Generator with static DC magnetic field excitation

Abstract

Generators with static DC magnetic field excitation are disclosed that involve increased power density, efficiency, reliability and reduced complexity relative to conventional approaches. In one disclosed example, a generator (102) includes a stator (200), a stationary armature winding (202), a stationary direct current (DC) field winding, a magnetic shaft (208), and a DC power source (112). The magnetic shaft (208) includes a rotor pole structure including a north pole (214) and a south pole (216) axially offset relative to each other on the magnetic shaft (208) and positioned on opposite sides of the stationary DC field winding (204). A DC power source (112) is electrically connected to the stationary DC field winding (204) and is configured to induce a DC voltage in the stationary DC field winding (204) to generate a magnetic flux that is conducted through the magnetic shaft (208) and between the north pole (214) and the south pole (216) of the magnetic shaft (208).

Description

Technical Field

[0001] The present disclosure relates generally to the field of electronics, and more particularly to generators. Background Art

[0002] A conventional generator includes a shaft, an exciter, and a generator. The shaft is driven by a prime mover (such as an engine or a turbine) that provides mechanical energy to rotate the shaft. The exciter and the main generator include electronic components coupled to the shaft. In particular, the exciter includes a rotor winding and a rectifier that are coupled to the shaft and rotate based on the rotation of the shaft. In addition, the main generator includes an excitation winding that is coupled to the shaft and rotates based on the rotation of the shaft. In the exciter, the rotor winding induces an alternating current (AC) that is converted into a direct current (DC) current by the rectifier. The DC current output from the exciter is supplied to the excitation winding of the main generator to generate a magnetic field around the shaft. In the main generator, the magnetic field generated by the excitation winding interacts with the magnetic field generated by the rotation of the shaft to induce an output voltage in the stator winding of the main generator. The output voltage can be controlled and adjusted as needed to maintain a stable power supply by adjusting the DC current generated by the exciter.

[0003] Such conventional generators have various problems. As an example, the rotating electronic components coupled to the shaft make the conventional generator manufacturing relatively complex. This is because the rotating electronic components must be designed to be assembled in the internal cavity of the stator so that the shaft and the rotating electronic components can have a gap to rotate in the cavity. In addition, the electrical connection for the rotating electronic components is complicated. As another example, the rotating electronic components coupled to the shaft are prone to deterioration because they move constantly during operation. This reduces the reliability of conventional generators because conventional generators may not work properly when the rotating electronic components deteriorate. In addition, the operating cost of conventional generators is relatively high because the rotating electronic components need to be replaced more frequently when deteriorated. As another example, the rotating electronic components generate a large amount of thermal stress on the conventional generator, which needs to be solved via a cooling solution (such as an air cooling solution or an oil cooling solution). This cooling solution also increases the cost and complexity of conventional generators. Summary of the invention

[0004] Examples of generators having increased power density, efficiency, reliability, operating life, and reduced complexity and operating cost relative to conventional generators described above are disclosed. In one disclosed example, the generator includes a stator, a stationary armature winding, a stationary direct current (DC) field winding, a magnetic shaft, and a DC power supply. The magnetic shaft includes a rotor pole structure including a north pole and a south pole that are axially offset relative to each other on the magnetic shaft and are positioned on opposite sides of the stationary DC field winding. The DC power supply is electrically connected to the stationary DC field winding and is configured to induce a DC voltage in the stationary DC field winding to generate a magnetic flux that is conducted through the magnetic shaft and between the north pole and the south pole of the magnetic shaft.

[0005] The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 An exemplary embodiment of an aircraft including a generator of the present disclosure is schematically illustrated.

[0007] Figure 2 Shows Figure 1 Top view of the generator.

[0008] Figure 3 Shows Figure 1 Perspective view of a generator.

[0009] Figure 4 Shows Figure 1 A cross-sectional view of a generator.

