JP2012178917A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle that, without suddenly obstructing the operation of the vehicle, manages the temperature of a motor and can swiftly take appropriate countermeasures.SOLUTION: This electric vehicle includes: a motor 6 that drives wheels 2; and a control device that controls the motor 6. The electric vehicle includes in the motor coil of the motor 6, a temperature sensor Sa that detects the temperature Tc of the motor coil, and includes a motor current reduction means 95 that reduces, when the temperature Tc detected by the temperature sensor Sa exceeds the threshold value, the current value of the motor 6 until dTc/dt that is a value differentiated the temperature Tc with respect to time t becomes 0 or less.

Description

  The present invention relates to an electric vehicle to be an in-wheel motor vehicle such as a battery drive or a fuel cell drive equipped with a motor for driving wheels.

In an electric vehicle, a decrease in performance or failure of a motor for driving the vehicle greatly affects running performance and safety. In particular, battery-driven electric vehicle drive systems use IPM-type motors (embedded magnet-type synchronous motors) that use high-performance neodymium magnets to improve cruising distance under limited battery capacity. Is done.
Conventionally, in order to ensure reliability in an in-wheel motor drive device, the temperature of wheel bearings, reducers, motors, etc. is measured to monitor overload, and the motor drive current is determined according to the measured temperature value. There are proposals that limit the motor speed and reduce the motor rotation speed (for example, Patent Document 1).

JP 2008-168790 A

For example, in an electric vehicle, the driving conditions of the vehicle constantly change, and the motor rotation speed and the current flowing through the motor coil also change significantly. In particular, in an in-wheel electric vehicle, it is below the suspension spring, that is, below the spring. Since the motor is provided, the motor is in a harsh environment, such as being constantly vibrated. When operating in such a poor environment on a slope or the like in a state where high torque is continuously generated, the motor temperature rises and there is a high possibility of deteriorating the insulation of the motor coil. Managing the temperature of the motor is important for safe driving of the vehicle.
As described above, in an in-wheel motor drive device, when the motor temperature is measured to monitor an overload and the drive current of the motor is limited, there is a risk that the operation of the vehicle is abruptly hindered.

  An object of the present invention is to provide an electric vehicle in which the temperature of a motor is controlled and an appropriate countermeasure can be quickly performed without abruptly hindering the driving of the vehicle.

  The electric vehicle according to the present invention is an electric vehicle including a motor 6 for driving the wheel 2 and a control device U1 for controlling the motor 6. The motor coil 78 of the motor 6 is supplied with the temperature Tc of the motor coil 78. A temperature sensor Sa to detect is provided, and when the temperature Tc detected by the temperature sensor Sa exceeds a threshold value, the current value of the motor 6 is reduced until dTc / dt obtained by differentiating the temperature Tc with respect to time t becomes 0 or less. The motor current reducing means 95 is provided.

According to this configuration, the temperature sensor Sa constantly detects the temperature Tc of the motor coil 78 of the motor 6. For example, when the electric vehicle is operated in a state where high torque is generated continuously on a slope or the like, the temperature Tc of the motor coil 78 increases. The motor current reducing unit 95 determines whether or not the detected temperature Tc exceeds a predetermined threshold value. The motor current reduction means 95 performs control to reduce the current value of the motor 6 when it is determined that the temperature Tc has exceeded the threshold value. Thereafter, when the tendency of the temperature Tc to change or to decrease is recognized, that is, when the temperature increase rate dTc / dt becomes 0 or less, the motor current is reduced without waiting for the actual temperature Tc to decrease. Since the control to be reduced is released, the sudden drive limitation of the motor 6 is prevented.
Even if the temperature Tc of the motor coil 78 starts to increase due to the cancellation of the control of the motor current reducing means 95, at this time, if the temperature Tc is equal to or higher than the threshold value, control is performed to reduce the current value of the motor 6 again. Therefore, when the rate of temperature increase is 0 or less, overload can be reliably prevented even if the control for reducing the motor current is canceled.

