US20020149289A1 - Permanent magnet type rotary electric machine and electrically driven vehicle using the same - Google Patents
Permanent magnet type rotary electric machine and electrically driven vehicle using the same Download PDFInfo
- Publication number
- US20020149289A1 US20020149289A1 US10/107,245 US10724502A US2002149289A1 US 20020149289 A1 US20020149289 A1 US 20020149289A1 US 10724502 A US10724502 A US 10724502A US 2002149289 A1 US2002149289 A1 US 2002149289A1
- Authority
- US
- United States
- Prior art keywords
- rotor core
- stator
- core
- rotor
- electric machine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K1/00—Arrangement or mounting of electrical propulsion units
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
- B60L3/0061—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electrical machines
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L50/00—Electric propulsion with power supplied within the vehicle
- B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
- B60L50/51—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells characterised by AC-motors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L50/00—Electric propulsion with power supplied within the vehicle
- B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
- B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
- B60L50/66—Arrangements of batteries
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/10—Vehicle control parameters
- B60L2240/36—Temperature of vehicle components or parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/421—Speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/423—Torque
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/425—Temperature
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
Definitions
- the present invention relates to a compact, lightweight, high-torque permanent magnet type rotary electric machine suitable for use at high temperatures, and also to an electrically driven vehicle using the rotary electric machine.
- a driving motor for use in an electrically driven vehicle, especially, in an electric vehicle is desired to have a compact, lightweight configuration and high efficiency, because the capacity of a battery mounted on the electric vehicle is limited and it is necessary to ensure a sufficient distance traveled by the capacity of the battery once fully charged.
- a permanent magnet motor is recommendable rather than a DC motor and an induction motor.
- a so-called internal magnet motor having a permanent magnet holding portion in a steel plate, e.g., a silicon steel plate, having a permeability higher than that of permanent magnets is suitable for the high-efficient motor. The reason is that the internal magnet motor can be operated up to high speeds by field weakening control and can be operated with high efficiency by field weakening control.
- the rotor of the internal magnet motor has an advantage such that the rotational strength of the rotor is determined by the strength of the silicon steel plate, resulting in high reliability in high-speed rotation.
- An example of such a motor configuration is disclosed in Japanese Patent Laid-open No. 3-138050.
- the motor configuration disclosed in this publication is such that permanent magnets are embedded in a rotor core formed of a magnetic material having a permeability higher than that of the permanent magnets, and that auxiliary magnetic poles composed of the permanent magnets and the rotor core are arranged in a circumferential portion of the rotor core.
- the motor configuration disclosed in the above publication has no consideration on a fixing method for the permanent magnets, especially, on a fixing method for the permanent magnets in the axial direction of the rotor core.
- the above publication describes that the permanent magnets are bonded in holes, there is a possibility that the permanent magnets may axially escape from the holes because of a reduction in adhesive strength by bonding only in the case of a rotary electric machine to be operated at high temperatures.
- each side ring is formed of a nonmagnetic material to prevent short of magnetic flux.
- an eddy current is generated in each side ring by a change in magnetic flux from stator windings, because of conductivity of the metal material, causing abnormal heating of each side ring. Accordingly, there is a possibility of high-temperature demagnetization of the permanent magnets due to the heat from each side ring.
- the outer diameter of each of a pair of retainer plates mounted on the axial ends of a rotor core is set smaller than the outer diameter of the rotor core, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from stator windings.
- the difference between the outer diameter of the rotor core and the outer diameter of each retainer plate is set to 1 ⁇ 2 or more of the difference between the inner diameter of the stator core and the outer diameter of the rotor core.
- each retainer plate is formed of a metal material having a resistivity of 10 ⁇ cm or higher, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- each retainer plate is set smaller than the outer diameter of the rotor core, and each retainer plate is formed of a metal material having a resistivity of 10 ⁇ cm or higher, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- each retainer plate is a nonmagnetic member formed of a nonmetal material, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- an electrically driven vehicle comprising a battery for supplying a DC voltage; an inverter for converting the DC voltage supplied from the battery into an AC voltage; and a permanent magnet type rotary electric machine for outputting a drive torque for driving the vehicle at the AC voltage.
- the permanent magnet type rotary electric machine in this electrically driven vehicle is the permanent magnet type rotary electric machine according to the present invention.