[0010] Figure 5 A cross-sectional view of an exemplary embodiment of a generator including a flux path created by the generator is shown. DETAILED DESCRIPTION

[0011] Conventional generators have various problems associated with rotating electronic components coupled to the shaft of conventional generators. Therefore, the present disclosure is directed to a generator having increased power density, efficiency, reliability, operating life, and reduced complexity and operating cost relative to conventional generators. In one disclosed example, the generator includes a stator, a stationary armature winding, a stationary direct current (DC) field winding, a magnetic shaft, and a DC power supply. The magnetic shaft includes a rotor pole structure, the rotor pole structure including a north pole and a south pole, the north pole and the south pole being axially offset relative to each other on the magnetic shaft and being positioned on opposite sides of the stationary DC field winding. The DC power supply is electrically connected to the stationary DC field winding and is configured to induce a DC voltage in the stationary DC field winding to generate a magnetic flux, which is conducted through the magnetic shaft and between the north pole and the south pole of the magnetic shaft.

[0012] Because the armature windings and DC field windings are stationary in the generator rather than located on the shaft, the design and manufacturing complexity of the generator is reduced. As an example, the design of the stationary windings and the rotor pole structure on the shaft alleviates the need for exciter components, which significantly reduces the complexity of the generator. As another example, the electrical connections of these stationary windings are less complex than the electrical connections (e.g., brushes) of a traditional generator that includes rotating electronic components located on the shaft. As yet another example, the simplified shaft design allows airflow to be introduced through the internal cavity of the generator as the magnetic shaft rotates to reduce thermal stresses on the magnetic shaft. This allows the cooling scheme for the generator to be simplified or eliminated.

[0013] In addition, since the armature windings and DC field windings are stationary, the likelihood of these stationary windings deteriorating during generator operation is reduced relative to conventional generators where the electronic components located on the shaft are constantly rotating during operation. This increases the reliability and operating life of the generator relative to conventional generators and reduces operating costs.

[0014] These benefits make generators suitable for a variety of applications. As one example, in aircraft applications, generators can be used to generate electricity to meet the power needs of the aircraft. More specifically, generators can be employed to generate power for various onboard systems and devices, such as avionics devices, lighting systems, environmental control systems (ECS), galley devices, entertainment systems, and other electrical devices.

[0015] Figure 1 An exemplary embodiment of an aircraft 100 including a generator 102 of the present disclosure is schematically shown. The aircraft 100 includes an engine nacelle 104. Note that Figure 1 A phantom cutout 106 is depicted, which schematically illustrates relevant components within the nacelle 104 for discussion purposes. The cutout 106 does not exist in the actual nacelle 104 .

[0016] The aircraft 100 includes an engine 108 within the nacelle 104. In one example, the engine 108 is a gas turbine / jet engine configured to provide power to propel the aircraft 100. More specifically, a jet engine operates by compressing incoming air, mixing the air with fuel, combusting the mixture, and then expanding and accelerating the exhaust gases to generate thrust that overcomes drag and propels the aircraft 100 through the air during flight. In other embodiments, the engine 108 may take another form, such as a piston engine or a turboprop engine. The engine 108 may take any suitable form depending on the type of aircraft.

[0017] The auxiliary shaft 110 is driven by the engine 108 to provide mechanical power to drive various accessories and systems of the aircraft 100. The auxiliary shaft 110 is coupled to the generator 102. More specifically, the auxiliary shaft 110 is coupled to the magnetic shaft 206 of the generator 102 (at Figures 2 to 4 ), such that rotation of the auxiliary shaft 110 causes rotation of the magnetic shaft 206.

[0018] In some embodiments, the speed of the auxiliary shaft 110 varies with the speed of the engine 108. In other embodiments, the speed of the auxiliary shaft 110 may be controlled by a constant speed drive (not shown) and / or fixed at a constant speed.

[0019] The generator 102 is configured to convert mechanical energy generated by the rotation of the auxiliary shaft 110 into electrical energy for various electrical loads of the aircraft 100. In particular, the generator 102 includes a DC power source 112 configured to generate a DC field winding 204 ( Figure 2-Figure 4 ) to induce a DC voltage to generate a magnetic flux which is conducted through the magnetic axis 206 ( Figure 2-Figure 4 206 to produce an output voltage that satisfies the electrical load of the aircraft 100. The arrangement of the rotor pole structure 212 enables magnetic flux to flow along a flux path that extends three-dimensionally across the rotor pole structure in radial and axial directions relative to the magnetic axis 206. More specifically, the flux path travels between a north pole 214 and a south pole 216 of the magnetic axis 206, which are located on opposite sides of the stationary DC field winding 204.