  The control device U1 controls the ECU 21 that is an electric control unit that controls the entire vehicle, a power circuit unit 28 including an inverter 31 that converts DC power of the battery 19 into AC power used to drive the motor 6, and the ECU 21. And an inverter device 22 having a motor control unit 29 for controlling the power circuit unit 28 at least.

  When the control device U1 includes the ECU 21 and the inverter device 22, the motor control unit 29 is provided with motor current reduction means 95, and the motor current reduction means 95 has a temperature detected by the temperature sensor Sa exceeding a threshold value. And a control unit 40 that instructs the power circuit unit 28 to reduce the current value of the motor 6 when it is determined that the detected temperature exceeds the threshold value. It may be. When the motor current reducing means 95 is provided in the motor control unit 29 of the inverter device 22, the detection temperature can be determined at a location close to the motor 6, which is advantageous in terms of wiring and quicker than the case where it is provided in the ECU 21. Control can be performed, and problems in running the vehicle can be quickly avoided. Further, it is possible to reduce the burden on the ECU 21 that is becoming more complicated due to higher functions.

  When the determination unit 39 determines that the detected temperature exceeds the threshold, the inverter device 22 may be provided with an abnormality report means 41 that outputs an abnormality report of the motor 6 to the ECU 21. Since the ECU 21 is a device that controls the vehicle in general, when the motor current reduction means 95 in the inverter device 22 detects an abnormality in the motor coil 78, the ECU 21 outputs an abnormality report of the motor 6 to the ECU 21. The ECU 21 can appropriately control the entire vehicle. The ECU 21 is a higher-level control unit that gives a drive command to the inverter device 22. After the emergency control by the inverter device 22, the ECU 21 can perform more appropriate control of the subsequent drive. In some cases, the motor current reducing means 95 may be included in the ECU 21.

  The motor 6 may be partly or wholly disposed in the wheel 2 to constitute the in-wheel motor drive device 8 including the motor 6, the wheel bearing 4, and the speed reducer 7. In the case of the in-wheel motor drive device 8, as a result of downsizing, the wheel bearing 4, the speed reducer 7, and the motor 6 are accompanied by a reduction in the amount of materials used and a high-speed rotation of the motor 6, so that reliability is ensured. Is an important issue. In particular, the current of the motor 6 can be controlled appropriately by detecting the temperature of the motor coil 78 and constantly monitoring abnormalities of the motor coil 78, such as insulation deterioration.

  A reduction gear 7 that reduces the rotation of the motor 6 is provided, and the reduction gear 7 may be a cycloid reduction gear. When the reduction gear 7 is a cycloid reduction gear and the reduction ratio is increased to, for example, 1/6 or more, the motor 6 can be downsized and the apparatus can be downsized. When the reduction ratio is increased, the motor 6 that rotates at high speed is used.

  The electric vehicle of the present invention is an electric vehicle including a motor for driving wheels and a control device for controlling the motor, and a temperature sensor for detecting a temperature Tc of the motor coil is provided in the motor coil of the motor. When the temperature Tc detected by the temperature sensor exceeds a threshold value, motor current reduction means for reducing the current value of the motor until dTc / dt obtained by differentiating the temperature Tc with respect to time t becomes 0 or less is provided. Without suddenly hindering the operation of the motor, the temperature of the motor can be controlled and appropriate measures can be quickly taken.

1 is a block diagram of a conceptual configuration showing an electric vehicle according to a first embodiment of the present invention in a plan view. It is a block diagram of conceptual composition, such as an inverter device of the electric vehicle. It is a block diagram of the control system of the electric vehicle. It is a figure which shows the relationship between the temperature of the motor coil of the motor of the same electric vehicle, and time. It is a fracture front view of the in-wheel motor drive device in the electric vehicle. It is sectional drawing of the motor part used as the VI-VI line cross section of FIG. It is sectional drawing of the reduction gear part used as the VII-VII line cross section of FIG. It is a partial expanded sectional view of FIG. It is a block diagram of conceptual composition, such as ECU of an electric vehicle concerning other embodiments of this invention.

