JP2015154528A - Control device of electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an electric automobile which can quickly cope with the demagnetization of a permanent magnet, and can prevent the generation of an unintended behavior to a vehicle caused by the imbalance of the motor torque of left and right drive wheels resulting from the demagnetization.SOLUTION: This control device of an electric automobile comprises a synchronous motor 6 having a permanent magnet, an ECU 21, and an inverter device 22 having a power circuit section 28 and a motor control section 29. Rotation number control means for controlling a rotation number of the motor 6 is arranged. There are arranged, at the motor control section 29, a demagnetization determination section 34 which determines whether or not demagnetization is generated in the permanent magnet from an acceleration/deceleration command imparted from the ECU 21, and a detection signal of a drive state of the motor 6, and changeover control means 38 which switches control from torque control to the rotation number control by the rotation number control means when the demagnetization is generated in the permanent magnet at the demagnetization determination section 34.

Description

  The present invention relates to a control device for an electric vehicle that individually drives a plurality of drive wheels of a vehicle with a plurality of permanent magnet type synchronous motors. When the permanent magnets of the permanent magnet type synchronous motors are demagnetized, the left and right wheel torques The present invention relates to a control technology that can eliminate the unbalance of the motor and perform stable driving.

  In an independent wheel drive electric vehicle that individually drives a plurality of drive wheels of a vehicle with a plurality of permanent magnet type synchronous motors, if an unbalance of output torque occurs between the motors that drive the left and right drive wheels, an unintended yaw Moments are generated that adversely affect vehicle behavior. For this reason, it is required to appropriately correct the imbalance between the output torques of the left and right drive wheels.

Prior art 1
Conventionally, when one of the motors is in a demagnetized state, the current command values for the plurality of motors are calculated so that the output torques of the plurality of motors match within the torque range that can be achieved by the demagnetized motor. A control device is disclosed (Patent Document 1).

Prior art 2
There has been proposed a technique for changing the timing at which the maximum current flows with respect to the phase of the rotor of the electric motor so as to increase the reluctance torque of the electric motor when demagnetization occurs during vehicle travel (Patent Document 2). Thereby, the fall of the driving force of an electric motor can be suppressed and an electric vehicle can be moved to a repair shop, a roadside, etc. by self-propelled.

JP 2010-268466 A JP 2013-110804 A

  In the prior art 1, when it becomes a demagnetization state, the electric current command value with respect to a some electric motor is each calculated so that the output torque of a some electric motor may correspond. For this reason, if the calculation time is long and the difference between the left and right torques is larger than the threshold value, the output torques of the plurality of electric motors cannot be matched immediately, and an unintended yaw moment is generated, which adversely affects the vehicle behavior. Concerned.

  In prior art 2, changing the timing at which the maximum current flows with respect to the phase of the motor rotor requires adjustment of the torque command map, and the adjustment work is not easy. Further adjustment time is required. Therefore, an unintended behavior may occur in the vehicle while adjusting the torque command map. For example, when only one wheel is demagnetized while the vehicle is running, the yaw moment may occur and the vehicle behavior may become unstable.

  An object of the present invention is to respond immediately when a permanent magnet is demagnetized, and to prevent an unintended behavior from being generated in a vehicle due to motor torque imbalance between left and right drive wheels caused by demagnetization. It is to provide a control device for an electric vehicle.

The control device for the electric vehicle of the present invention is:
A synchronous motor 6 having a permanent magnet and driving the wheel 2;
An ECU 21 that generates and outputs an acceleration / deceleration command according to the operation of the operation units 16 and 17;
An inverter having a power circuit unit 28 including an inverter 31 that converts DC power into AC power, and a motor control unit 29 that controls the torque of the motor 6 via the power circuit unit 28 in accordance with the acceleration / deceleration command given from the ECU 21 In an electric vehicle control device comprising the device 22,
A rotation speed control means 40 for controlling the rotation speed of the motor 6 is provided,
In the motor control unit 29,
A demagnetization determination unit 34 that determines whether or not demagnetization has occurred in the permanent magnet of the motor 6 according to a predetermined rule from an acceleration / deceleration command given from the ECU 21 and a detection signal of the driving state of the motor 6. When,
A switching control means 38 for switching from the torque control by the motor control section 29 to the rotation speed control by the rotation speed control means 40 when the demagnetization determination section 34 determines that demagnetization has occurred in the permanent magnet;
Is provided.
The predetermined rule is appropriately determined according to the result of, for example, a test or a simulation.