[0020] Depending on the embodiment, the DC power source 112 can take various forms. In some embodiments, the DC power source 112 includes a battery. In other embodiments, the DC power source 112 includes a permanent magnet generator. The permanent magnet generator allows the generator 102 to have a "zero start" capability, wherein the generator 102 can self-start under conditions where the auxiliary shaft 110 is rotating slowly or not rotating. This feature improves the overall efficiency and reliability of the generator 102 because the generator 102 can generate electricity as long as conditions permit, helping to maximize energy production and reduce downtime. In other embodiments, the DC power source 112 includes a DC electrical bus. For example, in a fixed / stationary application for a generator, the DC electrical bus can be used as a DC power source.

[0021] The generator 102 includes a controller 114 configured to monitor the operation of the generator 102 and control the power output by the generator 102. Specifically, the controller 114 is configured to measure the output voltage of the generator 102. The controller 114 is configured to determine a feedback error based on at least a difference between the output voltage and a target voltage (e.g., corresponding to an electrical load of the aircraft 100 or an electrical subsystem). The controller 114 is configured to adjust the DC excitation current applied to the stationary DC excitation winding 204 based on the feedback error to adjust the strength of the magnetic flux conducted through the north pole 214 and the south pole 216 of the magnetic axis 206, and thereby adjust the output voltage to be consistent with the target voltage.

[0022] In some embodiments, generator 102 is configured to output AC power to AC electrical bus 116. AC electrical bus 116 is configured to supply AC power to a wide range of AC loads and systems on aircraft 100. In such embodiments, magnetic shaft 206 ( Figure 2-Figure 4 The speed of the AC power (as shown) and the frequency of the AC power output from the generator 102 are linearly coupled.

[0023] In other embodiments, the generator 102 is configured to output DC power. More specifically, in such embodiments, the generator 102 may optionally include a stationary rectifier 118 configured to convert a DC current into a DC current at the stationary armature winding 202 ( Figure 2 The AC power generated in the generator 102 is converted into DC power. The generator 102 is configured to output the DC power to the DC electrical bus 120. The DC electrical bus 120 is configured to supply the DC power to a wide range of DC loads and systems on the aircraft 100.

[0024] Example electrical systems of the aircraft 100 that may receive AC power or DC power output from the generator 102 include avionics devices, lighting systems, environmental control systems (ECS), galley devices, entertainment systems, and other electrical devices.

[0025] In some embodiments, the controller 114 is configured to adjust the frequency of the power output by the generator 102 to a desired output frequency. More specifically, the controller 114 may control the output frequency of the output power by adjusting the frequency of the DC excitation current applied to the stationary DC excitation winding 204. In some embodiments, the controller 114 may be configured to adjust the frequency of the DC excitation current based on the speed of the auxiliary shaft 110 (and / or the magnetic shaft 206).

[0026] In some embodiments where the magnetic shaft 206 rotates at a constant speed (e.g., controlled by a constant speed drive), the generator 102 is configured to output constant frequency AC power. In other embodiments where the speed of the magnetic shaft is variable (e.g., as a function of the speed of the auxiliary shaft 110), the generator 102 is configured to output variable frequency AC power.

[0027] In the illustrated embodiment, the generator 102 is configured to output power to various loads and systems in an aircraft. In other embodiments, the generator 102 may be configured to output power in other types of vehicles (e.g., automobiles, spacecraft, ships, submersibles, etc.). In other embodiments, the generator 102 may be employed in stationary applications. In some embodiments, the generator 102 may be configured to provide AC power to a propulsion engine of an aircraft or another type of vehicle. In such embodiments, the generator 102 may alternatively or additionally be configured to operate in a motor operation mode.