  An electric vehicle according to a first embodiment of the present invention will be described with reference to FIGS. This electric vehicle is a four-wheeled vehicle in which the wheels 2 that are the left and right rear wheels of the vehicle body 1 are driving wheels, and the wheels 3 that are the left and right front wheels are steering wheels of driven wheels. Each of the wheels 2 and 3 serving as the driving wheel and the driven wheel has a tire and is supported by the vehicle body 1 via wheel bearings 4 and 5, respectively. The wheel bearings 4 and 5 are given the abbreviation “H / B” of the hub bearing in FIG. The left and right wheels 2, 2 serving as driving wheels are driven by independent traveling motors 6, 6, respectively. The rotation of the motor 6 is transmitted to the wheel 2 via the speed reducer 7 and the wheel bearing 4. The motor 6, the speed reducer 7, and the wheel bearing 4 constitute an in-wheel motor driving device 8 that is one assembly part, and the in-wheel motor driving device 8 is partially or entirely inside the wheel 2. Placed in. The in-wheel motor drive device 8 is also referred to as an in-wheel motor unit. The motor 6 may directly rotate and drive the wheels 2 without using the speed reducer 7. Each wheel 2, 3 is provided with an electric brake 9, 10.

  The wheels 3 and 3 that are the steering wheels that are the left and right front wheels can be steered via the steering mechanism 11 and are steered by the steering mechanism 12. The steering mechanism 11 is a mechanism that changes the angle of the left and right knuckle arms 11b that hold the wheel bearings 5 by moving the tie rod 11a to the left and right. An EPS (electric power steering) motor 13 is driven by a command from the steering mechanism 12. It is driven and moved left and right via a rotation / linear motion conversion mechanism (not shown). The steering angle is detected by the steering angle sensor 15, and the sensor output is output to the ECU 21, and the information is used for acceleration / deceleration commands for the left and right wheels.

  As shown in FIG. 5, the in-wheel motor drive device 8 has a reduction gear 7 interposed between the wheel bearing 4 and the motor 6, and the wheel 2 that is a drive wheel supported by the wheel bearing 4 (FIG. 2). ) And the rotation output shaft 74 of the motor 6 (FIG. 5) are connected coaxially. The reduction gear 7 should have a reduction ratio of 1/6 or more. The speed reducer 7 is a cycloid speed reducer, in which eccentric portions 82a and 82b are formed on a rotational input shaft 82 that is coaxially connected to a rotational output shaft 74 of the motor 6, and bearings 85 are provided on the eccentric portions 82a and 82b, respectively. The curvilinear plates 84a and 84b are attached to the discs, and the eccentric motion of the curvilinear plates 84a and 84b is transmitted to the wheel bearing 4 as rotational motion. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.

  The wheel bearing 4 includes an outer member 51 in which a double row rolling surface 53 is formed on the inner periphery, an inner member 52 in which a rolling surface 54 facing each of the rolling surfaces 53 is formed on the outer periphery, and these The outer member 51 and the inner member 52 are composed of double-row rolling elements 55 interposed between the rolling surfaces 53 and 54 of the inner member 52. The inner member 52 also serves as a hub for attaching the drive wheels. The wheel bearing 4 is a double-row angular ball bearing, and the rolling elements 55 are made of balls and are held by a cage 56 for each row. The rolling surfaces 53 and 54 have a circular arc cross section, and the rolling surfaces 53 and 54 are formed so that the contact angles are aligned with the back surface. An end on the outboard side of the bearing space between the outer member 51 and the inner member 52 is sealed with a seal member 57.

  The outer member 51 is a stationary raceway, has a flange 51a attached to the housing 83b on the outboard side of the speed reducer 7, and is formed as an integral part. The flange 51a is provided with bolt insertion holes 64 at a plurality of locations in the circumferential direction. Further, the housing 83b is provided with a bolt screw hole 94 whose inner periphery is threaded at a position corresponding to the bolt insertion hole 64. The outer member 51 is attached to the housing 83b by screwing the mounting bolt 65 inserted into the bolt insertion hole 94 into the bolt screwing hole 94.