According to this configuration, when the electric vehicle has the left and right motors 6 and 6 that individually drive the left and right drive wheels 2 and 2 as the motor 6, for example, the demagnetization determination unit 34 is configured to be connected to the ECU 21 when the vehicle is traveling. From the acceleration / deceleration command (acceleration / deceleration command) and the drive signal of the motor 6 that are given from the above, it is determined whether or not demagnetization has occurred in the permanent magnet of the motor 6 in accordance with a predetermined rule. The detection signal of the driving state of the motor 6 is, for example, currents Iu, Iv, Iw flowing in the respective phases of the three-phase coil of the motor 6, and the motor rotational speed. When the permanent magnet is not demagnetized, the motor control unit 29 performs the torque control.
When the demagnetization determining unit 34 determines that demagnetization has occurred in the permanent magnet, the switching control means 38 switches from the torque control to the rotational speed control by the rotational speed control means 40. As a result, the driver can evacuate the vehicle to the roadside belt for the time being and take necessary measures. For example, when demagnetization occurs in the drive wheel 2 on one side when the vehicle is traveling, the torque control is immediately switched to the rotation speed control, so that the motor torque of the left and right drive wheels 2 and 2 can be quickly unbalanced. And the behavior of the vehicle can be stabilized quickly by suppressing the generation of the yaw moment.

  The electric vehicle has left and right motors 6 and 6 that individually drive the left and right drive wheels 2 and 2 as the motor 6, and the motor control unit 29 performs acceleration / deceleration for each of the left and right motors 6 and 6. The motor 6 is torque-controlled in accordance with a torque command map that defines a relationship between a torque command serving as a command and a current command of the motor 6, and in response to a predetermined input, the torque of the left and right motors 6, 6 is controlled. May be provided in the motor control unit 29 so as to adjust the torque command map.

In this case, after switching from the torque control to the rotational speed control by the rotational speed control means 40, the driver temporarily retracts the vehicle to, for example, a roadside belt. Thereafter, the torque command map automatic adjustment unit 35 responds to a predetermined input, for example, an input signal from an external operation signal such as the switch 41 by the driver, so that the torques of the left and right motors 6 and 6 match. Adjust the torque command map. Thereafter, the motor control unit 29 controls the torque of the motor 6 according to the adjusted torque command map. In this way, the torques of the left and right motors 6 and 6 can be matched to prevent an unintended yaw moment from occurring in the vehicle.
After switching from the torque control to the rotational speed control, it is possible to drive the vehicle to a destination such as a repair shop or a home parking lot while maintaining the rotational speed control. Considering the maintenance of the performance, only low-speed traveling can be performed with the rotation speed control. In this case, it takes a long time to reach the destination, and the speed difference between this vehicle and other vehicles becomes large, resulting in trouble in traveling.
Therefore, after the vehicle is temporarily retracted by the rotational speed control, the torque command map is adjusted by the torque command map automatic adjustment unit 35 so that the torques of the left and right motors 6 and 6 coincide with each other, and torque control is performed again. Since it returns, it becomes possible to give a certain speed. Therefore, it is possible to make the vehicle run from the place where it is temporarily retracted to the destination in a shorter time without trouble in traveling than when traveling at a low speed while maintaining the rotational speed control.

The torque command map automatic adjustment unit 35 sets the current command corresponding to the torque command to zero when the demagnetization factor is zero for the torque command map of the motor 6 having the larger demagnetization among the left and right motors 6 and 6. The torque command map may be adjusted by gradually increasing the torque command map.
The demagnetization factor is an index representing the degree of demagnetization of the permanent magnet, and is represented as follows, for example.
Demagnetization factor: 1-K
1-K = (Vqm−Vqy) / ω × Ke × 100%
Vqm: q-axis target correction voltage Vqy: q-axis actual voltage ω: motor angular speed Ke: induced voltage constant In this case, the torque command map automatic adjustment unit 35 extracts the motor 6 having a large demagnetization from the left and right motors 6, 6. Then, the torque command map of the motor 6 is adjusted by gradually increasing the current command corresponding to the torque command until the demagnetization factor becomes zero. As a result, there is no difference between the q-axis target correction voltage Vqm and the q-axis actual voltage Vqy, and the motor 6 is torque-controlled according to this adjusted torque command map.

  The torque command map is provided in a power running control state and a regeneration control state of the motor 6, respectively, and the torque command map automatic adjustment unit 35 is divided into a power running control state and a regeneration control state of the motor 6, and The torque command map may be adjusted. In this way, the motor 6 can be finely controlled by dividing it into a power running control state and a regenerative control state of the motor 6.