[0028] Figure 2-Figure 4 A schematic diagram showing the relevant components is shown. Figure 1 Different views of the generator 102 . Figure 2 A top view of the generator 102 is shown. Figure 3 A perspective view of the generator 102 is shown. Figure 4 A partial cross-sectional view of the generator 102 is shown. The generator 102 includes a stator 200, a stationary armature winding 202, a stationary DC field winding 204, and a magnetic shaft 206.

[0029] The stator 200 is configured to provide mechanical support and stability for the generator 102, and more specifically, maintain its position relative to the magnetic axis 206. The stator 200 is configured to accommodate the stationary armature winding 202. In one example, the stator 200 includes a stack of laminations having high magnetic permeability. A plurality of slots 208 are formed in the stator 200 to accommodate the stationary armature winding 202.

[0030] The stationary armature winding 202 includes a plurality of conductive wire bundles or a large solid bar arranged in a specific pattern in the stator 200 to generate a magnetic field when powered with an alternating current. For example, the plurality of conductive wire bundles of the stationary armature winding 202 may be arranged in a plurality of slots 208 formed in the stator 200 and wound around a stack of laminations. The stationary armature winding 202 may include a highly conductive material, such as copper or aluminum.

[0031] The stator 200 forms a cylindrical cavity 210, and a stationary DC field winding 204 is coupled within the cylindrical cavity 210. In one example, the stationary DC field winding 204 is mounted in the cylindrical cavity 210 along the inner diameter of the stator 200. Note that the stationary DC field winding 204 is fixed within the cylindrical cavity 210 and does not move with the magnetic axis 206.

[0032] The stationary DC field winding 204 is a source of magnetic flux flowing through the rotor pole structure 212 of the magnetic axis 206. The number of turns of the stationary DC field winding 204 may be selected based at least on DC current amplitude, terminal voltage regulation range, thermal / insulation requirements, and / or other parameters of the generator 102.

[0033] The magnetic shaft 206 extends axially through the cylindrical cavity 210 within the stator 200 and the stationary DC field winding 204. The magnetic shaft 206 serves as a flux conducting component as well as a mechanical structural component to support high speed rotation during operation.

[0034] In some embodiments, the magnetic shaft 206 includes a hollow cavity 218 extending axially within the magnetic shaft 206. The hollow cavity 218 reduces the weight of the magnetic shaft 206 and increases the heat dissipation characteristics of the magnetic shaft 206.

[0035] The magnetic axis 206 includes a rotor pole structure 212 including one or more north poles 214 extending radially outward from the magnetic axis 206 and one or more south poles 216 extending radially outward from the magnetic axis 206. The one or more north poles 214 and the one or more south poles 216 are axially spaced apart along the magnetic axis 206 and positioned on opposite sides of the stationary DC field winding 204. Further, the one or more north poles 214 are axially offset relative to the one or more south poles 216 on the magnetic axis 206. The offset / pole spacing of the north poles relative to each other and the south poles relative to each other, and the offset between the north pole and south pole pairs on opposite sides of the stationary DC field winding 204 form a rotor pole structure 212 on the magnetic axis 206 that allows the generator 102 to output three-phase power via the stationary armature winding 202. In other embodiments, the arrangement of the poles 214, 216 of the rotor pole structure 212 on the magnetic axis 206 may be different based on the phase of the power output by the generator 102. Further, in some embodiments, the offset of the poles 214, 216 may be based at least on a desired output frequency of the electrical power output by the generator 102. In some embodiments, the offset is measured by a number of degrees of electrical angle.

[0036] Additionally, the number of north and south poles on opposite sides of the stationary DC field winding 204 included in the rotor pole structure 212 may be based at least on the number of phases of the power output by the generator 102. In the illustrated embodiment, the rotor pole structure 212 includes six north poles 214A, 214B, 214C, 214D, 214E, 214F and six south poles 216A, 216B, 216C, 216D, 216E, 216F. The six north and south pole pairs are multiples of three and correspond to the generation of a three-phase power output by the generator 102.

