JP4400220B2 - Motor and drive device - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for a motor capable of suppressing back electromotive force induced in an armature by a field magnetic field by mechanical means, a drive device including the motor, and suppression of the influence of back electromotive force. The present invention relates to a movable brush device that can be used in the field.

  As a motor that can be used as a power source for driving an automobile, there is a permanent magnet motor in which a permanent magnet is provided on one of a rotor and a stator. In this permanent magnet motor, when the back electromotive force induced in the armature coil during high-speed rotation increases, the current supplied to the coil decreases due to the output voltage limitation of the inverter drive circuit that supplies power to the armature. There is a case where a negative effect that the maximum rotational speed is suppressed to a low value may occur.

  Thus, for example, in Patent Document 1, in an electric vehicle that performs vector control by dividing the primary current of a permanent magnet motor into a field current component and a torque current component, the permanent magnet motor is rotating at a high speed at a predetermined rotation speed or higher. If the field current component of the primary current that generates a magnetic field in the opposite direction to the magnetic field generated by the permanent magnet of the motor is passed through the armature coil and the field magnetic field is weakened, the torque characteristics of the motor Is extended to the high speed rotation range (so-called field weakening control).

  In addition, in an electric vehicle using a motor as a power source and a hybrid vehicle combining an internal combustion engine and a motor, so-called regenerative braking is performed in which power is regenerated by operating the motor as a generator during deceleration. In order to prevent the speed from becoming excessive and causing a sense of incongruity, a method has been proposed in which the command value of the torque current component is set to zero and the field magnetic flux is weakened (so-called zero torque control).

JP-A-6-225402

  However, such field-weakening control and zero-torque control are limited in the number of controllable revolutions, and therefore, at high speeds exceeding that range, the control cannot follow and a negative electromotive force has occurred.

  Therefore, an object of the present invention is to provide a novel means for suppressing the influence of the counter electromotive force induced in the armature by the field magnetic field.

1st this invention is a motor which consists of a stator provided with several stator coils, and the rotor accommodated inside the said stator, Comprising: Operation which moves these stator coils in the separation direction from the said rotor The operation mechanism further includes a substantially annular band to which the plurality of stator coils are fixed, and an actuator for operating a circumferential length of the band, and the operation mechanism includes the plurality of stators. In accordance with the separation operation for separating the coil from the rotor, the electrical connection between the plurality of stator coils is cut off .

In the first aspect of the present invention, the number of magnetic fluxes interlinked with the stator coil is reduced by moving the plurality of stator coils in the direction away from the rotor by the operating mechanism, and thus the counter electromotive force induced in the armature. Can be suppressed with a simple configuration . Further, the back electromotive force can be more effectively suppressed by separating the electrical connection between the plurality of stator coils with the operation mechanism being separated.

According to a second aspect of the present invention, there is provided a driving device including the motor according to claim 1 , further comprising control means for controlling the operation mechanism based on the number of rotations of the motor. It is the drive device which does.

In the second aspect of the present invention, the effects of the first aspect of the present invention can be effectively utilized in a high rotational speed region.

According to a third aspect of the present invention, there is provided a driving device including the motor according to claim 2 , wherein a failure detecting means for detecting a failure of the motor or a driving circuit for driving the motor, and the failure detected And a control means for controlling the operation mechanism to disconnect the electrical connection when the operation is performed.

In a third aspect of the present invention, by controlling the operation mechanism, since to divide the electrical connection between the plurality of stator coils when the inverter other driver circuits for driving the motor or the motor fails, the first and second The configuration of the present invention can be used for fail-safe purposes.

4th this invention is a motor of Claim 1 , Comprising: The fluid chamber provided in the said magnetic field in order to accommodate a magnetic fluid, The supply / discharge mechanism which supplies / discharges magnetic fluid to this fluid chamber, The motor is characterized by comprising:

In the fourth aspect of the present invention, since the magnetic fluid accommodated in the fluid chamber provided in the field is supplied and discharged by the supply / discharge mechanism, the back electromotive force can be controlled with a simple configuration.

According to a fifth aspect of the present invention, there is provided a driving device including the motor according to claim 4 , wherein the motor or the driving circuit for driving the motor is malfunctioned by controlling the supply / discharge mechanism. The drive device is characterized by comprising a control means for discharging a magnetic fluid in an amount that is substantially the entire amount or a field magnetic field does not reach until the motor is driven or regenerated.

