferromagnetic materials. In some examples, FPFCs made of nickel-iron, for example, have higher effective magnetic permeability than ferromagnetic materials. FPFCs are typically constructed as shielded poles of conductive material looped around a core of a core material with higher magnetic permeability than the conductive material. The conductive material of the loop may also provide the shielded pole with a higher effective electrical conductivity than the core material (e.g., iron). The FPFC may include multiple materials, which are arranged in alternating layers. In some embodiments, the alternating layers form interlayer interfaces of multiple different materials. In some embodiments, the first layer may be more conductive than the second layer. In some embodiments, the second layer of the pair is more magnetically permeable than the first layer. In some embodiments, the current skin depth of each of the first and second layers is greater than the thickness of each layer in a direction perpendicular to the nominal gap at a particular operating frequency.

[0085] Another material property of interest is the quotient of electrical conductivity and magnetic permeability (e.g., per Henry-Siemens), referred to as the EMF shielding factor. The EMF shielding factors of two materials can be determined simultaneously by placing equal-sized samples of both materials on a non-conductive support and moving them between two parallel Helmholtz coils of larger diameter than the samples, so that the primary conduction planes of both samples (e.g., their orientation during operation in a magnetic system) are perpendicular to the magnetic field generated during excitation of the Helmholtz coils. For a given excitation waveform (e.g., voltage, shape, and frequency), the current in the Helmholtz coils will be proportional to the EMF shielding factor of the material between the coils, and for a constant excitation, an increase in the EMF shielding factor will be observed as an increase in current.

[0086] As mentioned above and explained in more detail below, FPFCs can be configured to be diamagnetic. The permeability of the flux barrier can be controlled by adjusting the induction frequency through the FPFC. In this way, the motor can have significantly different magnetic properties at different magnetic frequencies.

[0087] To operate the FPFC at the operating frequency, sinusoidal or square wave control can be used, with the stator poles interacting with the FPFC as the primary power source for the machine. During operation, pulsed waveforms ranging from a continuous sinusoidal wave, occurring depending on the mover speed, from a pulse to a locked state (e.g., 0 Hz), can be used. This is because at high speeds, the pulse and charge cycles overlap when the mechanical timing reaches the pulse frequency. Therefore, the waveform employs a fundamental wave. Transition to synchronous operation can occur at 10,000 Hz in certain embodiments, more preferably between 1,000 Hz and 10,000 Hz, more preferably between 100 Hz and 500 Hz, and more preferably between 10 Hz and 100 Hz. In some embodiments, 10,000 Hz can be considered substantially synchronous operation, and more preferably between 10,000 Hz, more preferably between 1,000 Hz, more preferably between 100 Hz, and more preferably between 100 Hz and 100 Hz. Under these generally synchronous conditions, further frequency modulation can be performed. For example, as shown in FIGS. 3A-3D, during each active pole's energization duty cycle, the motor controller 107 is configured to pulse current 302 through the winding of the stator pole 304. Unlike an induction motor, which pulses each pole sequentially once at low speeds, the motor controller 107 pulses reversing current 306 multiple times when the stator pole 304 is between two adjacent mover poles 308. This "hardens" the FPFC 310. Details of the charging and hardening cycles are provided throughout this disclosure. The multiple reversing pulses 306 described above, applied to the same pole before pulsing the next pole, constitute one energization duty cycle. In some examples, the motor controller pulses current, including a train of at least three reversing pulses 306, through the winding of the active stator pole 304 during that pole's energization duty cycle. The electrical circuit including the electrical windings of each pole is configured so that the ratio of reversal pulses 306 to pulses 302 through the stator windings is at least 4:1, in some cases at least 7:1, or in some cases at least 10:1.There are some operating conditions in which the reversal pulse 306 is not required, and in such operating conditions the motor can be driven through the stator poles 304 with a standard sinusoidal or trapezoidal waveform.

[0088] The above-described combination of pulse current 302 and reverse pulse current 306 creates an alternating magnetic field strength, e.g., an alternating magnetic field, which induces a current in FPFC 310. This induced current generates a secondary magnetic field that opposes the applied alternating magnetic field, resulting in a repulsive force. This repulsive force can concentrate and redirect the magnetic flux more tangentially along the direction of relative motion between the mover and stator, thereby increasing the force available for operation. Additionally, FPFCs 310 made of different materials or designs can have different characteristics. The horizontal force generated depends on the magnetic frequency and the structure of FPFC 310.

[0089] The magnetic frequency of the FPFC 310 (and thus the generated force) can be determined by the pulse frequency of the current flowing through the windings of the stator poles 304 during the energization duty cycle of each active pole 304. The pulse frequency can be, for example, between 2 hertz and 1 megahertz in some cases, between 10 hertz and 20 kilohertz in some cases, between 100 hertz and 5,000 hertz in some cases, between 5,000 and 15,000 hertz, and in some cases between 15,000 hertz and 25,000 hertz or more, depending on the fundamental frequency. In some cases, the motor controller is configured to maintain the pulse frequency at least through a change in motor speed up to a motor speed at which the energization duty cycle frequency of each active pole is at least half the pulse frequency. In some cases, the motor controller is configured to pulse the current only below a motor speed corresponding to one pulse per energization duty cycle. In some embodiments, at least one of the electrical windings includes multiple coils conductively connected in parallel and wound on a common core, which can have low reactance and allow for faster decay of current between pulses.

[0090] <Motor example> Various designs / configurations of Frequency Programmable Flux Channels (FPFCs) for electric motors, radial gap motors, axial gap motors, and linear motors are presented and described below. While various variations of these motors are shown and described in detail, other motor configurations with FPFCs can be constructed without departing from this disclosure.

[0091] <Radial gap motor with passive FPFC> This section primarily describes embodiments related to radial gap motors with passive FPFCs. In this disclosure, a "passive" FPFC is one that has nothing but a shorted conductor that completely surrounds at least one pole of the mover. That is, there is only the inherent capacitance, inductance, and resistance created by the FPFC, without the addition of any other discrete components. Various embodiments described herein are described with both an inner mover and an outer mover. While individual embodiments may be described as using either an inner mover or an outer mover, it should be noted that aspects of the embodiments described herein are applicable to both the inner mover and the outer mover, regardless of whether a particular embodiment is described.

[0092] 4A-4C are diagrams illustrating an example of a passive frequency programmable magnetic flux channel (FPFC) 400 that can be used in aspects of the present disclosure. FIG. 5A is a perspective view of a portion of an electric motor 500 that uses the passive FPFC 400 shown in FIGS. 4A-4C. FIG. 5B is a plan view of a portion of an electric motor 500 that uses the passive FPFC 400 shown in FIGS. 4A-4C. FIG. 5C is a cross-sectional plan view of a portion of an electric motor 500 that uses the passive FPFC 400 shown in FIGS. 4A-4C. FIG. 5D is a cross-sectional perspective view of a portion of an electric motor 500 that uses the passive FPFC 400 shown in FIGS. 4A-4C. FIGS. 4A-5D are used in combination to describe the electric motor 500 and the FPFC 400.

[0093] The electric machine 500 includes a stator 502 having a plurality of stator poles 504 with electrical windings 506 attached to the stator poles 504. A mover 508 has a plurality of mover poles 510. The mover 508 is movable relative to the stator 502. In this example, the mover 508 is positioned to rotate inside the stator 502. The mover 508 and stator 502 together define a nominal gap 512 between the stator poles 504 and the mover poles 510. In this example, the nominal gap 512 is a radial gap where the stator 502 circumferentially surrounds the mover 508. The mover poles 510 include a magnetically permeable pole material, such as iron. The mover 508 also includes an array of frequency programmable flux channels (FPFCs) 400. Each FPFC 400 includes a conductive loop 402 that surrounds or encircles a corresponding mover pole 510. In the illustrated embodiment, each mover pole 510 is enclosed. In some embodiments, the stator 502 and mover 508 are arranged such that, upon startup, the electrical windings 506 of the stator 502 excite a current in at least one of the FPFCs 400. In other words, the mover 508 comprises a variable magnetomotive force source, the FPFC 400, that is controllable by the controlled magnetic field generated by the stator windings 506. Cleats or brushes that conduct electricity to supply current to the mover 508 upon startup are not required in all embodiments described herein.

[0094] The mover 508 can be made of a magnetically permeable material such as iron. In some embodiments, the mover 508 can be constructed from mover laminations 514 to reduce eddy currents in the back yoke of the mover 508. The stator 502 can likewise be constructed from stator laminations 516 to reduce eddy currents in the back yoke of the stator 502. In some embodiments, the poles 510 of the mover 508 include a material with non-zero remanence. In the illustrated embodiment, the mover poles have lips 518 positioned to hold each FPFC 400 to the corresponding mover pole 510 at a desired operating speed. Other arrangements for holding each FPFC 400 can be used, such as using various fasteners, adhesives, or resins.

[0095] As shown, the mover 508 includes multiple permanent magnetic spokes 520 extending from the central axis of the mover 508. Each permanent magnetic spoke 520 is positioned between the poles 510, including the FPFC 400, of the mover. The permanent magnetic spokes 520 can extend the entire longitudinal length of the mover 508 or can extend partially through the mover 508. In some embodiments, the permanent magnetic spokes 520 can be constructed from multiple layers or laminated sheets. The permanent magnetic spokes 520 can be made from a variety of materials, including ferrite, SmFeN, N35, and N45. While low-power permanent magnetic materials are typically used, smaller amounts of higher-power magnetic materials can be used without departing from this disclosure. While a spoke-like configuration has been shown and described as being positioned between the mover poles 510 on the back side of the FPFC 400, other configurations are possible without departing from this disclosure. In some embodiments, no permanent magnetic material is used.