[0037] The magnetic shaft 206 acts as a flux conducting member to allow magnetic flux to flow between the north pole and the south pole of the rotor pole structure 212. The arrangement of the rotor pole structure 212 enables the magnetic flux to flow along a flux path that extends transversely across the rotor pole structure in three dimensions in radial and axial directions relative to the magnetic shaft 206. More specifically, the flux path travels between the north pole 214 and the south pole 216 of the magnetic shaft 206, which are located on opposite sides of the stationary DC excitation winding 204. The stationary DC excitation winding 204 generates magnetic flux on the north pole 214 and the south pole 216 and couples the flux path of the magnetic flux to the stationary armature winding 202 to form a closed loop. The closed loop flux path allows the generator 102 to convert mechanical energy from the moving torque on the rotating magnetic shaft 206 into electrical power in the form of voltage and current in the stationary armature winding 202. Output terminals (not shown) may be electrically connected to the stationary armature winding 202 to distribute the electrical power generated by the generator 102 to various electrical loads and systems.

[0038] The rotor pole structure 212 of the magnetic shaft 206 is configured to introduce airflow through the stationary DC field winding 204 as the magnetic shaft 206 rotates during operation of the generator 102 in order to reduce thermal stress on the magnetic shaft 206. Specifically, the shape / design of the cavity 210, the rotor pole structure 212, and the stationary DC field winding 204 together form an air channel 220 that allows air to flow through the cavity 210. This air flow provides cooling for various components of the generator 102. In some embodiments, the generator 102 may optionally include a liquid cooling jacket formed within the stator to provide additional cooling capabilities.

[0039] Figure 5 A cross-sectional view of an exemplary embodiment of a generator 500 is shown. For example, the generator 500 may correspond to Figure 1 1. The generator 500 includes a single-stage design of a rotor pole structure and is configured to output DC power. The generator 500 includes a frame 502, a stator 504, a stationary armature winding 506, a stationary DC field winding 508, a magnetic shaft 510, a controller 512, a DC power supply 514, and a stationary rectifier 516.

[0040] The frame 502 is configured to support and enclose the electronic components of the generator 500. The frame 502 includes a liquid cooling jacket 518 configured to circulate a liquid coolant through the frame 502 to dissipate heat generated by the generator 500. In some embodiments, the liquid cooling jacket 518 can be incorporated into other components of the generator 500, such as the stator 504.

[0041] The stator 504 is configured to provide mechanical support and stability to the generator 500 and maintain its position relative to the magnetic axis 510. The stator 504 is configured to house a stationary armature winding 506. The stator 504 forms an internal cavity 520 extending axially therein.

[0042] The stationary armature winding 506 is coupled to and supported by the stator 504. The stationary armature winding 506 is electrically connected to a stationary rectifier 516.

[0043] The stationary DC field winding 508 is coupled to the stator 504 within the internal cavity 520. In one example, the stationary DC field winding 508 is mounted along the inner diameter of the stator 504. Note that the stationary DC field winding 508 is fixed within the internal cavity 520 and does not move with the magnetic axis 510.

[0044] The magnetic axis 510 extends through an interior cavity 520 formed by the stator 504 and the stationary DC field winding 508. The magnetic axis 510 includes a rotor pole structure 522 including a north pole 524 extending radially outward from the magnetic axis 510 and a south pole 526 extending radially outward from the magnetic axis 510. More specifically, the north pole 524 and the south pole 526 are axially spaced apart along the magnetic axis 510 and are positioned on opposite sides of the stationary DC field winding 508. Note that, although not discernible in this figure, the north pole 524 is axially offset on the magnetic axis 510 relative to the south pole 526.

[0045] In some embodiments, the magnetic shaft 510 includes a hollow cavity 528 extending axially within the magnetic shaft 510. The hollow cavity 528 reduces the weight of the magnetic shaft 510 and improves the heat dissipation characteristics of the magnetic shaft 510.