According to the fifth aspect of the present invention, by controlling the supply / discharge mechanism to discharge the magnetic fluid from the fluid chamber in an amount that is substantially the entire amount or the field magnetic field does not reach until the motor is driven (or regenerated), Since the electromotive force can be suppressed, the configuration of the fourth aspect of the present invention can be used for fail-safe purposes.

  Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a motor 1 according to a first embodiment of the present invention. The motor 1 is a rotating field type three-phase AC synchronous motor, and includes a stator 10 and a rotor 20 as main members.

  A stator 10 as an outer armature is obtained by fixing a large number of stator coils 13 at substantially equal angular intervals to a substantially annular band 11 made of, for example, spring steel.

  The stator coil 13 is formed by individually winding coils 13b around an iron core 13a formed by laminating silicon steel plates. On both sides in the circumferential direction of each stator coil 13, connection terminals 13 c protruding toward the adjacent stator coil 13 are provided. The connection terminal 13c positions the plurality of stator coils 13 with each other and electrically connects a pair of the plurality of stator coils 13 that need to be connected to each other. In addition, for a pair of the plurality of stator coils 13 that need not be connected, an insulating layer (not shown) is formed on the boundary surfaces of the connection terminals 13c and 13c between them, and such connection terminals 13c and 13c It functions as a simple positioning spacer.

  The band 11 has bases 11a and 11b standing at both ends, and a case 15a of a hydraulic cylinder 15 is fixed to one base 11a. The hydraulic cylinder 15 has a rod 16 operable in the protruding and retracting direction. The rod 16 is always urged in the backward direction by a return spring 17, and the tip of the rod 16 penetrates the base 11a and is fixed to the base 11b.

  The motor 1 according to the present embodiment includes, for example, four sets of three stator coils 13 that are V-connected, and the caps 11a and 11b are located between the two stator coils 13 in one set. ing. In the present embodiment, the operation mechanism using the hydraulic cylinder 15 is provided at one location, but such an operation mechanism may be provided at a plurality of locations on the stator 10.

  A rotor 20 is rotatably supported inside the stator 10 by a motor case (not shown). The rotor 20 is configured with a substantially cylindrical iron core formed by laminating silicon steel plates as a main member, and fluid chambers 12 extending in the axial direction are formed at equal angular intervals in the iron core. In the fluid chamber 12, magnetizing coils (not shown) are individually arranged, and a supply / exhaust mechanism 36 shown in FIG. 2 is connected. Here, the rotor 20 may be an IPM type motor incorporating a rare earth magnet.

  Therefore, when the rod 16 of the hydraulic cylinder 15 operates in the protruding direction (right direction in the figure), the distance between the caps 11a and 11b is increased, and the radius of the band 11 is increased. Due to the enlargement of the radius, the plurality of stator coils 13 fixed to the band 11 are moved away from the rotor 20 and the air gap δ is enlarged. In addition, as the rod 16 of the hydraulic cylinder 15 protrudes, the connection terminals 13c and 13c corresponding to the caps 11a and 11b are separated from each other, and the electricity between the pair of stator coils 13 sandwiching these connection terminals is provided. Connection is broken.

  The magnetic fluid accommodated in and discharged from the fluid chamber 12 is a so-called MR fluid (Magneto-Rheological Fluid). For example, ferromagnetic particles having a particle size of about 1 to 10 μm are used as surfactants and antiwear agents. It is a slurry dispersed at a high concentration in a liquid such as added mineral oil or silicon oil, and exhibits a high viscosity by strongly attracting particles magnetized by an external magnetic field.

  As shown in FIG. 2, an inverter 31 that enables driving and regenerative operation is connected to the motor 1. The inverter 31 includes a well-known three-phase bridge circuit, a booster circuit, and the like, and converts the DC power of the battery 32 into three-phase AC or converts the three-phase AC from the motor 1 into DC power and supplies it to the battery 32. A timing signal and a voltage instruction signal from a motor electronic control unit (hereinafter referred to as a motor ECU) 33 are input to the inverter 31.

  A hydraulic control valve 34 is connected to the hydraulic cylinder 15 of the motor 1. The hydraulic control valve 34 supplies hydraulic pressure from the oil pan 35 and the oil pump OP to the hydraulic cylinder 15 in accordance with an instruction signal from the motor ECU 33.