- FIG. 1 is an axial sectional view of a permanent magnet type rotary electric machine according to a preferred embodiment of the present invention
- FIG. 2 is a cross section taken along the line A-A in FIG. 1;
- FIG. 3 is an enlarged view of a portion B shown in FIG. 1;
- FIG. 4 is a perspective view showing a schematic configuration of an electric vehicle using the permanent magnet type rotary electric machine of the present invention.
- FIG. 1 is an axial sectional view of a permanent magnet type rotary electric machine (which will be hereinafter referred to simply as a rotary electric machine) 1 according to a preferred embodiment of the present invention
- FIG. 2 is a cross section taken along the line A-A in FIG. 1.
- the rotary electric machine 1 is composed generally of a stator 2 and a rotor 3 .
- the stator 2 is composed of a cylindrical housing 10 , an end bracket 11 fixed to the housing 10 by bolts, a cylindrical stator core 4 fixed to the inner circumferential surface of the housing 10 , and a plurality of stator windings 5 wound on the stator core 4 .
- the rotor 3 is composed of a cylindrical rotor core 8 , a plurality of permanent magnets 6 inserted in a plurality of holes 7 formed in the rotor core 8 near its outer circumferential surface, a rotating shaft 9 fixed to the rotor core 8 at its central portion, and a pair of side rings 81 mounted on the axial opposite ends of the rotor core 8 for retaining the rotor core 8 and the permanent magnets 6 .
- the rotating shaft 9 is rotatably supported at its opposite ends to a pair of bearings 12 fixed to the end bracket 11 and the housing 10 .
- the end bracket 11 is screwed to be fixed to the housing 10 of the rotator 2 side.
- Each of the permanent magnets 6 is arcuate as shown in FIG. 2, and they are arranged in the circumferential direction of the rotor core 8 with a given pitch.
- the shape of each permanent magnet 6 is merely illustrative and not limitative in the present invention.
- Each side ring 81 is formed of a nonmagnetic material to prevent short of the magnetic flux generated by the permanent magnets 6 .
- each side ring 81 is formed of a nonmagnetic metal material, it is affected by a change in the magnetic flux generated by the stator windings 5 because of the conductivity of the metal material, resulting in generation of an eddy current in each side ring 81 to cause abnormal heating of each side ring 81 .
- This heat is transmitted to the permanent magnets 6 to possibly demagnetize the permanent magnets 6 .
- each permanent magnet 6 is a rare-earth magnet, it has such a characteristic that demagnetization tends to occur at high temperatures. Therefore, it is necessary to prevent heating of each side ring 81 , thereby preventing a reduction in performance of the rotary electric machine.
- each side ring 81 is set smaller than the outer diameter of the rotor core 8 .
- FIG. 3 is an enlarged view of a portion B shown in FIG. 1.
- the difference between the outer diameter D 2 of the rotor core 8 and the outer diameter D 3 of each side ring 81 is set preferably to 1 ⁇ 2 or more of the difference between the inner diameter D 1 of the stator core 4 and the outer diameter D 2 of the rotor core 8 .
- ⁇ 1 is the difference between the inner diameter D 1 of the stator core 4 and the outer diameter D 2 of the rotor core 8
- k is the constant determined by a shape, a voltage input to the stator, etc.
- Eq. (1) also holds for the difference ⁇ 2 between the outer diameter D 2 of the rotor core 8 and the outer diameter D 3 of each side ring 81 , so that the relation between F and ⁇ 2 is shown in Table 1.
- Table 1 F Ratio of decrease in F to ⁇ 2 0.5 4 k — the same as ⁇ 1 0.6 2.8 k 70% 0.75 1.8 k 45% 1.5 times ⁇ 1 1.00 1.0 k 25% 1.25 0.64 k 16%
- the influence of an eddy current generated in each side ring 81 due to the magnetic flux generated by the stator windings 5 can be reduced to a half or less by setting ⁇ 2 to a value 1.5 times or more ⁇ 1 , i.e., by setting the difference between the outer diameter D 2 of the rotor core 8 and the outer diameter D 3 of each side ring 81 to 1 ⁇ 2 or more of the difference between the inner diameter D 1 of the stator core 4 and the outer diameter D 2 of the rotor core 8 .
