JP2009027814A - Driving force controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force controller that is simple in configuration and control and is capable of enhancing the behavior stability of a vehicle, wherein the driving force is distributed between two left and right wheels or two front and rear wheels through the utilization of a difference in number of rotations during turning. <P>SOLUTION: The driving force controller is capable of individually supplying the driving force to each of two wheels of a vehicle by an induction motor. The induction motor has such torque characteristics that there are two ranges, a range where torque is increased with an increase in rotational speed or a decrease in slip and a range where torque is reduced with the same. One of the two wheels is coupled with a first rotor and the other is coupled with a second rotor. Identical stators are used for the first rotor and the second rotor so that the details of control, including frequency control, are identical. The driving force controller includes a torque characteristic controlling means (S06) that changes torque characteristics when there is a difference in number of rotations between two wheels, thereby changing a difference in driving torque between the two wheels. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle driving force control device configured to be capable of individually controlling driving forces of at least two wheels by an induction motor.

  The driving force of the left and right wheels of the vehicle or the front and rear wheels on one side greatly affects the behavior stability and turning performance of the vehicle. For example, in order to improve the straight running stability of the vehicle, it is preferable that the driving force of each wheel is the same, and in order for the vehicle to turn, the inner and outer wheels so that the vehicle passes on a target turning radius. There is preferably a predetermined difference between the driving force and the rotational speed. Therefore, in the device described in Patent Document 1, the rotor bar of the induction motor is divided into two parts, one of which is connected to one of the left and right wheels, and the other is connected to the other of the left and right wheels, and the vehicle turns. The effective value of the contact area on the dividing surface of the rotor bar is decreased, thereby increasing the secondary resistance value of the entire rotor and moving the peak value of the output torque of the motor to the low speed side. Further, in the apparatus described in Patent Document 2, in a vehicle equipped with an in-wheel motor, the difference between the turning radius with respect to the steering amount with respect to the target turning radius is determined, and the inverter is controlled so as to reduce the difference, and the left and right It is comprised so that the driving force of the wheel may be controlled.

JP-A-6-225498 JP 2005-328657 A

  The device described in the above-mentioned Patent Document 1 increases the secondary resistance value of the rotor by utilizing the difference in rotational speed generated between the left and right wheels when the vehicle turns, and moves the peak value of the torque to the low speed side. It is the apparatus comprised as follows. Therefore, although the driving torque can be increased when the vehicle speed decreases during turning, the turning performance of the vehicle is influenced by the difference in driving torque between the left and right wheels, but is described in Patent Document 1. In the existing apparatus, the driving forces of the left and right wheels cannot be individually and actively controlled, so there is room for improvement in order to improve turning performance and vehicle behavior stability.

  Further, in the apparatus described in Patent Document 2, since a motor is individually attached to or connected to each wheel, the driving force of each wheel can be appropriately controlled, and accordingly, along the target turning radius. It is possible to control the vehicle so that it travels. However, the electric motor is controlled by adjusting the power supplied by the inverter. Therefore, it is necessary to provide an inverter for each motor and control it individually. May become larger and control may be complicated.

  The present invention has been made by paying attention to the above technical problem, and by using the difference in the rotational speed during turning to distribute the driving force between the left and right two wheels or the two front and rear wheels, the configuration and control are simple. An object of the present invention is to provide a driving force control device capable of improving the behavior stability of a vehicle.

  In order to achieve the above object, the invention of claim 1 is directed to a vehicle driving force control apparatus capable of individually applying driving force to each of left and right two wheels or front and rear two wheels in a vehicle by an induction motor. The motor has a torque characteristic having two regions, a region in which the torque increases in response to an increase in rotational speed or a decrease in slip, and a region in which the torque decreases. A first rotor in the motor is connected, and a second rotor in the induction motor is connected to the other, and the stator in the induction motor with respect to the first rotor and the second rotor controls the frequency. The control details including the And it is characterized in that it comprises a torque characteristic control means for changing the difference in driving torque of the two-wheel by changing the torque characteristics at a certain state.

  According to a second aspect of the present invention, in the first aspect of the invention, the stator includes a single stator in which the first rotor and the second rotor are inserted on the inner peripheral side. A driving force control device for a vehicle.

