JP7135361B2 - TORQUE CONTROL METHOD AND TORQUE CONTROL DEVICE FOR ELECTRIC VEHICLE - Google Patents

Description

The present disclosure relates to a torque control method and a torque control device for an electric vehicle having a motor as a drive source for running.

Conventionally, in an electric vehicle equipped with a motor as a drive source for running, an electric vehicle that uses a motor to perform vibration suppression control for the purpose of reducing driving force fluctuations caused by torsional vibration of the power train system and gear backlash. A damping control device is known (see Patent Document 1, for example).

JP 2014-220919 A

The damping control in the conventional device can produce the damping effect only when the engine or motor is directly connected to the drive wheels (tires). Therefore, when a clutch element provided in the driving system is in a slip engagement state, such as during shift control or engine start-up, the damping control operation is prohibited. Therefore, if the shift control intervenes during running, the damping control is prohibited during the shift control, and the damping control is reactivated after the shift ends. However, when the damping control is reactivated during braking deceleration, the braking reaction force from the tires becomes a disturbance factor for the F/B control system of the damping control, and until the F/B control system stabilizes, the motor torque may fluctuate more than necessary, causing driving force fluctuations.

The present disclosure has been made with a focus on the above-mentioned problem, and aims to achieve both reduction of driving force fluctuation in the braking deceleration start scene and suppression of driving force fluctuation in the damping control reactivation scene during braking deceleration. and

In order to achieve the above object, the present disclosure provides an electric vehicle that performs damping control to output a motor torque command that is obtained by adding a motor torque due to the reverse phase characteristic of the driving force fluctuation characteristic to the motor torque that obtains the target driving torque of the vehicle. is a torque control method.
A torque range defined by the upper limit torque and the lower limit torque in which the target drive torque is allowed to fluctuate is referred to as an operation limit range of the motor torque in damping control.
During braking, when the target drive torque switches from the positive side higher than the positive torque determination threshold value set near zero torque to the negative side, vibration suppression control is performed until the target drive torque reaches the negative torque determination threshold value on the negative side. Motor torque limitation is performed by setting the operation limitation range of the motor torque in the torque range in which the correction of the motor torque is allowed.
During braking, when the target drive torque switches from the negative side, which is lower than the negative torque determination threshold, to the positive side, until the target drive torque reaches the positive torque determination threshold, the operation limit range of the motor torque in damping control is set to The motor torque is limited to a torque range narrower than the torque range when the target drive torque switches from the positive side to the negative side .

In this way, by varying the motor torque operation limit in damping control according to the switching direction of the target drive torque, it is possible to reduce driving force fluctuations at the start of braking deceleration and to reduce the driving force in the damping control reactivation scene during braking deceleration. It is possible to achieve both suppression of fluctuations.

1 is a hardware configuration diagram showing a powertrain system of a hybrid vehicle to which the torque control method and torque control device of Embodiment 1 are applied; FIG. 1 is a software configuration diagram showing a control system of a hybrid vehicle to which the torque control method and torque control device of Embodiment 1 are applied; FIG. 1 is a skeleton diagram showing an example of an automatic transmission interposed between a motor/generator and drive wheels in Embodiment 1. FIG. 4 is an engagement operation table showing the engagement state of each frictional element and the second clutch for each gear stage in the automatic transmission according to the first embodiment; 4 is a shift map diagram showing an example of a shift map used in shift control by the automatic transmission of the first embodiment; FIG. 4 is a computation block diagram showing the internal configuration of the integrated controller of Example 1. FIG. 4 is a driving force map diagram showing a target steady driving force map (a) and an MG assist driving force map (b) used for calculation in a target driving force calculating section of the integrated controller; FIG. FIG. 4 is an engine start/stop line map diagram showing engine start line characteristics and engine stop line characteristics used for operation mode selection calculation in a mode selection unit of an integrated controller; FIG. 4 is a required power generation output map while running showing a required power generation output characteristic while running with respect to the battery SOC used for calculation in a target power generation output calculation unit of the integrated controller; FIG. 5 is a best fuel consumption line characteristic diagram showing the best fuel consumption line of the engine used for calculation in the target power generation output calculation unit of the integrated controller; 4 is a flowchart showing the flow of torque region determination processing executed by a torque region determination processing section of the integrated controller; 5 is a flow chart showing the flow of motor torque limiting processing during damping control operation executed by a damping control section of a motor controller; 9 is a time chart showing a problem when damping control is reactivated from a state in which damping control is prohibited due to gear shifting during brake deceleration in Comparative Example 1; 10 is a time chart showing a rebound problem in Comparative Example 2 in which countermeasures for solving the problem in Comparative Example 1 are taken; 5 is a time chart showing each characteristic when damping control is reactivated from a state in which damping control is prohibited due to shifting during brake deceleration in the first embodiment; 10 is a time chart showing each characteristic when damping control is reactivated from a state in which damping control is prohibited due to gear shifting during brake deceleration in another embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the torque control method and torque control apparatus of the electric vehicle by this indication is demonstrated based on Example 1 shown on drawing.