  The inner member 52 is a rotating raceway, and the outboard side member 59 having a hub flange 59a for wheel mounting and the outboard side member 59 are fitted to the inner periphery of the outboard side member 59. The inboard side material 60 is integrated with the outboard side material 59 by fastening. In each of the outboard side material 59 and the inboard side material 60, the rolling surface 54 of each row is formed. A through hole 61 is provided in the center of the inboard side member 60. The hub flange 59a is provided with press-fit holes 67 for hub bolts 66 at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 59a of the outboard side member 59, a cylindrical pilot portion 63 that guides driving wheels and braking components (not shown) protrudes toward the outboard side. A cap 68 that closes the outboard side end of the through hole 61 is attached to the inner periphery of the pilot portion 63.

  The motor 6 is a radial gap type IPM motor (that is, an embedded magnet type synchronous motor) in which a radial gap is provided between a motor stator 73 fixed to a cylindrical motor housing 72 and a motor rotor 75 attached to the rotation output shaft 74. ). The rotation output shaft 74 is cantilevered by two bearings 76 on the cylindrical portion of the housing 83 a on the inboard side of the speed reducer 7.

  FIG. 6 is a cross-sectional view of the motor (cross-section VI-VI in FIG. 5). The rotor 75 of the motor 6 includes a core portion 79 made of a soft magnetic material and a permanent magnet 80 built in the core portion 79. The permanent magnets 80 are arranged so that two adjacent permanent magnets face each other in a cross-sectional shape on the same circumference in the rotor core portion 79. The permanent magnet 80 is a neodymium magnet. The stator 73 includes a core part 77 and a coil 78 made of a soft magnetic material. The core portion 77 has a ring shape with an outer peripheral surface having a circular cross section, and a plurality of teeth 77a protruding inward on the inner peripheral surface are formed side by side in the circumferential direction. The coil 78 is wound around the teeth 77 a of the stator core portion 77.

As shown in FIG. 5, the motor 6 is provided with an angle sensor 36 that detects a relative rotation angle between the motor stator 73 and the motor rotor 75. The angle sensor 36 detects and outputs a signal representing a relative rotation angle between the motor stator 73 and the motor rotor 75, and an angle calculation circuit 71 that calculates an angle from the signal output from the angle sensor body 70. And have. The angle sensor main body 70 includes a detected portion 70a provided on the outer peripheral surface of the rotation output shaft 74, and a detecting portion 70b provided in the motor housing 72 and disposed in close proximity to the detected portion 70a, for example, in the radial direction. Become. The detected portion 70a and the detecting portion 70b may be arranged close to each other in the axial direction. The angle sensor 36 may be a resolver. In this motor 6, in order to maximize the efficiency, each phase of each wave of alternating current flowing through the coil 78 of the motor stator 73 based on the relative rotation angle between the motor stator 73 and the motor rotor 75 detected by the angle sensor 36. Is controlled by the motor drive control unit 33 of the motor control unit 29.
Note that the motor current wiring of the in-wheel motor driving device 8 and various sensor system and command system wiring are collectively performed by a connector 99 provided in the motor housing 72 or the like.

  The speed reducer 7 is a cycloid speed reducer as described above, and the two curved plates 84a and 84b formed by the wavy trochoid curve having a gentle outer shape as shown in FIG. The shaft 82 is attached to each eccentric part 82a, 82b. A plurality of outer pins 86 for guiding the eccentric movements of the curved plates 84a and 84b on the outer peripheral side are provided across the housing 83b, and a plurality of inner pins 88 attached to the inboard side member 60 of the inner member 2 are provided. The curved plates 84a and 84b are engaged with a plurality of circular through holes 89 provided in the inserted state. The rotation input shaft 82 is spline-coupled with the rotation output shaft 74 of the motor 6 and rotates integrally. The rotary input shaft 82 is supported at both ends by two bearings 90 on the inboard side housing 83a and the inner diameter surface of the inboard side member 60 of the inner member 52.

