JP2008024010A - Control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a hybrid vehicle obtaining large deceleration without causing a sharp increase of engine speed. <P>SOLUTION: The control device for the hybrid vehicle comprises a motor generator outputting driving force and applying regenerative braking force to driving wheels, and an automatic travel control means for controlling the braking and driving force of the motor generator to attain a target vehicle speed. The control device further comprises a downhill travel determining means for determining a downhill when a vehicle speed exceeds the target vehicle speed in spite of applying the regenerative braking force to the limit to the driving wheels, and a limit value changing means for changing the regenerative braking force limit value of the motor generator to increase the regenerative braking force when determining the downhill. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a hybrid vehicle provided with an automatic travel control system.

Conventionally, Patent Document 1 is disclosed as an automatic travel control device. In this publication, as a means for setting a target vehicle speed and controlling the braking / driving force for maintaining the target vehicle speed, the gear ratio of the automatic transmission is changed to control the engine braking force.
JP-A-5-162565

  However, in the prior art, when traveling on a steep downhill, a downshift is performed in order to obtain a large deceleration, so that there has been a problem that the engine speed rapidly increases and the driver feels uncomfortable.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a control device for a hybrid vehicle capable of obtaining a large deceleration without causing a rapid increase in engine speed.

  In order to achieve the above object, in the hybrid vehicle control apparatus of the present invention, a motor generator that outputs a driving force to the driving wheels and applies a regenerative braking force, and a braking / driving force of the motor generator so as to achieve a target vehicle speed are achieved. In the hybrid vehicle control device comprising: an automatic traveling control means for controlling the vehicle, a downward gradient is obtained when the target vehicle speed is exceeded even though the regenerative braking force is applied to the drive wheels to the limit. Characterized in that it comprises a downward gradient traveling determination means for determining, and a limit value changing means for changing the regenerative braking force limit value of the motor generator so that the regenerative braking force is increased when it is determined to be a downward gradient. To do.

  If the regenerative braking force is applied to the limit and the acceleration is still accelerated, the target vehicle speed can be maintained without downshifting by changing the regenerative braking force limit value. Can be prevented. Moreover, since the downward gradient is determined without using a gradient sensor, a longitudinal acceleration sensor, or the like, an increase in cost can be suppressed.

  Hereinafter, the best mode for realizing a control device for a hybrid vehicle of the present invention will be described based on a first embodiment 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 gear protection 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, an output sprocket OS, and a power split mechanism TM (within claims) Equivalent to the described transmission mechanism).

  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. The sun gear S is connected to a first motor generator MG1. 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).

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 (high power unit), a battery 4 (secondary battery), and a brake controller 5. And an integrated controller 6.

  The integrated controller 6 includes an accelerator opening sensor 7, a vehicle speed sensor 8, an engine speed sensor 9, a first motor generator speed sensor 10, a second motor generator speed sensor 11, and a second motor generator. Input information is provided from the torque sensor 27 and the cruise control operation switch 30 for setting the target vehicle speed by the driver's operation. 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 and the lateral acceleration sensor 28 provide 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 power supply system that can supply power to both motor generators MG1 and MG2 with less current, and includes a joint box, a boost converter, a drive motor inverter, And a generator generator inverter and a capacitor. A drive motor inverter is connected to the stator coil of the second motor generator MG2. A generator generator inverter is connected to the stator coil of the first motor generator MG1. The joint box is connected to a battery 4 that is discharged during power running and charged during regeneration.

  The brake controller 5 performs ABS control by 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, etc. 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 said integrated controller 6 manages the energy consumption of the whole vehicle, and bears the function for running a vehicle with the highest efficiency. Specifically, the engine operating point control is performed by a control command to the engine controller 1 during acceleration traveling or the like. Further, 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. Further, a cruise control calculation unit 300 is provided, and a required torque is calculated so that the target vehicle speed set by the cruise control operation switch 30 is obtained, and a control command is sent to the engine controller 1 and the motor controller 2 via the command torque calculation unit 600. Is output.

  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, the vehicle mode will be described.
The vehicle modes in the hybrid vehicle of the first embodiment include “stop mode”, “start mode”, “engine start mode”, “steady travel mode”, and “acceleration mode”.

  In the “stop mode”, the engine E, the first motor generator MG1, and the second motor generator MG2 are stopped. In “start mode”, the vehicle is started by driving only the motor generator MG2. In the “engine start mode”, the sun gear S rotates and the engine E is started by the first motor generator MG1 having a function as an engine starter. In the “steady traveling mode”, the vehicle travels mainly by the engine E, and power generation is minimized to increase efficiency. In the “acceleration mode”, the number of revolutions of the engine E is increased and power generation by the generator MG1 is started, and the driving power of the motor generator MG2 is applied and accelerated using the power and the power of the battery 4.

  In reverse travel, in the “steady travel mode”, if the rotation speed of the first motor generator MG1 is increased while the increase in the rotation speed of the engine E is suppressed, the rotation speed of the motor generator MG2 shifts to the negative side, causing the vehicle to move backward. 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 running at a very low speed, the fuel is cut in a region where the engine efficiency is poor, the engine is stopped, and the vehicle is driven by the second motor generator MG2.