The demagnetization determination unit 34 may determine that demagnetization has occurred in the permanent magnet when the demagnetization factor is equal to or greater than a certain threshold and continues for a certain time. For example, a value larger than zero is set as the constant threshold, and a time of, for example, several milliseconds to several tens of milliseconds is set as the fixed time by a test or simulation. In this case, it is possible to accurately determine the demagnetization of the permanent magnet.
When the demagnetization determination unit 34 determines that demagnetization has occurred in the permanent magnet, the rotation speed control means 40 responds to a predetermined input with the rotation speed at which the motor 6 is set to a low speed running. The rotational speed may be controlled. The rotation speed at which the predetermined low-speed traveling is performed is the rotation speed when the mode is shifted to the adjustment mode for adjusting the torque command map, and is the motor rotation speed at which the vehicle speed is, for example, several km / h or less.
If the motor 6 is operated for a long time in the high-speed rotation state after the switching control means 38 is switched from the torque control to the rotation speed control, the demagnetization of the permanent magnet may proceed. Therefore, for example, a warning lamp or the like is used to output a display notifying the abnormality to call the driver's attention, and the driver can quickly evacuate the vehicle to the roadside zone for the time being. Thereafter, in response to a predetermined input, for example, an input signal from an external operation signal such as the switch 41 by the driver, it is possible to shift to an adjustment mode for adjusting the torque command map. In this adjustment mode, the torque command map of one motor 6 on the adjustment side is adjusted by torque control, and the other motor 6 on the non-adjustment side is rotated at the rotation speed at which the low-speed traveling is determined. Control. Further, when adjusting the torque command map of the other motor 6, the rotational speed of the non-adjusted motor 6 is controlled at the predetermined rotational speed and the other motor 6 on the adjusted side. The torque command map of the motor 6 is adjusted by torque control.

  The motor 6 is a motor 6 that constitutes an in-wheel motor drive device 8, and this motor 6 is provided for one or both of the left and right front wheels 3, 3 and the left and right rear wheels 2, 2. It may be a thing.

  The control apparatus for an electric vehicle according to the present invention includes a synchronous motor that has a permanent magnet and drives wheels, an ECU that generates and outputs an acceleration / deceleration command according to an operation of an operation unit, and DC power to AC power. In an electric vehicle control device comprising: a power circuit unit including an inverter to be converted; and an inverter device having a motor control unit for torque controlling the motor via the power circuit unit in accordance with the acceleration / deceleration command given from the ECU. , A rotation speed control means for controlling the rotation speed of the motor is provided, and the motor control unit is configured according to a predetermined rule from an acceleration / deceleration command given from the ECU and a detection signal of the driving state of the motor. Demagnetization determination unit for determining whether or not demagnetization has occurred in the permanent magnet, and demagnetization in the permanent magnet by the demagnetization determination unit When there was boss, provided with switching control means for switching from said torque control by the motor control unit to the speed control by the speed control means. For this reason, it is possible to respond immediately when the permanent magnet is demagnetized, and it is possible to prevent an unintended behavior from occurring in the vehicle due to the motor torque imbalance between the left and right drive wheels caused by demagnetization. .

1 is a block diagram of a conceptual configuration showing an electric vehicle according to an 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 conceptual block diagram of the IPM motor of the same electric vehicle. It is a figure which shows the torque command map in the control apparatus of the same electric vehicle. It is a figure which shows the demagnetization determination part etc. in the same control apparatus. It is a flowchart of the demagnetization determination by the same demagnetization determination part. 3 is a block diagram of a torque / rotational speed control system in the control device. FIG.

  An electric vehicle control apparatus according to an embodiment of the present invention will be described with reference to FIGS. The following description also includes a description of a control method for the electric vehicle. FIG. 1 is a block diagram of a conceptual configuration showing the electric vehicle in a plan view. 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 rotatably supported by the vehicle body 1 via wheel bearings 4 and 5, respectively.

  The wheel bearings 4 and 5 are abbreviated as “H / B” 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 motor 6 is an embedded magnet type synchronous motor (that is, an IPM motor) in which a permanent magnet is built in the core portion of the rotor. As the permanent magnet, for example, a neodymium magnet is used.
The reduction gear 7 consists of a cycloid reduction gear, for example. Each wheel 2, 3 is provided with an electric brake 9, 10. Further, the wheels 3 and 3 which are the steering wheels which are the left and right front wheels can be steered via the steering mechanism 11 and are steered by a steering means 12 such as a steering wheel.

FIG. 2 is a block diagram of a conceptual configuration of an inverter device and the like of the electric vehicle.
The electric vehicle includes an ECU 21 that is an electric control unit that controls the entire vehicle, and an inverter device 22 that controls the traveling motor 6 in accordance with an acceleration / deceleration command of the ECU 21. The ECU 21 includes a computer, a program executed by the computer, various electronic circuits, and the like. The ECU 21 includes a torque / rotation speed control command unit 21a and a power running / regeneration control command unit 21b.

The torque / rotational speed control command unit 21a is basically means for performing torque control, but has a rotational speed command unit 21aa for performing rotational speed control for emergency treatment when the permanent magnet is demagnetized. . The torque / rotation speed control command unit 21a is configured to calculate the left and right wheels from the acceleration command (drive) output from the accelerator operation unit 16, the deceleration command (regeneration) output from the brake operation unit 17, and the turning command from the steering means 12. Acceleration / deceleration commands given to the traveling motors 6 and 6 are generated as torque command values and output to the inverter device 22. In addition to the above, the torque / rotational speed control command unit 21a outputs an acceleration / deceleration command to be output to a rotation sensor (for example, a wheel bearing 4, 5 (FIG. 1) of each wheel 2, 3 (FIG. 1). You may have the function corrected using the information of the tire rotation speed obtained from (not shown) and the information of each vehicle-mounted sensor.
The power running / regeneration control command unit 21b gives a command flag for switching between power running / regeneration to a motor power running / regeneration control unit 33 of the motor control unit 29 described later.

