JP2013219942A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle that can efficiently and stably drive regardless of a vehicle speed.SOLUTION: An electric vehicle includes a synchronous motor 6 of a permanent magnet type and an induction motor 6A as wheel drive motors. A determination means 39 determines whether a vehicle speed operated by a vehicle speed calculation means 38 is a medium or low speed region or a high speed region. A use motor switching means 40 switches a use motor based on a determination result so as to drive one motor and to make the other motor freely rotate. For instance, the use motor is switched so that the motor 6 is used and the motor 6A is made to freely rotate in the medium or low speed region and that the motor 6A is used and the motor 6 is made to freely rotate in the high speed region.

Description

  The present invention relates to an electric vehicle provided with a motor for driving wheels.

Conventionally, an electric vehicle using an induction motor as a drive source has been proposed. However, when the vehicle is driven in a medium or low speed range in an urban area or the like, the current consumption increases by the amount of excitation current in the induction motor, so that the efficiency is lowered and it is difficult to extend the cruising distance under a limited battery capacity.
In recent years, in order to improve the cruising distance under a limited battery capacity in an electric vehicle, for example, an IPM type motor using a neodymium magnet having high efficiency performance (an embedded magnet type synchronous motor) is used as a motor for driving wheels. It has been proposed to use a synchronous motor such as a motor (Patent Document 1).

JP 2011-188541 A

As described above, in an electric vehicle using an induction motor, when the vehicle is driven in a medium / low speed range, the current consumption increases by an amount corresponding to the excitation current, so the efficiency decreases, and the cruising distance can be extended under a limited battery capacity. difficult.
In the electric vehicle using the synchronous motor, for example, when the speed of the vehicle is in a high speed range, an energy loss is generated as compared with the case where the induction motor is used due to resistance by a permanent magnet. Also, in a motor using a neodymium magnet, the heat resistance temperature of the permanent magnet is low, and if the vehicle is irreversibly demagnetized, for example, by continuously operating the vehicle in a high speed range, the driving ability is hindered.

  An object of the present invention is to provide an electric vehicle that can be driven efficiently and stably regardless of the vehicle speed.

  The electric vehicle according to the present invention includes a permanent magnet type synchronous motor and an induction motor as the motors 6 and 6A for driving the wheels 2 and 3, and the synchronous motor and the induction motor according to a predetermined vehicle speed range. It has the use motor switching means 40 which switches a use motor so that either one may be driven and the other may be made free rotation.

  According to this configuration, the vehicle speed is constantly monitored, one of the synchronous motor and the induction motor is driven, and the other is freely rotated. For example, the use motor switching means 40 can use a synchronous motor in the medium / low speed range, so that the excitation current is not required and the efficiency in the so-called low load range can be increased as compared with the case where the induction motor is used. This makes it possible to extend the cruising distance under a limited battery capacity. By switching the motor so that the induction motor is used in the high speed region, energy loss due to the resistance of the permanent magnet 80 can be eliminated in the high speed region and the motor can be driven efficiently. By switching the motor used in this way, it can be driven efficiently and stably regardless of the vehicle speed. In addition, when the vehicle is continuously operated in a high speed range, the induction motor is driven and the synchronous motor is freely rotated, so that the permanent magnet 80 of the synchronous motor is prevented from becoming higher than the predetermined heat-resistant temperature. However, there is no irreversible demagnetization.

One of the synchronous motor and the induction motor is arranged as a motor for driving the front wheels of the wheels 2 and 3, and the other motor is arranged as a motor for driving the rear wheels of the wheels 2 and 3. May be. In this case, front wheel driving or rear wheel driving is performed according to the vehicle speed. In addition, the drive configuration of the electric vehicle can be simplified without requiring a clutch or the like for switching the motor to be used.
Both the synchronous motor and the induction motor are arranged as motors for driving the front wheels or the rear wheels of the wheels 2 and 3, and the used motor switching means 40 selects the used motor in accordance with the predetermined vehicle speed range. It may be switched.

  It is good also as what drives both the said synchronous motor and the said induction motor according to the defined driving | running condition. As a predetermined operating condition, for example, when a high torque such as an uphill road is required, the required high torque can be generated by driving both the synchronous motor and the induction motor.