[0096] With respect to the FPFC 400, the FPFC 400 includes at least one conductive loop 402 having at least one turn of shorted conductive material. That is, the conductive material completely surrounds the mover pole 510 and shorts itself to form a loop. In some embodiments, the conductive loop 402 includes a material that is more conductive than the mover core material. In some embodiments, the conductive loop 402 includes a material that is less magnetically permeable than the mover core material. Materials that meet one or both of the above criteria include, but are not limited to, single types of materials such as aluminum, copper, brass, silver, zinc, gold, pyrolytic graphite, bismuth, graphene, or carbon nanotubes. In some examples, ferromagnetic combinations of materials, such as copper-iron, nickel-iron, lead-iron, brass-iron, silver-iron, zinc-iron, gold-iron, bismuth-iron, aluminum-iron, pyrolytic graphite-iron, graphene-iron, copper-carbon nanotubes, carbon nanotubes-iron, or AlNiCo (aluminum-nickel-cobalt) alloy, can be used as magnetic flux barriers and often have higher electrical conductivities than the ferromagnetic materials (e.g., iron) that make up the poles of the mover. In some examples, FPFCs made of, for example, copper-iron have lower effective permeabilities than ferromagnetic materials. In some examples, FPFCs made of, for example, nickel-iron have higher effective permeabilities than ferromagnetic materials. Generally, FPFCs 400 have substantially uniform inductance, particularly in the radial direction. This criterion allows for complete skin-effect penetration of each FPFC 400 at a specified drive frequency. Conductor geometry, such as the thickness of the individual conductors in the conductive loop, is taken into consideration when designing FPFCs 400. In some embodiments, the drive frequency can range from 0 Hertz to 20 Hertz. In some embodiments, the drive frequency can range from 100 Hertz to 2000 Hertz. In other embodiments, the drive frequency can operate at greater than 20 kilohertz. While this embodiment illustrates a configuration in which the FPFC 400 has a substantially rectangular cross-section, other cross-sectional shapes can be used without departing from this disclosure. Other examples of FPFCs using different cross-sectional shapes are described throughout this disclosure.

[0097] 6A-6C are diagrams illustrating an example of a passive FPFC 600 that can be used in various aspects of the present disclosure. FIG. 7A is a perspective view of a portion of an electric motor 700 that uses the passive FPFC 600 shown in FIGS. 6A-6C. FIG. 7B is a plan view of a portion of an electric motor 700 that uses the passive FPFC 600 shown in FIGS. 6A-6C. FIG. 7C is a cross-sectional plan view of a portion of an electric motor 700 that uses the passive FPFC 600 shown in FIGS. 6A-6C. FIG. 7D is a cross-sectional perspective view of a portion of an electric motor 700 that uses the passive FPFC 600 shown in FIGS. 6A-6C. Electric motor 700 is substantially similar to electric motor 500, except for all differences described herein.

[0098] FPFC 600 has a substantially circular cross-section with a smaller cross-sectional area than FPFC 400. The smaller cross-sectional area allows for a higher operating frequency at which full skin depth penetration is possible. Mover poles 710 in mover 708 are shortened to help maintain the geometry of their respective FPFC 600.

[0099] 8A-8C are diagrams illustrating an example of a passive FPFC 800 that can be used in various aspects of the present disclosure. FIG. 9A is a perspective view of a portion of an electric motor 900 that uses the passive FPFC 800 shown in FIGS. 8A-8C. FIG. 9B is a plan view of a portion of an electric motor 900 that uses the passive FPFC 800 shown in FIG. 8 attached to the rear side of the permanent magnets 920 of the mover 908. FIG. 9C is a cross-sectional plan view of a portion of an electric motor 900 that uses the passive FPFC 800 shown in FIG. 8 attached to the rear side of the permanent magnets 920 of the mover 908. FIG. 9D is a cross-sectional perspective view of a portion of an electric motor 900 that uses the passive FPFC 800 shown in FIG. 8 attached to the rear side of the permanent magnets 920 of the mover 908. Electric motor 900 operates on the same principles as electric motor 500 and should be considered similar to electric motor 700, except for any differences described herein.

[0100] The electric motor 900 includes a mover 908 that circumferentially surrounds the stator 902. Each FPFC 800 surrounds a corresponding mover pole 910, and the FPFCs 800 have a cross-section shaped like a rounded rectangle. In the illustrated embodiment, the mover poles have lips 918 that are positioned to hold each FPFC 800 to the corresponding mover pole 910. Other configurations for holding each FPFC 800 are also possible, such as using various fasteners, adhesives, or resins. Because the illustrated embodiment uses an outer mover 908, centrifugal forces during operation can also help hold the FPFCs 800 in place.

[0101] In this embodiment, the FPFC is positioned behind the permanent magnets 920 located on each mover pole 910. The permanent magnets 920 can be made from a variety of materials, including ferrite, SmFeN, N35, and N45. Typically, low-power permanent magnetic materials are used, although higher-power magnetic materials can be used in smaller amounts without departing from this disclosure. The permanent magnets 920 can extend the entire longitudinal length of each mover pole 910 or partially across each mover pole 910. In some embodiments, the permanent magnets 920 can be constructed from multiple layers or laminated sheets.

[0102] 10A-10C are diagrams illustrating an example of a passive FPFC 1000 that can be used in various aspects of the present disclosure. FIG. 11A is a perspective view of a portion of an electric motor 1100 that uses the passive FPFC 1000 shown in FIGS. 10A-10C. FIG. 11B is a plan view of a portion of an electric motor 1100 that uses the passive FPFC 1000 shown in FIGS. 10A-10C. FIG. 11C is a cross-sectional plan view of a portion of an electric motor 1100 that uses the passive FPFC 1000 shown in FIGS. 10A-10C. FIG. 11D is a cross-sectional perspective view of a portion of an electric motor 1100 that uses the passive FPFC 1000 shown in FIGS. 10A-10C. Electric motor 1100 is substantially similar to electric motor 900, except for all differences described herein.

[0103] The FPFC 1000 includes multiple laminated plates 1002 surrounding the mover poles. Thinner laminated plates allow for higher operating frequencies with full skin-depth penetration. Each laminated plate 1002 in each FPFC 1000 is electrically isolated from each other. Permanent magnets are not used in this embodiment because the FPFC 1000 has the ability to reflect all of the magnetic flux generated by the stator winding 1106, which then exerts an electromotive force on the mover 1108. This capability is inherent in all FPFC embodiments described herein. In the illustrated embodiment, the mover poles 1110 do not have lips around each mover pole 1110 to hold the FPFC 1000 in place. Instead, fasteners, adhesives, resins, friction fits, or interference fits can be used to secure the FPFC 1000 around each mover pole 1100.

[0104] 12A-12C are diagrams illustrating an example of a passive FPFC 1200 that can be used in various aspects of the present disclosure. FIG. 13A is a perspective view of a portion of an electric motor 1300 that uses the passive FPFC 1200 shown in FIGS. 12A-12C. FIG. 13B is a plan view of a portion of an electric motor 1300 that uses the passive FPFC 1200 shown in FIGS. 12A-12C. FIG. 13C is a cross-sectional plan view of a portion of an electric motor 1300 that uses the passive FPFC 1200 shown in FIGS. 12A-12C. FIG. 13D is a cross-sectional perspective view of a portion of an electric motor 1300 that uses the passive FPFC 1200 shown in FIGS. 12A-12C. Electric motor 1300 is substantially similar to electric motor 500, except for all differences described herein.

[0105] The FPFC 1200 includes at least one shorted-loop winding similar to the winding 1306 used in the stator 1302. In other words, one conductor 1202 encircles each mover pole 1310 multiple times before shorting back to itself. This configuration allows the conductor 1202 of the FPFC 1200 to have a smaller cross-sectional area, which in turn allows for a higher operating frequency at which full skin-depth penetration is possible. This configuration also allows for improved uniform inductance across the FPFC 1200 compared to a solid conductor with a larger cross-sectional area per loop encircling each pole 1310.

[0106] 14A-14C illustrate an example of a passive FPFC 1400 that can be used in various aspects of the present disclosure. FIG. 15A is a perspective view of a portion of an electric motor 1500 that uses the passive FPFC 1400 shown in FIGS. 14A-14C. FIG. 15B is a plan view of a portion of an electric motor 1500 that uses the passive FPFC 1400 shown in FIGS. 14A-14C. FIG. 15C is a cross-sectional plan view of a portion of an electric motor 1500 that uses the passive FPFC 1400 shown in FIGS. 14A-14C. FIG. 15D is a cross-sectional perspective view of a portion of an electric motor 1500 that uses the passive FPFC 1400 shown in FIGS. 14A-14C. Electric motor 1500 is substantially similar to electric motor 900, except for all differences described herein.

[0107] Each FPFC 1400 includes a shorted coil 1402. In other words, one conductor encircles each armature pole 1510 multiple times before shorting back to itself. This configuration allows for a smaller cross-sectional area of ​​the conductors in the FPFC 1400, which in turn allows for a higher operating frequency at which full skin depth penetration is possible. This configuration also provides for improved uniform inductance across the FPFC 1400 compared to solid conductors with larger cross-sectional areas. While the illustrated embodiment includes conductors with substantially rectangular cross-sections, other cross-sectional shapes may be used without departing from this disclosure.

[0108] The mover 1508 can include multiple permanent magnetic channels 1520. In some embodiments, multiple permanent magnetic channels 1520 can be provided for each mover pole 1510. In the illustration, each pole includes four channels 1520 arranged in a substantially "M" or "W" configuration, although other configurations can be used without departing from this disclosure. The permanent magnetic channels 1520 can include various materials, including ferrite, SmFeN, N35, and N45. While low-power permanent magnetic materials are typically used, higher-power magnetic materials can be used in smaller amounts without departing from this disclosure. The permanent magnetic channels 1520 can extend the entire longitudinal length of each mover pole 1510 or partially across each mover pole 1510. In some embodiments, the permanent magnetic channels 1520 can be constructed from multiple layers or laminated sheets.