  The accelerator operation unit 16 includes an accelerator pedal 16a and a sensor 16b that detects the amount of depression of the accelerator pedal 16a. The brake operation unit 17 includes a brake pedal 17a and a sensor 17b that detects the amount of depression of the brake pedal 17a.

  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. Although not shown, the inverter device 22 is provided for each motor. The motor control unit 29 may be provided in common for each power circuit unit 28 or may be provided separately. Even when the motor control unit 29 is provided in common for each power circuit unit 28, the left and right motors 6 and 6 can be controlled independently so that the torques of the motors 6 and 6 are different from each other. The power circuit unit 28 includes an inverter 31 that converts the DC power of the battery 19 into three-phase AC power used for powering and regeneration of the motor 6, and a PWM driver 32 that controls the inverter 31.

  The motor 6 is a three-phase synchronous motor. The motor 6 is provided with a rotation angle sensor 36 that detects a rotation angle as an electrical angle of the rotor of the motor 6. The inverter 31 is composed of a plurality of semiconductor switching elements, 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. The motor control unit 30, the demagnetization determination unit 34, and the torque map automatic adjustment unit 35 are the basic control units. And a control parameter adjustment unit 37. The motor drive control unit 30 includes an acceleration / deceleration command based on a torque command or a rotational speed command given from the torque / rotational speed control command part 21a in the ECU 21 which is the host control means, and a power running / regeneration control command part 21b. A command current to the motor 6 is generated by using a preset torque command map by a command flag for regenerative control.

  The motor drive control unit 30 includes a motor power running / regeneration control unit 33 and a switching control unit 38. The motor power running / regeneration control unit 33 includes a power running control unit and a regeneration control unit. One of the power running control means and the regeneration control means is selected by a command flag from the power running / regenerative control command section 21b. When the power running control means is selected by the command flag, the power running control means increases the power running command torque as the depression amount of the accelerator pedal 16a increases. When the regeneration control means is selected by the command flag, the regeneration control means increases the regeneration command torque as the depression amount of the brake pedal 17a increases.

  The torque command map is obtained by determining a current command for each motor rotation speed range with respect to a torque command serving as an acceleration / deceleration command for each of the left and right motors 6. The current command has a primary current Ia that flows to the motor 6 and a current advance angle β between the rotating magnetic field and the rotor permanent magnet. Further, the torque command map is provided separately for the power running control state and the regenerative control state of the motor 6. The motor control unit 29 torque-controls the motor 6 according to the torque command map set for each of the left and right motors 6 and for each powering control state / regenerative control state. In this example, the torque command map is stored in the storage means 39 in the motor control unit 29 so as to be rewritable.

  As the storage means 39, a nonvolatile memory (for example, EEPROM) is applied. Note that the storage means 39 may be provided at other locations in the inverter device 22 or may be provided outside the inverter device 22. The motor drive control unit 30 controls the motor 6 by PI control so that the actual detection value obtained by the current detection unit 43 for the drive current applied to the motor 6 matches the command current.

When the demagnetization determination unit 34 determines that the demagnetization has occurred in the permanent magnet, the switching control unit 38 switches from torque control by the motor control unit 29 to rotation speed control by the rotation number control unit 40 (FIG. 7) described later.
The demagnetization determination unit 34 (described later) reduces the permanent magnet of the motor 6 according to a predetermined rule from the acceleration / deceleration command given from the torque / rotation speed control command unit 21a and the detection signal of the driving state of the motor 6. It is determined whether or not magnetism has occurred.

  The torque command map automatic adjustment unit 35 responds to a predetermined input, for example, an input signal from an external operation signal such as the switch 41 by the driver, so that the torques of the left and right motors 6 and 6 match. Adjust the command map. For example, the switch 41 provides an input signal to the inverter device 22, but may provide an input signal to the ECU 21. In response to such an input signal, the torque command map in the storage means 39 is rewritten. Thereafter, the motor control unit 29 controls the torque of the motor 6 according to the adjusted torque command map.

For example, the control parameter adjustment unit 37 appropriately adjusts the PI control gain in accordance with the motor rotation speed and torque that change from moment to moment. The adjustment amount of the PI control gain is determined based on, for example, the results of the bench test and the actual vehicle test.
Further, the motor control unit 29 has an abnormality report means 42. When the demagnetization determination unit 34 determines that the demagnetization has occurred in the permanent magnet, the abnormality report unit 42 outputs abnormality occurrence information indicating that demagnetization has occurred to the ECU 21. The ECU 21 receives the abnormality occurrence information output from the abnormality reporting means 42 and, for example, turns on a warning lamp installed on a console panel or the like, or when the vehicle is equipped with a display device, Let the display to inform.