  The motors 6 and 6A may be partly or wholly disposed in the wheels 2 and 3 to constitute the in-wheel motor driving device 8 including the motors 6 and 6A and the wheel bearings 4 and 5. good. As a result of the downsizing of the in-wheel motor drive device 8, a motor with a high-speed rotation specification is often used. When the synchronous motor rotates at a high speed, eddy current loss increases and heat generation due to eddy current loss increases. Therefore, the permanent magnet of the synchronous motor is likely to become high temperature, and the permanent magnet is likely to be demagnetized due to the high temperature. In this configuration, the synchronous motor is not driven in the high speed range, and the induction motor is driven, so that heat generation due to eddy current loss in the synchronous motor can be suppressed to a low level. Therefore, demagnetization of the permanent magnet 80 due to high temperature can be prevented in advance.

The in-wheel motor drive device 8 may include a speed reducer 7 that decelerates and transmits the rotation of the motors 6 and 6A to the wheels 2 and 3.
The speed reducer 7 may be a cycloid speed reducer.
According to the cycloid reducer, for example, a high reduction ratio of 1/6 or more can be obtained.

  The electric vehicle according to the present invention includes a permanent magnet type synchronous motor and an induction motor as motors for driving wheels, and drives either the synchronous motor or the induction motor according to a predetermined vehicle speed range. And since it has the use motor switching means which switches a use motor so that the other may be made free rotation, it can drive efficiently and stably irrespective of a vehicle speed.

It is a figure which shows schematic structure of the drive source of the electric vehicle which concerns on 1st Embodiment of this invention. It is a block diagram of the conceptual composition which shows the electric vehicle with a top view. It is a fracture front view of the in-wheel motor drive device of the rear wheel of the electric vehicle. It is sectional drawing of the motor part used as the IV-IV line cross section of FIG. It is a fracture front view of the important section of the in-wheel motor drive device in the front wheel of the electric vehicle. It is a block diagram of a conceptual structure of the inverter apparatus of the same electric vehicle. It is a figure which shows schematic structure of the drive source of the electric vehicle which concerns on other embodiment of this invention.

  A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, this electric vehicle is a four-wheel drive vehicle in which wheels 2 as left and right rear wheels of a vehicle body 1 are drive wheels, and wheels 3 as left and right front wheels are drive wheels and steering wheels. It is a car. Each of the wheels 2 and 3 serving as driving wheels has a tire and is supported by the vehicle body 1 via wheel bearings 4 and 5 (FIG. 2). In this example, an induction motor, which will be described later, is arranged as the motor 6A that drives the wheel 3 that is the front wheel, and a synchronous motor, which is described later, is arranged as the motor 6 that drives the wheel 2 that is the rear wheel.

  FIG. 2 is a block diagram of a conceptual configuration showing the electric vehicle in a plan view. The wheel bearings 4 and 5 are given the abbreviation “H / B” of the hub bearing in FIG. The left and right rear wheels 2 and 2 are driven by independent traveling motors 6 and 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. Each wheel 2 is provided with an electric brake 9. Note that the motor 6 may directly drive the wheel 2 without using the speed reducer 7.

  As shown in FIG. 3, the in-wheel motor drive device 8 has a reduction gear 7 interposed between the wheel bearing 4 and the motor 6. The in-wheel motor driving device 8 coaxially connects the hub of the wheel 2 that is the rear wheel and the rotation output shaft 74 of the motor 6. 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 is fixed 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. 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 It has double row rolling elements 55 interposed between the rolling surfaces 53 and 54 of the outer member 51 and the inner member 52. The wheel bearing 4 is a double row angular contact ball bearing in which the contact angles of the rolling surfaces 53 and 54 are back to back. The outer member 51 has a flange 51a attached to the housing 83b on the outboard side of the speed reducer 7, and a bolt insertion hole 64 is provided in the flange 51a. A bolt screw hole 94 is provided in the housing 83b at a position corresponding to the bolt insertion hole 64. The attachment bolt 65 is screwed into the bolt screw hole 94, and the outer member 51 is attached to the housing 83b.

