JP2006136175A - Motor traction controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor traction controller for a vehicle which makes compatible both the prevention of hunting on a low-μ road and the prevention of vibration on a high-μ road when controllihg the motor traction is controlled. <P>SOLUTION: The motor traction controller for the vehicle includes at least one motor installed at a power source which drives driving wheels, and a motor traction control means which detects drive slips of the driving wheels and recovers a grips of the driving wheels by motor torque down control. In the controller, an estimating means of an equivalent value to the friction coefficient of a road surface which estimates the equivalent value is provided, wherein, when the motor traction is controlled, the motor traction control means makes a phase lag of a motor torque command value lesser to a calculated motor torque limit value when the equivalent value to the friction coefficient of the road surface is at a lower friction coefficient side, while the motor traction control means makes the phase lag of the motor torque command value larger with respect to a calculated motor torque limit value when the equivalent value for the friction coefficient of the road surface is on a higher friction coefficient side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor traction control device for a vehicle that is applied to a hybrid vehicle, an electric vehicle, and the like and in which at least one motor is installed in a power source that drives a drive wheel.

In hybrid vehicles and electric vehicles equipped with a motor as the power source for driving the drive wheels, when the drive wheels slip, the motor over-rotates in accordance with the drive slip of the drive wheels, and an overcurrent is generated in the motor drive circuit. Therefore, it is necessary to converge the drive slip with good response in order to protect the parts. The motor traction control device for converging the drive slip for the purpose of protecting the components is configured to predict that the drive slip will occur when the change rate (angular acceleration) of the rotational angular velocity of the drive wheel is equal to or greater than a predetermined value, and to reduce the motor torque. And driving slip that occurs with an increase in motor torque is prevented (see, for example, Patent Document 1).
JP-A-10-304514

  However, in the above-described conventional motor traction control device, the motor torque is reduced when the driving slip occurs. However, when the angular acceleration is lowered thereafter, the increase of the motor torque is permitted and the slip may occur again. In such a case, the occurrence of slip and the stop are repeated (hunting). Therefore, reducing the phase delay by reducing the time constant of the filter with respect to the torque limit value calculated by this angular acceleration is effective in reducing hunting on low μ roads, but as a rebound, high μ On the road, there is an excessive response to changes in angular acceleration, and there is a problem that vibration due to fluctuations in motor torque occurs.

  The present invention has been made paying attention to the above problems, and provides a motor traction control device for a vehicle capable of achieving both prevention of hunting on a low μ road and prevention of vibration on a high μ road during motor traction control. The purpose is to do.

In order to achieve the above object, in the motor traction control device for a vehicle according to the present invention, at least one motor provided in a power source for driving the drive wheels and a drive slip of the drive wheels are detected and driven by motor torque down control. In a motor traction control device for a vehicle provided with motor traction control means for recovering the grip of the wheel,
A road surface friction coefficient equivalent value estimating means for estimating a road surface friction coefficient equivalent value is provided,
The motor traction control means reduces the phase lag of the motor torque command value with respect to the calculated motor torque limit value when the road surface friction coefficient equivalent value is low on the motor friction control side, and the road surface friction coefficient equivalent value is On the high friction coefficient side, the phase delay of the motor torque command value with respect to the calculated motor torque limit value is increased.

  Therefore, in the motor traction control device for a vehicle according to the present invention, the motor traction control value in the motor traction control means corresponds to the motor torque limit value calculated on the low friction coefficient side at the time of motor traction control. The phase lag of the motor torque command value with respect to the calculated motor torque limit value is increased when the road surface friction coefficient equivalent value is on the high friction coefficient side. That is, at the time of drive slip on a low μ road, the phase delay of the motor torque command value with respect to the motor torque limit value is reduced, and the response delay of the motor torque command value with respect to the generation and convergence of the drive slip is suppressed to reduce the occurrence of slip. Hunting that is repeatedly stopped and stopped can be prevented. On the other hand, at the time of drive slip on the high μ road, the phase delay of the motor torque command value with respect to the motor torque limit value is increased, the fluctuation of the motor torque command value is smoothed, and vibration due to the slight fluctuation of the motor torque can be prevented. As a result, at the time of motor traction control, both hunting prevention on the low μ road and vibration prevention on the high μ road can be achieved.

  Hereinafter, the best mode for realizing a motor traction control device for a vehicle according to the present invention will be described based on Examples 1 to 3 shown in the drawings.

First, the drive system configuration of the hybrid vehicle will be described.
FIG. 1 is an overall system diagram showing a drive system of a hybrid vehicle to which the motor traction control device of Embodiment 1 is applied. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a first motor generator MG1, a second motor generator MG2 (motor), an output sprocket OS, and a power split mechanism TM. Have.

  The engine E is a gasoline engine or a diesel engine, and the opening degree of a throttle valve and the like are controlled based on a control command from an engine controller 1 described later.

The first motor generator MG1 and the second motor generator MG2 are synchronous motor generators in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. Based on a control command from the motor controller 2 described later, Each is controlled independently by applying a three-phase alternating current generated by the control unit 3.
Both of the motor generators MG1 and MG2 can operate as electric motors that are rotated by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “powering”), and the rotor is rotated by an external force. If it is, the battery 4 can be charged by functioning as a generator that generates electromotive force at both ends of the stator coil (hereinafter, this state is referred to as “regeneration”).

  The power split mechanism TM is configured by a simple planetary gear having a sun gear S, a pinion P, a ring gear R, and a pinion carrier PC. And the connection relationship of the input / output member with respect to the three rotating elements (sun gear S, ring gear R, and pinion carrier PC) of the simple planetary gear will be described. A first motor generator MG1 is connected to the sun gear S. A second motor generator MG2 and an output sprocket OS are connected to the ring gear R. An engine E is connected to the pinion carrier PC via an engine damper ED. The output sprocket OS is connected to the left and right front wheels via a chain belt CB, a differential and a drive shaft (not shown).