FIG. 3 is a conceptual configuration diagram of the IPM motor of the electric vehicle.
As shown in FIG. 3C, when the motor driving the wheel is an IPM motor, that is, an embedded magnet type synchronous motor, the magnet torque Tm generated by the interaction between the rotor-side permanent magnet and the stator, and the rotor-side core The reluctance torque Tr resulting from the attractive force between the stator and the stator is generated and rotated with two types of torques Tm and Tr. The magnet torque Tm is proportional to the current and becomes maximum when the phase, which is the current advance angle β between the rotating magnetic field and the rotor permanent magnet, is zero. On the other hand, the reluctance torque Tr is proportional to the square of the current, and becomes maximum when the phase is 45 °. Therefore, the interior magnet type synchronous motor is normally driven under a current application condition in which the sum (Tm + Tr) of both torques Tm and Tr is maximized.

  As shown in FIG. 3A, when the motor for driving the wheel is an embedded magnet type synchronous motor, the magnetic resistance in the q-axis direction perpendicular to the d-axis direction, which is the magnet axis, is smaller, so that the salient pole The q-axis inductance Lq is larger than the d-axis inductance Ld. Due to this saliency, reluctance torque Tr can be used in addition to magnet torque Tm, and high torque and high efficiency can be achieved.

Magnet torque Tm: Torque generated by attracting and repelling the magnetic field generated by the permanent magnet of the rotor and the rotor magnetic field generated by the winding.
Reluctance torque Tr: A torque generated when a salient pole portion of a rotor is attracted to a rotating magnetic field by a winding.

The total torque generated by the motor is as follows.
T = p × {Ke × Iq + (Ld−Lq) × Id × Iq} = Tm + Tr
p: number of pole pairs Ld: d-axis inductance of motor Lq: q-axis inductance of motor Ke: effective value of motor induced voltage constant

As shown in FIG. 3 (b), there is a vector control method in which the primary current Ia flowing through the IPM motor is separated into a torque generation current q-axis current Iq and a magnetic flux generation current d-axis current Id and can be controlled independently. It is well known.
Id = −Ia × sin β
Iq = Ia × cosβ
(Β: current advance angle)

FIG. 4 is a diagram showing a torque command map in the control device for the electric vehicle.
This torque command map is created in advance by a motor stand test and is written in the storage means 39 (FIG. 2). As shown in the figure, the torque command map shows current commands (primary current Ia, current advance for each torque command value Trq_0, Trq_1,... Trq_n for each motor rotation speed range Rot_0, Rot_1,. Defines the angle β).

During the torque control of the motor, the motor is controlled by extracting the corresponding primary current (Ia) and current advance angle (β) from the torque command map based on the accelerator signal and the speed signal. Further, the vector control is capable of independently generating a q-axis current Iq that is a torque generation current and a d-axis current Id that is a magnetic flux generation current from the primary current (Ia) and the current advance angle (β).
Id = −Ia × sin β
Iq = Ia × cosβ

  When the two left and right rear wheels are driven by torque control as in this embodiment, the power running / regeneration characteristics are different even if the left and right motors are different or the same motor. For this reason, the torque command map is provided separately for the left and right motors, and is provided separately for the power running control state and the regeneration control state of the motor. That is, two types of torque command maps are provided for the left and right motors in the power running control state, and two types of torque command maps are provided for the left and right motors in the regeneration control state. Therefore, a total of four types of torque command maps are provided. When driving the front and rear wheels, a total of eight types of torque command maps are provided.

FIG. 5 is a diagram illustrating a demagnetization determination unit and the like.
As shown in FIG. 5A, the demagnetization determination unit 34 is a functional unit that calculates the demagnetization amount of the permanent magnet mounted on the motor and determines the degree of demagnetization. The demagnetization determination unit 34 includes a q-axis target voltage acquisition unit 44, a q-axis voltage correction unit 45, a q-axis actual voltage correction unit 46, a demagnetization factor calculation unit 47, and a demagnetization factor determination unit 48. The q-axis target voltage acquisition unit 44 has a q-axis target voltage map 44a (FIG. 5B), and acquires the q-axis target voltage Vqr based on the following voltage equation or the like.

ω: motor angular velocity Ke: induced voltage constant Id: d-axis current Iq: q-axis current Ld: d-axis inductance Lq: q-axis inductance R: armature resistance p: differential operator q-axis voltage Vq is expressed as follows: Is done.
Vq = R × Iq + pLq × Iq + ω × Ld × Id + ω × Ke

  As described above, when driving the left and right rear wheels, the accelerator signal is converted into the command torque, and the commands of the left and right motors are based on the torque command map (FIG. 4) in either the power running control state or the regenerative control state. A current (Ia, β) is generated. Even with the same command torque, the command currents of the left and right motors do not necessarily match.

The q-axis target voltage Vqr is expressed as follows.
Vqr = R × O_Iq + pLq × O_Iq + ω × Ld × O_Id + ω × Ke
O_Id: d-axis target current O_Iq: q-axis target current The q-axis target voltage map (FIG. 5B) shows the power running control state and regeneration according to the motor angular velocity ω, the command q-axis current O_Iq, and the command d-axis current O_Id. Each map of control states is provided.