The inner member 52 is a rotation-side raceway, and includes an outboard side member 59 and an inboard side member 60. The outboard side member 59 has a hub flange 59a for wheel mounting, and the inboard side member 60 is fitted to the inner periphery of the outboard side member 59 and the outboard side member 59 is crimped to the outboard side member 59. It is integrated. A through hole 61 is provided at the center of the inboard side member 60, and a press-fitting hole 67 of a hub bolt 66 is provided in the hub flange 59a.
The wheel bearing 4 is provided with a rotation sensor 24 including, for example, a magnetic encoder and a magnetic sensor. The magnetic encoder is a ring-shaped member that is provided on the outer periphery of the inner member 52 and magnetizes the magnetic poles N and S alternately in the circumferential direction. The magnetic sensor is provided on the outer member 51 so as to face the magnetic encoder. In this example, the rotation sensor 24 is disposed between both rows of rolling elements 55, 55, but may be installed at the end of the wheel bearing 4.

  The motor 6 is a radial gap type IPM motor in which a radial gap is provided between a stator 73 fixed to a cylindrical motor housing 72 and a rotor 75 attached to a rotation output shaft 74 (that is, three-homogeneous of an embedded magnet type). Motor). 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. A coolant channel 95 that cools the stator 73 is provided in the peripheral wall portion of the motor housing 72.

  FIG. 4 is a sectional view of the motor 6 (IV-IV section in FIG. 3). The rotor 75 of the motor 6 has 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 the shape of a cross section on the same circumference in the core portion 79. As the permanent magnet 80, for example, a neodymium magnet is used. The stator 73 has a core portion 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 each tooth 77 a of the core portion 77.

  As shown in FIG. 3, the motor 6 is provided with an angle sensor 36 that detects a relative rotation angle between the stator 73 and the rotor 75. The angle sensor 36 detects and outputs a signal representing a relative rotation angle between the stator 73 and the rotor 75, and an angle calculation circuit 71 that calculates an angle from the signal output from the angle sensor body 70. 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 on the motor housing 72 and disposed in close proximity to the detected portion 70a in the radial direction or the axial direction. Have In this motor 6, in order to maximize the efficiency, application of each phase of each wave of alternating current flowing to the coil 78 of the stator 73 based on the relative rotation angle between the stator 73 and the rotor 75 detected by the angle sensor 36. The timing is controlled by the motor drive control unit 33 of the motor control unit 29 (FIG. 6). The motor drive control unit 33 drives the motor 6 in accordance with a predetermined vehicle speed. Specifically, as will be described later, the motor 78 controls the coil 78 in accordance with the vehicle speed obtained from the rotation sensor 24 attached to the wheel bearing 4. To determine whether or not to apply a current.

  In the speed reducer 7 which is a cycloid speed reducer, two curved plates 84a and 84b formed with wavy trochoidal curves having a gentle outer shape are respectively connected to the eccentric portions 82a and 82b of the rotary input shaft 82 via bearings 85, respectively. It is attached. The rotary input shaft 82 is supported at both ends by two bearings 90 on the housing 83a on the inboard side and the inner diameter surface of the inboard side member 60 of the inner member 52. A plurality of outer pins 86 for guiding the eccentric movement 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 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.

  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 less can be obtained with a single-stage cycloid reducer.

  The two curved plates 84a and 84b are mounted on the eccentric portions 82a and 82b of the rotary input shaft 82 so as to be shifted in phase by 180 ° so that the eccentric motion is canceled out. Counterweights 91 and 91 are mounted on both axial sides of the eccentric portions 82a and 82b, respectively. The counterweights 91 and 91 are decentered in the direction opposite to the eccentric direction of the eccentric portions 82a and 82b so as to cancel the vibration caused by the eccentric movement of the curved plates 84a and 84b.

  As shown in FIG. 2, the wheels 3 and 3 which are the steering wheels serving as 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.

  The wheels 3 and 3 as the left and right front wheels are driven by independent motors 6A and 6A, respectively. The rotation of the motor 6 </ b> A is transmitted to the wheel 3 through the speed reducer 7 and the wheel bearing 4. The motor 6A, the speed reducer 7, and the wheel bearing 4 constitute an in-wheel motor drive device 8 that is one assembly part. The in-wheel motor drive device 8 is partially or entirely inside the wheel 3. Placed in. Each wheel 3 is provided with an electric brake 10.