Due to the above connection relationship, the first motor generator MG1 (sun gear S), the engine E (planet carrier PC), the second motor generator MG2 and the output sprocket OS (ring gear R) are arranged in this order on the alignment chart shown in FIG. It is possible to introduce a rigid lever model (a relationship in which three rotational speeds are always connected by a straight line) that can simply express the dynamic operation of a simple planetary gear.
Here, the “collinear diagram” is a velocity diagram used in a simple and easy-to-understand method of drawing instead of the method of obtaining by equation when considering the gear ratio of the differential gear, Take the number of rotations (rotation speed) of the rotating elements, take each rotating element on the horizontal axis, and based on the gear ratio λ of sun gear S and ring gear R, the interval between each rotating element (S ~ PC): (PC ~ R ) Length ratio is 1: λ.

Next, the control system of the hybrid vehicle will be described.
As shown in FIG. 1, the control system of the hybrid vehicle in the first embodiment includes an engine controller 1, a motor controller 2, a power control unit 3, a battery 4 (secondary battery), a brake controller 5, and an integrated controller. 6.

  The integrated controller 6 receives input information from an accelerator opening sensor 7, a vehicle speed sensor 8, an engine speed sensor 9, a first motor generator speed sensor 10, and a second motor generator speed sensor 11. Brought about. Note that the vehicle speed sensor 8 and the second motor generator rotation speed sensor 11 are for detecting the output rotation speed of the same power split mechanism TM, so the vehicle speed sensor 8 is omitted and the second motor generator rotation speed sensor 11 The sensor signal may be used as a vehicle speed signal.

  The brake controller 5 includes a front left wheel speed sensor 12, a front right wheel speed sensor 13, a rear left wheel speed sensor 14, a rear right wheel speed sensor 15, a steering angle sensor 16, and a master cylinder pressure sensor 17. The brake stroke sensor 18 provides input information.

  The engine controller 1 responds to an engine operating point (Ne) according to a target engine torque command or the like from an integrated controller 6 that inputs an accelerator opening AP from an accelerator opening sensor 7 and an engine speed Ne from an engine speed sensor 9. , Te), for example, is output to a throttle valve actuator (not shown).

  The motor controller 2 receives the motor of the first motor generator MG1 in response to a target motor generator torque command or the like from the integrated controller 6 that inputs the motor generator rotational speeds N1 and N2 from the motor generator rotational speed sensors 10 and 11 by the resolver. A command for independently controlling the operating point (N1, T1) and the motor operating point (N2, T2) of the second motor generator MG2 is output to the power control unit 3. The motor controller 2 uses information on the battery S.O.C that indicates the state of charge of the battery 4.

  The power control unit 3 constitutes a high-power unit with a high voltage of the power supply system that can supply power to both motor generators MG1 and MG2 with a smaller current. As shown in FIG. It has a converter 3b, a drive motor inverter 3c, a generator generator inverter 3d, and a capacitor 3e. A drive motor inverter 3c is connected to the stator coil of the second motor generator MG2. A generator generator inverter 3d is connected to the stator coil of the first motor generator MG1. The joint box 3a is connected to a battery 4 that is discharged during power running and charged during regeneration.

  The brake controller 5 performs ABS control according to a control command to a brake hydraulic pressure unit 19 that independently controls the brake hydraulic pressure of the four wheels during low-μ road braking, sudden braking, and the like. At the time of braking by the brake, regenerative brake cooperative control is performed by issuing a control command to the integrated controller 6 and a control command to the brake hydraulic pressure unit 19. The brake controller 5 includes wheel speed information from the wheel speed sensors 12, 13, 14, 15, steering angle information from the steering angle sensor 16, braking operation from the master cylinder pressure sensor 17 and the brake stroke sensor 18. Quantity information is entered. And based on these input information, a predetermined calculation process is performed and the control command by the process result is output to the integrated controller 6 and the brake hydraulic pressure unit 19. A front left wheel wheel cylinder 20, a front right wheel wheel cylinder 21, a rear left wheel wheel cylinder 22, and a rear right wheel wheel cylinder 23 are connected to the brake fluid pressure unit 19.

  The integrated controller 6 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The integrated controller 6 performs engine operating point control by a control command to the engine controller 1 during acceleration running or the like. In addition, the motor generator operating point control is performed by a control command to the motor controller 2 at the time of stopping, running, braking, or the like. The integrated controller 6 includes the accelerator opening AP, the vehicle speed VSP, the engine speed Ne, the first motor generator speed N1, and the second motor generator speed N2 from the sensors 7, 8, 9, 10, and 11. Entered. And based on these input information, a predetermined calculation process is performed and the control command by the process result is output to the engine controller 1 and the motor controller 2. FIG. The integrated controller 6 and the engine controller 1, the integrated controller 6 and the motor controller 2, and the integrated controller 6 and the brake controller 5 are connected by bidirectional communication lines 24, 25, and 26, respectively, for information exchange.

Next, driving force performance will be described.
As shown in FIG. 2 (b), the driving force of the hybrid vehicle of the first embodiment includes the engine direct driving force (the driving force obtained by subtracting the generator driving amount from the total engine driving force) and the motor driving force (both motor generators MG1). , Driving force by the sum of MG2). As shown in FIG. 2A, the maximum driving force is configured such that the lower the vehicle speed, the greater the motor driving force. In this way, since the vehicle does not have a transmission and travels by adding the direct driving force of the engine E and the motor driving force that is electrically converted, the full power of the accelerator pedal is fully opened from low speed to high speed from the state of low steady driving power. Until now, it is possible to control the driving force seamlessly with good response to the driver's required driving force (torque on demand).
In the hybrid vehicle of the first embodiment, the engine E, the motor generators MG1 and MG2, and the left and right front wheels are connected without a clutch via the power split mechanism TM. Further, as described above, most of the engine power is converted into electric energy by a generator, and the vehicle is driven by a motor with high output and high response. For this reason, for example, when driving on slippery roads such as an ice burn, when the driving force of the vehicle changes suddenly due to slipping of driving wheels or locking of driving wheels during braking, the power control unit 3 from excessive current It is necessary to protect the parts from the pinion over rotation of the power split mechanism TM. On the other hand, taking advantage of the characteristics of high-output and high-response motors, it has been developed from a component protection function to detect the drive slip of the drive wheel instantly, recover its grip, and drive the vehicle safely Adopts traction control.