  A supply / discharge mechanism 36 such as a pump is connected to the fluid chamber 12 (shown in FIG. 1) of the rotor 20 of the motor 1. The supply / discharge mechanism 36 is configured to supply the magnetic fluid stored in the magnetic fluid tank 37 to the fluid chamber 12 and discharge the fluid from the fluid chamber 12 in response to an instruction signal from the motor ECU 33.

  The vehicle according to the present embodiment is a hybrid vehicle, and includes an engine 40 that is a gasoline internal combustion engine in addition to the motor 1. An engine ECU 41 for controlling the engine 40 is connected to the engine 40.

  The motor ECU 33 is a microcomputer that executes back electromotive force suppression processing described below and normal operation control performed in cooperation with the engine ECU 41 separately from the present invention, and includes a CPU, a RAM, a ROM, and an input / output port. Is included. In addition to the engine ECU 41, various sensors such as a motor rotation sensor 38 provided near the rotor shaft (not shown) are connected to the input side of the motor ECU 33. The motor ECU 33 inputs signals from various sensors in accordance with programs and various maps stored in the ROM, executes arithmetic processing based on the input signals, and outputs various control signals based on the calculation results. In this embodiment and the second embodiment to be described later, a motor rotation sensor 38 for detecting the rotation speed of the motor 1 is provided for easy understanding. However, the rotation speed of the motor 1 is determined by depressing the accelerator pedal. It can also be detected by other means such as using a motor rotation speed command value calculated from the amount or the like and a vehicle speed calculated by taking in a tire rotation sensor.

  Next, the operation of the first embodiment will be described. The basic operation of the engine 40 and the motor 1 in the present embodiment is the same as that of the prior art. The vehicle travels with the driving force of the motor 1 when the vehicle starts or runs at a low speed. When the load is high, the vehicle travels by both power sources of the engine 40 and the motor 1. Further, when the vehicle is decelerated or braked, the motor 1 is caused to function as a generator, and the deceleration energy is regenerated as electric power.

  In the series of operations described above, when the rotation speed of the motor 1 is below a predetermined value (during power running and power regeneration by the motor 1), the rod 16 of the hydraulic cylinder 15 is moved to the retracted position by the urging force of the return spring 17. The bases 11a and 11b of the band 11 are closed. At this time, the hydraulic control valve 34 drains the hydraulic pressure from the hydraulic path A to the hydraulic cylinder 15 and pressurizes the hydraulic path B. If the caps 11a and 11b cannot be completely closed, the hydraulic path is adjusted as necessary. It operates so as to pressurize D, whereby the caps 11a and 11b are completely closed. Note that, after the closing is completed, the hydraulic path D is closed, thereby reducing the power for pressurization. For example, detection of whether or not the caps 11a and 11b are completely closed can be performed by, for example, detecting the current value of each power supply line to the motor 1 or the difference between the indicated value of the rotation speed and the current value and a predetermined reference value. This can be done by comparison or by installing limit switches on the caps 11a and 11b.

  When the rotational speed of the motor 1 exceeds a predetermined control start reference value, the inverter 31 is subjected to field weakening control, that is, a primary current that generates a magnetic field in a direction opposite to the magnetic field generated by the rotor 20 of the motor 1. Control is performed to extend the torque characteristics of the motor 1 to a high-speed rotation range by flowing a field current component through the stator coil 13 and weakening the field magnetic field.

  In parallel with the field weakening control, a back electromotive force suppression process is performed. That is, the hydraulic cylinder 15 operates in the protruding direction by duty control of the motor ECU 33. This operation is performed in accordance with the rotational speed of the motor 1, and in response to the increase in the rotational speed, the inner diameter of the stator 10, and thus the air gap δ between the stator coil 13 and the rotor 20, gradually increases. At this time, the hydraulic control valve 34 operates so as to supply hydraulic pressure to the hydraulic passages A and C (backup) with the hydraulic passages B and D to the hydraulic cylinder 15 being slightly opened. Realize operation. Due to the expansion of the air gap δ, the number of magnetic fluxes linked to the stator coil 13 decreases, thereby suppressing the back electromotive force induced in the stator 10 as an armature.