  When the rotation output shaft 74 of the motor 6 rotates, the curved plates 84a and 84b attached to the rotation input shaft 82 that rotates integrally therewith perform an eccentric motion. The eccentric motions of the curved plates 84 a and 84 b are transmitted to the inner member 52 as rotational motion by the engagement of the inner pins 88 and the through holes 89. The rotation of the inner member 52 is decelerated with respect to the rotation of the rotation output shaft 74. For example, a reduction ratio of 1/10 or more can be obtained with a single-stage cycloid reducer.

  The two curved plates 84a and 84b are attached to the eccentric portions 82a and 82b of the rotary input shaft 82 so as to cancel out the eccentric motion with each other, and are mounted on both sides of the eccentric portions 82a and 82b. A counterweight 91 that is eccentric in the direction opposite to the eccentric direction of the eccentric portions 82a and 82b is mounted so as to cancel the vibration caused by the eccentric movement of the curved plates 84a and 84b.

  As shown in an enlarged view in FIG. 8, bearings 92 and 93 are mounted on the outer pins 86 and the inner pins 88, and outer rings 92a and 93a of the bearings 92 and 93 are respectively connected to the curved plates 84a and 84b. It comes into rolling contact with the outer periphery and the inner periphery of each through-hole 89. Therefore, the contact resistance between the outer pin 86 and the outer periphery of each curved plate 84a, 84b and the contact resistance between the inner pin 88 and the inner periphery of each through hole 89 are reduced, and the eccentric motion of each curved plate 84a, 84b is smooth. Can be transmitted to the inner member 52 as a rotational motion.

  In FIG. 5, the wheel bearing 4 of the in-wheel motor drive device 8 is attached to the vehicle body via a suspension device (not shown) such as a knuckle on the outer periphery of the housing 83b of the speed reducer 7 or the housing 72 of the motor 6. Fixed.

  The control system will be described. As shown in FIG. 1, the control device U <b> 1 includes an ECU 21 that is an electric control unit that controls the entire automobile, and an inverter device 22 that controls the traveling motor 6 in accordance with a command from the ECU 21. The ECU 21, the inverter device 22, and the brake controller 23 are mounted on the vehicle body 1. The ECU 21 includes a computer, a program executed by the computer, various electronic circuits, and the like.

  The ECU 21 is roughly divided into a drive control unit 21a and a general control unit 21b when classified roughly by function. The drive control unit 21a gives the left and right wheel motors 6 and 6 the acceleration command output from the accelerator operation unit 16, the deceleration command output from the brake operation unit 17, and the turning command output from the steering angle sensor 15. The given acceleration / deceleration command is generated and output to the inverter device 22. In addition to the above, the drive control unit 21a outputs an acceleration / deceleration command to be output, information on the tire rotation speed obtained from the rotation sensor 24 provided on the wheel bearings 4 and 5 of the wheels 2 and 3, You may have the function to correct | amend using the information of each sensor. The accelerator operation unit 16 includes an accelerator pedal and a sensor 16a that detects the amount of depression and outputs the acceleration command. The brake operation unit 17 includes a brake pedal and a sensor 17a that detects the amount of depression and outputs the deceleration command.

  The general control unit 21b of the ECU 21 processes a function of outputting a deceleration command output from the brake operation unit 17 to the brake controller 23, a function of controlling various auxiliary machine systems 25, and an input command from the console operation panel 26. A function, a function of displaying on the display means 27, and the like. The auxiliary machine system 25 is, for example, an air conditioner, a light, a wiper, a GPS, an air bag, and the like, and is shown here as a representative block.

  The brake controller 23 is means for giving a braking command to the brakes 9 and 10 of the wheels 2 and 3 in accordance with a deceleration command output from the ECU 21. In addition to the command generated by the deceleration command output from the brake operation unit 17, the braking command output from the ECU 21 includes a command generated by means for improving the safety of the ECU 21. In addition, the brake controller 23 includes an antilock brake system. The brake controller 23 is configured by an electronic circuit, a microcomputer, or the like.

  The inverter device 22 includes a power circuit unit 28 provided for each motor 6 and a motor control unit 29 that controls the power circuit unit 28. The motor control unit 29 may be provided in common for each power circuit unit 28 or may be provided separately, but even if it is provided in common, each power circuit unit 28. For example, can be controlled independently so that the motor torque is different from each other. The motor control unit 29 has a function of outputting information (referred to as “IWM system information”) such as detection values and control values related to the in-wheel motor 8 of the motor control unit 29 to the ECU.