- R is the electrical resistance
- the influence of the eddy current is reduced in proportion to the square of a distance, so that it is preferable to maximize the difference ⁇ 2 between the outer diameter of the rotor core 8 and the outer diameter of each side ring 81 .
- each side ring 81 It is sufficient to use a nonmagnetic material as the material of each side ring 81 .
- the nonmagnetic material is a material having a relatively low resistivity, such as copper and aluminum, the amperage of the eddy current is large. Accordingly, a nonmagnetic metal material having a relatively high resistivity of 10 ⁇ cm or higher, such as stainless steel, is preferable as the material of each side ring 81 .
- An increase in resistivity means an increase in electrical resistance R in the following equation.
- E is the voltage induced to each side ring.
- each side ring 81 is set smaller than the outer diameter of the rotor core 8 , and the material of each side ring 81 is a metal material such as stainless steel having a resistivity of 10 ⁇ cm or higher, thereby enhancing the effect.
- a nonmetal material such as resin may also be used as the material of each side ring 81 .
- the resistivity of a resin material is much higher than that of a metal material, so that no eddy current flows in each side ring 81 , thereby eliminating abnormal heating.
- a method of mounting platelike members of resin on the opposite ends of the rotor core 8 and a resin molding method of molding the opposite ends of the rotor core 8 with resin may be realized.
- the present invention is applicable alto to a rotary electric machine employing an external rotor or the like having a structure such that both sides of magnets are sandwiched by a pair of side rings.
- the rotary electric machine of the present invention is effective in the case that it is used as a drive motor for an electrically driven vehicle.
- FIG. 4 As an example of the electrically driven vehicle using the rotary electric machine of the present invention as a drive motor, a schematic configuration of an electric vehicle is shown in FIG. 4.
- the electric vehicle includes a rotary electric machine 10 according to the present invention, a battery 20 for supplying a DC voltage, an inverter 30 for converting the DC voltage supplied from the battery into an AC voltage, and a control unit 40 for controlling a drive torque and a rotating speed of the rotary electric machine 10 . Accordingly, the drive wheels of the vehicle are driven by the rotary electric machine 10 with a given torque and rotating speed controlled by the control unit 40 .
- the rotary electric machine of the present invention can suppress a temperature rise as compared with a conventional rotary electric machine. Accordingly, the rotary electric machine of the present invention can be reduced in size to contribute to mountability on the vehicle and weight reduction of the vehicle, thereby improving the performance of the vehicle.
- thermal demagnetization of the permanent magnets can be prevented to thereby effect a reduction in size and weight of the permanent magnet type rotary electric machine and also effect a high torque thereof.
- the vehicle can be reduced in weight to thereby improve the performance of the vehicle.
Abstract
A plurality of permanent magnets 6 are embedded in a cylindrical rotor core 8 and arranged in a circumferential direction of the rotor core 8. A pair of side rings 81 are mounted on the axial ends of the rotor core 8. The outer diameter of each side ring 81 is set smaller than the outer diameter of the rotor core 8. With this structure, an eddy current generated in each side ring 81 can be suppressed to thereby prevent abnormal heating and accordingly prevent thermal demagnetization of the permanent magnets 6.
Description
- The present invention relates to a compact, lightweight, high-torque permanent magnet type rotary electric machine suitable for use at high temperatures, and also to an electrically driven vehicle using the rotary electric machine.
- A driving motor for use in an electrically driven vehicle, especially, in an electric vehicle is desired to have a compact, lightweight configuration and high efficiency, because the capacity of a battery mounted on the electric vehicle is limited and it is necessary to ensure a sufficient distance traveled by the capacity of the battery once fully charged.
- To make a motor compact and lightweight, it is desired to be fit for high-speed rotation. Further, as a high-efficient motor, a permanent magnet motor is recommendable rather than a DC motor and an induction motor. In particular, as compared with a surface magnet motor having permanent magnets on the outer circumferential surface of a rotor, a so-called internal magnet motor having a permanent magnet holding portion in a steel plate, e.g., a silicon steel plate, having a permeability higher than that of permanent magnets is suitable for the high-efficient motor. The reason is that the internal magnet motor can be operated up to high speeds by field weakening control and can be operated with high efficiency by field weakening control.
- Further, as compared with the rotor of the surface magnet motor, the rotor of the internal magnet motor has an advantage such that the rotational strength of the rotor is determined by the strength of the silicon steel plate, resulting in high reliability in high-speed rotation. An example of such a motor configuration is disclosed in Japanese Patent Laid-open No. 3-138050.