[0046] The DC power supply 514 is electrically connected to the stationary DC excitation winding 508. When the magnetic shaft 510 rotates in the electromagnetic induction process, the DC power supply 514 is configured to induce a DC excitation voltage and current in the stationary DC excitation winding 508 to generate magnetic flux based on the interaction between the north pole 524, the south pole 526 and the stationary DC excitation winding 508. The magnetic flux is conducted through the magnetic shaft 510 and the stator 504, and between the north pole 524 and the south pole 526. Specifically, the magnetic flux follows a flux path 530 that extends laterally across the rotor pole structure 522 and extends three-dimensionally in radial and axial directions relative to the magnetic shaft 510.

[0047] In some embodiments, the DC power source comprises a battery. In some embodiments, the DC power source comprises a DC electrical bus. In some embodiments, the DC power source comprises a permanent magnet generator.

[0048] The magnetic flux generates AC power in the stationary armature winding 506. The stationary armature winding 506 is electrically connected to a stationary rectifier 516. The stationary rectifier 516 is configured to convert the AC power generated in the stationary armature winding into DC power. The generator 500 is configured to output the DC power from the stationary rectifier 516 to various electrical loads and systems.

[0049] The controller 512 is configured to measure the output voltage of the DC power output by the generator 500. Further, the controller 512 is configured to determine a feedback error based at least on the difference between the output voltage and the target voltage. For example, the target voltage may correspond to the voltage of the electrical load. The controller 512 is configured to adjust the DC excitation voltage and / or current applied to the stationary DC excitation winding 58 based on the feedback error to adjust the intensity of the magnetic flux, and thereby adjust the output voltage to be consistent with the target voltage. In some embodiments, the controller 512 is configured to adjust the frequency of the DC power output by the generator 500 in a similar manner based on the feedback.

[0050] The design complexity of various embodiments of the generator disclosed herein is significantly reduced relative to conventional generators, which results in a generator having a reduced number of components and assemblies, more specifically, a reduction in moving parts. This allows for low cost, faster and easier manufacture and maintenance of the generator. Furthermore, these features of the generator result in a longer operating life and reduced operating costs relative to conventional generators.

[0051] In an example, a generator includes: a stator; a stationary armature winding coupled to the stator; a stationary direct current (DC) field winding coupled to the stator; a magnetic axis extending through the stator and the stationary DC field winding and including a rotor pole structure, the rotor pole structure including one or more north poles extending radially outward from the magnetic axis and one or more south poles extending radially outward from the magnetic axis, wherein the one or more north poles and the one or more south poles are axially spaced apart along the magnetic axis and positioned on opposite sides of the stationary DC field winding, and wherein the one or more north poles are axially offset on the magnetic axis relative to the one or more south poles; and a DC power source electrically connected to the stationary DC field winding and configured to induce a DC voltage in the stationary DC field winding to generate a magnetic flux that is directed through the magnetic axis and between the one or more north poles and the one or more south poles of the magnetic axis. In this example and / or other examples, the generator can be configured to output alternating current (AC) power, and the speed of the magnetic axis and the frequency of the AC power output from the generator can be linearly coupled. In this example and / or other examples, the speed of the magnetic shaft can be constant, and the generator can be configured to output constant frequency AC power. In this example and / or other examples, the speed of the magnetic shaft can be variable, and the generator can be configured to output variable frequency AC power. In this example and / or other examples, the magnetic shaft can be coupled to a variable speed shaft of an engine of an aircraft. In this example and / or other examples, the generator can further include a stationary rectifier electrically connected to a stationary armature winding and configured to convert AC power generated in the stationary armature winding into DC power, and the generator can be configured to output DC power. In this example and / or other examples, the generator can further include a controller configured to 1) measure the output voltage of the generator, 2) determine a feedback error based on at least the difference between the output voltage and the target voltage, and 3) adjust the DC excitation current applied to the stationary DC excitation winding based on the feedback error to adjust the intensity of the magnetic flux and thereby adjust the output voltage to be consistent with the target voltage. In this example and / or other examples, the rotor pole structure of the magnetic shaft can be configured to introduce airflow through the stationary DC excitation winding when the magnetic shaft rotates. In this example and / or other examples, the DC power supply can include a battery. In this example and / or other examples, the DC power supply can include a DC electrical bus. In this example and / or other examples, the DC power supply can include a permanent magnet generator.