  According to a third aspect of the present invention, in the first aspect of the present invention, the stator includes two stators connected in series so as to have the same frequency, and the first stator is disposed on an inner peripheral side of one stator. And the second rotor is inserted on the inner peripheral side of the other stator.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the torque characteristic control means has a magnitude relationship between a driving torque of one wheel having a rotational speed difference and a driving torque of the other wheel. The vehicle driving force control device includes means for changing the torque characteristic so as to be reversed.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the torque characteristic control means changes the torque characteristic by changing the frequency of the current flowing through the stator and changing the synchronous rotational speed. A vehicle driving force control apparatus comprising:

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the torque characteristic control means changes the difference in driving torque between the two wheels so that the actual behavior of the vehicle approaches the target behavior. A driving force control apparatus for a vehicle including means.

  According to the first aspect of the invention, the first rotor in the induction motor is connected to either one of the left and right wheels or one of the front and rear wheels, and the second rotor is connected to the other wheel. Since they are connected, the driving torque of each of these two wheels can be controlled individually. The stator for these rotors is shared by each rotor. That is, the above-described first and second rotors are arranged in one stator, or the stator and the stator for the second rotor are connected in series to the first rotor. Are the same. And the torque characteristic of the induction motor, that is, the characteristic that the torque with respect to the rotational speed or the slip has a peak value, and the torque increases in accordance with the increase of the rotational speed or the decrease of the slip before and after the peak value. And a region in which the torque decreases as the rotational speed increases or the slip decreases. The torque characteristic can be changed according to the control contents such as the frequency of the current supplied to the stator and the secondary resistance value of the rotor. Alternatively, the difference in driving torque between the two wheels is changed by changing the torque characteristics of the induction motor in a state where there is a difference in the rotational speed between the two front and rear wheels. Therefore, when turning, the yaw of the vehicle can be controlled by changing the frequency of the stator for each rotor in common or by changing the secondary resistance value of each rotor in common. The overall configuration and control for performing the control can be simplified.

  In particular, in the invention of claim 2, since only one stator is required for the two rotors, the configuration and control can be simplified.

  In the invention of claim 3, since the frequency of the current supplied to the two stators may be the same, the control can be simplified and the configuration can be simplified.

  According to the invention of claim 4, since the magnitude relationship between the driving torques of the left and right two wheels or the magnitude relationship between the driving torques of the two front and rear wheels during turning can be reversed, the yaw of the vehicle can be increased or vice versa. The vehicle behavioral stability or running stability can be improved with a simple configuration and control.

  According to the invention of claim 5, by changing the frequency of the current supplied to the stator, it is possible to control the driving torque of the left and right two wheels or the driving torque of the two front and rear wheels.

  Further, according to the invention of claim 6, by changing the torque characteristic of the induction motor, the behavior of the vehicle approaches the target behavior, and the behavior stability or running stability of the vehicle can be improved.

  Next, the present invention will be described more specifically. The present invention is a driving force control device capable of individually controlling the driving force of two left and right wheels or the driving force of two front and rear wheels in a vehicle. The vehicle includes an internal combustion engine such as a gasoline engine or a diesel engine, or an internal combustion engine and an electric motor. A hybrid drive device or a motor that is used in combination as a main driving force source, a vehicle that travels by transmitting the power output from the driving force source to a predetermined two-wheel or four-wheel, a predetermined two-wheel power of the main driving force source So-called four-wheel drive vehicle that drives with two motors other than the drive wheel by an electric motor, so-called in-wheel motor vehicle that can rotate each wheel individually by a motor, three-wheel vehicle or more than four wheels Any of a vehicle etc. may be sufficient.

  An induction motor is provided that applies driving force to each of the left and right two wheels or the front and rear two wheels in the vehicle. FIG. 1 shows an example in which a driving force is applied to the left and right two wheels W1, W2 from the induction motors M1, M2. That is, a first induction motor M1 is provided corresponding to one wheel W1, and a second induction motor M2 is provided corresponding to the other wheel W2. These induction motors M1 and M2 generate stators S1 and S2 that generate a rotating magnetic field by an alternating current flowing in the coil, and generate an induced current in the coil by the rotating magnetic field, and the interaction between the induced current and the rotating magnetic field Rotors R1 and R2 that rotate by generated torque are provided, and the rotors R1 and R2 are individually connected to the left and right wheels W1 and W2. An appropriate transmission mechanism such as a universal joint, a constant velocity joint, or a transmission can be interposed between the rotors R1, R2 and the wheels W1, W2. These induction motors M1 and M2 are arranged adjacent to each other on the same axis in a casing C constituting a part of the vehicle body.