  During normal travel, the driving force of the engine E is driven directly by the power split mechanism TM, and the other drives the first motor generator MG1 and assists the second motor generator MG2. At the time of full open acceleration, power is supplied from the battery 4 and further driving force is added.

  At the time of deceleration or braking, the wheel drives the second motor generator 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 first motor generator MG1 is driven by the engine E to start charging. When the vehicle is stopped, the engine E is automatically stopped except when the air conditioner is used or when the battery is charged.

  FIG. 2 is a block diagram showing a control configuration in the integrated controller 6. The integrated controller 6 is set by a cruise control operation switch 30 and a command torque calculation unit 600 that calculates a command torque for the engine E as a power source and the motor generators MG1 and MG2 based on the accelerator opening AP and the vehicle speed VSP. The cruise control calculation unit 300 that calculates the required torque that represents the driving force or braking force required to achieve the target vehicle speed, and the descending that determines the downward gradient and performs the limit value correction calculation of the regenerative braking force when the gradient is downward It is comprised of a regenerative braking force limit value correction calculation unit 301 at the time of gradient.

  The command torque calculation unit 600 is obtained by a regenerative torque without changing the rotation speed of each motor generator MG1, MG2 at the current gear ratio, and a request torque calculation unit 601 that calculates the required torque based on the accelerator opening. A regenerative braking force limit value calculation unit 602 that calculates the regenerative braking force limit value is provided.

  The cruise control calculation unit 300 executes vehicle speed tracking feedback control for calculating a required torque based on a deviation between the target vehicle speed set by the cruise control operation switch 30 and the current vehicle speed. When the cruise control switch 30 is operated, the command torque calculation unit 600 calculates the required torque calculated by the vehicle speed tracking feedback control in the cruise control calculation unit 300 based on the accelerator opening AP and the like in the request torque calculation unit 601. Is replaced with the required torque. The command torque calculation unit 600 outputs a command signal to the motor controller 2 and the engine controller 1 based on the replaced request torque.

  Next, the regenerative braking force limit value correction control process at the time of the downward slope according to the first embodiment will be described. FIG. 3 is a flowchart showing a regenerative braking force limit value correction control process. This control is a process performed when cruise control is executed, and the required torque in the flowchart is the required torque calculated by the cruise control calculation unit 300.

  In step 101, as input processing, the vehicle speed signal VSP is read from the vehicle speed sensor 8, and the regenerative braking force limit value and the required torque (driving force, braking force) are read from the command torque calculation unit 600.

  In step 102, regenerative braking force limit determination is performed. Specifically, it is determined whether or not the required torque ≦ the regenerative braking force limit value. If the required torque is greater than the regenerative braking force limit value, the routine proceeds to step 104 and it is determined that there is a margin in the regenerative braking force. On the other hand, when the required torque ≦ the regenerative braking force limit value, the routine proceeds to step 105, where it is determined that the regenerative braking force has already reached the limit.

  In step 105, it is determined whether or not the regenerative braking force has reached the limit. When the limit is reached, the target vehicle speed is not updated and the previous value is held as the target vehicle speed. On the other hand, when it is determined that the regenerative braking force has a margin, the routine proceeds to step 107, where the current vehicle speed is substituted as the target vehicle speed during regenerative braking.

  In step 106, a vehicle speed deviation between the current vehicle speed and the target vehicle speed is calculated. When it is determined that there is a margin during regenerative braking, the vehicle speed deviation is zero.

  In step 108, it is determined whether or not the regenerative braking force reaches a limit and the vehicle speed deviation is positive. A positive vehicle speed deviation means that the current vehicle speed is higher than the target vehicle speed. Therefore, in this step, it is determined whether the vehicle is accelerating despite the regenerative braking force being applied to the limit. When the condition is satisfied, it is determined in step 109 that the vehicle is traveling on a downward slope. On the other hand, when the condition is not satisfied, it is determined in step 110 that the vehicle is traveling on a flat road.

  In step 111, a regenerative braking force expansion execution permission determination is performed. Specifically, it is determined whether or not the current regenerative braking force limit value has reached the rated lower limit of each motor generator MG1 and MG2, and if not reached, expansion is permitted. Prohibit expansion.

  In step 112, the regenerative braking force expansion correction amount is set according to the vehicle speed deviation. Specifically, the correction amount is set to be larger as the vehicle speed deviation is larger.

  In step 113, the regenerative braking force expansion amount is cleared and the correction amount is set to zero. This is because any further correction may be less than the lower limit of the rating and may cause an abnormality.

  In step 114, the required torque is set. Specifically, a value obtained by adding the regenerative braking force expansion correction amount to the regenerative braking force limit value is set as the required torque.

  Next, the operation based on the control flow will be described. First, when cruise control is being executed, the required torque is calculated by the cruise control calculation unit 300, and the command torque calculation unit 600 achieves the required torque by operating command control commands for the engine E and the motor generators MG1 and MG2. Is output.