[0109] FIG. 16A is a perspective view of a mover equipped with the passive FPFC 1400 shown in FIG. 14. FIG. 16B is a top cross-sectional view of the mover 1608 shown in FIG. 16A. The electrical mover 1608 shown in FIGS. 16A-16B is substantially similar to the mover shown in FIGS. 15A-15D, except for all differences described herein. In this embodiment, each pole includes one "V"-shaped permanent magnetic channel 1620. Other configurations may be used without departing from this disclosure.

[0110] FIG. 17A is a perspective view of an electric motor 1700 in which an example passive FPFC 1701 is attached to the rear side of a permanent magnet 1720 in a mover 1708. FIG. 17B is a plan view of a portion of the electric motor 1700 shown in FIG. 17A. FIG. 17C is a plan cross-sectional view of a portion of the electric motor 1700 shown in FIG. 17A. FIG. 17D is a perspective cross-sectional view of a portion of the electric motor 1700 shown in FIG. 17A. The electric motor 1700 is substantially similar to the electric motor 900 shown in FIGS. 9A-9D, except for all differences described herein. The FPFC 1701 used in the electric motor 1700 is similar to the FPFC 1200 shown in FIGS. 12A-12C. That is, the FPFC 1701 is composed of a winding. The conductor of the winding encircles each mover pole 1710 multiple times before shorting itself out.

[0111] FIG. 18 is a perspective view of an example electrical mover 1800 including an example passive FPFC 1801. The FPFC 1801 is constructed from Litz wire. As shown, a shorted ribbon of Litz wire surrounds each mover pole 1810 and is shorted at termination point 1803 to form a conductive loop. Litz wire has multiple thin strands that do not occupy the same radial position in the FPFC along the length of the conductive loop. That is, the Litz wire is provided with a wavy or twisted pattern such that, for a portion of the FPFC's length, individual strands are inside the FPFC and for a portion of the FPFC's length, individual strands are outside the FPFC. In some embodiments, the thickness of the individual strands is less than the effective skin depth. That is, the thickness of the strands is small enough to achieve full skin effect penetration at the desired drive frequency. This configuration helps ensure that the conductive loop formed by the FPFC 1801 has a substantially uniform inductance, particularly in the radial direction.

[0112] 19A-19C illustrate an example of a passive FPFC 1900 that can be used in aspects of the present disclosure. FIG. 20A is a perspective view of a portion of an electric motor 2000 that uses the passive FPFC 1900 shown in FIGS. 19A-19C. FIG. 20B is a plan view of a portion of an electric motor 2000 that uses the passive FPFC 1900 shown in FIGS. 19A-19C. FIG. 20C is a cross-sectional plan view of a portion of an electric motor 2000 that uses the passive FPFC 1900 shown in FIGS. 19A-19C. The electric machine 2000 is substantially similar to the electric machine shown in FIGS. 11A-11D, except for all differences described herein.

[0113] In the illustrated embodiment, the FPFC 1900 includes a shorted inner conductive loop 1902 and an outer conductive loop 1904. The inner conductive loop surrounds a first armature pole 2010a, and the outer conductive loop surrounds two adjacent poles 2010b. The FPFCs can be nested to create localized inductive asymmetry between adjacent armature teeth. Such an embodiment can help create localized inductive asymmetry between adjacent armature teeth to enable torque generation at zero rotation speed in a locked armature condition.

[0114] 21A-21C are diagrams illustrating an example of a passive FPFC 2100 that can be used in various aspects of the present disclosure. FIG. 22A is a perspective view of a portion of an electric motor 2200 that uses the passive FPFC 2100 shown in FIGS. 21A-21C. FIG. 22B is a plan view of a portion of an electric motor 2200 that uses the passive FPFC 2100 shown in FIGS. 21A-21C. FIG. 22C is a cross-sectional plan view of a portion of an electric motor 2200 that uses the passive FPFC 2100 shown in FIGS. 21A-21C. FIG. 22D is a cross-sectional perspective view of a portion of an electric motor 2200 that uses the passive FPFC 2100 shown in FIGS. 21A-21C. Electric motor 2200 is substantially similar to electric motor 2100 shown in FIGS. 20A-20C, except for all differences described herein.

[0115] In the illustrated embodiment, the FPFC 2100 comprises an inner conductive loop 2102 and an outer conductive loop 2104, which are electrically isolated from each other. The inner conductive loop 2102 surrounds the first armature pole 2210a, and the outer conductive loop 2104 surrounds two adjacent poles 2210b. Both the inner loop 2102 and the outer loop 2104 have coiled conductors that surround their respective poles (2210a and 2210b) before shorting out to themselves.

[0116] In some embodiments, the inner conductive loop 2102, the outer conductive loop 2104, or both, comprise a material that is more electrically conductive than the mover core material. In some embodiments, the first conductive loop 2102, the second conductive loop 2104, or both, comprise a material that is less magnetically permeable than the mover core material. Materials meeting the above criteria include, but are not limited to, single materials such as aluminum, copper, brass, silver, zinc, gold, pyrolytic graphite, bismuth, graphene, or carbon nanotubes. In some examples, ferromagnetic combinations of materials, such as copper-iron, nickel-iron, lead-iron, brass-iron, silver-iron, zinc-iron, gold-iron, bismuth-iron, aluminum-iron, pyrolytic graphite-iron, graphene-iron, carbon nanotube-iron, or AlNiCo (aluminum-nickel-cobalt) alloy, can be used as flux barriers, often because they have a higher electrical conductivity than the ferromagnetic material (e.g., iron) from which the mover poles are made. In some cases, FPFCs made of, for example, copper-iron, have a lower effective magnetic permeability than ferromagnetic materials. In some cases, FPFCs made of, for example, nickel-iron, have a higher effective magnetic permeability than ferromagnetic materials.

[0117] In some embodiments, the first conductive loop 2102, the second conductive loop 2104, or both each have a substantially uniform inductance, particularly in the radial direction. In some embodiments, the first conductive loop 2102 can have a different inductance than the second conductive loop 2104. In some embodiments, the first conductive loop 2102 can have a substantially equal inductance to the second conductive loop 2104, within standard manufacturing tolerances. In some embodiments, the individual conductors of both the first loop 2102 and the second loop 2104 have a sufficiently small cross-sectional area to allow full skin effect penetration at the drive frequency. Such a configuration allows for flux pinning during operation of the motor 2200. More details about flux pinning are provided throughout this disclosure.

[0118] Numerous embodiments using passive FPFCs have been described. While described as individual embodiments, the features of each embodiment can be mixed and matched without departing from the present disclosure. For example, the first conductive loop 2102, the second conductive loop 2104, or both, can be made from shorted Litz wire. Additionally, other passive components, such as capacitors, resistors, or inductors, can be added in parallel or series with the various embodiments described herein.

[0119] <Example of a radial gap motor with a commutated FPFC> This section primarily describes embodiments related to radial gap motors with commutated FPFCs. In this disclosure, a "commutated" FPFC is one with a rectifier connecting both ends of a conductor that completely surrounds at least one pole of the mover. Various embodiments described herein are described with both an inner mover and an outer mover. While individual embodiments may be described as using either an inner mover or an outer mover, it should be noted that aspects of the embodiments described herein are applicable to both the inner mover and the outer mover, regardless of whether a particular embodiment is described.

[0120] 23A-23C are diagrams illustrating an example of a commutated FPFC 2300 that can be used in accordance with aspects of the present disclosure. FIG. 24A is a perspective view of a portion of an electric motor 2400 that uses the commutated FPFC 2300 shown in FIG. 23. FIG. 24B is a plan view of a portion of an electric motor 2400 that uses the commutated FPFC 2300 shown in FIG. 23. FIG. 24C is a cross-sectional plan view of a portion of an electric motor 2400 that uses the commutated FPFC 2300 shown in FIG. 23. FIG. 24D is a cross-sectional perspective view of a portion of an electric motor 2400 that uses the commutated FPFC 2300 shown in FIG. 23. Electric motor 2400 is substantially similar to electric motor 500, except for all differences described herein.

[0121] FPFC 2300 has a similar geometry to FPFC 400 shown in FIGS. 4A-4C, but adds a rectifier 2306 to conductive loop 2302 to maintain the direction of current flow within the conductive loop. That is, conductive loop 2302 includes rectifiers 2306 in series with both ends of conductive loop 2302. In some embodiments, the rectifier can include a diode. Multiple types of diodes can be used, such as pn junction diodes, gas diodes, Zener diodes, or Schottky diodes. In some embodiments, when a Schottky diode is used, the Schottky diode can be a silicon carbide diode. The selection of the diode depends on various factors, including voltage drop, reverse voltage breakdown, and recovery time. Different diodes can be used depending on the desired operating conditions. While multiple types of diodes are listed, other diodes can be used without departing from this disclosure. In general, the directionality of each diode or the winding direction of each FPFC alternates depending on the polarity of each mover pole.

[0122] 25A-25C illustrate an example of a commutated FPFC 2500 that can be used in various aspects of the present disclosure. FIG. 26A is a perspective view of a portion of an electric motor 2600 employing the commutated FPFC 2500 shown in FIG. 25. FIG. 26B is a plan view of a portion of an electric motor 2600 employing the commutated FPFC 2500 shown in FIG. 25. FIG. 26C is a cross-sectional plan view of a portion of an electric motor 2600 employing the commutated FPFC 2500 shown in FIG. 25. FIG. 26D is a cross-sectional perspective view of a portion of an electric motor 2600 employing the commutated FPFC 2500 shown in FIG. 25. Electric motor 2400 is substantially similar to electric motor 900, except for all differences described herein. FPFC 2500 is substantially similar to FPFC 800, previously shown in FIG. 8, except for the addition of rectifier 2306 to conductive loop 2502. The operation of rectifier 2306 has been previously described.