The q-axis voltage correction unit 45 corrects the q-axis target voltage Vqr acquired by the q-axis target voltage acquisition unit 44 according to the q-axis voltage correction map (FIG. 5C).
Switching control is performed by providing a dead time to prevent the switching elements from being turned on at the same time. When the dead time is constant, as the DC power supply voltage Vc increases, the dead time increases and the actual drive voltage decreases. Become. Therefore, it is necessary to correct the motor voltage in accordance with the DC power supply voltage Vc.
Further, the power running state and the regenerative operation state differ in the magnitude of the electric power affected by the dead time even if the DC power supply voltage Vc is the same. For this reason, q-axis voltage correction maps for the power running control state and the regenerative control state are provided.

The q-axis actual voltage correction unit 46 outputs the q-axis actual voltage Vqy from the d-axis actual current Idy and the q-axis actual current Iqy calculated by the three-phase / two-phase conversion unit 50 according to a voltage equation.
That is, the three-phase / two-phase conversion unit 50 uses the rotation angle Θ obtained from the rotation angle sensor to convert the three-phase motor currents Iu, Iv, Iw flowing in the respective phases of the three-phase coil of the motor into the d-axis and the q-axis. Are converted into actual currents Idy and Iqy.

The voltage equation is expressed as follows:
Vqy = R × Iqy + pLq × Iqy + ω × Ld × Idy + ω × K × Ke
Vqy: q-axis actual voltage Idy: d-axis actual current Iqy: q-axis actual current K: Represents the residual rate of magnetic flux.
Therefore, the q-axis actual voltage correction unit 46 outputs the q-axis actual voltage Vqy from the d-axis actual current Idy and the q-axis actual current Iqy according to the voltage equation.

The demagnetizing factor calculation unit 47 calculates the following equation from the q-axis target correction voltage Vqm corrected by the q-axis voltage correction unit 45, the q-axis actual voltage Vqy output by the q-axis actual voltage correction unit 46, the motor angular velocity ω, and the like. To calculate the demagnetization factor.
Demagnetization factor: 1-K
1-K = (Vqm−Vqy) / ω × Ke × 100%
Vqm: q-axis target correction voltage Vqy: q-axis actual voltage ω: motor angular velocity Ke: induced voltage constant

  The demagnetization factor determination portion 48 determines the demagnetization for each of the left and right motors according to the power running control state and the regenerative control state. The demagnetization factor determination portion 48 determines that demagnetization has occurred in the permanent magnet when, for example, (1−K) ≧ a constant threshold and continues for a certain time or more. FIG. 6 is a flowchart of the demagnetization determination by the demagnetization determination unit. This will be described with reference to FIG.

  After the start of the demagnetization determination process, the demagnetization factor determination unit 48 determines whether or not the demagnetization factor (1-K) calculated by the demagnetization factor calculation unit 47 is equal to or greater than a certain threshold value (step S1). If NO (step S1: NO), the process returns. If it is determined that the demagnetization factor (1-K) is equal to or greater than a certain threshold value (step S1: YES), the demagnetization factor determination portion 48 determines whether or not the demagnetization factor equal to or greater than the certain threshold value continues for a certain period of time. Is determined (step S2). If NO (step S2: NO), the process returns to step S1.

  When it is determined that the demagnetization factor has continued for a certain time (step S2: YES), the demagnetization factor determination portion 48 determines that demagnetization has occurred in the permanent magnet (step S3). Thereafter, this process is terminated. When determining the demagnetization, the left and right motors may be demagnetized, and only one of the left and right motors may be demagnetized. The motor control after the demagnetization determination unit 34 determines that demagnetization has occurred in the permanent magnet will be described with reference to FIG.

FIG. 7 is a block diagram of a torque / rotation speed control system in this control apparatus. This will be described with reference to FIG.
The motor drive control unit 30 of the motor control unit 29 includes a current command unit 51. The current command unit 51 detects a drive current applied to the motor 6 by the current detection unit 43 and a torque in the ECU 21. / From the torque command value by the acceleration / deceleration command generated by the rotation speed control command unit 21a, a corresponding command current is generated by using a torque command map preset in the inverter device 22. That is, according to the torque command value from the ECU 21, PI feedback control is performed to eliminate the deviation of the command current value generated inside the inverter. The direction of the command current is switched by a command flag given from the power running / regenerative control command unit 21b of the ECU 21.

  The motor power running / regeneration control unit 33 obtains the rotation angle of the rotor of the motor 6 from the rotation angle sensor 36 and performs vector control. Here, the motors 6 provided on the left and right rear wheels 2 of the vehicle body have different directions of torque generation during power running and during regeneration. That is, when the motor 6 is viewed from the direction of the output shaft, the left motor 6 generates clockwise torque, and the right motor 6 generates counterclockwise torque (the left and right sides are viewed from the rear of the vehicle). Determined by). Torques generated by the left and right motors 6 and 6 are transmitted to the tire by reversing the torque direction via the speed reducer 7 and the wheel bearing 4. Further, the direction of torque generation during regeneration in the motor 6 for the left and right tires is different from the direction of torque generation during power running.