  FIG. 5 is a cutaway front view of the main part of the in-wheel motor drive device 8 in the front wheel. The in-wheel motor drive device 8 for the front wheels employs an induction motor as the motor 6A instead of the IPM motor described above. The configuration other than the motor 6A is the same as the speed reducer 7 and the wheel bearing 4 in the in-wheel motor drive device 8 for the rear wheels. For example, a three-phase induction motor is applied as the induction motor, and the motor 6A includes a stator 73 fixed to the motor housing 72 and a rotor 75 attached to the rotation output shaft 74. When an electric current is passed through the coil 78 of the stator 73 by the motor drive control unit of the motor control unit 29 (FIG. 6), a rotating magnetic field is generated, and an induced current flows through a conducting wire 75a provided in the rotor 75. 75 rotates. Further, the motor drive control unit drives the motor 6A according to the determined vehicle speed. Specifically, although described later, the motor drive control unit responds to the vehicle speed obtained from the rotation sensor 24 attached to the wheel bearing 5 (FIG. 2). Whether to apply a current to the coil 78 is determined.

FIG. 6 is a block diagram of a conceptual configuration of the inverter device 22 of the electric vehicle.
The power circuit unit 28 includes inverters 31 and 31A that respectively convert into three-phase AC power used for driving the motors 6 and 6A of the battery 19, and PWM drivers 32 and 32A that control the inverters 31 and 31A. Each inverter 31, 31 </ b> A is composed of a plurality of semiconductor switching elements (not shown), and the PWM drivers 32, 32 </ b> A perform pulse width modulation on the input current command and give 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 based on a torque command or the like given from the ECU 21 that is the host control unit, and gives the current command to the PWM drivers 32 and 32A. The motor drive control unit 33 obtains a motor current value to be passed from the inverters 31 and 31A to the motors 6 and 6A from the current sensor 35, and performs current feedback control. The motor drive control unit 33 obtains the rotation angle of the rotors of the motors 6 and 6A from the angle sensors 36 and 36, and performs vector control.

In this embodiment, the motor control unit 29 having the above configuration is provided with a vehicle speed calculation means 38, a determination means 39, and a used motor switching means 40. The vehicle speed calculation means 38, the determination means 39, and the used motor switching means 40 may be provided in the ECU 21 instead of the configuration provided in the motor control unit 29.
The vehicle speed calculation means 33 is connected to rotation sensors 24 and 24 attached to the wheel bearings 4 and 5, respectively, and is connected to current sensors 35 and 35, respectively. The vehicle speed calculation means 38 obtains information on the tire rotation speed from each rotation sensor 24 and calculates the vehicle speed, or obtains a motor current value from each current sensor 35 and converts it into vehicle speed data proportional to the motor current value. Based on this, the vehicle speed is calculated.

  The determination means 39 always determines whether the vehicle speed calculated by the vehicle speed calculation means 38 is a medium low speed range (for example, the vehicle speed is greater than 0 km / h and less than 80 km / h) or a high speed range (for example, the vehicle speed is 80 km / h or more). . Based on this determination result, the used motor switching means 40 drives one motor and switches the used motor so that the other motor is freely rotated. For example, in the middle / low speed range, the motor 6 that is an IPM motor is used, and the motor 6A that is an induction motor is freely rotated. Thus, the motor drive control unit 33 issues a drive command to the PWM driver 32, but stops the drive command to the PWM driver 32A. Instead of stopping the drive command to the PWM driver 32A, the output of the inverter 31A may be cut off. In the high speed range, the motor 6A is used and the motor to be used is switched so that the motor 6 is freely rotated. Thus, the motor drive control unit 33 issues a drive command to the PWM driver 32A, but stops the drive command to the PWM driver 32. Instead of stopping the drive command to the PWM driver 32, the output of the inverter 31 may be cut off.