[0123] 27A-27C illustrate an example of a commutated FPFC 2700 that can be used in various aspects of the present disclosure. FIG. 28A is a perspective view of a portion of an electric motor 2800 employing the commutated FPFC 2700 shown in FIG. 27. FIG. 28B is a plan view of a portion of an electric motor employing the commutated FPFC 2700 shown in FIG. 27. FIG. 28C is a cross-sectional plan view of a portion of an electric motor 2800 employing the commutated FPFC 2700 shown in FIG. 27. FIG. 28D is a cross-sectional perspective view of a portion of an electric motor 2800 employing the commutated FPFC 2700 shown in FIG. 27. Electric motor 2600 is substantially similar to electric motor 700, except for all differences described herein. FPFC 2700 is substantially similar to FPFC 600, previously shown in FIG. 8, except for the addition of rectifier 2306 to conductive loop 2702. The operation of rectifier 2306 has been previously described.

[0124] 29A-29C illustrate an example of a commutated FPFC 2900 that can be used in various aspects of the present disclosure. FIG. 30A is a perspective view of a portion of an electric motor 3000 that uses the commutated FPFC 2900 shown in FIG. 29. FIG. 30B is a plan view of a portion of an electric motor 3000 that uses the commutated FPFC 2900 shown in FIG. 29. FIG. 30C is a cross-sectional plan view of a portion of an electric motor 3000 that uses the commutated FPFC 2900 shown in FIG. 29. Electric motor 3000 is substantially similar to electric motor 1500, except for all differences described herein. FPFC 2900 is substantially similar to FPFC 1400 previously shown in FIG. 14, except for the addition of rectifier 2306 to conductive loop 2902. The operation of rectifier 2306 has been previously described.

[0125] FIG. 31A is a perspective view of an electric motor 1700 in which an example commutated FPFC 3101 is attached to the rear side of the permanent magnet 3120 in the mover 3108. FIG. 31B is a plan view of a portion of the electric motor 3100 shown in FIG. 31A. FIG. 31C is a cross-sectional plan view of a portion of the electric motor 3100 shown in FIG. 31A. The electric motor 3100 is substantially similar to the electric motor 1700, except for all differences described herein. The FPFC 3101 is substantially similar to the FPFC 1701 previously shown in FIG. 17, except for the addition of a rectifier 2306 to the conductive loop. The operation of the rectifier 2306 has been previously described.

[0126] 32A-32C are diagrams illustrating an example of a commutated FPFC 3200 that can be used in accordance with aspects of the present disclosure. FIG. 33A is a perspective view of a portion of an electric motor 3300 that uses the commutated FPFC 3200 shown in FIG. 32. FIG. 33B is a plan view of a portion of an electric motor 3300 that uses the commutated FPFC 3200 shown in FIG. 32. FIG. 33C is a cross-sectional plan view of a portion of an electric motor 3300 that uses the commutated FPFC 3200 shown in FIG. 32. FIG. 33D is a cross-sectional perspective view of a portion of an electric motor 3300 that uses the commutated FPFC 3200 shown in FIG. 32. Electric motor 3300 is substantially similar to electric motor 2200, except for all differences described herein. FPFC 3200 is substantially similar to FPFC 2100 previously shown in Figures 21A-21C, except for the addition of a first rectifier 2306a to first conductive loop 3202 and a second rectifier 2306b to second conductive loop 3204. Rectifiers 2306a and 2306b are substantially identical to rectifier 2306 previously described.

[0127] Numerous embodiments using a rectified FPFC have been described. While described as individual embodiments, the features of each embodiment can be mixed and matched without departing from the present disclosure. For example, the first conductive loop 3202, the second conductive loop 3204, or both, can be made from shorted Litz wire. Additionally, other passive components, such as capacitors, resistors, or inductors, can be added in parallel or series with the various embodiments described herein. For example, in some embodiments, a discrete capacitor (not shown) can be added to any of the rectified FPFCs described herein. The discrete capacitor can be wired in parallel or series with any of the rectifiers described herein. Adding such a capacitor can tune the FPFC to respond to a specified frequency.

[0128] <Example of a radial gap motor equipped with an active FPFC> This section primarily describes embodiments related to radial gap motors with active FPFCs. For purposes of this disclosure, an "active" FPFC is an FPFC that includes any logic circuit, such as a transistor, connecting across a conductor that completely surrounds at least one pole of the mover. Various embodiments described herein are described with both an inner mover and an outer mover. While individual embodiments may be described as using either an inner mover or an outer mover, it should be noted that aspects of the embodiments described herein are applicable to both the inner mover and the outer mover, regardless of whether a particular embodiment is described.

[0129] 34A-34C illustrate an example of an active FPFC 3400 that can be used in various aspects of the present disclosure. FIG. 35A is a perspective view of a portion of an electric motor 3500 that uses the active FPFC 3400 shown in FIG. 34. FIG. 35B is a plan view of a portion of an electric motor 3300 that uses the active FPFC 3400 shown in FIG. 34. FIG. 35C is a plan cross-sectional view of a portion of an electric motor 3500 that uses the active FPFC 3400 shown in FIG. 34. FIG. 35D is a perspective cross-sectional view of a portion of an electric motor 3500 that uses the active FPFC 3400 shown in FIG. 34. FIG. 35E is a perspective view of an example motor 3500 that uses the active FPFC 3400 shown in FIG. 34. FIG. 35F is a longitudinal cross-sectional view of an example motor 3500 that uses the active FPFC 3400 shown in FIG. 35E. FIG. 35G is a perspective cross-sectional view of an example motor 3500 that uses the active FPFC 3400 shown in FIG. 35E. Motor 3500 is substantially similar to motor 500 shown above in Figures 5A-5D, except for all differences described herein. Active FPFC 3400 is substantially similar to passive FPFC 1400, except for all differences described herein.

[0130] FPFC 3400 includes a rectifier 3406 in series with both ends of conductive loop 3402. Logic circuit 3406 can include transistors such as field effect transistors, dual gate field effect transistors, or bipolar junction transistors.

[0131] As shown, logic circuit 3406 includes a transistor having a source 3408 and a drain 3410, which are formed by a shorted FPFC 3400. A gate 3412 of the transistor is connected to a slip ring 3520 that provides a control signal. In some embodiments, the leads, the transistor, or both may be integrated into a printed circuit board (PCB) to which the FPFC and slip ring 3520 or other control mechanism are connected. Three slip rings 3521 are provided, one for each phase (one of which is shown), with three leads 3522. The slip rings 3521 are grounded to the armature by a fourth slip ring 3524, as shown in FIGS. 35F-35G. The drain 3410 of the transistor is also shown grounded to the armature 3508. Leads 3522 leading from the slip ring of the armature shaft are coupled to a controller, such as controller 130 (FIG. 2).

[0132] The addition of logic circuitry 3406 allows FPFC 3400 to be effectively "off" during operation, which can be advantageous during high-speed, low-load conditions, such as inertial motion. In some implementations of an active FPFC, the active rectifier's switches can be implemented to act passively during unpowered conditions. For example, in some implementations, a bipolar junction transistor rectifies current across the active rectifier when not actively controlled. This allows the active rectifier to act as a passive rectifier during motor start-up until actively controlled.

[0133] Although mainly illustrated and described as being wired-connected to a controller via a conductive lead 3522, it is also possible to transmit a control signal to a control circuit using other communication media, for example, by an optical sensing diode, a capacitive coupling mechanism, an inductive coupling mechanism, or other wireless communication media.

[0134] 《Other Motors Using FPFC》 This section mainly describes embodiments related to other electrical machines such as linear motors, axial gap motors, and distributed winding radial gap motors. However, the description here can also be applied to other embodiments of radial machines or salient pole machines (for example, concentrated windings, fractional slots, or radial machines, etc.).

[0135] <Axial Gap Motor with FPFC> FIG. 36A is a perspective view of an example axial gap motor 3600 that can be used in multiple aspects of the present disclosure. FIG. 36B is a side view of the example axial gap motor 3600 shown in FIG. 36A. FIG. 36C is a perspective view of the rotor 3608 used in the motor 3600 shown in FIG. 36A. FIG. 36D is a perspective view of the stator 3602 used in the motor 3600 shown in FIG. 36A.

[0136] The electric machine 3600 includes a stator 3602 having a plurality of stator poles 3604 with electrical windings 3606. As shown, the stator poles 3604 are sector-shaped, although other shapes can be used without departing from this disclosure. The mover 3608 includes a plurality of mover poles 3610. The mover poles 3610 are also sector-shaped, like the stator poles 3604, although other shapes can be used without departing from this disclosure. This embodiment includes stator poles 3604 shaped similarly to the mover poles 3610, although the stator poles 3604 and mover poles 3610 can be different from one another without departing from this disclosure. The mover 3608 is movable relative to the stator 3620. In this example, the mover 3608 is positioned to rotate adjacent to the stator 3602. The mover 3608 and stator 3602 together define a nominal gap 3612 between the stator poles 3604 and the mover poles 3610. In this case, the nominal gap 3612 is an axial gap. The mover poles 3610 include a magnetically permeable pole material, such as iron. The mover 3608 also includes an array of frequency programmable flux channels (FPFCs) 3601. Each FPFC 3601 includes a respective conductive loop 3603 that surrounds or encircles a corresponding mover pole 3610. In the illustrated embodiment, each mover pole 3610 is enclosed. The stator 3602 and mover 368 are positioned such that an electrical winding 3606 in the stator 3602 induces an excitation current in the FPFCs 3601.

[0137] The mover 3608 can be made of a magnetically permeable material such as iron. In some embodiments, the mover 3608 can be constructed from mover laminations to reduce eddy currents in the back yoke of the mover 3608. The stator 3602 can likewise be constructed from stator laminations to reduce eddy currents in the back yoke of the stator 3602. In some embodiments, the poles 3610 of the mover 3608 include a material with non-zero remanence. Various fasteners, adhesives, or resins can be used to hold each FPFC 3601 to its corresponding mover pole 3610. In some embodiments, the FPFCs 3601 are held by a friction fit or an interference fit.

[0138] In the illustration, mover 3608 does not include a permanent magnet, however, permanent magnetic materials could be used in stator 3602, mover 3608, or both without departing from this disclosure.