  FIG. 2 is a block diagram showing a conceptual configuration of the inverter device 22 and the like. The power circuit unit 28 includes an inverter 31 that converts the DC power of the battery 19 into three-phase AC power that is used to drive the motor 6, and a PWM driver 32 that controls the inverter 31. The motor 6 is composed of a three-phase synchronous motor or the like. The inverter 31 is composed of a plurality of semiconductor switching elements (not shown), and the PWM driver 32 performs pulse width modulation on the input current command and gives an on / off command to each of the semiconductor switching elements.

  The motor control unit 29 includes a computer, a program executed on the computer, and an electronic circuit, and includes a motor drive control unit 33 as a basic control unit. The motor drive control unit 33 is a unit that converts the current command into a current command in accordance with an acceleration / deceleration command by a torque command or the like given from the ECU that is the host control unit, and gives the current command to the PWM driver 32 of the power circuit unit 28. The motor drive control unit 33 obtains a motor current value to be passed from the inverter 31 to the motor 6 from the current detection unit 35 and performs current feedback control. The motor drive control unit 33 obtains the rotation angle of the rotor of the motor 6 from the angle sensor 36 and performs vector control.

In this embodiment, the motor control unit 29 having the above configuration is provided with the following motor current reduction means 95 and the abnormality report means 41, and the ECU 21 is provided with the abnormality display means 42. The motor 6 is provided with a temperature sensor Sa for detecting the temperature Tc of the motor coil 78 (FIG. 5).
The motor current reducing means 95 is for reducing the current value of the motor 6. When the temperature Tc of the motor coil 78 detected by the temperature sensor Sa exceeds a predetermined threshold value, the motor current reducing means 95 has dTc / dt obtained by differentiating the temperature Tc with respect to time t to 0 or less. Until the current value of the motor 6 is reduced. Specifically, the motor current reducing unit 95 includes a determination unit 39 and a control unit 40.

For example, a thermistor is used as the temperature sensor Sa. By fixing the thermistor in contact with the motor coil 78, the temperature Tc of the motor coil 78 can be detected. In this example, as shown in FIGS. 2 and 3, the detection value detected by the thermistor is amplified by the amplifier Ap, and this amplification value is determined by the determination unit 39.
The determination unit 39 always determines whether or not the temperature Tc detected by the temperature sensor Sa exceeds a predetermined threshold value. The threshold is appropriately determined based on the relationship between the temperature and time of the motor coil 78 that causes insulation in the motor coil, for example, through experiments and simulations. Whether or not insulation has occurred in the motor coil 78 can be determined by comparing the motor current value with respect to the motor applied voltage applied to the motor 6 with a reference value in which insulation has not occurred. The motor applied voltage is obtained by a voltage sensor (not shown) provided at a subsequent stage or the like of the current detection means 35, and the motor current value is obtained by the current detection means 35. The obtained threshold values are stored as a table in a rewritable storage means (not shown).

  When it is determined that the detected temperature Tc of the motor coil 78 exceeds a predetermined threshold, the control unit 40 is configured to reduce the current value of the motor 6 via the motor drive control unit 33 so as to reduce the current value of the motor 6. Command to 28. The motor current may be reduced at a predetermined rate (for example, 90%) with respect to the current current, or may be reduced by a predetermined value. Thereafter, when an indication that the degree of change in temperature Tc is constant or reduced is recognized, that is, when dTc / dt, which is the rate of temperature increase, becomes 0 or less, the motor current is not waited for the actual temperature Tc to decrease. Release the control to reduce. For this reason, sudden drive restriction of the motor 6 is prevented. The dTc / dt being 0 or less is synonymous with the fact that the gradient of the temperature Tc in an arbitrary minute time is 0 or less. The temperature of the motor coil 78 does not drop suddenly, and if the motor current is reduced until the temperature drops to some extent, the driving of the vehicle may be hindered due to the sudden drive restriction of the motor 6, but the temperature drop as described above. By detecting the signs and releasing the current limit, problems due to the sudden drive limit of the motor 6 can be avoided.