Next, the braking force performance will be described.
In the hybrid vehicle of the first embodiment, the kinetic energy of the vehicle is converted into electric energy by operating the second motor generator MG2 operating as a motor as a generator (generator) during braking by an engine brake or a foot brake. Then, a regenerative braking system that recovers and reuses the battery 4 is adopted.
As shown in Fig. 3 (a), the general regenerative brake cooperative control in this regenerative brake system calculates the required braking force with respect to the brake pedal depression amount, regardless of the magnitude of the required braking force. The required braking force is shared by the regenerative component and the hydraulic component.
In contrast, the regenerative brake cooperative control employed in the hybrid vehicle of the first embodiment calculates the required braking force with respect to the brake pedal depression amount as shown in FIG. 3 (b), and calculates the calculated required braking force. On the other hand, the regenerative brake is given priority, and as long as the regenerative portion can cover it, the regenerative portion is expanded to the maximum without using the hydraulic component. Thereby, especially in a traveling pattern in which acceleration / deceleration is repeated, energy recovery efficiency is high, and energy recovery by regenerative braking is realized up to a lower vehicle speed.

Next, the vehicle mode will be described.
As the vehicle mode in the hybrid vehicle of the first embodiment, as shown in the collinear diagram of FIG. 4, “stop mode”, “start mode”, “engine start mode”, “steady travel mode”, “acceleration mode” Have
In the “stop mode”, as shown in FIG. 4A, the engine E, the generator MG1, and the motor MG2 are stopped. In the “start mode”, as shown in FIG. 4 (2), the vehicle starts by driving only the motor MG2. In the “engine start mode”, as shown in FIG. 4 (3), the sun gear S rotates to start the engine E by the generator MG1 having a function as an engine starter. In the “steady travel mode”, as shown in FIG. 4 (4), the vehicle travels mainly by the engine E, and power generation is minimized in order to increase efficiency. In the “acceleration mode”, as shown in FIG. 4 (5), the engine E is rotated and the generator MG1 starts generating power. The electric power of the battery 4 is used to increase the driving force of the motor MG2. In addition, it accelerates.
In reverse running, in the “steady running mode” shown in FIG. 4 (4), if the rotation speed of the generator MG1 is increased while the increase in the rotation speed of the engine E is suppressed, the rotation speed of the motor MG2 becomes negative. Transition and reverse travel can be achieved.

  At the time of start-up, when the ignition key is turned, the engine E starts, and after the engine E is warmed up, the engine E stops immediately. When starting or at a light load, when starting or when going down a gentle hill that runs at a very low speed, the fuel is cut in areas where engine efficiency is low, and the engine stops and the motor MG2 runs. During normal travel, the driving force of the engine E is driven directly by one of the wheels by the power split mechanism TM, while the other drives the generator MG1 and assists the motor MG2. At the time of full open acceleration, power is supplied from the battery 4 and further driving force is added. When decelerating or braking, the wheel drives the motor MG2 and acts as a generator to perform regenerative power generation. The collected electrical energy is stored in the battery 4. When the charge amount of the battery 4 decreases, the generator MG1 is driven by the engine E and charging is started. When the vehicle is stopped, the engine E is automatically stopped except when the air conditioner is used or when the battery is charged.

Next, the operation will be described.
[Motor traction control process]
FIG. 6 is a flowchart showing the flow of the motor traction control process executed by the integrated controller 6 of the first embodiment. Each step will be described below (motor traction control means).

  In step S1, based on the sensor signals from the wheel speed sensors 12, 13, 14, and 15, the wheel speeds of the left and right front wheels that are driving wheels and the wheel speeds of the left and right rear wheels that are driven wheels are calculated, and the process proceeds to step S2. To do.

In step S2, following the wheel speed calculation in step S1, a driving wheel wheel speed that is an average value of the wheel speeds of the left and right front wheels and a driven wheel speed that is an average value of the wheel speeds of the left and right rear wheels are obtained.
Slip amount S = drive wheel wheel speed−driven wheel speed
Slip amount S = {(drive wheel wheel speed−driven wheel speed) / driven wheel speed} × 100 [%]
The slip amount S is calculated by the following equation, and the process proceeds to step S3.

In step S3, following the calculation of the slip amount S in step S2, a slip amount torque limit value TSlim is calculated based on the calculated slip amount S, and the process proceeds to step S4.
Here, as shown in FIG. 7, the “slip amount torque limit value TSlim” is set with a map or an arithmetic expression for the relationship between the torque limit value TSlim and the slip amount S, and the slip amount S is set to the slip amount set value S1. Until, the torque limit value TSlim is a constant value, and when the slip amount S exceeds the slip amount set value S1, the torque limit value TSlim is proportionally decreased as the slip amount S increases.

In step S4, following the calculation of the slip amount torque limit value TSlim in step S3, the angular acceleration ω ′ of the front wheels (= second motor generator MG2) is calculated based on the sensor signal from the second motor generator rotation speed sensor 11. Then, the process proceeds to step S5.
Here, the calculation of “angular acceleration ω ′” can be performed by differentiating the angular velocity (= second motor generator rotational speed) with respect to time. As a differential calculation method, for example, when the sampling time is 10 msec, the differential value is calculated by taking the deviation between the current second motor generator rotation speed measurement value and the second motor generator rotation speed measurement value 10 msec before. be able to.