  Stator S1, S2 in each said induction motor M1, M2 is shared by each rotor R1, R2. Here, “common” means that the rotor is substantially configured to function as a single stator, and the stator S1, S2 side coils for the rotors R1, R2 are the same, Even if the coils on the stator S1, S2 side for each of the rotors R1, R2 are different, the control content such as the frequency is the same by connecting them in series. Each induction motor M1, M2 is connected to an inverter Iv that converts direct current into alternating current and controls its frequency.

  FIG. 2 conceptually shows the torque characteristics (slip-torque characteristics) of the induction motors M1, M2. The horizontal axis in FIG. 2 indicates the rotation speed or slip, and the vertical axis indicates the torque. As shown in FIG. 2, the torque has a peak value, and in the region on the low rotational speed side (high slip side) than the rotational speed (slip) corresponding to the peak value, the rotational speed increases (slide decreases). ) And the torque decreases in response to the increase in the number of rotations (decrease in the slip) in the region of the higher number of rotations (slip) than the number of rotations (slip) corresponding to the peak value. It has become a characteristic.

The symbol Ns in FIG. 2 indicates the synchronous rotation speed, which is represented by the frequency f, the slip S, and the pole number P.
Ns = 120f (1-S) / P
Is required. Accordingly, the synchronous rotation speed Ns changes depending on the frequency, and the torque characteristic curve changes accordingly as shown by a broken line or a chain line in FIG. That is, the torque peak value changes to the low speed side or the high speed side, and accordingly, the so-called right-up region and right-down region change to the low speed side or the high speed side. .

  The inverter Iv is connected to the electronic control unit ECU. This electronic control unit ECU is mainly composed of a microcomputer, performs calculation using input data and data stored in advance, outputs the calculation result to the inverter Iv as a control signal, and induction motor M1. , M2 is controlled. The data used for the control is data such as vehicle speed, steering angle, yaw rate, rotational speed of each wheel W1, W2 and required driving force such as accelerator opening, and these are sensors for detecting the respective data. (Not shown).

  The control device according to the present invention changes the torque characteristics of the induction motors M1 and M2 according to the deviation between the actual behavior of the vehicle and the target behavior in a state where the rotational speeds of the wheels W1 and W2 are different. Is configured to do. FIG. 3 is a flowchart for explaining an example of the change control. First, data such as the rotation speed, steering angle, vehicle speed, and driving force required amount of each wheel W1, W2 is read (step S01). It is determined whether or not there is a difference between the rotational speeds of the left and right wheels W1, W2 based on the data (step S02). More specifically, the determination in step S02 can be made by determining whether or not the difference between the rotational speeds of the left and right wheels W1 and W2 is equal to or greater than a threshold value determined in advance as a determination criterion.

  If the determination in step S02 is negative, the routine shown in FIG. 3 is temporarily terminated without performing any particular control. On the other hand, when there is a positive difference in step S02 due to the difference in the rotational speed, a target value is calculated (step S03). This target value is a target value of vehicle behavior such as a target yaw rate and a target turning radius, and can be calculated based on the data read in step S01. A deviation between the calculated target value and the actual value is calculated (step S04). This actual value is data indicating the actual behavior of the vehicle, such as the actual yaw rate detected by the yaw rate sensor, the actual turning radius determined from the change in the position of the vehicle, the centrifugal force, and the like.

  Next, it is determined whether or not the deviation calculated in step S04 is larger than a predetermined reference value α (step S05). The reference value α is for avoiding sensitive control in response to an error or a temporary deviation, and can be determined in advance based on experiments, simulations, or the like. If the determination in step S05 is negative, that is, if the calculated deviation is equal to or smaller than the reference value α, the routine shown in FIG. 3 is temporarily terminated without performing any particular control. On the other hand, if the deviation is larger than the reference value α and affirmative determination is made in step S05, the torque characteristics of the induction motors M1 and M2 are changed according to the deviation (step S06). That is, the torque characteristics are changed so that the deviation becomes smaller, in other words, the behavior of the vehicle becomes the target behavior. Thereafter, the routine of FIG. 3 is terminated.