  When the rotational speed of the motor 1 exceeds a predetermined cutting reference value that is higher, the hydraulic cylinder 15 further operates in the protruding direction under the control of the motor ECU 33. At this time, the hydraulic control valve 34 opens the hydraulic paths B and D to supply further hydraulic pressure to the hydraulic paths A and C, thereby realizing the above operation of the hydraulic cylinder 15. As a result of this operation, the connection terminals 13c and 13c at positions corresponding to the caps 11a and 11b are disconnected from each other (see FIG. 3), and the electrical connection between the stator coils 13 on both sides thereof is disconnected. By this division, a part of the stator coil 13 in the stator 10 is disconnected from the power supply side.

  On the other hand, when the rotational speed of the motor 1 exceeds the cutting reference value, the supply / exhaust mechanism 36 causes almost the entire amount in the fluid chamber 12 or an amount of magnetic fluid not sufficient to drive (or regenerate) the field magnetic field. It is extracted and collected in the magnetic fluid tank 37. By discharging the magnetic fluid, the number of magnetic fluxes acting on the stator 10 from the rotor 20 is further reduced.

  As described above, in the present embodiment, since the plurality of stator coils 13 are moved away from the rotor 20 by the hydraulic cylinder 15 as the operation mechanism, the number of magnetic fluxes interlinked with the stator coil 13 is reduced, thereby the stator. The counter electromotive force induced by 10 can be suppressed.

  Further, in this embodiment, the operation mechanism is configured by the generally annular band 11 to which the plurality of stator coils 13 are fixed and the hydraulic cylinder 15 that operates the circumferential length of the band 11. The desired effect of the invention can be obtained.

  In the present embodiment, since the electrical connection between the plurality of stator coils 13 is divided in the region where the rotation speed of the motor 1 is high, the counter electromotive force can be more effectively suppressed.

  In the present embodiment, since the magnetic fluid accommodated in the fluid chamber 12 provided in the rotor 20 that is a field magnet is supplied and discharged by the supply / discharge mechanism 36, the back electromotive force can be controlled with a simple configuration.

  Note that a fail-safe function can be realized by using the mechanical configuration of the present embodiment. That is, a means for detecting a failure in a motor or an inverter or other drive circuit that drives the motor (for example, a processing program that determines that a failure occurs when the output deviates from a predetermined correspondence with the input to these) It is also possible to configure the system so as to disconnect the electrical connection between the plurality of stator coils 13 by controlling the hydraulic cylinder 15 when a failure is detected.

Similarly, when a failure of the motor or the inverter that drives the motor is detected, the supply / exhaust mechanism 36 is controlled until almost the entire amount or field magnetic field from the fluid chamber 12 drives (or regenerates) the motor. The system may be configured to discharge an unacceptable amount of magnetic fluid, whereby the back electromotive force in the stator 10 can be suppressed, and the mechanical configuration of this embodiment can be used for fail-safe purposes.
In the present embodiment, the electrical disconnection between the stator coils 13 and 13 and the discharge of the magnetic fluid by the supply / discharge mechanism 36 are performed using a common cutting reference value as a reference value. May be used as a reference value. Further, the discharge of the magnetic fluid by the supply / discharge mechanism 36 may be performed stepwise, gradually increasing / decreasing by duty control of the supply / discharge mechanism.

  In the present embodiment, the operation mechanism for moving the stator coil 13 is realized by using the hydraulic cylinder 15. However, the operation mechanism in the present invention is not limited to such a configuration. Various configurations such as those using the power of the engine 40 and those using the power of the engine 40 can be employed.

Next, reference examples related to the present invention will be described. This reference example relates to a novel structure of a rectifying unit in a DC motor, and more specifically, the contact pressure or relative position between the brush and the commutator is variable.

FIG. 4 schematically shows the configuration of the movable brush device 50 according to this reference example . The movable brush device 50 includes a generally cylindrical case 51 and a mover 61 accommodated in the case 51 so as to be movable in the axial direction of the case 51. Driving coils 52 a and 52 b are installed on the outer periphery of the case 51. A heater 53 is installed adjacent to the upper side of the driving coils 52a and 52b in the figure.

  The mover 61 closes a part of the case 51 to form a fluid chamber 54 in the case 51. The mover 61 is formed by fixing an upper surface plate 62, a magnetic shielding plate 63, a permanent magnet 64 and a brush 65 to a shaft 66. A fluid chamber 54 is defined by the inner surface of the case 51, the upper surface plate 62 and the magnetic shielding plate 63. The magnetic shielding plate 63 is preferably made of a material having a high saturation magnetic flux density such as JIS-PB permalloy (Ni—Fe). In FIG. 4, for easy understanding, the commutator 90 is illustrated as being flat. However, the commutator 90 is actually arranged in a circumferential shape as in a known DC motor.