In step S5, following the calculation of the angular acceleration ω ′ in step S4, an angular acceleration torque limit value Tω′lim is calculated, and the process proceeds to step S6.
Here, as shown in FIG. 8, the “angular acceleration torque limit value Tω′lim” is obtained by setting the relationship of the torque limit value Tω′lim with respect to the angular acceleration ω ′ using a map or an arithmetic expression. Until the angular acceleration set value ω'1, the torque limit value Tω'1lim is a constant value. When the angular acceleration ω 'exceeds the angular acceleration set value ω'1, the torque limit increases proportionally as the angular acceleration ω' increases. Let the value Tω'lim be a small value.

  In step S6, following the calculation of the angular acceleration torque limit value Tω'lim in step S5, the motor torque limit value is calculated by a select low of the slip amount torque limit value TSlim and the angular acceleration torque limit value Tω'lim. The process proceeds to S7.

In step S7, following the calculation of the motor torque limit value in step S6, a road surface friction coefficient is estimated, a filter time constant is set according to the estimated size of the road surface μ, and the process proceeds to step S8.
Here, as shown in FIG. 9, the “filter time constant” is set according to the estimated size of the road surface μ, and is low in the low μ region where the estimated road surface μ is equal to or less than the first set value μ1. A filter time constant based on a constant value is set, and in the region where the estimated road surface μ is between the first set value μ1 and the second set value μ2, the filter time constant increases proportionally as the estimated road surface μ increases. In the high μ region where the estimated road surface μ is equal to or greater than the second set value μ2, a filter time constant is set with a constant value of a high value.
In addition, the estimation of the “road surface μ” is performed by, for example, obtaining wheel speeds VW1 to VW4 of each wheel and braking / driving forces F1 to F4 per unit load, and these wheel speeds VW1 to VW4 and braking / driving forces F1 per unit load. The points for each wheel representing the combination of ~ F4 are represented on two-dimensional coordinates, straight lines representing these points are obtained, and the road surface friction coefficient μ is estimated based on the gradient (road surface friction coefficient equivalent value estimation means) . Details will be described later.

  In step S8, following the setting of the filter time constant in step S7, the motor torque command value is determined based on the motor torque limit value calculated in step S6 and the filter time constant set in step S7. The command value is output to the motor controller 2 and the process proceeds to return.

[Estimation of road surface μ]
The estimation of the road surface μ in step S7 in FIG. 6 is performed by the following method.
The change characteristic of the road surface friction coefficient μ with respect to the wheel slip ratio S (in other words, the braking / driving force of the wheel) is as shown by a solid line in FIG. It is known that the dot-dash line in FIG. In either case, the maximum value μmax of the road surface friction coefficient is different, but exhibits characteristics having almost the same tendency. It is well known that the above relationship holds true not only in the region of S ≦ So during acceleration but also in the region of S ≧ −So during braking as shown in FIG. 10 (a). Is the fact of

  In the region of the region below the wheel slip rate So where the change characteristic of the road surface friction coefficient μ with respect to the wheel slip rate S can be regarded as almost linear, the wheel speed and the braking / driving force per unit load are shown in FIG. ) When the combinations of the wheel speeds VW1 to VW4 of the wheels 1 to 4 and the braking / driving forces F1 to F4 per unit load are plotted for each wheel on the two-dimensional coordinates of), the four points generated by the plot are shown in the figure. As shown by the solid line in FIG. The wheel speed value at the point where the straight line intersects the wheel speed (VW) axis of the two-dimensional coordinate is the vehicle body speed Vx itself, and the gradient of the straight line with respect to the wheel speed (VW) axis is shown in FIG. This is the driving stiffness k of the vehicle corresponding to the rising gradient of the road surface friction coefficient μ with respect to the horizontal axis (wheel slip ratio S) of (a).

  Here, as is clear from the comparison between the solid line characteristic and the one-dot chain line characteristic shown in FIG. 10 (a), between the driving stiffness k and the maximum value μmax of the road surface friction coefficient, for example, FIG. 10 (c) And the maximum friction coefficient μmax is an absolute slippage difficulty of the road surface (in this specification, since this absolute slippage difficulty is also a general term, the road surface friction coefficient Therefore, the road surface friction coefficient μ, which is the absolute difficulty of slipping on the road surface, is estimated from the gradient of the straight line (driving stiffness k) with respect to the wheel speed (VW) axis in FIG. 10 (b). can do.

  Therefore, in Example 1, the wheel speeds VW1 to VW4 and the braking / driving forces F1 to F4 per unit load are obtained for the wheels in the linear region that are not greatly slipped. The points for each wheel representing the combinations of VW1 to VW4 and braking / driving forces F1 to F4 per unit load are indicated on the two-dimensional coordinates as shown in FIG. 10 (b), and a straight line representing these points is obtained. The vehicle speed Vx and the road surface friction coefficient μ are estimated in the manner described above.

[Background of traction control]
For example, Japanese Patent Application Laid-Open No. 10-304514 discloses a technique (angular acceleration control) for improving torque down response in the initial stage of slip. This technique is often applied to a vehicle using a motor as a unit for generating a driving force, such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle. The basis of this technology is a configuration that predicts that drive slip will occur when the rate of change (angular acceleration) of the rotational angular velocity of the drive wheels is greater than or equal to a predetermined value, and reduces the motor torque. With this configuration, it is possible to prevent a drive slip that occurs with an increase in motor torque.

Here, the reason why “angular acceleration control” that suppresses slip with high responsiveness in the early stage of generation of drive slip in a hybrid vehicle using a motor as a unit that generates drive force will be described.
If there is no motor traction control device and the drive slips, the power generation of the engine cannot catch up and the motor draws more current from the battery. Therefore, an overcurrent is generated in the motor drive circuit, and the elements on the circuit are damaged. For example, in the power control unit 3 of the first embodiment, as shown by the arrow in FIG. 5, when an overcurrent flows through the capacitor 3e, the fuse of the joint box 3a and the switching circuit of the boost converter 3b are damaged. There is a case. Moreover, in a hybrid vehicle or a fuel cell vehicle, overcurrent tends to flow as the motor output (motor output ratio) is larger than that of the secondary battery. In addition, overvoltage and overcurrent flow more easily as the output of the engine and fuel cell (engine output ratio) is larger than that of the secondary battery. There is a relationship. Therefore, in order to reliably protect the parts, it is necessary to perform motor traction control that converges the drive slip with good response by "angular acceleration control" in which torque is limited when slipping.