  At this time, it is determined whether or not the regenerative braking force has already reached the regenerative braking force limit value. If not, there is no problem because the regenerative braking force may be further increased as necessary. Therefore, the target vehicle speed is substituted as the current vehicle speed, and the vehicle speed deviation is set to 0. Thereby, the regenerative braking force limit value is not unnecessarily corrected.

  On the other hand, if the regenerative braking force has reached the regenerative braking force limit value, no more regenerative braking force can be obtained, so even if the required torque requires further deceleration, the desired deceleration cannot be achieved. . In this case, the regenerative braking force limit value is corrected within the range of the rated lower limit of each motor generator MG1, MG2.

  At this time, the correction amount is set to a correction amount corresponding to the vehicle speed deviation. That is, when the current vehicle speed is significantly higher than the target vehicle speed, a large deceleration is required, in other words, a larger regenerative braking force is required. On the other hand, when the current vehicle speed is slightly higher than the target vehicle speed, a very large deceleration is not necessary. In other words, a very large regenerative braking force is not necessary.

  Therefore, a correction amount is set according to the vehicle speed deviation, and a value obtained by adding the regenerative braking force expansion correction amount to the regenerative braking force limit value is set as the required torque. Thereby, the command torque according to this required torque is calculated, and a desired deceleration can be obtained.

  As described above, the effects listed below can be obtained in the first embodiment.

  (1) When the target vehicle speed is exceeded even though the regenerative braking force is applied to the drive wheels to the limit, it is judged as a downward gradient, and the regenerative braking force limit value of each motor generator MG1, MG2 is set as the regenerative braking force. Changed to be larger.

  Therefore, when the regenerative braking force is applied to the limit and the acceleration is still accelerated, the target vehicle speed can be maintained without downshifting by changing the regenerative braking force limit value. It is possible to prevent giving to the driver. Moreover, since the downward gradient is determined without using a gradient sensor, a longitudinal acceleration sensor, or the like, an increase in cost can be suppressed.

  (2) A power split mechanism TM, which is a speed change mechanism, is provided between the drive wheel and the motor generator, and the regenerative braking force limit value is changed with the speed ratio of the power split mechanism TM being constant. Therefore, the engine speed does not increase, and the uncomfortable feeling given to the driver can be prevented.

  (3) The regenerative braking force limit value after the change is set based on the deviation between the target vehicle speed and the current vehicle speed.

  Therefore, the regenerative amount can be changed by a necessary amount. Further, when the vehicle speed deviation is negative, the target vehicle speed is substituted for the current vehicle speed, so that the regenerative braking force limit value is not corrected, and unnecessary changes can be avoided.

  Although the first embodiment has been described above, for example, not only the regenerative braking force limit value but also the battery charge limit value may be changed to increase the charge amount. That is, a charging limit is set for the battery, and when a predetermined charging amount is reached, no further charging is performed from the viewpoint of the durability of the battery. At this time, a sufficient braking force can be ensured by temporarily changing the charging limit value of the battery from the viewpoint of securing a predetermined braking force when traveling on a downward slope.

  In the first embodiment, an example of application to a hybrid vehicle by front wheel drive provided with one engine, two motor generators, and a power split mechanism has been shown. Can be applied.

1 is an overall system diagram illustrating a hybrid vehicle according to a first embodiment. FIG. 3 is a block diagram illustrating a control configuration executed by the integrated controller according to the first embodiment. It is a flowchart which shows the flow of the regenerative braking force limit value correction | amendment control processing performed with the integrated controller of Example 1. FIG.

Explanation of symbols

E engine
MG1 1st motor generator (motor for power generation)
MG2 Second motor generator (drive motor)
OS output sprocket
TM Power split mechanism (planetary gear 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 27 Second motor generator torque sensor 28 Lateral acceleration sensor

Claims (4)

A motor generator that outputs a driving force to the driving wheels and applies a regenerative braking force;
Automatic travel control means for controlling the braking / driving force of the motor generator so as to achieve the target vehicle speed;
In a hybrid vehicle control device comprising:
A downward gradient traveling determination means for determining a downward gradient when the target vehicle speed is exceeded even though the regenerative braking force is applied to the drive wheel to the limit;
Limit value changing means for changing the regenerative braking force limit value of the motor generator so as to increase the regenerative braking force when it is determined as a downward slope;
A control apparatus for a hybrid vehicle, comprising: In the hybrid vehicle control device according to claim 1,
A transmission mechanism between the drive wheel and the motor generator;
The control device for a hybrid vehicle, wherein the limit value changing means makes a speed ratio of the speed change mechanism constant. In the hybrid vehicle control device according to claim 1 or 2,
The limit value changing means sets the changed limit value based on a deviation between the target vehicle speed and the current vehicle speed. In the hybrid vehicle control device according to any one of claims 1 to 3,
The limit value changing means changes the charge limit value of the battery so as to increase the charge amount.

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