  The torque characteristic is changed by changing the frequency of the current supplied to the stators S1 and S2 to the high frequency side or the low frequency side by the inverter Iv. This will be explained based on a specific example. If a difference in rotational speed occurs between the left and right wheels W1 and W2 while traveling with a torque characteristic CH1 indicated by a solid line in FIG. 2, the rotational speeds or slips S are different from each other. As a result, the driving torques of the wheels W1 and W2 are different. For example, the rotational speed of each of the wheels W1 and W2 is in a region where the torque increases as the rotational speed increases in the torque characteristic CH1 (so-called right upward region), and the vehicle turns right as indicated by an arrow in FIG. In this case, since the rotational speed of the outer ring W1 in the turning direction becomes a relatively high rotational speed, the torque generated by the rotor R1 connected thereto (that is, the driving torque of the outer ring W1) becomes relatively large. On the other hand, since the rotation speed of the inner ring W2 is relatively low, the torque generated in the rotor R2 connected thereto (that is, the driving torque of the inner ring W2) is relatively small.

  When the actual yaw rate or turning radius detected in this state is larger than the target value and the deviation exceeds the reference value α, the frequencies of the stators S1 and S2 are set so that the synchronous rotational speed becomes low. Is changed, for example, to a torque characteristic indicated by reference sign CH2 in FIG. By doing so, the rotational speed of each of the wheels W1, W2 enters a region where the torque characteristic CH2 is lowered to the right, that is, a region where the torque decreases as the rotational speed increases. As a result, the driving torque of the inner ring W2 is reduced to the outer ring. It becomes larger than the driving torque of W1. In other words, the magnitude relationship between the driving torques at the wheels W1 and W2 is reversed. When the driving torque of the inner ring W2 becomes relatively large in this way, an action (yaw moment) that suppresses the right turn of the vehicle occurs, and thus the yaw of the vehicle is suppressed. That is, behavior such as yaw or turning radius is brought close to the target value.

  It is also possible to change the torque characteristics so that the difference in driving torque between the wheels W1, W2 changes. That is, the gradient of torque change according to the number of revolutions varies depending on the number of revolutions as shown in FIG. 2, and there is a number of revolutions at which the torque becomes equal at the number of revolutions on both sides of the torque peak value. To do. Therefore, for example, if the synchronous rotational speed (frequency) is changed so that the torque characteristic indicated by CH3 in FIG. 2 is obtained, the rotational speeds of the wheels W1 and W2 enter the region where the torque change gradient is small. A difference in driving torque between the wheels W1 and W2 can be reduced.

  According to the control device according to the present invention that performs the control shown in FIG. 3, as described above, the drive torques of the left and right wheels W1, W2 are controlled so that the actual behavior of the vehicle approaches the target behavior. Therefore, it is possible to improve the behavioral stability or running stability of the vehicle, or to run near the driving intended by the driver. In addition, by controlling the frequency with one inverter Iv, it is possible to control the driving torque of each wheel W1, W2 or the magnitude relationship thereof, so that the overall configuration and control of the device can be simplified. .

  FIG. 4 is a schematic view showing another example of the present invention. The example shown here is an example in which the reduction motor is provided and the induction motor M is downsized. That is, the rotors R1 and R2 connected to the wheels W1 and W2 are arranged adjacent to each other on the same axis, and in that state, are inserted so as to be rotatable inside the single stator S. Yes. The stator S generates a rotating magnetic field when a high current is supplied, and is connected to the inverter Iv. The inverter Iv is connected to the electronic control unit ECU.