[0139] Similar to the embodiments described above, the FPFC 3601 includes at least one conductive loop 3603 having at least one turn of shorted conductive material. That is, the conductive material completely surrounds the mover pole 3610 and shorts itself to form a loop. In some embodiments, the conductive loop 3603 includes a material with a higher conductivity than the mover core material. In some embodiments, the conductive loop 3603 includes a material with a lower magnetic permeability than the mover core material. Similar to the radial gap embodiment, the FPFC 3601 has a substantially uniform inductance, particularly in the radial direction. This criterion allows for full skin effect penetration of each FPFC 3601 at a specified drive frequency. Conductor geometry, such as the thickness of the individual conductors in the conductive loop, is taken into consideration when designing the FPFC 3601. In some embodiments, the drive frequency can range from 0 Hz to 20 Hz. In some embodiments, the drive frequency can range from 100 Hz to 2000 Hz. In some embodiments, the drive frequency can range from 2,000 Hz to 15,000 Hz. FPFC 3601 is shown as a rectified FPFC with rectifier 2306. While shown as using a rectified FPFC, a passive or active FPFC could also be used without departing from the present disclosure.

[0140] <Distribution Winding> Figure 37A is a perspective view of an example electric motor 3700 with distributed stator windings 3706 that can be used in accordance with aspects of the present disclosure. Figure 37B is a side view of the example electric motor 3700 shown in Figure 37A. Figure 37C is a perspective view of the stator 3702 of the electric motor 3700 shown in Figure 37A. Figure 37D is a cross-sectional top view of the example motor 3700 shown in Figure 37A. Figure 37E is a cross-sectional perspective view of the example motor 3700 shown in Figure 37A. Figure 38 is a cross-sectional perspective view of the example motor 3800 with distributed stator windings 3806 that can be used in accordance with aspects of the present disclosure.

[0141] The above embodiments described in this disclosure have involved salient-pole movers and salient-pole stators. In some embodiments, a stator with distributed stator poles can be used. In such embodiments, the stator windings overlap each other. Details of how such embodiments are controlled and any differences in control that may exist between a motor with salient-pole stator windings and a distributed-winding motor are described in detail later in this disclosure. While distributed stator windings can be used without departing from this disclosure, the mover poles and their associated FPFCs are salient and non-overlapping in all embodiments described herein. In some embodiments, multiple FPFCs in the same phase can be shorted together without departing from this disclosure. Such a configuration is also considered a non-distributed mover pole.

[0142] Linear motor with frequency-programmable flux channels FIG. 39A is a perspective view of an example linear motor 3900 with a commutated FPFC mounted on a "mover" 3908 (passive magnetics). FIG. 39B is a longitudinal side view of the example linear motor 3900 shown in FIG. 39A. FIG. 39C is a longitudinal cross-sectional view of the example linear motor 3900 shown in FIG. 39A. FIG. 39D is a perspective view of the stator 3902 (active magnetics) of the example linear motor 3900 shown in FIG. 39A. FIG. 39E is a perspective view of the "mover" 3908 of the example linear motor 3900 shown in FIG. 39A.

[0143] The electric machine 3900 includes a stator 3902 having a plurality of stator poles 3904 with electrical windings 3906 attached to the stator poles 3904. A mover 3908 has a plurality of mover poles 3910. While this embodiment includes stator poles 3904 shaped similarly to the mover poles 3910, the stator poles 3904 and mover poles 3910 can differ from one another without departing from this disclosure. As shown, the stator 3902 is movable relative to the mover 3908. The mover 3908 can act as a passive magnetic track across which the active magnetic stator 3902 travels. The mover 3908 and stator 3902 together define a nominal gap 3912 between the stator poles 3904 and the mover poles 3910. In this case, the nominal gap 3912 is a lateral gap. The mover poles 3910 include a magnetically permeable pole material such as iron. The mover 3908 also includes an array of frequency programmable flux channels (FPFCs) 3901. Each FPFC 3901 includes a conductive loop 3903 that surrounds or encircles a corresponding mover pole 3910. In the illustrated implementation, every other mover pole 3910 is surrounded. The stator 3902 and mover 3908 are positioned such that an electrical winding 3906 in the stator 3902 induces an excitation current in the FPFCs 3901.

[0144] The mover 3908 can be made of a magnetically permeable material such as iron. In some embodiments, the mover 3908 can be constructed from mover laminations 3914 to reduce eddy currents in the back yoke of the mover 3908. The stator 3902 can likewise be constructed from stator laminations 3916 to reduce eddy currents in the back yoke of the stator 3902. In some embodiments, the poles 3910 of the mover 3908 include a material with non-zero remanence. Various fasteners, adhesives, or resins can be used to hold each FPFC 3901 to its corresponding mover pole 3910. In some embodiments, the FPFCs 3901 are held by a friction fit or an interference fit.

[0145] In the illustration, mover 3908 does not include a permanent magnet, however, permanent magnetic materials could be used in stator 3902, mover 3908, or both without departing from this disclosure.

[0146] Similar to the embodiments described above, the FPFC 3901 includes at least one conductive loop 3903 having at least one turn of shorted conductive material. That is, the conductive material completely surrounds the mover pole 3910 and shorts itself to form a loop. In some embodiments, the conductive loop 3903 includes a material with a higher conductivity than the mover core material. In some embodiments, the conductive loop 3903 includes a material with a lower magnetic permeability than the mover core material. Similar to the radial gap embodiment, the FPFC 3901 has a substantially uniform inductance, particularly in the radial direction. This criterion allows for full skin effect penetration of each FPFC 3901 at a specified drive frequency. Conductor geometry, such as the thickness of the individual conductors in the conductive loop, is taken into consideration when designing the FPFC 3901. In some embodiments, the drive frequency can range from 0 Hz to 20 Hz. In some embodiments, the drive frequency can range from 100 Hz to 2000 Hz. In some embodiments, the drive frequency can range from 2,000 Hz to 15,000 Hz. In the figure, FPFC 3901 is a rectified FPFC with rectifier 2306.

[0147] FIG. 40A is a perspective view of an example linear motor 4000 having a commutated FPFC in a "mover" 4008 and a stator 4002. FIG. 40B is a longitudinal side view of the example linear motor 4000 shown in FIG. 40A. FIG. 40C is a longitudinal cross-sectional view of the example linear motor 4000 shown in FIG. 40A. FIG. 40D is a perspective view of the stator 4002 of the example linear motor 4000 shown in FIG. 40A. Linear motor 4000 is substantially similar to linear motor 39000 except for all differences described herein.

[0148] The stator 4002 includes two commutated FPFCs 4001 per stator pole 4004. The addition of two commutated FPFCs per stator pole 4004 allows for flux pinning at the stator pole 4004, i.e., the flux is topologically constrained to a desired region of the stator pole. While illustrated using commutated FPFCs, passive or active FPFCs could also be used without departing from this disclosure.

[0149] Operation of a motor with frequency-programmable flux channels This section describes general motor concepts applicable to electric motors with FPFCs. While primarily focused on rotary electric motors, the concepts described herein are applicable to other motors as well. In some instances, the concepts described herein may also be applicable to motors without FPFCs.

[0150] Magnetic materials can be classified as "soft" or "hard" based on their coercivity. Traditionally, synchronous motors lack a magnetizing current to magnetize the material, so magnets must be magnetized in the factory or before installation. Therefore, if the magnetic material demagnetizes during operation (e.g., due to excessive loading of the stator on the magnetic material or due to thermal effects generated throughout operation), the magnets can be damaged or the motor can become completely inoperable. Therefore, "hard" materials are often used in permanent magnet synchronous machines. Furthermore, regardless of the magnetic material, a sufficiently large amount of such material is typically used to ensure a given magnetic field strength (B) and coercivity (H). Figure 41A shows the hysteresis curve for a "soft" magnetic material, and Figure 41B shows the hysteresis curve for a "hard" magnetic material. The coercivity of a "hard" magnetic material is greater than that of a "soft" magnetic material. 3A-3D, the reversal pulse 306 can harden (or magnetically strengthen) the mover pole 308, including the FPFC 310. The FPFC itself can also help support the magnetic flux of a given magnetic or permeable material throughout the entire operating period (e.g., via sinusoidal or square wave control).

[0151] FIG. 42 is a schematic diagram of an electric motor 4300 with markings indicating the alignment of the mover 4308 and stator 4301. Position D defines the alignment of opposite stator and mover poles, Q and Q' are completely misaligned (same poles, opposite poles close together), and D' is the alignment of the same stator and mover poles. Motor components and control are sometimes described with reference to the D-axis 4302 and Q-axis 4304 of the motor mover and / or stator. In this transformed system, the direct or D-axis 4302 of the motor can be defined as the pole centerline perpendicular to the air gap 4306 and can apply to either the stator poles 4308 or the mover poles 4312. The mover can be characterized by the D-axis 4302 of each pole in a synchronous coordinate system. In a motor with salient mover poles and FPFC, whether the FPFC is concentrated in one large slot or distributed among several smaller slots, the D-axis 4302 is the center point of the resulting magnetic center of the pole on which the FPFC is located. Stator poles can be similarly characterized.

[0152] The Q axis 4304 is the axis in the magnetic coordinate system that is perpendicular to the D axis 4302. In some embodiments, the Q axis 4304 is electrically perpendicular to the D axis 4302, and both axes lie in the plane in which the mover rotates. In general, a force along the Q axis 4304 generates an electromotive force, such as a torque. Topologically, the Q axis 4304 of the mover or stator is typically located directly between two poles.