- The motor configuration disclosed in this publication is such that permanent magnets are embedded in a rotor core formed of a magnetic material having a permeability higher than that of the permanent magnets, and that auxiliary magnetic poles composed of the permanent magnets and the rotor core are arranged in a circumferential portion of the rotor core. By forming such an internal magnet configuration that the permanent magnets are embedded in the rotor core formed of a magnetic material having a permeability higher than that of the permanent magnets, field weakening control can be performed and the motor can be operated with high efficiency up to a high-speed region.
- However, the motor configuration disclosed in the above publication has no consideration on a fixing method for the permanent magnets, especially, on a fixing method for the permanent magnets in the axial direction of the rotor core. Although the above publication describes that the permanent magnets are bonded in holes, there is a possibility that the permanent magnets may axially escape from the holes because of a reduction in adhesive strength by bonding only in the case of a rotary electric machine to be operated at high temperatures.
- To cope with this problem, a pair of retainer plates (which will be hereinafter referred to as side rings) for preventing the escape of the permanent magnets are mounted on the axial ends of the rotor. Each side ring is formed of a nonmagnetic material to prevent short of magnetic flux. However, in the case that each side ring is formed of a metal material, an eddy current is generated in each side ring by a change in magnetic flux from stator windings, because of conductivity of the metal material, causing abnormal heating of each side ring. Accordingly, there is a possibility of high-temperature demagnetization of the permanent magnets due to the heat from each side ring.
- It is accordingly an object of the present invention to provide a permanent magnet type rotary electric machine which can prevent thermal demagnetization of the permanent magnets to thereby effect a reduction in size and weight and a high torque.
- It is another object of the present invention to provide an electrically driven vehicle using the permanent magnet type rotary electric machine.
- According to an aspect of the present invention, the outer diameter of each of a pair of retainer plates mounted on the axial ends of a rotor core is set smaller than the outer diameter of the rotor core, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from stator windings.
- Preferably, the difference between the outer diameter of the rotor core and the outer diameter of each retainer plate is set to ½ or more of the difference between the inner diameter of the stator core and the outer diameter of the rotor core.
- According to another aspect of the present invention, each retainer plate is formed of a metal material having a resistivity of 10 μΩcm or higher, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- According to a further aspect of the present invention, the outer diameter of each retainer plate is set smaller than the outer diameter of the rotor core, and each retainer plate is formed of a metal material having a resistivity of 10 μΩcm or higher, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- According to a still further aspect of the present invention, each retainer plate is a nonmagnetic member formed of a nonmetal material, thereby suppressing the generation of an eddy current in each retainer plate due to magnetic flux from the stator windings.
- According to a still further aspect of the present invention, there is provided an electrically driven vehicle comprising a battery for supplying a DC voltage; an inverter for converting the DC voltage supplied from the battery into an AC voltage; and a permanent magnet type rotary electric machine for outputting a drive torque for driving the vehicle at the AC voltage. The permanent magnet type rotary electric machine in this electrically driven vehicle is the permanent magnet type rotary electric machine according to the present invention.
- FIG. 1 is an axial sectional view of a permanent magnet type rotary electric machine according to a preferred embodiment of the present invention;
- FIG. 2 is a cross section taken along the line A-A in FIG. 1;
- FIG. 3 is an enlarged view of a portion B shown in FIG. 1; and
- FIG. 4 is a perspective view showing a schematic configuration of an electric vehicle using the permanent magnet type rotary electric machine of the present invention.
-
- There will now be described a permanent magnet type rotary electric machine and an electrically driven vehicle using the same according to a preferred embodiment of the present invention with reference to the drawings.