[0052] In another example, a generator includes: a stator; a stationary armature winding coupled to the stator; a stationary direct current (DC) field winding coupled to the stator; a magnetic axis extending through the stator and the stationary DC field winding and including a rotor pole structure, the rotor pole structure including one or more north poles extending radially outward from the magnetic axis and one or more south poles extending radially outward from the magnetic axis, wherein the one or more north poles and the one or more south poles are axially spaced apart along the magnetic axis and positioned on opposite sides of the stationary DC field winding, and wherein the one or more north poles are axially spaced apart on the magnetic axis relative to the one or more south poles. A DC power supply electrically connected to the stationary DC field winding and configured to induce a DC voltage in the stationary DC field winding to generate a magnetic flux, which is guided through the magnetic axis and between the one or more north poles and the one or more south poles of the magnetic axis; and a controller configured to 1) measure the output voltage of the generator; 2) determine a feedback error based on at least the difference between the output voltage and the target voltage; and 3) adjust the DC field current applied to the stationary DC field winding based on the feedback error to adjust the intensity of the magnetic flux, thereby adjusting the output voltage to be consistent with the target voltage. In this example and / or other examples, the generator can be configured to output alternating current (AC) power, and the speed of the magnetic shaft and the frequency of the AC power output from the generator can be linearly coupled. In this example and / or other examples, the speed of the magnetic shaft can be constant, and the generator can be configured to output constant frequency AC power. In this example and / or other examples, the speed of the magnetic shaft can be variable, and the generator can be configured to output variable frequency AC power. In this example and / or other examples, the magnetic shaft may be coupled to a variable speed shaft of an engine of the aircraft. In this example and / or other examples, the generator may further include a rectifier electrically connected to the stationary armature winding and configured to convert the AC power generated in the stationary armature winding into DC power, and the generator may be configured to output DC power. In this example and / or other examples, the DC power source may include a battery. In this example and / or other examples, the DC power source may include a permanent magnet generator (PMG).

[0053] In yet another example, a generator includes a stator; a stationary armature winding coupled to the stator; a stationary direct current (DC) field winding coupled to the stator; a magnetic axis extending through the stator and the stationary DC field winding and including a rotor pole structure, the rotor pole structure including one or more north poles extending radially outward from the magnetic axis and one or more south poles extending radially outward from the magnetic axis, wherein the one or more north poles and the one or more south poles are axially spaced apart along the magnetic axis and positioned on opposite sides of the stationary DC field winding, and wherein the one or more north poles are axially offset on the magnetic axis relative to the one or more south poles; and a DC power supply electrically connected to the stationary DC field winding and configured to induce a DC voltage in the stationary DC field winding to generate a magnetic flux that is directed through the magnetic axis and between the one or more north poles and the one or more south poles of the magnetic axis, wherein the generator is configured to output alternating current (AC) power, and wherein a speed of the magnetic shaft and a frequency of the AC power output from the generator are linearly coupled.

[0054] The present disclosure includes all novel and non-obvious combinations and sub-combinations of the various features and techniques disclosed herein. The various features and techniques disclosed herein are not necessarily required for all examples of the present disclosure. In addition, the various features and techniques disclosed herein may define patentable subject matter other than the disclosed examples, and may find utility in other implementations not explicitly disclosed herein.

Claims

1. A generator (102), comprising: stator(200); A stationary armature winding (202) coupled to the stator (200); A stationary DC excitation winding (204) connected to the stator (200); a magnetic axis (208) extending through the stator (200) and the stationary DC field winding (204) and comprising a rotor pole structure (212), the rotor pole structure (212) comprising one or more north poles (214) extending radially outward from the magnetic axis (208) and one or more south poles (216) extending radially outward from the magnetic axis (208), wherein the one or more north poles (214) and the one or more south poles (216) are axially spaced apart along the magnetic axis (208) and positioned on opposite sides of the stationary DC field winding (204), and wherein the one or more north poles (214) are axially offset on the magnetic axis (208) relative to the one or more south poles (216); and A DC power source (112) is electrically connected to the stationary DC field winding (204) and is configured to induce a DC voltage in the stationary DC field winding (204) to generate a magnetic flux that is directed through the magnetic axis (208) and between the one or more north poles (214) and the one or more south poles (216) of the magnetic axis (208).