  The current command unit 51 generates a primary current (Ia) and a current advance angle (β) of the motor 6 based on the calculated torque command value. The current command unit 51 generates two command currents of a d-axis current (field component) O_Id and a q-axis current O_Iq based on the values of the primary current (Ia) and the current advance angle (β).

  The current PI control unit 52 is a two-phase current calculated by the three-phase / two-phase conversion unit 50 from the values of the d-axis current O_Id and q-axis current O_Iq output from the current command unit 51 and the motor current and the rotor angle. Control amounts Vd and Vq based on voltage values by PI control are calculated from Id and Iq. In the three-phase / two-phase converter 50, the detected value of the u-phase current (Iu) and the v-phase current (Iv) of the motor 6 detected by the current detecting means 43 is obtained by the following formula Iw = − (Iu + Iv). A w-phase current (Iw) is calculated and converted from a three-phase current of Iu, Iv, and Iw to a two-phase current of Id and Iq. The rotor angle of the motor 6 used for this conversion is acquired from the rotation angle sensor 36. The detected rotation angle (phase) is corrected by the rotation angle (phase) correction unit 53, and the motor 6 can be controlled with high accuracy.

  The two-phase / three-phase converter 54 determines the three-phase PWM duty Vu, Vv, Vw from the input two-phase control amounts Vd, Vq and the rotation angle corrected by the rotation angle (phase) correction unit 53. Convert to The power conversion unit 55 performs PWM control of the inverter 31 (FIG. 2) according to the PWM duties Vu, Vv, and Vw, and drives the motor 6.

  When the permanent magnet of the motor is in a demagnetized state, as in the prior art 1, in the configuration in which the current command values for the plurality of motors are respectively calculated so that the output torques of the plurality of motors match, the calculation time is Take it. Furthermore, when the left and right torque difference is larger than the threshold value, the output torques of the plurality of electric motors cannot be matched immediately, and there is a concern that an unintended yaw moment may occur and adversely affect the vehicle behavior.

  Therefore, in this embodiment, when the demagnetization determination unit 34 determines that demagnetization has occurred in the permanent magnet, the switching control means 38 switches the motor 6 from torque control to rotation speed control by the rotation speed control means 40. The rotational speed control means 40 is means for controlling the rotational speed of the motor 6, and includes a rotational speed command section 21aa in the torque / rotational speed control command section 21a and a rotational speed / torque conversion section 56 in the motor drive control section 30. .

The rotation speed command unit 21aa gives a rotation speed command to the rotation speed / torque conversion unit 56. The rotation speed / torque converter 56 converts the input rotation speed command into a command torque. As a result, the driver can operate the switch 41 for adjusting the torque command map by retracting the vehicle to the roadside belt or the like for the time being.
In response to the input signal from the operation signal of the switch 41, the torque command map automatic adjustment unit 35 adjusts the torque command map so that the torques of the left and right motors 6 and 6 coincide. The torque command map automatic adjustment unit 35 shifts to an adjustment mode for adjusting the torque command map in response to an input signal from the switch 41.

  For example, the torque command map automatic adjustment unit 35 adjusts the torque command map by gradually increasing the demagnetization factor in the motor 6 with the larger demagnetization among the left and right motors 6 and 6 until it becomes zero. For example, when it is determined that demagnetization has occurred in the right motor 6, the torque command map of the right motor 6 is adjusted. In the adjustment mode in which the torque command map is adjusted, the left motor 6 on the non-adjustment side is controlled by the rotation speed control at the motor rotation speed at which the vehicle speed is, for example, several km / h or less, and the right motor on the adjustment side 6 is executed by torque control. After completion of the adjustment mode, the left and right motors 6 and 6 are torque-controlled according to the respective torque command maps.

  When the demagnetization occurs in both the left and right motors, in the adjustment mode in which the torque command map is adjusted, for example, the non-adjustment side motor 6 is controlled to rotate at low speed and the other motor to be adjusted is adjusted. While controlling the torque of the motor 6, the torque command map of the other motor 6 is adjusted. Next, the speed of the other motor 6 after the adjustment is controlled at a low speed, and the torque command map of the one motor 6 is adjusted while controlling the torque of the motor 6 to be adjusted.

The effect will be described.
When the vehicle travels, the demagnetization determination unit 34 determines whether demagnetization has occurred in the permanent magnet of the motor 6. When no demagnetization occurs in the permanent magnet, the motor control unit 29 performs torque control. When the demagnetization determination unit 34 determines that demagnetization has occurred in the permanent magnet, the switching control means 38 switches from the torque control to the rotation speed control by the rotation speed control means 40, and the abnormality report means 42 demagnetizes the ECU 21. Outputs information on the occurrence of an error indicating that a problem has occurred.