  However, in the conventional “angular acceleration control”, priority is given to component protection on a low μ road where drive slip is likely to occur, and a large motor torque down amount is provided when the occurrence of drive slip is predicted. For this reason, when the driving wheel speed increases due to the occurrence of driving slip, the motor torque decreases, and the driving wheel speed also decreases as the motor torque decreases. This decrease in the wheel speed of the drive wheel exceeds the optimum slip amount range and decreases to the vehicle body speed level. When the driving wheel speed decreases to the vehicle body speed level, the motor torque is allowed to increase, and the driving wheel speed becomes a re-slip situation where the driving wheel speed increases again. Repeated.

  In other words, in the case of “angular acceleration control”, the occurrence of overcurrent can be prevented by detecting the start of slip early and entering torque down control, but the actual control range has a slip amount that is higher than the optimum slip amount range with high cornering power. Because it has expanded to a low area, the drive wheel potential is not fully used. For this reason, in the case of “angular acceleration control”, although protection of parts can be achieved, if the output reduction of the drive torque is too great and the driving wheel speed sticks to the vehicle speed (vehicle speed), acceleration failure due to rattling (stumble ) Will occur.

In the case of “angular acceleration control”, hunting in which slip generation (slip amount is large) and slip convergence (slip amount is small) is repeatedly generated in the drive wheels. If the phase delay is reduced by reducing the filter time constant with respect to the torque limit value calculated by this "angular acceleration control", it is effective in reducing hunting on low μ roads. On the road, there is an excessive response to changes in angular acceleration, and vibration due to fluctuations in motor torque occurs.
In other words, when the filter time constant is given as a fixed value, if the filter time constant is made small with emphasis on hunting reduction, the low μ road and the high μ road in the case of μ jump from low μ road to high μ road shown in FIG. It is difficult to achieve both the prevention of hunting and the prevention of vibration, such that vibration is generated on the high μ road side on the road surface where the abruptly changes.

[Motor traction control function]
In the first embodiment, with respect to the problem of the occurrence of the stumble by only the conventional “angular acceleration control”, the “slip amount” for converging the slip amount of the drive wheel to the optimum slip amount range with high cornering power is applied to “angular acceleration control”. In combination with control, the motor traction control reliably prevents the occurrence of stumble and ensures vehicle acceleration.

  That is, when a drive slip occurs, in the flowchart of FIG. 6, the flow proceeds from step S1, step S2, step S3, step S4, step S5, and step S6. In step S6, the angular acceleration torque limit value Tω′lim The motor torque limit value is calculated by select low with the slip amount torque limit value TSlim.

  Therefore, for example, at the time of start, the angular acceleration torque limit value Tω′lim by the “angular acceleration control” is effective for the occurrence of the first slip, and the driving slip is suppressed early. When the change in angular acceleration is small and the wheel speed converges, the slip amount torque limit value TSlim by “slip amount control” is effective, and thereafter the drive wheel wheel speed is within the optimum slip amount range. Wheel speed is controlled.

  As described above, by combining “angular acceleration control” and “slip amount control” as motor traction control and adopting select low control of the angular acceleration torque limit value Tω′lim and the slip amount torque limit value TSlim, The stumble is improved after the first slip, and acceleration is ensured at the time of start and intermediate acceleration.

  Further, in the first embodiment, for the problem of low μ road hunting and high μ road vibration only by the conventional “angular acceleration control”, the estimated road surface μ is higher than the calculated motor torque limit value. By increasing the filter time constant and determining the motor torque command value as shown, even if the road surface μ changes suddenly while driving, both hunting prevention on low μ roads and vibration prevention on high μ roads I planned.

  That is, when the motor torque limit value is calculated in step S6 of FIG. 6, the process proceeds to step S7. In step S7, the filter time constant is set as shown in FIG. 9 according to the estimated size of the road surface μ. In the next step S8, the motor torque command value is determined based on the motor torque limit value calculated in step S6 and the filter time constant set in step S7.

  Therefore, as shown in FIG. 12, in the case of a μ jump in which the road surface μ changes suddenly from the low μ road to the high μ road, the motor torque command for the motor torque limit value is set by setting a small filter time constant on the low μ road side. The phase lag of the motor torque command value with respect to the motor torque limit value is increased by setting a large filter time constant on the high μ road side.

  Thus, as motor traction control, the filter time constant used to determine the motor torque command value from the motor torque limit value is set according to the estimated road surface μ, thereby preventing hunting on low μ roads and high Both vibration prevention on the μ road can be achieved. In particular, in the case of a μ jump in which the road surface μ changes suddenly from a low μ road to a high μ road, it is possible to prevent vibration immediately after entering the high μ road, or from a high μ road to a low μ road. In the case of a μ jump in which the road surface μ changes suddenly, it is possible to prevent a slip immediately after entering a low μ road and to prevent an overcurrent from occurring in the high voltage unit.

Next, the effect will be described.
In the vehicle motor traction control device of the first embodiment, the effects listed below can be obtained.

  (1) Provided with at least one motor provided in a power source for driving the driving wheel, and motor traction control means for detecting driving slip of the driving wheel and recovering the grip of the driving wheel by motor torque down control. In a motor traction control device for a vehicle, road surface friction coefficient equivalent value estimation means for estimating a road surface friction coefficient equivalent value is provided, and the motor traction control means is configured such that, during motor traction control, the road surface friction coefficient equivalent value is on the low friction coefficient side. To reduce the phase lag of the motor torque command value relative to the calculated motor torque limit value, and to increase the phase lag of the motor torque command value relative to the calculated motor torque limit value when the road surface friction coefficient equivalent value is on the high friction coefficient side In motor traction control, both hunting prevention on low μ road and vibration prevention on high μ road Rukoto can.