Even if the temperature Tc of the motor coil 78 starts to increase due to the cancellation of the control of the motor current reducing means 95, at this time, if the temperature Tc is equal to or higher than the threshold value, control is performed to reduce the current value of the motor 6 again. Therefore, when the rate of temperature increase becomes 0 or less, overload can be reliably prevented even if the control for reducing the motor current is canceled. Specifically, FIGS. 4A to 4C are diagrams showing the relationship between the temperature Tc of the motor coil 78 of the motor 6 of this electric vehicle and the time t, respectively.
In FIG. 4A, when the temperature Tc of the motor coil 78 rises and time t1, the determination unit 39 determines that the temperature Tc of the motor coil 78 has exceeded the threshold value Ea. The control unit 40 receives the determination result and instructs the power circuit unit 28 via the motor drive control unit 33 to reduce the current value of the motor 6. The motor drive control unit 33 gives a current command to the PWM driver 32 of the power circuit unit 28 in accordance with a command given from the control unit 40. The power circuit unit 28 reduces the current supplied to the motor 6.

  When the temperature increase rate dTc / dt becomes “0” (temperature Tc is constant) at time t <b> 2, the control unit 40 releases the control for reducing the current value of the motor 6. In the example of FIG. 4A, since dTc / dt becomes negative (temperature Tc decreases) after time t2, even if the motor temperature Tc is equal to or higher than the threshold value Ea, it waits for the actual temperature Tc to decrease. Instead, the control unit 40 continues to cancel the control to reduce the motor current.

  Also in FIG. 4B, at time t1, the control unit 40 receives the determination result by the determination unit 39 and reduces the current value of the motor 6 via the motor drive control unit 33. Command to 28. After the time t2, even if the temperature Tc of the motor coil 78 starts to rise due to the cancellation of the control of the motor current reduction means 95, the controller 40 determines again that the temperature Tc is equal to or higher than the threshold at time t3. Control to reduce the current value of the motor 6 is performed. Therefore, when the rate of temperature increase is 0 or less, overload can be reliably prevented even if the control for reducing the motor current is canceled.

As shown in FIG. 2, the abnormality reporting unit 41 is a unit that outputs abnormality occurrence information to the ECU 21 when the determination unit 39 determines that the temperature Tc has exceeded a threshold value.
The abnormality display unit 42 provided in the ECU 21 is a unit that receives the abnormality occurrence information of the motor 6 output from the abnormality report unit 41 and causes the display device 27 in the driver's seat to perform a display notifying the abnormality. The display on the display device 27 is a display using characters or symbols, for example, an icon.

The effect will be described.
According to this configuration, the temperature sensor Sa always detects the temperature Tc of the motor coil 78. For example, when the electric vehicle is operated in a state where high torque is generated continuously on a slope or the like, the temperature Tc of the motor coil 78 increases. The determination unit 39 determines whether or not the detected temperature Tc exceeds a predetermined threshold value, and when it is determined that the detected temperature Tc has exceeded, the control unit 40 causes the power circuit unit 28 to reduce the current value of the motor 6. Command. After that, when the tendency of the temperature Tc to decrease becomes constant, that is, when the temperature increase rate dTc / dt becomes 0 or less, the motor current is reduced without waiting for the actual temperature Tc to decrease. Since the control is released, sudden drive restriction of the motor 6 is prevented.
Even if the temperature Tc of the motor coil 78 starts to increase due to the cancellation of the control of the motor current reducing means 95, at this time, if the temperature Tc is equal to or higher than the threshold value, control is performed to reduce the current value of the motor 6 again. Therefore, when the rate of temperature increase is 0 or less, overload can be reliably prevented even if the control for reducing the motor current is canceled.