The effect will be described.
According to the electric vehicle described above, the vehicle speed is constantly monitored, one of the motor 6 that is a synchronous motor and the motor 6A that is an induction motor is driven, and the other is freely rotated. For example, by using the motor 6 that is a synchronous motor in the middle / low speed range, the excitation current is not required, and the efficiency in the so-called low load region can be increased as compared with the case of using the induction motor. This makes it possible to extend the cruising distance under a limited battery capacity. By switching the motor so that the motor 6A that is an induction motor is used in the high-speed range, energy loss due to the resistance of the permanent magnet 80 can be eliminated in the high-speed range and the motor can be driven efficiently. By switching the motor used in this way, it can be driven efficiently and stably regardless of the vehicle speed. In addition, when the vehicle is continuously operated in a high speed region, the permanent magnet 80 of the motor 6 is prevented from becoming higher than a predetermined heat-resistant temperature by driving the motor 6A and freely rotating the motor 6. However, there is no irreversible demagnetization.
In addition, since it is sufficient to switch the motor to be used according to the vehicle speed, the front wheel drive or the rear wheel drive is sufficient. Therefore, the drive configuration of the electric vehicle can be simplified without requiring a clutch or the like for switching the motor to be used. .

  As a result of the downsizing of the in-wheel motor drive device 8, motors 6 and 6 </ b> A often have high-speed rotation specifications. When the synchronous motor rotates at a high speed, eddy current loss increases and heat generation due to eddy current loss increases. Therefore, the permanent magnet of the synchronous motor is likely to become high temperature, and the permanent magnet is likely to be demagnetized due to the high temperature. In this configuration, the synchronous motor is not driven in the high speed range, and the induction motor is driven, so that heat generation due to eddy current loss in the synchronous motor can be suppressed to a low level. Therefore, demagnetization of the permanent magnet 80 due to high temperature can be prevented in advance.

Another embodiment will be described.
Both the motor 6 that is a synchronous motor and the motor 6A that is an induction motor may be driven in accordance with the determined operating conditions. As a predetermined operating condition, for example, when a high torque such as an uphill road is required, the required high torque can be generated by driving both the synchronous motor and the induction motor. It is determined whether or not a predetermined operating condition is satisfied from the detected values of the drive torques of the motors 6 and 6A, the detected values of the wheel rotation speed, and other sensors not shown.
Instead of the IPM motor of the motor 6, an SPM motor in which a permanent magnet is provided on the rotor surface can be applied.

  As shown in FIG. 7, both the synchronous motor 6 and the induction motor 6A are arranged as motors for driving the front wheels 3 or the rear wheels 2, and the used motor switching means 40 switches the used motor according to the vehicle speed. good. As the used motor switching means 40, for example, a clutch or the like is used. For example, the rotation output shafts of the synchronous motor 6 and the induction motor 6A are connected to a clutch, and wheels are connected to the clutch via a differential unit 41 and the like. In this case, the same effects as those of the above embodiments can be achieved, and the synchronous motor 6 and the induction motor 6A can be unitized and attached to the vehicle body, thereby reducing the number of man-hours. In addition, existing gasoline engine clutches and differential units can be applied.

DESCRIPTION OF SYMBOLS 2,3 ... Wheel 4,5 ... Wheel bearing 6,6A ... Motor 7 ... Reduction gear 8 ... In-wheel motor drive device 40 ... Used motor switching means

Claims (7)

  As a motor for driving the wheels, a permanent magnet type synchronous motor and an induction motor are provided, and either the synchronous motor or the induction motor is driven according to a predetermined vehicle speed range, and the other is freely rotated. An electric vehicle comprising: a used motor switching means for switching a used motor in such a manner.   The electric motor according to claim 1, wherein one of the synchronous motor and the induction motor is disposed as a motor for driving a front wheel of the wheel, and the other motor is disposed as a motor for driving a rear wheel of the wheel. Automobile.   2. The motor according to claim 1, wherein both the synchronous motor and the induction motor are arranged as motors for driving front wheels or rear wheels of the wheels, and the use motor switching means is used according to the range of the determined vehicle speed. An electric vehicle that switches motors.   The electric vehicle according to any one of claims 1 to 3, wherein both the synchronous motor and the induction motor are driven according to a predetermined operating condition.   5. The electric vehicle according to claim 1, wherein the motor is partly or wholly disposed in the wheel and constitutes an in-wheel motor drive device including the motor and a wheel bearing. 6.   6. The electric vehicle according to claim 5, wherein the in-wheel motor drive device includes a speed reducer that reduces the rotation of the motor and transmits the reduced speed to the wheels.   The electric vehicle according to claim 6, wherein the speed reducer is a cycloid speed reducer.

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