  (2) During the motor traction control, the motor traction control means determines the motor torque command value by increasing the filter time constant as the estimated road surface μ is higher than the calculated motor torque limit value. Therefore, regardless of whether the running road surface μ is low or high μ, during motor traction control, the estimated road surface μ prevents hunting on the low μ road side, and the estimated road surface μ prevents vibration on the high μ road side. can do.

  (3) The motor traction control means includes a slip amount torque limit value TSlim based on a slip amount S of a drive wheel to which the motor is connected and each acceleration torque based on an angular acceleration ω ′ of the drive wheel to which the motor is connected. Since the motor torque limit value is calculated by the select low of the limit value Tω′lim, it is possible to achieve both the protection of parts by the “angular acceleration control” and the prevention of the occurrence of the stumble by the “slip amount control”.

  (4) The road surface friction coefficient equivalent value estimation means obtains wheel speeds VW1 to VW4 and braking / driving forces F1 to F4 per unit load of each wheel, and these wheel speeds VW1 to VW4 and braking / driving forces per unit load. The road surface used in motor traction control to express the points for each wheel representing the combination of F1 to F4 on two-dimensional coordinates, to obtain a straight line representing these points, and to estimate the road surface friction coefficient μ based on the gradient Highly accurate road surface friction coefficient information can be obtained as the friction coefficient information.

  The second embodiment is an example in which the slip amount due to the difference between the driving wheel speed and the driven wheel speed is set to the road surface friction coefficient equivalent value. In addition, since the structure of Example 2 is the same as that of Example 1, illustration and description are abbreviate | omitted.

  Explaining the operation, the flowchart showing the flow of the motor traction control process executed by the integrated controller 6 of the second embodiment is the same as the flowchart of the first embodiment shown in FIG. 6 except for step S7.

In step S7 of the second embodiment, following the calculation of the motor torque limit value in step S6, the slip amount S due to the difference between the drive wheel wheel speed and the driven wheel wheel speed is calculated, and the calculated slip amount S is set to the magnitude. Accordingly, the filter time constant is set, and the process proceeds to step S8.
Here, as shown in FIG. 13, the “filter time constant” is set according to the calculated slip amount S, and in the high μ region where the calculated slip amount S is equal to or less than the first set value S1. The filter time constant is set with a high constant value, and in the region where the calculated slip amount S is from the first set value S1 to the second set value S2, the filter time constant increases in proportion to the calculated slip amount S. In a low μ region where the calculated slip amount S is greater than or equal to the second set value S2, a filter time constant is set with a constant value of a low value.

  That is, when the same driving force is applied to the driving wheels, the driving slip is generated more greatly as the road is low, and the driving slip is generated as the road is high. Since this driving slip can be grasped by the slip amount S due to the difference between the driving wheel wheel speed and the driven wheel wheel speed, as the road surface μ estimation method in the second embodiment, the magnitude of the slip amount S is directly used as the road friction coefficient equivalent value. I used it. Since other operations are the same as those of the first embodiment, description thereof is omitted.

Next, the effect will be described.
In the motor traction control device for a vehicle according to the second embodiment, the following effects can be obtained in addition to the effects (1), (2), and (3) of the first embodiment.

  (5) The road surface friction coefficient equivalent value estimation means sets the slip amount S due to the difference between the driving wheel speed and the driven wheel speed to the road surface friction coefficient equivalent value, so that the slip amount calculated by the “slip amount control” is calculated. By a simple method using S, road surface friction coefficient information for determining the filter time constant can be obtained.

  The third embodiment is an example in which the occurrence of vibration or slip immediately after the μ jump is reliably prevented with respect to the μ jump in which the road surface μ changes suddenly regardless of the estimation accuracy of the road surface μ. In addition, since the structure of Example 3 is the same as that of Example 1, illustration and description are abbreviate | omitted.

Next, the operation will be described.
[Motor traction control process]
FIG. 14 is a flowchart illustrating the flow of the motor traction control process executed by the integrated controller 6 according to the third embodiment. Each step will be described below. In addition, since each step of step S31-step S36 is the same process as each step of step S1-step S6 of FIG. 6, description is abbreviate | omitted.

In step S39, following the calculation of the motor torque limit value in step S36, it is determined whether or not the angular acceleration ω ′ calculated in step S34 shows a negative angular acceleration equal to or less than the first set value −α1. If YES, the process proceeds to step S40, and if NO, the process proceeds to step S41.
Here, “first set value−α1” is a value set as a determination threshold for μ jump when the road surface μ changes suddenly from a low μ road to a high μ road.

In step S40, the filter time constant is set to a large value based on the determination that the angular acceleration ω ′ in step S39 is a low μ → high μ μ jump that is equal to or less than the first set value −α1, and step S38. Move to '.
Here, the filter time constant at the time of μ jump from low μ to high μ may be given as a fixed value with a large value, and the negative angular acceleration whose angular acceleration ω ′ is equal to or less than the first set value −α1. The higher the level, the larger the variable value.

In step S41, following the determination that the angular acceleration ω ′ exceeds the first set value −α1 in step S39, the angular acceleration ω ′ calculated in step S34 is a positive value greater than or equal to the second set value + β2. It is determined whether or not the angular acceleration is shown. If YES, the process proceeds to step S42, and if NO, the process proceeds to step S37 ′.
Here, the “second set value + β2” is a value set as a determination threshold for μ jump when the road surface μ changes suddenly from a high μ road to a low μ road.

In step S42, the filter time constant is set to a small value based on the determination that the angular acceleration ω ′ in step S41 is a high μ → low μ μ jump greater than or equal to the second set value + β2, and step S38 ′. Migrate to
Here, the filter time constant at the time of μ jump from high μ to low μ may be given as a fixed value with a small value, and the angular acceleration ω ′ is a positive angular acceleration with the second set value + β2 or more. You may make it give by the variable value by a small value, so that a level is large.