Since the motor current reducing means 95 is provided in the motor control unit 29 of the inverter device 22 so that the detected temperature can be determined at a location close to the motor 6, it is advantageous in terms of wiring, and quicker control than in the case where it is provided in the ECU 21. It is possible to quickly avoid problems in running the vehicle. Further, it is possible to reduce the burden on the ECU 21 that is becoming more complicated due to higher functions.
Since the ECU 21 is a device that controls the vehicle in general, when the motor current reduction means 95 in the inverter device 22 detects an abnormality in the motor coil 78, the ECU 21 outputs an abnormality report of the motor 6 to the ECU 21. The ECU 21 can appropriately control the entire vehicle. The ECU 21 is a higher-level control unit that gives a drive command to the inverter device 22. After the emergency control by the inverter device 22, the ECU 21 can perform more appropriate control of the subsequent drive.

  In addition, in the case of the in-wheel motor drive device 8, as a result of downsizing, the wheel bearing 4, the speed reducer 7, and the motor 6 are accompanied by a reduction in the amount of material used and a high-speed rotation of the motor 6. Ensuring safety is an important issue. In particular, the current of the motor 6 can be controlled appropriately by detecting the temperature of the motor coil 78 and constantly monitoring abnormalities of the motor coil 78, such as insulation deterioration.

  When the reduction gear 7 in the in-wheel motor drive device 8 is a cycloid reduction gear and the reduction ratio is increased to, for example, 1/6 or more, the motor 6 can be downsized and the device can be downsized. When the reduction ratio is increased, the motor 6 that rotates at high speed is used. When the motor 6 is in a high-speed rotation state, abnormalities such as insulation deterioration of the motor coil 78 of the motor 6 can be detected at an early stage, and appropriate measures can be quickly taken.

When the current of the motor 6 is reduced, the predetermined ratio for reducing the motor current may be reduced by, for example, several percent of the total motor current value for each elapsed time, or the motor current for each elapsed time. You may make it increase the ratio which reduces a value for a while.
As shown in FIG. 9, the motor current reducing means 95 may be provided in the ECU 21 that is an electric control unit that controls the entire vehicle.

DESCRIPTION OF SYMBOLS 2 ... Wheel 4 ... Wheel bearing 6 ... Motor 7 ... Reduction gear 8 ... In-wheel motor drive device 19 ... Battery 21 ... ECU
DESCRIPTION OF SYMBOLS 22 ... Inverter apparatus 28 ... Power circuit part 29 ... Motor control part 31 ... Inverter 39 ... Determination part 40 ... Control part 41 ... Abnormality report means 78 ... Motor coil 95 ... Motor current reduction means Sa ... Temperature sensor U1 ... Control apparatus

Claims (6)

In an electric vehicle equipped with a motor for driving wheels and a control device for controlling the motor,
The motor coil of the motor is provided with a temperature sensor for detecting the temperature Tc of the motor coil. When the temperature Tc detected by the temperature sensor exceeds a threshold value, dTc / dt obtained by differentiating the temperature Tc with respect to time t is An electric vehicle comprising motor current reduction means for reducing the current value of the motor until it becomes 0 or less.   2. The control device according to claim 1, wherein the control device includes an ECU that is an electric control unit that controls the entire vehicle, a power circuit unit that includes an inverter that converts DC power of the battery into AC power used to drive the motor, and control of the ECU. And an inverter device having a motor control unit for controlling at least the power circuit unit.   The motor control unit according to claim 2, wherein the motor control unit is provided with a motor current reduction unit. The motor current reduction unit includes a determination unit that determines whether or not the temperature detected by the temperature sensor exceeds a threshold value, and the detected temperature is An electric vehicle comprising: a control unit that commands the power circuit unit to reduce the current value of the motor when it is determined that the threshold value has been exceeded.   The electric vehicle according to claim 3, wherein when the determination unit determines that the detected temperature exceeds the threshold value, the inverter device includes an abnormality report unit that outputs a motor abnormality report to the ECU.   5. The electric motor according to claim 1, wherein the motor is partly or wholly disposed in a wheel and constitutes an in-wheel motor drive device including the motor, a wheel bearing, and a speed reducer. Car.   The electric vehicle according to any one of claims 1 to 5, further comprising a speed reducer that decelerates rotation of the motor, wherein the speed reducer is a cycloid speed reducer.

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