- FIG. 1 is an axial sectional view of a permanent magnet type rotary electric machine (which will be hereinafter referred to simply as a rotary electric machine)1 according to a preferred embodiment of the present invention, and FIG. 2 is a cross section taken along the line A-A in FIG. 1. The rotary electric machine 1 is composed generally of a
stator 2 and arotor 3. - The
stator 2 is composed of acylindrical housing 10, an end bracket 11 fixed to thehousing 10 by bolts, acylindrical stator core 4 fixed to the inner circumferential surface of thehousing 10, and a plurality ofstator windings 5 wound on thestator core 4. - The
rotor 3 is composed of acylindrical rotor core 8, a plurality ofpermanent magnets 6 inserted in a plurality ofholes 7 formed in therotor core 8 near its outer circumferential surface, arotating shaft 9 fixed to therotor core 8 at its central portion, and a pair ofside rings 81 mounted on the axial opposite ends of therotor core 8 for retaining therotor core 8 and thepermanent magnets 6. The rotatingshaft 9 is rotatably supported at its opposite ends to a pair ofbearings 12 fixed to the end bracket 11 and thehousing 10. The end bracket 11 is screwed to be fixed to thehousing 10 of therotator 2 side. Each of thepermanent magnets 6 is arcuate as shown in FIG. 2, and they are arranged in the circumferential direction of therotor core 8 with a given pitch. However, the shape of eachpermanent magnet 6 is merely illustrative and not limitative in the present invention. - Each
side ring 81 is formed of a nonmagnetic material to prevent short of the magnetic flux generated by thepermanent magnets 6. In the case that eachside ring 81 is formed of a nonmagnetic metal material, it is affected by a change in the magnetic flux generated by thestator windings 5 because of the conductivity of the metal material, resulting in generation of an eddy current in eachside ring 81 to cause abnormal heating of eachside ring 81. This heat is transmitted to thepermanent magnets 6 to possibly demagnetize thepermanent magnets 6. Particularly in the case that eachpermanent magnet 6 is a rare-earth magnet, it has such a characteristic that demagnetization tends to occur at high temperatures. Therefore, it is necessary to prevent heating of eachside ring 81, thereby preventing a reduction in performance of the rotary electric machine. - To reduce the influence of a change in magnetic flux from the
stator windings 5 and thereby suppress the generation of an eddy current, the outer diameter of eachside ring 81 is set smaller than the outer diameter of therotor core 8. - Such a diameter difference will now be described in more detail with reference to FIG. 3 which is an enlarged view of a portion B shown in FIG. 1. The difference between the outer diameter D2 of the
rotor core 8 and the outer diameter D3 of eachside ring 81 is set preferably to ½ or more of the difference between the inner diameter D1 of thestator core 4 and the outer diameter D2 of therotor core 8. - The reason for this setting will now be described.
- In considering the influence of an eddy current on each
side ring 81 as a force F acting between thestator core 4 and therotor core 8, the following equation holds. - F=k·1/δ1 2 (1)
- where δ1 is the difference between the inner diameter D1 of the
stator core 4 and the outer diameter D2 of therotor core 8, and k is the constant determined by a shape, a voltage input to the stator, etc. - Eq. (1) also holds for the difference δ2 between the outer diameter D2 of the
rotor core 8 and the outer diameter D3 of eachside ring 81, so that the relation between F and δ2 is shown in Table 1.TABLE 1 δ2 F Ratio of decrease in F to δ2 0.5 4 k — the same as δ1 0.6 2.8 k 70% 0.75 1.8 k 45% 1.5 times δ1 1.00 1.0 k 25% 1.25 0.64 k 16% - As understood from Table 1, the influence of an eddy current generated in each
side ring 81 due to the magnetic flux generated by thestator windings 5 can be reduced to a half or less by setting δ2 to a value 1.5 times or more δ1, i.e., by setting the difference between the outer diameter D2 of therotor core 8 and the outer diameter D3 of eachside ring 81 to ½ or more of the difference between the inner diameter D1 of thestator core 4 and the outer diameter D2 of therotor core 8. - When the eddy current becomes a half, the loss W is reduced to ¼ in accordance with the following equation.
- W=I 2 ·R (2)
- where R is the electrical resistance.
- Accordingly, a temperature rise of each
side ring 81 is also reduced to ¼. - Thus, the influence of the eddy current is reduced in proportion to the square of a distance, so that it is preferable to maximize the difference δ2 between the outer diameter of the
rotor core 8 and the outer diameter of eachside ring 81. - It is sufficient to use a nonmagnetic material as the material of each
side ring 81. However, if the nonmagnetic material is a material having a relatively low resistivity, such as copper and aluminum, the amperage of the eddy current is large. Accordingly, a nonmagnetic metal material having a relatively high resistivity of 10 μΩcm or higher, such as stainless steel, is preferable as the material of eachside ring 81. - An increase in resistivity means an increase in electrical resistance R in the following equation.