  In step S37 ′, when the angular acceleration ω ′ is less than the second set value + β2, that is, the angular acceleration ω ′ is a value between the first set value −α1 and the second set value + β2 in step S41, the embodiment As in step S7, the road surface friction coefficient is estimated, the filter time constant is set according to the estimated road surface μ, and the process proceeds to step S38 ′.

  In step S38 ′, following the setting of the filter time constant in step S37 ′ or step S40 or step S42, the motor torque limit value calculated in step S36 and the filter time constant set in step S37 ′ or the like are set. Thus, the motor torque command value is determined, this command value is output to the motor controller 2, and the process proceeds to return.

[Motor traction control function]
In the first embodiment, the road surface μ is abruptly increased during traveling by increasing the filter time constant and determining the motor torque command value as the estimated road surface μ increases with respect to the calculated motor torque limit value. Even when switched to, hunting prevention on the low μ road and vibration prevention on the high μ road were achieved. That is, if the road surface μ estimation response is high, the μ jump can be handled, but if the road surface μ estimation response is bad, the control cannot cope with the μ jump. Therefore, in the third embodiment, even if a road surface μ estimation method that cannot follow the change of the road surface μ, such as estimating the road surface μ with a motor torque at the start of driving slip, or a road surface μ estimation method with a poor estimation response is used. In addition, it is possible to prevent the occurrence of vibrations immediately after entering the high μ road during the μ jump from low μ to high μ, and to prevent slip immediately after entering the low μ road during the μ jump from high μ to low μ.

  That is, when the motor torque limit value is calculated in step S36 in FIG. 14, the process proceeds to step S39. In step S39, the process proceeds to step S40 if ω ′ ≦ −α1, and the filter time constant is large in step S40. Set to a value. If ω ′> − α1 in step S39, the process proceeds to step S41. If ω ′ ≧ + β2 in step S41, the process proceeds to step S42. In step S42, the filter time constant is set to a small value.

  Therefore, in the case of the μ jump in which the road surface μ changes suddenly from the low μ road to the high μ road, the process proceeds from step S39 to step S40, and the motor time with respect to the motor torque limit value is set by setting the filter time constant to a large value. The phase delay of the command value is increased, and the occurrence of vibration immediately after entering the high μ road can be prevented.

  In the case of a μ jump in which the road surface μ changes suddenly from a high μ road to a low μ road, the process proceeds from step S39 to step S41 to step S42, and the motor time limit value is set by setting the filter time constant to a small value. The phase delay of the motor torque command value with respect to is reduced, slipping immediately after entering the low μ road can be prevented, and the occurrence of overcurrent in the high voltage unit can be prevented.

  As described above, in the third embodiment, the control method of determining the μ jump based on the negative change or the positive change of the angular acceleration ω ′ and setting the filter time constant based on the μ jump determination is adopted. Regardless of the coefficient estimation accuracy and responsiveness, at the time of μ jump, it is possible to achieve a good response and reliably prevent vibration immediately after entering the high μ road and prevent slipping immediately after entering the low μ road. .

Next, the effect will be described.
In the vehicle motor traction control device of the third embodiment, in addition to the effects (1) to (4) of the first embodiment, the effects listed below can be obtained.

  (6) Motor angular acceleration detecting means (step S34) for detecting the motor angular acceleration ω ′ is provided, and the motor traction control means indicates a negative angular acceleration in which the motor angular acceleration ω ′ is equal to or less than a first set value −α1. In this case, it is determined that the road friction coefficient suddenly changes from the low μ road to the high μ road, and the road surface friction coefficient is determined by increasing the filter time constant with respect to the calculated motor torque limit value to determine the motor torque command value. Regardless of the estimation accuracy and responsiveness, it is possible to prevent the occurrence of vibration immediately after entering the high μ road with a good response at the time of a low μ → high μ jump.

  (7) When the motor angular acceleration ω ′ indicates a positive angular acceleration equal to or greater than the second set value + β2, the motor traction control means determines that the μ jump has a sudden change in the road surface friction coefficient from the high μ road to the low μ road. Because the motor torque command value is determined by reducing the filter time constant with respect to the calculated motor torque limit value, the response at the time of μ jump from high μ to low μ, regardless of the estimation accuracy and responsiveness of the road surface friction coefficient It is good and can reliably prevent the occurrence of slip immediately after entering the low μ road.

  As mentioned above, although the motor traction control apparatus of the vehicle of this invention has been demonstrated based on Example 1-Example 3, it is not restricted to these Examples about a concrete structure, Each of Claims Design changes and additions are permitted without departing from the scope of the claimed invention.

  In the first to third embodiments, the motor torque limit value is calculated as it is based on the slip amount and the angular acceleration, but the motor torque is calculated by subtracting the motor torque down amount calculated based on the slip amount and the angular acceleration from the motor torque request value. A limit value may be calculated.

  In the first to third embodiments, examples of means for adjusting the filter time constant have been shown as means for adjusting the phase delay of the motor torque command value with respect to the motor torque limit value. A method other than the time constant adjustment may be used.

  In the first to third embodiments, as the motor traction control, a preferable control example by “low” of “angular acceleration control” + “slip amount control” is shown, but only one of “angular acceleration control” or “slip amount control” is shown. Alternatively, control by combination with other control or the like may be employed. In short, the motor traction control means includes any means as long as it detects the driving slip of the driving wheel and recovers the grip of the driving wheel by the motor torque down control.

In Examples 1 to 3, as road surface friction coefficient equivalent value estimation means, points for each wheel representing a combination of braking / driving forces per wheel speed and unit wheel load are represented on two-dimensional coordinates, and these points are representative. An example of a means for estimating a road surface friction coefficient by obtaining a straight line and a means for setting a slip amount as a road surface friction coefficient equivalent value has been shown. Road surface friction coefficient equivalent value estimation means other than those shown may be used.
For example,
A means for setting the limited motor torque output value during the slip to a road surface friction coefficient equivalent value, a means for setting the motor torque output value at the start of the slip to a road surface friction coefficient equivalent value, or the like may be used.