  Accordingly, the driver operates the switch 41 by retracting the vehicle to a roadside belt, for example. In response to the input signal from the operation signal of the switch 41, the torque command map automatic adjustment unit 35 adjusts the torque command map so that the torques of the left and right motors 6 and 6 coincide. Thereafter, the motor control unit 29 controls the torque of the motor 6 according to the adjusted torque command map. In this way, the torques of the left and right motors 6 and 6 can be matched to prevent an unintended yaw moment from occurring in the vehicle.

After switching from the torque control to the rotational speed control, it is possible to drive the vehicle to a destination such as a repair shop or a home parking lot while maintaining the rotational speed control, but considering the safety of the motor 6 Only the low-speed running can be performed with the rotation speed control. In this case, it takes a long time to reach the destination, and the speed difference between this vehicle and other vehicles becomes large, resulting in trouble in traveling.
Therefore, after the vehicle is temporarily retracted by the rotational speed control, the torque command map is adjusted by the torque command map automatic adjustment unit 35 so that the torques of the left and right motors 6 and 6 coincide with each other, and torque control is performed again. Since it returns, it becomes possible to give a certain speed. Therefore, it is possible to make the vehicle run from the place where it is temporarily retracted to the destination in a shorter time without trouble in traveling than when traveling at a low speed while maintaining the rotational speed control.

The motor 6 may directly rotate and drive the wheels 2 without using the speed reducer 7.
In this embodiment, an embedded magnet type synchronous motor with a built-in permanent magnet is applied, but a so-called SPM motor in which a permanent magnet is provided on the rotor surface may be applied.
In the in-wheel motor drive device, an example in which a cycloid type speed reducer is adopted has been shown. However, the present invention is not limited to this, and a planetary speed reducer, a two-axis parallel speed reducer, and other speed reducers can be applied. A so-called direct motor type that does not employ a reduction gear may be used.

2 ... Wheel 6 ... Motor 8 ... In-wheel motor drive device 16 ... Accelerator operation unit 17 ... Brake operation unit 21 ... ECU
DESCRIPTION OF SYMBOLS 22 ... Inverter apparatus 28 ... Power circuit part 29 ... Motor control part 31 ... Inverter 34 ... Demagnetization determination part 35 ... Torque command map automatic adjustment part 38 ... Switching control means 40 ... Speed control means

Claims (7)

A synchronous motor having permanent magnets and driving wheels;
An ECU that generates and outputs an acceleration / deceleration command according to an operation of the operation unit;
A power circuit unit including an inverter for converting DC power to AC power, and an inverter device having a motor control unit for torque controlling the motor via the power circuit unit in accordance with the acceleration / deceleration command given from the ECU. In the control device of an electric vehicle,
A rotational speed control means for controlling the rotational speed of the motor;
In the motor control unit,
A demagnetization determining unit that determines whether or not demagnetization has occurred in the permanent magnet of the motor, according to a predetermined rule, from an acceleration / deceleration command given from the ECU and a detection signal of the driving state of the motor;
A switching control means for switching from the torque control by the motor control section to the rotation speed control by the rotation speed control means when it is determined by the demagnetization determination section that the demagnetization has occurred in the permanent magnet;
An electric vehicle control device characterized by comprising:   2. The control apparatus for an electric vehicle according to claim 1, wherein the electric vehicle includes left and right motors for individually driving left and right drive wheels as the motor, and the motor control unit is configured to add the motor for each of the left and right motors. The motor is torque-controlled according to a torque command map that defines a relationship between a torque command serving as a deceleration command and a motor current command, so that the torques of the left and right motors match in response to a predetermined input. In addition, a control apparatus for an electric vehicle, wherein a torque command map automatic adjustment unit for adjusting the torque command map is provided in the motor control unit.   3. The control apparatus for an electric vehicle according to claim 2, wherein the torque command map automatic adjustment unit corresponds to the torque command with respect to the torque command map of the motor having a larger demagnetization among the left and right motors. An electric vehicle control apparatus that adjusts the torque command map by gradually increasing a current command until a demagnetization factor becomes zero.   4. The electric vehicle control device according to claim 2, wherein the torque command map is provided in each of a power running control state and a regenerative control state of the motor, and the torque command map automatic adjustment unit includes the motor An electric vehicle control device that adjusts the torque command map separately for a power running control state and a regenerative control state.   5. The electric vehicle control device according to claim 1, wherein the demagnetization determination unit determines that the permanent magnet has a demagnetization factor that is equal to or greater than a certain threshold and continues for a certain time. An electric vehicle control apparatus that determines that demagnetization has occurred.   6. The electric vehicle control device according to claim 1, wherein when the demagnetization determination unit determines that demagnetization has occurred in the permanent magnet, A control device for an electric vehicle that controls the number of revolutions of the motor at a predetermined number of revolutions in response to an input.   7. The electric vehicle control device according to claim 1, wherein the motor is a motor constituting an in-wheel motor drive device, and the motor includes left and right front wheels and left and right rear wheels. The control apparatus of the electric vehicle provided with respect to any one or both.

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