[0153] In the DQ coordinate system, the current phasor angle is the relative angle of the mover D-axis 4302 with respect to the stator magnetic center. A positive current phasor angle indicates that the stator magnetic center is leading the mover poles in the direction of motion. This situation causes the stator magnetic center to "pull" the mover poles toward the stator magnetic center. A negative current angle indicates that the stator magnetic center is lagging the mover poles. This situation causes the mover poles to "pull" in the opposite direction. Such negative current phasor angles can be used in braking situations. In some implementations, current phasor angles greater than 90° can be used. These large phasor current angles can "push" adjacent poles in the direction of motion. Current phasor angles less than -90° can be used to "push" adjacent poles in the opposite direction, such as during braking operations. Current phasor angles can be converted between stationary and synchronous coordinate systems using the following formula: θ e =(P / 2)θ m (1) where θ e is the current phasor angle in the synchronous coordinate system, P is the number of stator poles, and θ m is the current phasor angle in the stationary coordinate system. Regardless of the current phasor angle, it can be resolved into a D-axis component and a Q-axis component. In general, in the motors and generators described herein, the D-axis component acts to "charge" or modulate the magnetic field in the mover poles and FPFC, while the Q-axis component acts to impart a force or torque on the mover poles.

[0154] FIG. 43A is a graph showing torque on the mover versus its relative position with respect to the stator. In some embodiments, particularly for movers with high salient pole ratios, peak torque occurs between positions D and Q in the synchronous coordinate system (due, for example, to their reluctance components). In other embodiments, peak torque occurs between positions Q and D'. When using permanent magnet motors, peak torque operation can cause demagnetization at high loads, which may require field weakening at high speeds. Weaker magnets can be used at the expense of size / weight and / or torque production. FPFCs are used to improve magneto-current capability without risking demagnetization. FIG. 43B is a graph showing current flow in an FPFC during mover rotation. A negative current section 4310 is provided in simple FPFC implementations but is omitted in commutated or active FPFC implementations. At low torques, FPFC current can reduce cogging (resistance) torque degradation, eliminating the need for active flux weakening of strong permanent magnets. The advantage of FPFC is that the FPFC can be flux-weakening or flux-strengthening controlled by a control mechanism (e.g., by increasing or decreasing the current in the FPFC to increase or decrease the magnetic flux in the mover pole itself), for example, by changing the current phasor angle of the synchronous excitation from the stator. This eliminates the need for a secondary control system (e.g., to control the stator field) or additional commutation hardware, as in a wound-mover synchronous motor.

[0155] The control schemes for FPFC embodiments included herein do not necessarily require additional stator-mover coupling elements; rather, some embodiments use the stator winding and FPFC together with the mover to transmit excitation. This can help reduce parts count, improve performance (e.g., eliminate resistive losses in brushes), eliminate physical contacts and wear elements, reduce package size, and provide control flexibility compared to schemes that use specialized detectors, sensors, wired or wireless connections, or brushes to transmit signals from the stator to the mover.

[0156] Electrical machine designs often involve coupling the stator and mover to allow for power transfer and / or magnetic field modulation during operation. Coupling can be categorized as direct or indirect. Direct coupling occurs when the stator and mover are coupled primarily along the operating air gap. Indirect coupling occurs at a secondary interface away from the operating air gap.

[0157] Direct coupling is typically characterized as inductive coupling, e.g., a squirrel-cage induction armature is said to be directly coupled to the stator. Direct coupling is common and easy to control in asynchronous machines, but direct coupling in synchronous machines can be difficult and is difficult to control for reasons explained throughout this disclosure.

[0158] Indirect coupling operates in a secondary coupling, can be radial or axially oriented, and can communicate via electrical contact, inductive coupling through an alternative air gap, capacitive coupling, or optical coupling. Secondary coupling can be used for a variety of functions to improve the efficiency and / or overall controllability of the electric machine, but often requires additional components that can increase the weight, complexity, failure frequency, and cost (both operating and capital costs) of electric machines utilizing such approaches.

[0159] The motors and generators described in this disclosure are primarily energetically isolated (within standard electromagnetic shielding tolerances), and the motors and generators use direct coupling to transfer power and signals between the stator and mover without the need for indirect or secondary coupling. Direct coupling can control the torque, speed, and magnetic flux of the mover. The electric machines described herein have direct coupling between the mover 404 and stator 402 for both coupling and control of torque, speed, magnetic flux, and signals.

[0160] In some embodiments, frequency and harmonic impedances can be observed between the signal radiated by the stator and the fundamental operating frequency, which determines the mover speed. In some embodiments, the subject matter described herein can provide a constant excitation frequency to the mover regardless of mover speed, and can also use modulation of the stator excitation, such as frequency modulation, described herein, under constant or dynamic speed conditions. Control of the FPFC does not rely on the harmonic relationship between the stator and mover, nor on the fundamental frequency or higher harmonics, allowing the mover FPFC to be designed and controlled around its intrinsic parameters (e.g., control, materials, etc.). Various control schemes for the FPFC are discussed throughout this disclosure and will be discussed in more detail below.

[0161] In some cases, it may be necessary or beneficial to charge the FPFC when it is at position D or when transitioning from position D to position Q. "Charging" may mean inducing a current in the FPFC itself or transmitting, increasing, or storing magnetic flux in the mover, each of which may involve some power transfer from the stator to the mover. This may be done in various ways, such as by changing the stator excitation current phasor angle (e.g., by appropriately advancing or retarding the stator excitation current angle), increasing the frequency with which the stator excitation current phasor angle changes, increasing the amplitude of the stator excitation current (or increasing any component of the resulting stator signal), or any combination thereof. In some cases, the FPFC may be weakened (e.g., by reducing the level of current or magnetic flux present in the FPFC and / or the mover), for example, by operating at or near position D' (e.g., by transitioning from position Q to position D' or from position D' to position Q). This can be accomplished in various ways, such as by changing the current phasor angles (e.g., by appropriately advancing or retarding the stator excitation current angle), by reducing the frequency at which the stator excitation current phasor angles change, by reducing the amplitude of the stator excitation current, or any combination thereof. Alternatively, or in addition, field weakening can be achieved by passively dissipating the FPFC current through resistive losses.

[0162] As previously mentioned, active field weakening of the FPFC can be achieved by operating on D' or by replacing it with an active FPFC. Such an embodiment includes logic circuitry, such as transistors, which can be inductively or capacitively coupled and controlled, either conventionally via slip rings or a commutator, or wirelessly, and can include optional control means, such as light-emitting diodes, optical sensors, or primary controls. Reverse commutation by the logic circuitry allows for rapid reduction of the FPFC current via inductive coupling from the stator excitation. Leaving gate 3412 (FIGS. 34-35G) open prevents the FPFC current from building up, thereby generating reactive current.

[0163] In any of the embodiments described throughout this disclosure, when permanent magnetic materials are used in the magnetic poles, the polarity of the FPFC circuit windings and diodes can be arranged to provide multiple outputs. For example, in some embodiments, commutation can be constructive, such that it is constructive with respect to the material's polarity or magnetomotive force (MMF). This provides magnetic shielding against unwanted magnetic fields and harmonics, strengthens the mover field by increasing the residual field of the mover pole from its residual value during operation (e.g., amplification using a coil), and provides magnetic flux charge by magnetizing the material and creating a residual field (e.g., flux shaping in the material). In other embodiments, commutation can be non-constructive, allowing the magnetic field to be attenuated (e.g., field weakening). In some embodiments with an active FPFC, the active FPFC can provide bidirectional commutation, controlled using logic gates to select constructive or non-constructive commutation.

[0164] All concepts and operations described in this disclosure can be applied to electric machines with wound movers or permanent magnet-assisted wound movers. The details of increasing, decreasing, and maintaining FPFC charge depend on speed, torque, and other operating conditions. For example, at high torque demands and low speeds, more charge is required. For example, at high speeds and low torque, it may be necessary to minimize the average FPFC current as much as possible while maintaining the required torque. It should be noted that it is not intended to change mover speed when the stator excitation is leading or lagging. Torque and speed are held constant until control demand indicates a change.

[0165] In distributed stator pole implementations, to maintain substantially zero torque ripple (less than 1% in some implementations, 0-2% in others), the stator can be excited or boosted in the D position, where the excitation alignment or current phasor angle acts to increase the mover field. The current phasor angle (and resulting field) can then be rotated substantially near the peak torque position (or whatever the controller setpoint is) while maintaining synchronous timing. To control the FPFC for field strengthening, the excitation wave can be periodically shifted to the peak charge position. In implementations using a commutated FPFC, the excitation wave can have unequal periods. In such situations, current can be increased during the charge period to compensate for flux leakage and reluctance torque. The three-phase excitation timing can be timed to keep the excitation wave ahead of the mover or in a synchronous reference frame.

[0166] While steady-state operation has been described, a different drive waveform may be required for a locked mover (starting) condition. Figure 44A is a family of graphs showing drive waveforms 4400a, 4400b, and 4400c for a locked mover condition. Each waveform 4400a, 4400b, and 4400c is for one phase of a three-phase motor. During normal starting of a synchronous machine, DC current is sent to each phase to initiate rotation of the mover in the desired direction. In machines using FPFCs, periodic pulses of reversing current are used to charge the FPFC until the mover begins to move. This signal can range from a pulsed waveform to a continuous sinusoidal waveform, depending on the mover speed, as described elsewhere herein. At high speeds, the pulse and charge cycles overlap when the mechanical timing reaches the pulse frequency. Thus, the waveform employs a fundamental wave. In some implementations, a quasi-DC current or a variation thereof is applied for 9 milliseconds, followed by a pulse of reversing DC current for 1 millisecond. In some embodiments, the ratio of the duration of the quasi-DC current to the duration of the pulsed reverse current is between 1:1 and 100:1. In some embodiments, the ratio of the duration of the quasi-DC current to the duration of the pulsed reverse current is between 5:1 and 15:1. In some embodiments, the ratio of the duration of the quasi-DC current to the duration of the pulsed reverse current is 9:1. Regardless of the ratio used, once the mover begins to move, it can be driven by AC current through each phase. Such a transition is illustrated in FIG. 44B, which is a graph showing the transition from a locked mover state to a moving mover state. While the locked mover state is illustrated as a square wave and the drive frequency is illustrated as a sine wave, other waveforms can be used for each operating state without departing from this disclosure.