- I=E/R (3)
- where E is the voltage induced to each side ring.
- In comparing aluminum (resistivity: 2.8 μΩcm) and stainless steel (resistivity: 10 μΩcm), the resistivity of stainless steel is higher than the resistivity of aluminum by 3.6 times. Accordingly, the amperage in stainless steel becomes {fraction (1/3.6)} of the amperage in aluminum, and a temperature rise in stainless steel can be reduced to {fraction (1/13)} of that in aluminum.
- More preferably, the above-mentioned two features are combined. That is, the outer diameter of each
side ring 81 is set smaller than the outer diameter of therotor core 8, and the material of eachside ring 81 is a metal material such as stainless steel having a resistivity of 10 μΩcm or higher, thereby enhancing the effect. - Further, if the operating temperature condition and the rotational strength of the rotary electric machine1 are allowed, a nonmetal material such as resin may also be used as the material of each
side ring 81. The resistivity of a resin material is much higher than that of a metal material, so that no eddy current flows in eachside ring 81, thereby eliminating abnormal heating. In the case of applying a resin material to the opposite ends of therotor core 8 to configure the side rings 81, a method of mounting platelike members of resin on the opposite ends of therotor core 8 and a resin molding method of molding the opposite ends of therotor core 8 with resin may be realized. - Having thus described a specific preferred embodiment employing an internal rotor, the present invention is applicable alto to a rotary electric machine employing an external rotor or the like having a structure such that both sides of magnets are sandwiched by a pair of side rings.
- Further, the rotary electric machine of the present invention is effective in the case that it is used as a drive motor for an electrically driven vehicle.
- As an example of the electrically driven vehicle using the rotary electric machine of the present invention as a drive motor, a schematic configuration of an electric vehicle is shown in FIG. 4. The electric vehicle includes a rotary
electric machine 10 according to the present invention, abattery 20 for supplying a DC voltage, aninverter 30 for converting the DC voltage supplied from the battery into an AC voltage, and acontrol unit 40 for controlling a drive torque and a rotating speed of the rotaryelectric machine 10. Accordingly, the drive wheels of the vehicle are driven by the rotaryelectric machine 10 with a given torque and rotating speed controlled by thecontrol unit 40. - The rotary electric machine of the present invention can suppress a temperature rise as compared with a conventional rotary electric machine. Accordingly, the rotary electric machine of the present invention can be reduced in size to contribute to mountability on the vehicle and weight reduction of the vehicle, thereby improving the performance of the vehicle.
- According to the present invention, thermal demagnetization of the permanent magnets can be prevented to thereby effect a reduction in size and weight of the permanent magnet type rotary electric machine and also effect a high torque thereof.
- Further, by applying the permanent magnet type rotary electric machine of the present invention to an electrically driven vehicle, the vehicle can be reduced in weight to thereby improve the performance of the vehicle.
Claims (9)
1. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets embedded in said rotor core and arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein the outer diameter of each of said retainer plates is set smaller than the outer diameter of said rotor core.
2. A permanent magnet type rotary electric machine according to claim 1 , wherein the difference between the outer diameter of said rotor core and the outer diameter of each of said retainer plates is set to ½ or more of the difference between the inner diameter of said stator core and the outer diameter of said rotor core.
3. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets embedded in said rotor core and arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein each of said retainer plates is formed of a metal material having a resistivity of 10 μΩcm or higher.
4. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets embedded in said rotor core and arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein the outer diameter of each of said retainer plates is set smaller than the outer diameter of said rotor core, and each of said retainer plates is formed of a metal material having a resistivity of 10 μΩcm or higher.
5. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets embedded in said rotor core and arranged in a circumferential direction of said rotor core, and a pair of nonmagnetic members mounted on the axial ends of said rotor core;
wherein each of said nonmagnetic members is formed of a nonmetal material.
6. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein the outer diameter of each of said retainer plates is set smaller than the outer diameter of said rotor core.
7. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein each of said retainer plates is formed of a metal material having a resistivity of 10 μΩcm or higher.
8. A permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets arranged in a circumferential direction of said rotor core, and a pair of nonmagnetic members mounted on the axial ends of said rotor core;
wherein each of said nonmagnetic members is formed of a nonmetal material.