  In the first to third embodiments, an example of application to a hybrid vehicle including one engine, two motor generators, and a power split mechanism is shown. However, the motor traction control device of the present invention is a hybrid including another power unit structure. In short, any vehicle such as a car, an electric vehicle, a fuel cell vehicle, a motor 4WD vehicle, etc., which is equipped with at least one motor as a power source for driving the drive wheels can be applied.

1 is an overall system diagram illustrating a hybrid vehicle to which a motor traction control device according to a first embodiment is applied. FIG. 2 is a driving force performance characteristic diagram and a driving force conceptual diagram in a hybrid vehicle to which the motor traction control device of Embodiment 1 is applied. It is a contrast characteristic figure showing the braking force performance by regenerative cooperation in the hybrid car to which the motor traction control device of Example 1 was applied. It is an alignment chart which shows each vehicle mode in the hybrid vehicle to which the motor traction control device of Example 1 was applied. It is a block diagram which shows the high electric power unit (battery, power control unit, 1st motor generator, 2nd motor generator) of the hybrid vehicle of Example 1. FIG. 3 is a flowchart illustrating a flow of a motor traction control process executed by the integrated controller according to the first embodiment. It is a figure which shows an example of the characteristic of the slip amount torque limit value calculated by the motor traction control in Example 1. It is a figure which shows an example of the characteristic of the angular acceleration torque limitation value calculated by the motor traction control in Example 1. FIG. 5 is a diagram illustrating an example of a filter time constant characteristic with respect to a road surface μ set by motor traction control in the first embodiment. It is a figure which shows the road surface friction coefficient characteristic, the braking / driving force characteristic per unit wheel load, and the maximum friction coefficient characteristic for demonstrating the estimation method of the road surface friction coefficient of Example 1. FIG. It is a figure which shows the torque limit value characteristic and angular acceleration characteristic in the angular acceleration control which gave the filter time constant with the fixed value. It is a figure which shows the torque limiting value characteristic and angular acceleration characteristic in the motor traction control in Example 1. It is a figure which shows an example of the filter time constant characteristic with respect to the slip amount S set by the motor traction control in Example 2. FIG. 10 is a flowchart illustrating a flow of a motor traction control process executed by an integrated controller according to a third embodiment.

Explanation of symbols

E engine
MG1 1st motor generator
MG2 Second motor generator (motor)
OS output sprocket)
TM power split mechanism 1 engine controller 2 motor controller 3 power control unit 4 battery 5 brake controller 6 integrated controller 7 accelerator opening sensor 8 vehicle speed sensor 9 engine speed sensor 10 first motor generator speed sensor 11 second motor generator speed Sensor 12 Front left wheel speed sensor 13 Front right wheel speed sensor 14 Rear left wheel speed sensor 15 Rear right wheel speed sensor 16 Steering angle sensor 17 Master cylinder pressure sensor 18 Brake stroke sensor 19 Brake fluid pressure unit 20 Front left wheel wheel cylinder 21 Front right wheel wheel cylinder 22 Rear left wheel wheel cylinder 23 Rear right wheel wheel cylinder

Claims (7)

A motor for a vehicle, comprising: at least one motor provided in a power source for driving the driving wheels; and motor traction control means for detecting driving slip of the driving wheels and recovering the grip of the driving wheels by motor torque down control. In the traction control device,
A road surface friction coefficient equivalent value estimating means for estimating a road surface friction coefficient equivalent value is provided,
The motor traction control means reduces the phase lag of the motor torque command value with respect to the calculated motor torque limit value when the road surface friction coefficient equivalent value is low on the motor friction control side, and the road surface friction coefficient equivalent value is A motor traction control device for a vehicle, wherein a phase delay of a motor torque command value with respect to a calculated motor torque limit value is increased on a high friction coefficient side. In the vehicle motor traction control device according to claim 1,
The motor traction control means determines a motor torque command value by increasing the filter time constant as the road surface friction coefficient equivalent value shows a higher friction coefficient than the calculated motor torque limit value during motor traction control. A motor traction control device for a vehicle. In the motor traction control device for a vehicle according to claim 1 or 2,
The motor traction control means is a select low of a slip amount torque limit value based on the slip amount of the drive wheel to which the motor is connected and each acceleration torque limit value based on the angular acceleration of the drive wheel to which the motor is connected. A motor traction control device for a vehicle, characterized in that a motor torque limit value is calculated by: In the vehicle motor traction control device according to any one of claims 1 to 3,
The road surface friction coefficient equivalent value estimating means expresses a point for each wheel representing a combination of braking / driving force per wheel speed and unit wheel load on a two-dimensional coordinate, and obtains a straight line representing these points to determine the road surface. A motor traction control device for a vehicle characterized by estimating a friction coefficient. In the vehicle motor traction control device according to any one of claims 1 to 3,
The road surface friction coefficient equivalent value estimation means uses a road surface friction coefficient equivalent value as a slip amount due to a difference between a driving wheel speed and a driven wheel speed. In the vehicle motor traction control device according to any one of claims 1 to 5,
Motor angular acceleration detection means for detecting motor angular acceleration is provided,
The motor traction control means determines that the road friction coefficient suddenly changes from a low μ road to a high μ road when the detected motor angular acceleration value indicates a negative angular acceleration equal to or less than a first set value, and is calculated. A motor traction control device for a vehicle, wherein a motor torque command value is determined by increasing a filter time constant with respect to a motor torque limit value. In the motor traction control device for a vehicle according to claim 6,
The motor traction control means determines that the road friction coefficient suddenly changes from a high μ road to a low μ road when the detected motor angular acceleration value indicates a positive angular acceleration equal to or greater than a second set value, and is calculated. A motor traction control device for a vehicle, wherein a motor torque command value is determined by reducing a filter time constant with respect to a motor torque limit value.

Images