[0167] As mentioned above, the effect of FPFC can vary at different frequencies. For example, above a cutoff frequency such as 10 Hz, the force begins to increase, whereas at lower frequencies such as 10 Hz and 10 5 The increase between hertz can be more than an order of magnitude. At higher frequencies, the FPFC can exhibit stronger diamagnetic properties, which concentrates the magnetic flux towards the mover poles, which increases the component of force along the direction of motion.

[0168] The useful force can also be affected by operating conditions. At saturated and high frequencies, FPFCs can exhibit stronger diamagnetic properties than unsaturated ones, which causes the magnetic flux to concentrate towards the mover poles. As frequency increases, the useful force can continue to increase. For example, at 10 5 At high frequencies, such as Hertz, the horizontal force can increase by two orders of magnitude as the drive current increases from 10 ampere-turns (corresponding to unsaturated operating conditions) to 200 ampere-turns (corresponding to saturated operating conditions).

[0169] The number of teeth per pole can also affect the available force. Increasing the number of teeth per pole can gradually increase the force. However, as the gap size increases, e.g., 1.0 mm, the force may decrease with more teeth per pole.

[0170] Operation uses a high inductance, low resistance FPFC, which provides a high reactance in phase with the magnetic field. As the magnetic field travels up through the primary coil and reluctance teeth, it is reflected by the shielded teeth, presenting a high impedance to the magnetic field. The system can be operated with an alternating magnetic signal at only 50% of the duty cycle (e.g., from misaligned to aligned). Continuing through the full duty cycle (e.g., aligned to misaligned) can result in a counter torque. In some implementations, an impedance match or impedance network can be established.

[0171] Additionally, a high-reactance FPFC can enable a high-power-factor system that can generate torque more efficiently compared to conventional machines. A high-reactance, high-impedance FPFC design can prevent virtually all magnetic flux from penetrating the FPFC throughout the entire operating cycle. In this way, the motor can utilize diamagnetic properties over a wide temperature range (e.g., from room temperature to high temperatures) previously only available in superconducting motors. Furthermore, this can be less susceptible to temperature effects compared to permanent magnet motors, which tend to demagnetize above a critical temperature.

[0172] The motors described above with FPFCs can be dynamically driven with square-wave currents. When dynamically driven, square waves can be used at a relatively lower switching frequency than an equivalent sine wave, providing pulses at a relatively low frequency (e.g., 50 Hz) while increasing the reactance in the FPFC. This is partly because square waves have a higher proportion of harmonic content than sine waves. This also reduces the switching losses required in power electronic devices due to the high frequencies often required by pulse-width modulation (PWM) switching. For such operation, relatively thin (e.g., 0.127 mm) laminates can be used to reduce eddy current losses in the iron core, and low-gauge (e.g., 0.2 mm) or Litz wire windings can be used in the primary coil to reduce skin-effect losses in the core winding.

[0173] Additionally, the motors described throughout this disclosure can benefit from increased coil winding efficiency. While typical slot fill factors for windings are 30-40% of a given slot area, by using casting techniques to fill the slots between adjacent poles with FPFC, the motor can utilize nearly the entire slot volume (e.g., 85-95%) for FPFC. This reduces the total amount of wire required for the motor's primary winding, thereby reducing the number of turns in the primary winding compared to a typical motor.

[0174] As described above, filling the slots with FPFC allows for controlled concentration of magnetic flux during motor operation. Specifically, when the stator and mover are misaligned, significant internal electromagnetic reflections block most magnetic transmission from the opposite polarity surface. This diamagnetic shielding allows the magnetic slots to effectively push against the mover, while the electromagnetic pole reluctance pushes against the mover. This action allows for more energy to be produced by the system per cycle, and is comparable to that which can be produced by permanent magnets in certain configurations.

[0175] This effect provides a significant advantage over permanent magnets, which are prone to demagnetization due to high eddy currents. This effect can be observed in the BH curves used to measure the coercivity of permanent magnets. In the motors described throughout this disclosure, the high-reactance FPFC can approximate a permanent magnet with infinite coercivity in the reverse direction. Therefore, the FPFC can reflect the magnetic field it receives and achieve magnetic field levels beyond those achievable in typical permanent magnet motors, thereby generating greater back-EMF and increasing torque density, power density, and efficiency. Furthermore, while permanent magnets demagnetize at elevated temperatures, as previously mentioned, the FPFC can be constructed from materials that can withstand temperatures greater than the typical permanent magnet's endurance temperature, and that are more than 100 degrees Fahrenheit higher than the typical permanent magnet's endurance temperature.

[0176] Furthermore, while the magnetic field generated by permanent magnets is constant, FPFCs exist dynamically in transient states. This is advantageous from both an efficiency and safety perspective, as permanent magnet motors can produce potentially fatal dent, cogging, and braking torques due to the EMFs generated whether power is being used or not. The motor can be controlled to effectively freewheel for long periods of time, with losses coming only from bearing resistance.

[0177] Furthermore, unlike an IM, which has a significant inductive load that generates a continuous current, the current in each FPFC can be returned to near zero with each cycle. The higher the motor's operating frequency, the lower the current requirement needed in each FPFC to maintain reflection. Because the system is reactive, energy is either returned elastically or converted into kinetic energy of the mover with each switching period.

[0178] The fill factor of the FPFC slots can be tuned for specific applications and can also be dynamically tuned during operation. Unlike air, the magnetic properties of the system can be tuned, both in the amplitude of the magnetomotive force (MMF) for a specific position and in the frequency of the MMF. This allows real-time adaptive adjustment by varying the motor's switching frequency to weaken or strengthen the system's magnetic flux characteristics. This allows the back EMF in the primary coil to be modified, allowing the motor to achieve a wider speed range than traditional motors. Traditional motors have a fixed back EMF due to a fixed saliency ratio used to vary the magnetic field magnitude. The motor can vary the magnetic field magnitude in addition to the operating frequency of the motor's operation.

[0179] At high speeds, the motor can operate as a reactive reluctance motor. In conventional SRM operation, a peak voltage is applied at the beginning of a misalignment between the stator and mover (or stator tooth-mover tooth), and the current increases rapidly until the stator and mover (or stator tooth-mover tooth) reach the alignment point. At this point, a reverse voltage is applied, and then the current drops to zero. In a conventional SRM, when the mover is locked (stationary), the current is applied continuously, not pulsed. In a motor with a FPFC, current can be pulsed through the active coil while stationary. During motor acceleration, once the pole switching frequency exceeds the FPFC crossover frequency, each pole can be excited by a single pulse.

[0180] Example of method An embodiment of the present disclosure provides a method for driving an electric motor, which may be electric motor 102 of Figure 1, and which may be implemented by a motor controller, such as motor controller 107 of Figure 1 or controller 130 of Figure 2.

[0181] During operation, when a stator pole is aligned with a mover pole across a nominal gap, the motor controller supplies a pulse of magnetizing current for a specific duration to the stator coil of that stator pole. The magnetizing current charges the magnetic field at the mover pole via direct inductive coupling. The motor controller then supplies a load current pulse for a specific duration to the stator coil when the mover pole is positioned between adjacent stator poles. The load current pulse strengthens the magnetic field at the mover pole. The load current pulse has a greater number of pulses per time duration than the magnetizing current pulses.

[0182] In some cases, the magnetizing current is supplied as a single pulse of current for a specific time. The single pulse of current may include a half-sine wave, a half-square wave, a half-trapezoidal wave, or any combination thereof. Applying the magnetizing current strongly couples the mover poles to the stator poles. In some cases, for example, if the mover has sufficient magnetic field strength, no magnetizing current (or only a small amount of magnetizing current) is applied compared to the previous time step.

[0183] In some cases, a load current pulse is applied as the mover rotates from the first pole to the second pole. The load current pulses can include a half-sine wave, a half-square wave, a half-trapezoidal wave, a full-sine wave, a full-square wave, a full-trapezoidal wave, or a combination thereof. In some embodiments, the signal can have a DC offset. In some embodiments, the current pulses are independent of the mover speed. For example, in some embodiments, the current pulses are applied between 5 and 10 Hz. In some embodiments, the current pulses are applied between 5 and 1000 Hz, 10 and 500 Hz, 50 and 350 Hz, or 100 and 200 Hz.

[0184] In some embodiments, the controller maintains the mover magnetic flux within a desired range during peak load conditions. For example, the desired range can vary between 50 and 100%. In another example, the desired range can vary between 65 and 100%. In another example, the desired range can vary between 80 and 100%.

[0185] As described above, the motor controller can adjust the apparent magnetic strength in the permanent magnet channel or any other permanent magnetic material of the mover by inducing a current in the FPFC.

[0186] The above operating parameters can be achieved by the controller operating, over multiple cycles, a first switch between a voltage source and an electrical winding associated with a first active pole, opening and closing the first switch. The first switch can be associated with the first active pole and conductively coupled to the first active pole. The first switch can be switch 134 of FIG. 2 or power switch 200 of FIG. 2A.

[0187] Cooling and Thermal Relaxation Examples Electric motors can generate significant amounts of heat during operation, particularly at relatively high frequencies, and require cooling. Active cooling systems can be used to provide intermittent or continuous cooling of the surface by circulating a fluid coolant within the motor. The cooling system can be the cooling system described in pending U.S. patent application Ser. No. 62 / 675,207, filed May 23, 2018, entitled "Electric Motor," the contents of which are expressly incorporated by reference herein as if set forth in their entirety.

[0188] Additionally, the efficiency and power of an FPFC at a given frequency can be increased if the operating temperature is reduced. Typically, operating conditions are between -80°C and 300°C. To further reduce the temperature of the FPFC and increase its diamagnetic properties, a coolant can be added to the motor system.

[0189] The coolant can be any conventional fluid used for thermal mitigation. Under operating conditions, the coolant can be a low viscosity fluid, such as water or motor oil, in the range of 1 to 500 centipoise, to allow for both high cooling efficiency and rotational motion characteristics. The coolant can also provide damping for vibrations generated during operation and provide restoring force for harmonics generated at high rotational speeds.