  Each rotor R1, R2 is connected to speed reducers RD1, RD2 arranged between wheels W1, W2. These speed reducers RD1 and RD2 may be either a fixed speed ratio or a variable speed ratio, and FIG. 4 shows an example in which the speed reducer is configured in two stages for speed reduction. That is, drive gears DG1 and DG2 are attached to the rotors R1 and R2, and countershafts CS1 and CS2 are arranged in parallel therewith. First counter gears CG11 and CG21 that are larger in diameter than the drive gears DG1 and DG2 and mesh with the drive gears DG1 and DG2 are attached to the countershafts CS1 and CS2. The counter shafts CS1 and CS2 are provided with relatively small-diameter second counter gears CG12 and 22 which are integrated with the wheels W1 and W2 and have a larger diameter than the second counter gears CG12 and DG22. , Mesh with DNG2. Accordingly, a deceleration action is generated between the drive gears DG1, DG2 and the first counter gears CG11, CG21, and between the second counter gears CG12, 22 and the driven gears DNG1, DNG2.

  Therefore, in the configuration shown in FIG. 4, since only one stator S is required, the overall configuration can be downsized and the control can be simplified. In addition, since the torque can be increased and transmitted to the wheels W1 and W2 by the speed reducers RD1 and RD2, the induction motor M can be made small in size with low torque.

  In the induction motor, the torque characteristics change when the secondary resistance value of the rotor is changed. For example, when the secondary resistance value of the stator is increased, the peak value of the torque moves to the low rotational speed side (high slip side) even if the synchronous rotational speed is constant. Therefore, the region where the rotational speed of the wheel is included can be changed into a region where the torque increases as the rotational speed increases and a region where the torque decreases as the rotational speed increases. In the present invention, the torque characteristic is changed by changing the secondary resistance value of the rotor instead of changing the frequency as described above by using the characteristics of the induction motor. May be. Further, the behavior of the vehicle can be changed not only by changing the driving torque of the left and right wheels, but also by changing the driving torque of the front and rear wheels. Therefore, the present invention can be configured to control the driving torque of the front and rear wheels in addition to controlling the driving torque of the left and right wheels, or in addition to controlling the driving torque of the left and right wheels. Furthermore, in the specific example described above, the case of controlling to suppress yaw has been described, but the device of the present invention can change the torque characteristics of the induction motor so as to increase yaw.

It is a schematic diagram which shows roughly an example of the driving force control apparatus which concerns on this invention. It is a figure which shows notionally the torque characteristic of the induction motor. It is a flowchart for demonstrating the example of control performed with the control apparatus which concerns on this invention. It is a schematic diagram which shows roughly the other example of the driving force control apparatus which concerns on this invention.

Explanation of symbols

  W1, W2 ... Wheel, M, M1, M2 ... Induction motor, S1, S2 ... Stator, R1, R2 ... Rotor, C ... Casing, Iv ... Inverter, ECU ... Electronic control unit.

Claims (6)

In the vehicle driving force control device capable of individually applying driving force to each of the left and right two wheels or the front and rear two wheels in the vehicle by an induction motor,
The induction motor has a torque characteristic having two regions, a region where the torque increases in accordance with an increase in rotational speed or a decrease in slip, and a region where the torque decreases.
A first rotor in the induction motor is connected to one of the left and right two wheels or one of the front and rear two wheels, and a second rotor in the induction motor is connected to the other.
The stator in the induction motor for the first rotor and the second rotor is shared so that the control content including frequency control is the same,
A vehicle driving force control device comprising torque characteristic control means for changing the difference in driving torque between the two wheels by changing the torque characteristic in a state where there is a difference in rotational speed between the two wheels.   The vehicle driving force control device according to claim 1, wherein the stator includes a single stator in which the first rotor and the second rotor are inserted on an inner peripheral side. . The stator includes two stators connected in series so as to have the same frequency,
The said 1st rotor is inserted in the inner peripheral side of one stator, and the said 2nd rotor is inserted in the inner peripheral side of the other stator. Vehicle driving force control device.   The torque characteristic control means includes means for changing the torque characteristic so that the magnitude relationship between the driving torque of one wheel having a rotational speed difference and the driving torque of the other wheel is reversed. Item 4. The driving force control apparatus for a vehicle according to any one of Items 1 to 3.   The torque characteristic control means includes means for changing the torque characteristic by changing a frequency of a current flowing through the stator and changing a synchronous rotational speed. Vehicle driving force control device.   6. The torque characteristic control means according to claim 1, further comprising means for changing a difference in driving torque between the two wheels so that an actual behavior of the vehicle approaches a target behavior. Vehicle driving force control device.

Images