The torque control method and torque control device in the first embodiment are applied to a hybrid vehicle (an example of an electric vehicle) called a one-motor, two-clutch vehicle. Hereinafter, the configuration of the first embodiment will be described as "power train system configuration", "control system configuration", "general configuration of automatic transmission", "integrated controller configuration", "torque range determination processing configuration and damping control operation configuration". motor torque operation limit processing configuration”.

[Power train system configuration]
FIG. 1 shows a powertrain system of a hybrid vehicle to which the torque control method and torque control device of the first embodiment are applied. The configuration of the power train system will be described below with reference to FIG.

As shown in FIG. 1, the power train system includes an engine 1, a motor/generator 2 (motor), an automatic transmission 3 (transmission), a first clutch 4, a second clutch 5 (clutch), A differential gear 6 and drive wheels 7 are provided. In other words, it is a hybrid vehicle having a powertrain system configuration in which one motor and two clutches are added to the engine 1 . The main driving modes of the hybrid vehicle include an "HEV mode (hybrid vehicle mode)" by engaging the first clutch 4 and an "EV mode (electric vehicle mode)" by disengaging the first clutch 4.

The output shaft of the engine 1 and the input shaft of a motor/generator 2 (abbreviated as "MG") are connected via a first clutch 4 (abbreviated as "CL1") having a variable torque capacity.

The output shaft of the motor/generator 2 is connected to the input shaft of an automatic transmission 3 (abbreviated as "AT").

The automatic transmission 3 is a transmission having seven forward gears and one reverse gear. The automatic transmission 3 automatically selects a shift stage according to the vehicle speed VSP and the accelerator opening APO.

The second clutch 5 (abbreviated as "CL2") is one element with a variable torque capacity that is responsible for torque transmission among friction elements such as shift clutches and shift brakes that are incorporated as shift elements of the automatic transmission 3. is used. As a result, the automatic transmission 3 synthesizes the power of the engine 1 input via the first clutch 4 and the power input from the motor/generator 2 and outputs the combined power to the driving wheels 7 .

For the first clutch 4 and the second clutch 5, for example, a dry single-plate clutch, a wet multi-plate clutch, or the like, which can continuously control the oil flow rate and the hydraulic pressure with a proportional solenoid, may be used. This power train system has two operation modes depending on the engagement state of the first clutch 4. When the first clutch 4 is disengaged, the vehicle is in an "EV mode" in which the vehicle is driven only by the power of the motor/generator 2. The connected state of the first clutch 4 is the "HEV mode" in which the power of the engine 1 and the motor/generator 2 is used to drive the vehicle.

The power train system is provided with a CL1 input rotation sensor 10, a CL1 output rotation sensor 11, an AT input rotation sensor 12, and an AT output rotation sensor 13. A CL1 input rotation sensor 10 detects the input rotation speed of the first clutch 4 . The CL1 output rotation sensor 11 detects the output rotation speed of the first clutch 4 (=motor rotation speed). The AT input rotation sensor 12 detects the input shaft rotation speed of the automatic transmission 3 . The AT output rotation sensor 13 detects the output shaft rotation speed (=vehicle speed) of the automatic transmission 3 .

[Control system configuration]
FIG. 2 shows a hybrid vehicle control system to which the engine start control method and torque control device of the first embodiment are applied. The configuration of the control system will be described below with reference to FIG.

The control system, as shown in FIG. (Abbreviation: "ATCM"). These controllers 20, 21, 22, and 25 are connected by bidirectional communication lines (CAN communication lines, etc.) so that information can be exchanged.