  A coil spring 64 as an urging member is interposed between the upper surface plate 62 of the mover 61 and the case 51. The coil spring 64 is a push spring and constantly urges the movable element 61 toward the front end side thereof.

  The heater 53 is made of an electrothermal material such as Ni—Cr, and heats the case 51 and the fluid chamber 54 therein to a desired temperature by Joule heat accompanying power supply from the battery 71 and the power transistor 72 as a power source. A pulse signal from the motor ECU 73 is supplied to the base of the power transistor 72, and the temperature is controlled by the duty ratio.

  The fluid chamber 54 contains a magnetic fluid having a characteristic that the magnetizing force decreases as the temperature rises, for example, a temperature / magnetizing force characteristic as shown in FIG. As this magnetic fluid, it is preferable to use the same MR fluid as that used in the first embodiment.

  The motor ECU 73 is a microcomputer that executes brush drive processing described below and normal operation control performed separately from the present invention, and includes a CPU, a RAM, a ROM, and an input / output port. Various sensors such as a motor rotation sensor 74 provided near a rotor shaft (not shown) are connected to the input side of the motor ECU 73 in order to detect the rotation speed of the motor. In addition to the movable brush device 50, a DC-DC converter (not shown) for driving the motor itself is connected to the output side of the motor ECU 73. The motor ECU 73 inputs signals from various sensors in accordance with programs and various maps stored in the ROM, executes arithmetic processing based on the input signals, and outputs various control signals based on the calculation results.

In the movable brush device 50 in the motor of this reference example configured as described above, the portion of the magnetic fluid in the fluid chamber 54 that is present in the vicinity of the heater 53 (region 80A in FIG. 4) is heated by the heater 53. Magnetization force decreases. On the other hand, the remaining effective magnetic fluid (existing in the region 80B in FIG. 4) is attracted by the magnetic force of the drive coils 52a and 52b, so that the mover 61 is effectively magnetized in the axial direction of the case 51. The fluid is retracted until the center line 81a of the axial length of the fluid and the center line 81b of the drive coils 52a and 52b substantially coincide. As a result, the relative position between the brush 65 and the commutator 90 changes.

  Using such a movable brush device 50, the contact pressure between the brush 65 and the commutator 90 can be controlled. That is, it is possible to reduce brush wear by avoiding application of excessive contact surface pressure in a region where the rotational speed and required torque are small. Specifically, for example, a required torque / rotation number / applied current map as shown in FIG. 6 is prepared in advance, and the corresponding applied current is determined by the required torque and the rotational speed determined from the accelerator pedal depression amount by the driver. The value of I is read from the map, and this applied current value is applied to the drive coils 52a and 52b, thereby controlling the brush 65 in the protruding / retracting direction with respect to the commutator 90. According to such control, the contact surface pressure between the brush 65 and the commutator does not become excessive, and wear of the brush 65 can be reduced and the life can be extended by avoiding the excessive contact surface pressure.

  By the way, the contact resistance R, which is an electric resistance value between the brush 65 and the commutator 90, can be changed by the wear of the brush or the commutator, dirt, biting of foreign matter, and the like. It is also possible that will not respond correctly. In order to avoid the occurrence of such a state, in the present embodiment, the contact surface pressure can be corrected and the contact resistance R can always be set to an appropriate value by a learning process or a correction process.

  Specifically, the motor ECU 73 first refers to the required torque / rotational speed / applied current map of FIG. 6 based on the required torque and the rotational speed determined from the accelerator pedal depression amount by the driver, etc. The value of the applied current I is calculated. Next, the applied current I having the determined value is applied to the motor, and the current contact resistance R1 ′ is calculated from the terminal voltage value detected at the phase angle θ0 at that time.

  Next, the obtained current contact resistance R1 ′ is compared with the contact resistance R1 in the case of the phase angle θ0 in the phase angle / contact resistance map as shown in FIG. When the detection resistance R1 ′ deviates from the contact resistance R1 shown in the map by a predetermined value or more, the coil resistance I is determined by referring to the contact resistance / coil current map as shown in FIG. The torque / rotation speed / applied current map is corrected (I1 → I1 ′). Thereafter, an applied current value is obtained according to the corrected map, and the motor is operated by duty-controlling the driving coils 52a and 52b. The correction of the applied current value may be performed by preparing a plurality of types of the same map corresponding to the deviation amount ΔR in advance, and selecting one of them for use, or in the initial state of the same map. The correction may be performed approximately by adding a correction amount corresponding to the shift amount ΔR uniformly to the applied current value.