[0190] Active cooling can improve power density by providing a medium that absorbs heat from electrical coils and mechanical contact surfaces. Active lubrication systems can be used to circulate a fluid lubricant through a motor, providing intermittent or continuous lubrication of surfaces. For example, a fluid pump can mechanically promote lubricant flow from a fluid pump through a fluid path to the motor, where the lubricant can be released through directional nozzles to provide active lubrication and / or fluid cooling to specific locations in the motor. The fluid then collects by gravity in an oil pan at the bottom of the motor and is recirculated back to the pump through a fluid return path. In this way, the motor armature assembly can operate in a non-submerged, low-temperature environment. Additionally, a portion of the lubricant can be passed through a heat exchanger to add or remove heat from the lubricant, thereby varying the temperature and / or viscosity of the lubricant to meet the specific needs of the application.

[0191] The coolant can be any conventional fluid used for thermal mitigation. Under operating conditions, the coolant can be a low viscosity fluid, such as water or motor oil, in the range of 1 to 500 centipoise, to allow for both high cooling efficiency and rotational motion characteristics. The coolant can also provide damping for vibrations generated during operation and provide restoring force for harmonics generated at high rotational speeds.

[0192] The motor may include a collection pan to gravity collect coolant discharged into the motor assembly and send it to the fluid return path.

[0193] The cooling system may include a fluid pump that provides a pressure gradient to circulate the coolant through the fluid system. Such a pump may be a fixed displacement pump, such as a rotary pump, or a variable displacement pump, such as a gear pump or a piston pump. The pump may be operably connected to a mechanical or electrical power source and may operate continuously or intermittently during motor operation. A wet-sump active lubrication system may include a single fluid pump operably connected to a collection pan to circulate oil through fluid paths within the cooled system, with the majority of the oil supply remaining in the collection pan. Alternatively, multiple fluid pumps may operate in a dry-sump active cooling configuration, in which fluid from the collection pan is continuously transferred to a holding tank, and a second pump pumps the fluid at a separate, controlled rate back to the motor to complete the coolant circulation, preferably with a large height relative to its cross-sectional area.

[0194] The cooling system may include one or more directional nozzles for directing coolant to specific locations in the motor assembly, including, for example, the stator poles.

[0195] Other Implementations Any of the above motors can be controlled to generate electrical energy from dynamic energy (e.g., for regenerative braking of the motor). This can be achieved by modifying the timing of the excitation signal to pulse the stator current at (or slightly later than) the minimum air gap to generate a forward EMF during expansion. In this way, current can be generated and sent for storage in a corresponding battery, and a retarding torque can be applied to the armature to slow the motor down, even though the torque applied to the output shaft could mechanically drive the motor in the reverse direction.

[0196] Any of the above motors can be controlled to generate electrical energy from kinetic energy (e.g., for regenerative braking of the motor). This can be achieved by modifying the timing of the compression wave to pulse the stator current at (or slightly later than) the minimum air gap to generate a forward EMF during expansion. In this way, even though the motor is not mechanically backdribbled by torque applied to the output shaft, current can be generated and channeled to storage in an associated battery while a decelerating torque is applied to the armature to slow the motor.

[0197] While numerous examples have been set forth for illustrative purposes, the above description is not intended to limit the scope of the concepts of the present disclosure, which is defined by the appended claims. Other exemplary embodiments and modifications are included within the scope of the following claims, both present and future. Other embodiments and modifications are included within the scope of the following claims, which benefit from the present disclosure. All such embodiments and modifications are intended to be encompassed, and therefore the above description should be considered an illustrative recitation, not a limiting recitation. The actions or methods recited in the claims may be performed in a different order and still achieve desirable results. Additionally, the processes depicted in the accompanying figures do not necessarily need to be performed in the specific order or sequential order depicted in the figures, and various elements may be added, reordered, combined, omitted, or modified to achieve desirable results.

Claims

1. a stator having a plurality of distributed stator poles, the stator poles being provided with electrical windings, the electrical windings being overlapping; a mover having a plurality of mover poles, the mover being movable relative to the stator and mating with the stator to define a nominal gap between the stator poles and the mover poles, the mover poles including a magnetically permeable pole material; A synchronous electric machine comprising: the mover also includes an array of frequency programmable flux channels (FPFCs); each said frequency programmable magnetic flux channel comprising a conductive loop surrounding a corresponding said armature pole; the mover poles and their frequency programmable flux channels are salient and non-overlapping so that each frequency programmable flux channel does not overlap with an adjacent frequency programmable flux channel to reflect or redirect magnetic flux generated during operation of the synchronous electric machine to increase the component of the magnetically induced driving force aligned with the direction of movement of the mover; 1. A synchronous electric machine characterized in that:

2. the stator and the armature are arranged such that, upon start-up, an electrical winding of the stator induces an excitation current in at least one of the frequency programmable flux channels; and / or the stator and the armature are arranged such that, at start-up, an electrical winding on the stator magnetizes at least one of the armature poles; 2. A synchronous electric machine according to claim 1.

3. The inductance of the conductive loop is uniform.

2. A synchronous electric machine according to claim 1.

4. the conductive loop includes a rectifier connected to the conductive loop; 2. A synchronous electric machine according to claim 1.

5. the conductive loop comprising a discrete capacitor and / or logic circuit connected to the conductive loop, the capacitor and / or logic circuit configured to tune the frequency programmable flux channel to respond to a specified frequency; 2. A synchronous electric machine according to claim 1.

6. the conductive loop is a first conductive loop, the mover pole is a first mover pole, each said frequency programmable magnetic flux channel comprises a second conductive loop, a corresponding said mover pole, and an additional mover pole adjacent to said first mover pole; 2. A synchronous electric machine according to claim 1.

7. It also has a controller, The controller supplying a pulse of magnetizing current to a stator coil of a stator pole for a specific time when the stator pole is aligned with a mover pole across the nominal gap, thereby charging the magnetic field of the mover pole by inductive coupling; supplying a load current pulse to the stator coil for a specific time period when the mover pole is positioned between adjacent stator poles, the load current pulse strengthening the magnetic field at the mover pole; It is structured as follows: The synchronous electric machine of claim 1 , wherein the load current pulses have a greater number of pulses per time duration than the magnetizing current pulses.

8. the mover further comprises a permanent magnetic channel; the permanent magnetic channel comprises ferrite, SmFeN, or N45; 2. A synchronous electric machine according to claim 1.

9. 1. A motor control method, comprising: supplying a pulse of magnetizing current to the stator coil of a stator pole for a specified time when the stator pole is aligned with the mover pole across a nominal gap, thereby charging the magnetic field of the mover pole by inductive coupling; supplying a load current pulse to the stator coil for a specified time period to enhance a magnetic field at the mover pole when the mover pole is located between adjacent stator poles; The number of pulses per time width of the load current pulses is greater than the number of pulses of the magnetizing current. A motor control method comprising:

10. the magnetizing current is supplied as a single pulse of current for a specific period of time; 10. The motor control method of claim 9.

11. providing the load current pulses includes providing a plurality of current pulses over a specified time period as the armature rotates from a first pole to a second pole; the plurality of current pulses include a half sine wave, a half square wave, a half trapezoidal wave, a full sine wave, a full square wave, or a full trapezoidal wave; 10. The motor control method of claim 9.

12. the plurality of current pulses are independent of armature speed; and / or the plurality of current pulses are between 5 and 1000 Hz; 12. The motor control method of claim 11.

13. maintaining the armature flux within a desired range during peak load conditions.

12. The motor control method of claim 11.

14. a stator configured to generate a controlled magnetic field, the stator comprising a plurality of distributed stator poles with electrical windings disposed on the stator poles, the electrical windings overlapping one another; a mover that moves relative to the stator in response to the controlled magnetic field, the mover having a plurality of salient mover poles that mate with the stator to define a nominal gap between a surface of the mover and a surface of the stator, the mover including a magnetically permeable pole material; An electric machine comprising: the mover comprises a variable magnetomotive force source controllable by the controlled magnetic field generated by the stator; the variable magnetomotive force source also comprises an array of frequency programmable flux channels (FPFCs); each said frequency programmable magnetic flux channel comprising a conductive loop surrounding a corresponding said armature pole; At start-up, the magnetizing current of the frequency programmable flux channel is generated by the controlled magnetic field of the stator; each of the frequency programmable flux channels does not overlap with adjacent frequency programmable flux channels; and / or The inductance of the conductive loop in a direction perpendicular to the direction of movement of the mover is uniform.

1. An electric machine characterized by:

15. the current induced in each of the frequency programmable magnetic flux channels generates a magnetic field that opposes the alternating magnetic field induced between the stator and the mover, thereby creating a repulsive force; 2. A synchronous electric machine according to claim 1.

16. the repulsive force concentrates or redirects the magnetic flux of the magnetic field along a direction tangential to the direction of relative motion between the mover and the stator, increasing the force available for operation by the synchronous electric machine.

16. A synchronous electric machine according to claim 15.

17. the magnetic field opposing the alternating magnetic field is a reflective or obstructive magnetic field, whereby each of the frequency programmable flux channels controllably attenuates changes in magnetic flux throughout the synchronous electric machine during operation; 16. A synchronous electric machine according to claim 15.

18. further comprising controlling the magnetizing current and the load current pulses to change a magnetic characteristic of a motor including the mover and the stator.

10. The method of claim 9.

19. the magnetizing current generates a radial force vector relative to the axis of rotation of the mover, and the load current pulse generates a tangential force vector relative to the axis of rotation of the mover.

10. The motor control method of claim 9.

20. The supplying of the magnetizing current pulses for the specified time and the supplying of the load current pulses for the specified time are performed by rotating the armature in accordance with a sinusoidal drive frequency. in accordance with the ratio of the duration of the direct current to the duration of the reverse current pulse selected to harden the poles, 10. The motor control method of claim 9.

21. the ratio is 1:1, 100:1, 5:1, 15:1, or 9:1; 21. The motor control method of claim 20.

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