9. An electrically driven vehicle comprising:
a battery for supplying a DC voltage;
an inverter for converting said DC voltage supplied from said battery into an AC voltage; and
a permanent magnet type rotary electric machine for outputting a drive torque for driving said vehicle at said AC voltage;
said permanent magnet type rotary electric machine comprising:
a stator having a cylindrical stator core and a plurality of stator windings wound on said stator core; and
a rotor having a cylindrical rotor core opposed to an inner circumferential surface of said stator core with a given gap defined therebetween, a plurality of permanent magnets embedded in said rotor core and arranged in a circumferential direction of said rotor core, and a pair of retainer plates mounted on the axial ends of said rotor core;
wherein the outer diameter of each of said retainer plates is set smaller than the outer diameter of said rotor core.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/107,245 US20020149289A1 (en) | 1998-12-25 | 2002-03-28 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10369970A JP2000197290A (en) | 1998-12-25 | 1998-12-25 | Permanent magnet rotary electric machine and electric motor car using the same |
JP10-369970 | 1998-12-25 | ||
US09/472,519 US6426579B1 (en) | 1998-12-25 | 1999-12-27 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
US10/107,245 US20020149289A1 (en) | 1998-12-25 | 2002-03-28 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/472,519 Division US6426579B1 (en) | 1998-12-25 | 1999-12-27 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020149289A1 true US20020149289A1 (en) | 2002-10-17 |
Family
ID=18495763
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/472,519 Expired - Fee Related US6426579B1 (en) | 1998-12-25 | 1999-12-27 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
US10/107,245 Abandoned US20020149289A1 (en) | 1998-12-25 | 2002-03-28 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/472,519 Expired - Fee Related US6426579B1 (en) | 1998-12-25 | 1999-12-27 | Permanent magnet type rotary electric machine and electrically driven vehicle using the same |
Country Status (2)
Country | Link |
---|---|
US (2) | US6426579B1 (en) |
JP (1) | JP2000197290A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060033402A1 (en) * | 2001-02-28 | 2006-02-16 | Hitachi, Ltd. | Transport system and dynamo-electric machine |
US20110248110A1 (en) * | 2010-04-12 | 2011-10-13 | Liebherr-Werk Biberach Gmbh | Self-Propelled Surface Milling Machine with Electrical Mill Roll Drive |
TWI504307B (en) * | 2006-11-30 | 2015-10-11 | Creative Tech Corp | Sheet heater |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10118420B4 (en) * | 2001-04-12 | 2004-04-22 | Karl Hehl | Drive unit for one machine |
JP3833510B2 (en) * | 2001-10-16 | 2006-10-11 | 三菱電機株式会社 | Electric actuator |
US6894413B2 (en) * | 2001-12-20 | 2005-05-17 | Mitsubishi Denki Kabushiki Kaisha | Permanent magnet dynamo electric machine, and permanent magnet synchronous generator for wind power generation |
JP4745857B2 (en) | 2006-02-20 | 2011-08-10 | 三菱電機株式会社 | Electric machine |
JP2012125014A (en) * | 2010-12-07 | 2012-06-28 | Hitachi Automotive Systems Ltd | On-vehicle rotary electric machine and electric vehicle |
DE102012206442A1 (en) * | 2012-04-19 | 2013-10-24 | Robert Bosch Gmbh | Stator for an electric machine with winding heads pressed into a housing |
DE102012213465A1 (en) * | 2012-07-31 | 2014-02-06 | Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg | Permanent magnet synchronous motor and power steering assembly |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59194652A (en) * | 1983-04-20 | 1984-11-05 | Fanuc Ltd | Rotor of permanent magnet synchronous motor |
JPS61199448A (en) * | 1985-02-28 | 1986-09-03 | Fanuc Ltd | Permanent magnet field rotor assembly |
JPS6464548A (en) * | 1987-09-03 | 1989-03-10 | Fanuc Ltd | Rotor construction of synchronous motor |
US4918831A (en) * | 1987-12-28 | 1990-04-24 | General Electric Company | Method of fabricating composite rotor laminations for use in reluctance, homopolar and permanent magnet machines |