The integrated controller 20 inputs information from the rotation sensors 10, 11, 12, 13, the accelerator opening sensor 17, the brake switch 23, the battery SOC sensor 16, etc., and performs integrated control of the operating points of the powertrain system components. . The integrated controller 20 selects a driving mode that can realize the driving force desired by the driver according to the accelerator opening APO, the battery state of charge SOC, and the vehicle speed VSP. Then, the motor controller 22 is commanded for the target MG torque or the target MG rotation speed, the engine controller 21 is commanded for the target engine torque, and the AT controller 25 is commanded for the CL1 solenoid current and the target CL2 torque.

When the target engine torque command is input from the integrated controller 20, the engine controller 21 controls the engine 1 so as to obtain the target engine torque.

When receiving a target MG torque command or a target MG rotation speed command from the integrated controller 20, the motor controller 22 outputs a control command to the inverter 8 to control the motor/generator 2 (MG torque control, MG rotation speed control). Inverter 8 converts direct current from battery 9 to three-phase alternating current during power running to drive motor/generator 2 . The three-phase alternating current generated by the motor/generator 2 by the rotational energy from the drive wheels 7 during regeneration is converted into direct current, and the battery 9 is charged.

The motor controller 22 has a damping control unit 22a for outputting a motor torque command to the motor/generator 2, which is obtained by adding a motor torque for canceling changes in vehicle behavior to the motor torque for obtaining the target driving torque of the vehicle. When the damping control unit 22a detects fluctuations in the driving force caused by torsional vibration of the power train system, backlash of gears, etc., it adds motor torque due to the opposite phase characteristics of the driving force fluctuation characteristics, and controls the driving force. To suppress vehicle vibration by canceling force fluctuation.

The AT controller 25 controls the shift of the automatic transmission 3 . In addition to this shift control, when a CL1 solenoid current command is input from the integrated controller 20, the drive of the first solenoid valve 14 that controls the clutch hydraulic pressure to the first clutch 4 (CL1) is controlled. When a target CL2 torque command is input from the integrated controller 20, the second solenoid valve 15 that controls the clutch hydraulic pressure to the second clutch 5 (CL2) is driven and controlled.

[Schematic configuration of automatic transmission]
The schematic configuration of the automatic transmission 3 will be described below with reference to FIGS. 3 to 5. FIG.

The automatic transmission 3, as shown in FIG. 3, is a stepped automatic transmission having seven forward speeds and one reverse speed. Driving force from at least one of the engine 1 and the motor/generator 2 is input to the automatic transmission 3 from the transmission input shaft Input. A transmission gear mechanism having four planetary gears and seven friction elements changes the input rotation speed and outputs it from the transmission output shaft Output.

As a transmission gear mechanism, a first planetary gear set GS1 consisting of a first planetary gear G1 and a second planetary gear G2 and a second planetary gear set GS2 consisting of a third planetary gear G3 and a fourth planetary gear G4 are coaxially arranged in this order. are placed. Further, hydraulically operated friction elements include a first clutch C1, a second clutch C2, a third clutch C3, a first brake B1, a second brake B2, a third brake B3, and a fourth brake B4. are arranged. Two one-way clutches, a first one-way clutch F1 and a second one-way clutch F2, are arranged as engaging elements for mechanical operation.

The first planetary gear G1, the second planetary gear G2, the third planetary gear G3, and the fourth planetary gear G4 consist of a sun gear (S1-S4), a ring gear (R1-R4), and both gears (S1-S4), ( Carriers (PC1-PC4) supporting pinions (P1-P4) meshing with R1-R4), and a single pinion type planetary gear.

The transmission input shaft Input is connected to the second ring gear R2 and receives rotational driving force from at least one of the engine 1 and the motor/generator 2 . The transmission output shaft Output is connected to the third carrier PC3, and transmits the output rotational driving force to the drive wheels 7 via final gears and the like.

The first ring gear R1, the second carrier PC2 and the fourth ring gear R4 are integrally connected by a first connecting member M1. The third ring gear R3 and the fourth carrier PC4 are integrally connected by a second connecting member M2. The first sun gear S1 and the second sun gear S2 are integrally connected by a third connecting member M3.

FIG. 4 is an engagement operation table. In FIG. 4, the ◯ mark indicates that the friction element is in a hydraulic engagement state during driving (when the accelerator is ON). The (○) mark indicates that the relevant friction element is in a hydraulic engagement state (a one-way clutch is in operation during driving) during coasting (accelerator OFF). No mark indicates that the friction element is in the released state. Friction elements in an engaged state indicated by hatching indicate friction elements used as the second clutch 5 (CL2) in each shift stage.