2. The generator (102) according to claim 1, wherein: The generator (102) is configured to output alternating current (AC) power, and wherein a speed of the magnetic shaft (208) and a frequency of the AC power output from the generator (102) are linearly coupled.

3. The generator (102) according to claim 2, wherein: The speed of the magnetic shaft (208) is constant, and wherein the generator (102) is configured to output constant frequency AC power.

4. The generator (102) according to claim 2, wherein: The speed of the magnetic shaft (208) is variable, and wherein the generator (102) is configured to output variable frequency AC power.

5. The generator (102) according to claim 4, wherein: The magnetic shaft (208) is coupled to a transmission shaft (110) of an engine (108) of an aircraft (100).

6. The generator (102) according to claim 1, further comprising: A stationary rectifier (516) is electrically connected to the stationary armature winding (202) and is configured to convert AC power generated in the stationary armature winding (202) into DC power, and wherein the generator (102) is configured to output the DC power.

7. The generator (102) according to claim 1, further comprising: The controller (512) is configured to 1) measure the output voltage of the generator; 2) determining a feedback error based at least on a difference between the output voltage and a target voltage, and 3) adjusting a DC field current applied to the stationary DC field winding based on the feedback error to adjust the strength of the magnetic flux and thereby adjust the output voltage to be consistent with the target voltage.

8. The generator (102) according to claim 1, wherein: The rotor pole structure (212) of the magnetic shaft (208) is configured to induce airflow through the stationary DC field winding (204) as the magnetic shaft (208) rotates.

9. A generator (102), comprising: stator(200); A stationary armature winding (202) coupled to the stator (200); A stationary DC excitation winding (204) connected to the stator (200); a magnetic axis (208) extending through the stator (200) and the stationary DC field winding (204) and comprising a rotor pole structure, the rotor pole structure comprising one or more north poles (214) extending radially outward from the magnetic axis (208) and one or more south poles (216) extending radially outward from the magnetic axis (208), wherein the one or more north poles (214) and the one or more south poles (216) are axially spaced apart along the magnetic axis (208) and positioned on opposite sides of the stationary DC field winding (204), and wherein the one or more north poles (214) are axially offset on the magnetic axis (208) relative to the one or more south poles (216); a DC power source (112) electrically connected to the stationary DC field winding (204) and configured to induce a DC voltage in the stationary DC field winding (204) to generate a magnetic flux directed through the magnetic axis (208) and between the one or more north poles (214) and the one or more south poles (216) of the magnetic axis (208); and A controller is configured to 1) measure an output voltage of the generator (102), 2) determine a feedback error based on at least a difference between the output voltage and a target voltage, and 3) adjust a DC excitation current applied to the stationary DC excitation winding (204) based on the feedback error to adjust the intensity of the magnetic flux and thereby adjust the output voltage to be consistent with the target voltage.

10. A generator (102), comprising: stator(200); A stationary armature winding (202) coupled to the stator (200); A stationary DC excitation winding (204) connected to the stator (200); a magnetic axis (208) extending through the stator and the stationary DC field winding (204) and comprising a rotor pole structure comprising one or more north poles (214) extending radially outward from the magnetic axis (208) and one or more south poles (216) extending radially outward from the magnetic axis (208), wherein the one or more north poles (214) and the one or more south poles (216) are axially spaced apart along the magnetic axis (208) and positioned on opposite sides of the stationary DC field winding (204), and wherein the one or more north poles (214) are axially offset on the magnetic axis (208) relative to the one or more south poles (216); and a DC power source (112) electrically connected to the stationary DC field winding (204) and configured to induce a DC voltage in the stationary DC field winding (204) to generate a magnetic flux directed through the magnetic axis (208) and between the one or more north poles (214) and the one or more south poles (216) of the magnetic axis (208); The generator (102) is configured to output alternating current (AC) power, and the speed of the magnetic shaft (208) and the frequency of the AC power output from the generator (102) are linearly coupled.

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