KR890015482A (en) * | 1988-03-16 | 1989-10-30 | 이종섭 | Magnetic Excitation Induction Motor |
JP2574007B2 (en) * | 1988-08-02 | 1997-01-22 | ファナック株式会社 | Synchronous motor rotor |
US5397951A (en) * | 1991-11-29 | 1995-03-14 | Fanuc Ltd. | Rotor for a synchronous rotary machine |
US6049153A (en) * | 1996-02-23 | 2000-04-11 | Matsushita Electric Industrial Co., Ltd. | Motor |
JPH09285088A (en) * | 1996-04-12 | 1997-10-31 | Hitachi Ltd | Permanent magnet dynamo-electric machine and motor-driven vehicle employing the same |
JP3690616B2 (en) * | 1996-04-15 | 2005-08-31 | 日立金属株式会社 | Rotating machine |
US6133662A (en) * | 1996-09-13 | 2000-10-17 | Hitachi, Ltd. | Permanent magnet dynamoelectric rotating machine and electric vehicle equipped with the same |
JP3415406B2 (en) * | 1997-09-05 | 2003-06-09 | トヨタ自動車株式会社 | Magnet-embedded AC motor and its design method |
US6084330A (en) * | 1998-03-13 | 2000-07-04 | Kollmorgen Corporation | Permanent magnet rotor and method of assembly |
-
1998
- 1998-12-25 JP JP10369970A patent/JP2000197290A/en active Pending
-
1999
- 1999-12-27 US US09/472,519 patent/US6426579B1/en not_active Expired - Fee Related
-
2002
- 2002-03-28 US US10/107,245 patent/US20020149289A1/en not_active Abandoned
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060033402A1 (en) * | 2001-02-28 | 2006-02-16 | Hitachi, Ltd. | Transport system and dynamo-electric machine |
TWI504307B (en) * | 2006-11-30 | 2015-10-11 | Creative Tech Corp | Sheet heater |
US20110248110A1 (en) * | 2010-04-12 | 2011-10-13 | Liebherr-Werk Biberach Gmbh | Self-Propelled Surface Milling Machine with Electrical Mill Roll Drive |
US9080293B2 (en) * | 2010-04-12 | 2015-07-14 | Liebherr-Components Biberach Gmbh | Self-propelled surface milling machine with electrical mill roll drive |
Also Published As
Publication number | Publication date |
---|---|
JP2000197290A (en) | 2000-07-14 |
US6426579B1 (en) | 2002-07-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6452302B1 (en) | Rotary electric machine and electric vehicle using the same | |
US6967420B2 (en) | Electrical machine having a rotor specially adapted to high speeds | |
EP1014542B1 (en) | Motor having a rotor with interior split-permanent-magnet | |
US7462968B2 (en) | Electric wheel | |
US7521832B2 (en) | Rotating electric machine having rotor embedded-permanent-magnets with inner-end magnetic gaps and outer-end magnetic gaps, and electric car using the same electric machine | |
US7053508B2 (en) | Rotary electric machine and a rotor of the same | |
US5811904A (en) | Permanent magnet dynamo electric machine | |
US8217544B2 (en) | Motor-generator having stator and inner and outer rotors | |
US10284032B2 (en) | Reluctance rotor with runup aid | |
EP2226924A1 (en) | Motor and rotor for dynamo-electric machine | |
US6724115B2 (en) | High electrical and mechanical response structure of motor-generator | |
US6034456A (en) | Compact bearingless machine drive system | |
US8330319B2 (en) | Substantially parallel flux uncluttered rotor machines | |
WO2003084027A1 (en) | Electric motor integrated in a vehicle wheel | |
WO2008076568A2 (en) | Double-sided dual-shaft electrical machine | |
CN100454729C (en) | Bidirectional hybrid excitation brushless electric machine | |
US9973050B2 (en) | Asynchronous machine with optimized distribution of electrical losses between stator and rotor | |
US6426579B1 (en) | Permanent magnet type rotary electric machine and electrically driven vehicle using the same | |
JP2003032978A (en) | Dynamo-electric machine | |
US20110101817A1 (en) | Variable geometry electric machine | |
JPH1094230A (en) | Outer rotor concentrated winding rotating electric machine, and motor vehicle using it | |
JP3704881B2 (en) | Synchronous rotating machine with permanent magnet and driving method thereof | |
US20200036271A1 (en) | Brushless Doubly Fed Radial Wound Electric Machine | |
JP3543500B2 (en) | Vehicle drive system | |
JP7459155B2 (en) | Rotating electric machine and its field element manufacturing method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |