JP3685146B2 - Control device for hybrid vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus for a hybrid vehicle that uses an engine and an electric motor as a vehicle drive source, and that can change the output of the engine and output it to drive wheels. The present invention relates to a control apparatus for a hybrid vehicle that executes or prohibits shifting.
[0002]
[Prior art]
Recently, for the purpose of improving fuel efficiency, clean exhaust, etc., hybrid vehicles using an electric motor added to an internal combustion engine that operates by burning fuel such as gasoline as a drive source of the vehicle have been in the spotlight. ing. There are many types of hybrid vehicles in terms of the structure and operation of their powertrain, but it is possible to easily obtain a hybrid vehicle without making a significant change to a vehicle that uses only the current engine as a drive source, and electric Since there is no need to increase the size of the motor, a hybrid vehicle in which a stepped or stepless automatic transmission is mounted on the engine and the electric motor may be used.
As such a hybrid vehicle, there is one described in Japanese Patent Application Laid-Open No. 2000-324614.
[0003]
In a vehicle equipped with a transmission in this way, when deceleration is necessary, it is possible to obtain a strong engine braking force by shifting the transmission down.
However, if the driver expects a predetermined deceleration and operates the manual shift lever to shift down to forcibly shift the transmission down, the engine may overspeed depending on the driving condition.
Therefore, at this time, it is necessary to prohibit the transmission from shifting down despite the downshifting operation by the driver.
[0004]
Here, in a hybrid vehicle, the electric motor can be used as a generator to secure braking force and improve fuel efficiency by regenerating energy during vehicle braking. Instead, it has the advantage that expected deceleration can be compensated by generating regenerative torque from the electric motor and applying a braking force to the vehicle.
[0005]
[Problems to be solved by the invention]
However, in the above conventional hybrid vehicle control device, regarding the downshift of the transmission, the downshift of the transmission is performed when the driver performs a downshift operation in which the engine speed is excessive. Is prohibited to prevent the engine from over-rotating, but protection of the electric motor is not taken into consideration.
[0006]
Even during downshifts where the engine speed does not overspeed, there is no clutch between the engine and the motor, and it is impossible to shut off the power between them. Therefore, the temperature of the electric motor or the inverter side that controls the electric motor may rise, and the durability may be deteriorated.
Accordingly, an object of the present invention is to provide a control device for a hybrid vehicle that can reliably protect an electric motor and an inverter.
[0007]
[Means for Solving the Problems]
Therefore, the invention of claim 1 is provided with an internal combustion engine, an electric motor, and a transmission capable of shifting the drive output of the engine and the electric motor and outputting it to drive wheels, and the engine and the electric motor are always connected. And a field current value estimating means for estimating a field current value flowing in the electric motor when the transmission is downshifted, and a field current estimated by the field current estimating means. It is determined whether the temperature of the electric motor corresponding to the temperature reaches the protection temperature. When the temperature of the electric motor does not reach the protection temperature, the downshift of the transmission is allowed, and when the temperature of the electric motor reaches the protection temperature Is provided with a temperature protection calculation unit that prohibits downshifting of the transmission.
[0008]
According to a second aspect of the present invention, the field current value estimating means obtains the predicted rotational speed of the electric motor when the downshift is performed from the current rotational speed of the electric motor and the transmission gear ratio when the downshift is performed. The field current value is estimated from the predicted rotation speed and the torque command value when downshifting.
[0009]
According to a third aspect of the present invention, the temperature protection calculation unit obtains a predicted temperature in the case of downshifting from the field current value estimated by the field current value estimation means and the current temperature of the electric motor, and the predicted temperature And the protection temperature are compared to determine whether or not the temperature of the electric motor reaches the protection temperature.
[0010]
According to a fourth aspect of the present invention, the temperature protection calculation unit estimates a margin time until the temperature of the electric motor reaches the protection temperature, and prohibits a downshift of the transmission when the margin time is equal to or less than a specified time. It was.
The invention according to claim 5 calculates the margin time based on the current temperature of the electric motor and the field current value of the electric motor.
[0011]
According to a sixth aspect of the present invention, a notification unit is further provided, and when the downshift of the transmission is prohibited, the prohibition of the downshift is notified.
[0012]
【The invention's effect】
In the control apparatus for a hybrid vehicle according to the present invention, when the transmission is to be downshifted, the field current of the electric motor necessary for downshifting from the current rotational speed of the electric motor is predicted, and this estimation is performed. When the temperature of the electric motor corresponding to the field current reaches the protection temperature, the downshift of the transmission is prohibited, so that deterioration of the durability of the electric motor and the inverter that controls the electric motor due to the temperature rise is prevented. be able to.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows the overall configuration of a powertrain and its control device for a hybrid vehicle in an embodiment.
As a vehicle drive source, an engine (ENG) 1 that generates fuel by burning fuel such as gasoline, a motor function that generates power by receiving power supplied from an on-vehicle battery 4, and regenerative torque during braking And a motor / generator (M / G, hereinafter referred to as electric motor 2) having a generator function capable of collecting the energy at the time of braking as electric energy. The electric motor 2 is a synchronous motor.
[0014]
The engine 1 and the electric motor 2 can input these drive outputs to an automatic transmission (A / T) 3 configured as a step type or a stepless type, and the drive output is optimally shifted by the automatic transmission 3. And transmitted to the final reduction gear 6 through the propeller shaft 5.
The drive output input to the final speed reducer 6 is further decelerated by the final speed reducer 6 and is divided into power by the differential gear set (not shown) in the final speed reducer 6 to the left and right drive shafts 7a and 7b. The wheels 8a and 8b are driven.
[0015]
The engine 1, the electric motor 2, and the automatic transmission 3 are controlled by the following controller.
That is, the engine 1 is controlled by an engine controller (E / C) 9, the electric motor 2 is controlled by a motor controller (M / C) 10, and the automatic transmission 3 is controlled by an AT controller (AT / C) 11.
The engine controller 9, the motor controller 10, and the AT controller 11 can communicate with each other with the hybrid control module (HCM) 12.
[0016]
The hybrid control module 12 is configured to receive respective detection signals from an accelerator pedal sensor 13, a brake pedal sensor 14, a vehicle speed sensor 15, and the like.
Based on these detection signals, the hybrid control module 12 calculates and determines the magnitude of torque to be output from the engine 1 and the electric motor 2 and the gear position or gear ratio of the automatic transmission 3, so that the engine controller 9 and the motor A torque command value signal is input to the controller 10 and a gear ratio signal is input to the AT controller 11.
[0017]
In addition, an indicator (notification unit) 16 is connected to the hybrid control module 12.
When the hybrid control module 12 determines that the downshift of the automatic transmission 3 is prohibited, the hybrid control module 12 displays the fact on the indicator 12 and notifies the driver.
[0018]
Next, the configuration of the motor controller 10 will be described in more detail based on the control block diagram of FIG.
As the electric motor 2, a three-phase AC synchronous motor is used.
The hybrid control module 12 inputs a torque command value signal T * for the electric motor 2 determined based on detection signals from the various sensors 13 to 15 to the torque command value → current command value conversion unit 17 of the motor controller 10. .
The torque command value → current command value conversion unit 17 converts the input torque command value signal T * into two-phase AC current command value signals Id * and Iq * while referring to the rotation speed signal ω of the electric motor 2. And convert.
[0019]
The current command value signals Id * and Iq * are input to the current PI control unit 18, where PI control is performed while referring to the detected current signals Id and Iq of the electric motor 2, and current command value signals for two-phase AC Two-phase AC voltage command value signals Vd * and Vq * are generated from Id * and Iq *, and these signals are input to the two-phase → three-phase converter 19.
The two-phase → three-phase converter 19 refers to the input two-phase AC voltage command value signals Vd * and Vq * while referring to the rotation angle position signal θ of the electric motor 2, and the three-phase AC current command value signal Vu. *, Vv *, and Vw * are converted and output, and these signals are input to the inverter 20.
The inverter 20 supplies the three-phase alternating current voltages Vu *, Vv *, Vw * corresponding to these three-phase alternating current command value signals Vu *, Vv *, Vw * to the electric motor 2 and generates the torque command value signal T *. Generate the corresponding torque.
[0020]
The electric motor 2 is provided with a motor rotation sensor 24, a motor temperature sensor 25, and a motor current sensor 26, and the rotation equivalent signal ωn, the motor temperature signal TH, and the motor current signals Iu, Iv, Iw of the electric motor 2, respectively. Can be output.
The rotation signal ωn from the rotation sensor 24 is input to the rotation angle position / rotation number calculation unit 23, where the current rotation angle position and rotation number of the electric motor 2 are calculated to rotate the rotation angle position signal θ and rotation. The number signal ω is obtained.
[0021]
Among these, the rotation angle position signal θ is input to the two-phase → three-phase converter 19 and the three-phase → two-phase converter 22. The rotation speed signal ω is input to the torque command value → current command value conversion unit 17 and the downshift prohibition determination unit 21.
A motor temperature signal TH from the motor temperature sensor 25 is input to the downshift prohibition determination unit 21.
Motor current signals Iu, Iv, Iw related to the three-phase alternating current from the motor current sensor 26 are input to the three-phase → two-phase conversion unit 22. The three-phase → two-phase conversion unit 22 converts the three-phase AC motor current signals Iu, Iv, Iw into two-phase AC currents Id, Iq, and inputs them to the current PI control unit 18.
[0022]
On the other hand, the downshift prohibition determination unit 21 receives a speed ratio Rg when the automatic transmission 3 is downshifted and a torque command value T ** (T ** = T *) when the downshift is performed.
The downshift prohibition determination unit 21 determines whether or not a downshift is possible. If the determination result indicates that the downshift is acceptable, the downshift permission signal is displayed. If the determination result is that the downshift is not permitted, the downshift is prohibited. A signal is input to the hybrid control module 12.
[0023]
The hybrid control module 12 transmits the downshift allowance signal or prohibition signal received from the downshift prohibition determination unit 21 to the AT controller 11 together with the accelerator opening signal and the vehicle speed signal, and the AT controller 11 performs automatic transmission. 2 down-shifting is executed or down-shifting is prohibited.
[0024]
FIG. 3 shows a control system in the downshift prohibition judging unit 21.
The downshift prohibition determination unit 21 includes a downshift motor rotation number calculation unit 27 as a field current value estimation unit, a torque command value → current command value conversion unit 28, and a temperature protection calculation unit 29.
The current speed signal ω of the electric motor 2 and the speed ratio signal Rg when the downshift is performed (for example, a gear ratio in a step type automatic transmission) are input to the downshift motor speed calculation unit 27 and the downshift is performed. The expected number of revolutions of the electric motor 2 at this time is calculated by the following equation and output as the number of revolutions signal ωd.
ωd = current rotation speed × downshift ratio (1)
[0025]
The rotation speed signal ωd at the time of the downshift is input to the torque command value → current command value conversion unit 28. The torque command value → current command value conversion unit 28 is a two-phase AC current command value signal based on the rotation speed signal ωd at the time of downshift and the torque command value signal T ** at the time of downshift. The data is converted into Id * and Iq * and output to the temperature protection calculation unit 29. In the conversion, reference is made to the torque → rotation speed map shown in FIG.
[0026]
The current temperature signal TH of the electric motor 2 is further input from the motor temperature sensor 25 to the temperature protection calculation unit 29. Based on the current temperature signal TH and the input two-phase AC current command value signals Id * and Iq *, the temperature protection calculation unit 29 determines whether or not downshifting is prohibited, and outputs a signal corresponding to the determination result. Output to the hybrid control module 12.
[0027]
FIG. 5 is a flowchart showing the flow of control operation in the downshift prohibition judging unit 21.
First, when the downshift of the transmission 3 is to be executed, in step 100, the motor speed calculation unit 27 at the time of the downshift, the current speed signal ω of the electric motor 2 from the motor speed sensor 24 and the AT The controller 11 receives the gear ratio signal at the time of downshifting through the hybrid control module 12 from the controller 11, respectively, calculates the predicted number of revolutions of the electric motor 2 at the time of downshifting by the equation (1), and obtains this revolution number signal ωd. produce.
[0028]
In the subsequent step 101, in the torque command value → current command value conversion unit 28, from the predicted rotation speed signal ωd of the electric motor 2 when the downshift is performed and the torque command value signal T ** of the electric motor when the downshift is performed. Referring to the map of FIG. 4, the current command value when the downshift is performed is estimated, and current command value signals Id * and Iq * are obtained.
[0029]
A map showing the relationship between the motor speed and the field current of the electric motor 2 is shown in FIG. Here, an example is shown where the field current values of the electric motor 2 before and after the downshift are 50 amperes and 100 amperes when the motor rotation speeds before and after the downshift are, for example, 2500 rpm and 3500 rpm.
If this relationship map is used, the value of the field current after the downshift can be obtained from the motor speed before and after the downshift and the field current of the electric motor 2 before the downshift.
[0030]
In step 102, the temperature protection calculation unit 29 has a margin for reaching the protection temperature from the current command value signals Id * and Iq * obtained in step 2 and the current temperature signal TH of the electric motor 2 detected by the temperature sensor 21. The time is calculated from the motor temperature-margin time map in FIG.
In the motor temperature-margin time map of FIG. 7, for example, when the current temperature of the electric motor 2 detected by the motor temperature sensor 25 is 60 ° C. and the protection temperature of the electric motor 2 is set to 130 ° C., Expected elapsed temperature and expected margin when the magnitude of the current command value Ia (Ia is the square root of the sum of the square of the current command value Id and the square of Iq) is, for example, from X1 to X3 amps (X1> X3) The relationship lines x1, x2, x3 with time are illustrated.
From this relationship diagram, it can be seen that the larger the current command value Ia is, the shorter the margin time until the protection temperature is reached.
Here, it is shown that the margin time t1 when the current command value Ia is an intermediate value of X2 amperes is, for example, 30 seconds.
[0031]
In Step 103, it is checked whether or not the margin time obtained in Step 3 is equal to or shorter than the specified time. If it is equal to or shorter than the specified time, the process proceeds to Step 104, and if longer than the specified time, the process proceeds to Step 106.
That is, when the determination result is less than the specified time, a down shift prohibiting signal is output to the hybrid control module 12, and a down shift prohibiting signal of the automatic transmission 3 is output from the hybrid control module 12 to the AT controller 11, Downshifting of the automatic transmission 3 is prohibited.
[0032]
Subsequently, in step 105, the hybrid control module 12 notifies the driver that the downshift is not executed with the indicator 17, and the flow is ended.
[0033]
On the other hand, when the determination result is longer than the specified time, in step 106, a down shift permission signal is output to the hybrid control module 12, and the down shift permission signal of the automatic transmission 3 is output from the hybrid control module 12 to the AT controller 11. Thus, the downshift of the automatic transmission 3 is executed.
[0034]
As described above, in the hybrid vehicle control apparatus according to the present embodiment, the field current value in the case of downshifting is estimated, the temperature of the electric motor 2 corresponding thereto is obtained, and this temperature reaches the protection temperature. The margin time until the calculation is calculated and compared with the specified time. When the margin time is equal to or shorter than the specified time, the downshift of the automatic transmission 3 is prohibited, so that the electric motor 2 and the inverter 17 are prevented from rising to the protection temperature.
On the other hand, if the margin time is longer than the specified time, downshifting of the automatic transmission 3 is allowed, so that the regenerative torque is generated from the electric motor that has become high rotation, thereby effectively applying the braking force to the vehicle during deceleration. Can be made.
[0035]
Further, the downshift prohibition when the margin time is equal to or less than the specified time is executed not only at the time of deceleration but also at the downshift at the time of acceleration. In this case, deterioration of acceleration of the vehicle is also prevented.
That is, when the accelerator pedal is kicked down to accelerate the vehicle, the depression setting condition is satisfied and the automatic transmission 3 shifts down. In this case, the engine speed increases, and the electric motor also rotates. The number rises.
[0036]
At this time, the electric motor enters an area where weak field control is required, and the field current increases, causing the copper loss of the electric motor to increase the temperature of the electric motor and the inverter that controls the electric motor. If it does so, torque limitation will be applied to an electric motor with respect to this temperature rise, and the torque which an electric motor can generate | occur | produce will be restrained low.
For this reason, the acceleration expected by the driver cannot be obtained, and the acceleration feeling is impaired.
On the other hand, in the embodiment, since the downshift is prohibited when the temperature rises and the margin time is short, it is possible to prevent the phenomenon that the acceleration of the vehicle deteriorates against the above expectation. .
[0037]
When the time to reach the protection temperature is long, there is no torque limitation, and even if the electric motor is a small motor, it is possible to temporarily generate an output exceeding the temperature rating without any problem. Therefore, it is possible to temporarily increase the maximum torque that can be generated at the same rotational speed as usual, and to accelerate the vehicle with a stronger torque.
[0038]
Further, the current command value (field current value) at the time of downshifting is obtained by the motor speed calculation unit 27 at the time of downshifting and the current revolution number of the electric motor and the predicted revolution number of the electric motor 2 at the time of downshifting. In addition, since the torque command value → current command value conversion unit 28 estimates the estimated rotational speed and the torque command value when the downshift is performed, the change in the current command value when the downshift is easily performed can be grasped. Thus, it can be used to determine whether to allow or prohibit the downshift of the automatic transmission 3.
[0039]
In addition, since the temperature protection calculation unit 29 obtains the predicted temperature of the electric motor 2 when the downshift is performed from the current command value when the downshift is performed and the current temperature of the electric motor 2, The predicted temperature of the electric motor 2 can be easily obtained, and the margin time can be easily calculated by comparing the predicted temperature and the protection temperature.
[0040]
Similarly, in the temperature protection calculation unit 29, the allowance time and the specified time are compared to determine whether or not the downshift is allowed. Therefore, the downshift is allowed and the regenerative torque is generated during deceleration. When a large braking force is applied to the vehicle or when the vehicle is accelerated, a downshift is allowed to generate a large torque to generate an acceleration in the vehicle, and a case where there is a time margin that is actually effective can be distinguished.
In this case, since the margin time is calculated based on the current temperature of the electric motor 2 and the energization current of the electric motor 2, the margin time can be accurately obtained by a simple method.
[0041]
Further, since the indicator 16 informs the driver that the downshift is prohibited, the driver can easily check the operating state of the control device on the vehicle side and can drive with peace of mind.
[0042]
The present invention is not limited to the above embodiment. In the embodiment, the motor function for generating the driving force and the power generation function for generating the regenerative torque are realized by the single electric motor 2 to reduce the cost and reduce the mounting space. It can also be separated into generators.
[0043]
In the temperature protection calculation unit 29, the temperature of the electric motor 2 is detected and the time until the temperature reaches the protection temperature is calculated. However, the temperature of the inverter 17 can be detected and used. Further, the higher temperature of the two may be used.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a hybrid vehicle to which the present invention is applied.
FIG. 2 is a block diagram showing a configuration of the embodiment.
FIG. 3 is a block diagram illustrating a control system of a downshift prohibition determination unit.
FIG. 4 is a diagram showing a torque-rotation speed map;
FIG. 5 is a flowchart showing a flow of control operation in a downshift prohibition determination unit.
6 is a diagram showing a relationship map between the motor rotation speed and the field current of the electric motor 2. FIG.
FIG. 7 is a diagram showing a motor temperature-margin time map.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Electric motor 3 Automatic transmission 4 Battery 8a, 8b Drive wheel 9 Engine controller 10 Motor controller 11 AT controller 12 Hybrid control module 16 Indicator 17 Torque command-> current command value conversion part 18 Current PI control part 19 2-phase-> 3 Phase conversion unit 20 Inverter 21 Down shift prohibition determination unit 22 3 phase → 2 phase conversion unit 23 Rotation angle position / rotation number calculation unit 24 Motor rotation sensor 25 Motor current sensor 26 Motor current sensor 27 Motor rotation number calculation unit 28 during down shift Torque command value → current command value conversion unit 29 Temperature protection calculation unit

Claims (6)

A control device for a hybrid vehicle comprising an internal combustion engine, an electric motor, and a transmission capable of shifting a drive output of the engine and the electric motor and outputting the drive output to drive wheels, wherein the engine and the electric motor are always connected. And
A field current value estimating means for estimating a field current value flowing in the electric motor when the transmission is downshifted;
It is determined whether or not the temperature of the electric motor corresponding to the field current estimated by the field current estimation means reaches a protection temperature. If the temperature of the electric motor does not reach the protection temperature, the transmission is down. A control apparatus for a hybrid vehicle, comprising: a temperature protection calculation unit that allows a shift and prohibits a downshift of the transmission when the temperature of the electric motor reaches a protection temperature. The field current value estimating means obtains a predicted rotational speed of the electric motor when the downshift is performed from a current rotational speed of the electric motor and a transmission gear ratio when the downshift is performed, and the predicted rotational speed 2. The control apparatus for a hybrid vehicle according to claim 1, wherein a field current value is estimated from a torque command value when a downshift is performed. The temperature protection calculation unit obtains a predicted temperature when downshifting from the field current value estimated by the field current value estimation unit and the current temperature of the electric motor, and calculates the predicted temperature and the protection temperature. The control apparatus for a hybrid vehicle according to claim 2, wherein comparison is made. The temperature protection calculation unit estimates a margin time until the temperature of the electric motor reaches the protection temperature, and prohibits a downshift of the transmission when the margin time is equal to or less than a specified time. The control apparatus of the hybrid vehicle of any one of Claim 1 to 3 characterized by these. The hybrid vehicle control device according to claim 4, wherein the margin time is calculated based on a current temperature of the electric motor and a field current value of the electric motor. The hybrid vehicle control device according to any one of claims 1 to 5, further comprising a notification unit that notifies the downshift prohibition when the downshift of the transmission is prohibited.

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