  By performing such a process, even when the contact resistance R changes due to wear of the brush 65 or the commutator 90, dirt, biting of foreign matter, etc., the contact surface pressure is adjusted so that the contact resistance R becomes an appropriate value. Can be controlled.

Furthermore, in this reference example , the influence of the counter electromotive force induced in the armature can be suppressed. That is, when the rotational speed of the motor exceeds a predetermined cutting reference value, a current larger than the applied current value in the contact surface pressure control is applied to the driving coils 52a and 52b by the control of the motor ECU 73. The permanent magnet 64 of the mover 61 is attracted by the coils 52a and 52b, and the mover 61 is raised to a height at which the brush 65 and the commutator 90 are separated from each other. As a result, the electrical connection between them is broken, and both are substantially insulated. By this division, it is possible to suppress the influence of the counter electromotive force induced in the rotor as the armature on the power supply side or the load side.

Note that the fail-safe function can be realized by using the mechanical configuration of this reference example . In other words, a means for detecting a failure of the motor or the drive circuit that drives the motor (for example, a processing program that determines that a failure occurs when the output deviates from a predetermined correspondence with the input to these) is provided. It is also possible to configure the system to control the movable brush device 50 and to disconnect the electrical connection between the brush 65 and the commutator 90 when detected.

In addition, in the present reference example , by providing the permanent magnet 64, it is possible to improve the followability of the mover 61 with respect to control. However, the movable brush device according to the present invention may be configured without the permanent magnet 64. Moreover, in 2nd Embodiment, although there exists an advantage which can perform fine pressure control by comprising a movable brush apparatus using a magnetic fluid, the movable which controls the contact pressure of a brush and a commutator according to rotation speed. The brush device may be realized by another drive source, for example, a combination of a hydraulic cylinder and a solenoid valve, or a solenoid actuator.

1 is a partially cutaway front view of a motor according to a first embodiment of the present invention. It is a block diagram which shows the outline of the drive device which concerns on 1st Embodiment. It is a principal part front view in which the motor according to the first embodiment is partially cut out. It is a front view which shows the movable brush apparatus which concerns on the reference example relevant to this invention. It is a graph which shows the temperature / magnetizing force characteristic of the magnetic fluid used for a reference example . It is a graph which shows the required torque / rotation speed / applied current map used for a reference example . It is a graph which shows the phase angle / contact resistance map used for a reference example . It is a contact resistance / coil current map used for a reference example . It is an electric current map.

Explanation of symbols

1 Motor 10 Stator 11 Bands 12 and 54 Fluid Chamber 13 Stator Coil 15 Hydraulic Cylinder 50 Movable Brush Device 66 Brush 90 Commutator

Claims (5)

A motor comprising a stator having a plurality of stator coils and a rotor housed inside the stator,
An operation mechanism for moving the plurality of stator coils in a direction away from the rotor ;
The operation mechanism includes a generally annular band to which the plurality of stator coils are fixed, and an actuator for operating a circumferential length of the band.
The operation mechanism cuts off the electrical connection between the plurality of stator coils in accordance with a separating operation for separating the plurality of stator coils from the rotor . A drive device comprising the motor according to claim 1 ,
The drive device further comprising a control means for controlling the operation mechanism based on the rotation speed of the motor. The drive device according to claim 2 ,
A failure detection means for detecting a failure of the motor or a drive circuit for driving the motor;
Control means for controlling the operation mechanism to disconnect the electrical connection when the failure is detected;
A drive device comprising: The motor according to claim 1 ,
A motor comprising: a fluid chamber provided in the rotor for containing a magnetic fluid; and a supply / discharge mechanism for supplying and discharging the magnetic fluid to and from the fluid chamber. A drive device comprising the motor according to claim 4 ,
When the motor or the drive circuit for driving the motor is controlled by controlling the supply / exhaust mechanism, the magnetic fluid of almost the entire amount from the fluid chamber or the amount of magnetic fluid that does not reach the time when the field magnetic field drives or regenerates the motor. A drive device comprising control means for discharging the gas.

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