Each gear stage of seven forward gears and one reverse gear is realized by engaging three of the seven friction elements at each gear as shown in FIG. . When shifting to an adjacent shift stage, one of the three friction elements that has been engaged is released, and the other friction element that has been released is engaged. As shown in 4, seven forward speeds are realized.

The second clutch 5 (CL2) is set to the second brake B2 when the gear stage is 1st or 2nd gear. The second clutch C2 is used when the gear stage is the 3rd gear stage. The third clutch C3 is used when the gear stage is the 4th or 5th gear. The first clutch C1 is used when the speed is 6th or 7th. The fourth brake B4 is applied when the shift stage is reverse.

FIG. 5 is a shift map diagram showing an example of a shift map used for shift control of the automatic transmission 3. As shown in FIG. The shift map shown in FIG. 5 is stored and set in advance in the memory of the AT controller 22. Solid lines indicate upshift lines, and dotted lines indicate downshift lines.

When the D range is selected, the operating point (VSP, APO) determined based on the vehicle speed VSP from the AT output rotation sensor 13 (=vehicle speed sensor) and the accelerator opening APO from the accelerator opening sensor 17 exists on the shift map. to search for a position. Then, if the operating point (VSP, APO) does not move at all, or if the operating point (VSP, APO) moves but remains within one gear range on the shift map of FIG. maintain the same gear stage. On the other hand, when the operating point (VSP, APO) moves and crosses the upshift line on the shift map of FIG. 5, an upshift command is output, and when the downshift line is crossed, a downshift command is output.

[Integrated controller configuration]
FIG. 6 is a computation block diagram showing the integrated controller 20 of the first embodiment. The configuration of the integrated controller will be described below with reference to FIGS. 6 to 10. FIG.

The integrated controller 20, as shown in FIG. there is

The target driving force calculation unit 100 uses the target steady driving force map shown in FIG. 7A and the MG assist driving force map shown in FIG. force and MG assist driving force are calculated.

The target driving force calculation unit 100 has a torque region determination processing unit 20a that uses the calculation result of the target driving force (=target driving torque) of the vehicle to determine the torque region of the target driving torque.

The mode selection unit 200 calculates the driving mode (HEV mode, EV mode) using the engine start/stop line map set by the accelerator opening APO for each vehicle speed VSP shown in FIG. As represented by the characteristics of the engine start line (SOC high, SOC low) and the engine stop line (SOC high, SOC low), the engine start line and engine stop line show that as the battery SOC decreases, the accelerator opening APO is set as a characteristic that decreases in the direction of decreasing

The target power generation output calculation unit 300 calculates the target power generation output from the battery SOC using the requested power generation output map during running shown in FIG. Also, the output required to raise the engine torque from the current operating point to the best fuel consumption line shown in FIG. 10 is calculated, and the output smaller than the target power generation output is added to the engine output as the required output.

An operating point command unit 400 inputs the accelerator opening APO, the target steady driving force, the MG assist driving force, the target mode, the vehicle speed VSP, and the required power generation output. Then, using these pieces of input information as operating point attainment targets, transient target engine torque, target MG torque, target CL2 torque capacity, target gear ratio, and CL1 solenoid current command are calculated.

When an engine start request is issued to the operating point command unit 400 when the operating point (VSP, APO) crosses the engine start line in FIG. It has an engine start control unit 20b for starting the engine 1 as.

When an engine start request is issued, the engine start processing in the engine start control unit 20b reduces the torque capacity of the second clutch 5 (CL2), then controls the motor/generator 2 for MG rotation speed, and controls the second clutch. 5 (CL2) is slipped into a half-clutch state. When it is determined that the second clutch 5 (CL2) has started to slip, the slip engagement of the first clutch 4 (CL1) is started to increase the engine speed. When the engine speed reaches the speed at which the first explosion is possible, the engine 1 is operated in a self-sustaining manner, and when the MG speed and the engine speed become close to each other, the first clutch 4 (CL1) is completely engaged.

Based on the target CL2 torque capacity and the target gear ratio, the shift control unit 500 drives and controls the solenoid valves in the automatic transmission 3 so as to achieve these. From the vehicle speed VSP, the accelerator opening APO, and the shift map shown in FIG. 5, it is determined what the next gear stage should be from the current gear stage.

[Torque Region Determination Processing Configuration and Motor Torque Operation Restriction Processing Configuration During Damping Control Operation]
FIG. 11 shows the flow of torque region determination processing executed by the torque region determination processing section of the integrated controller 20. As shown in FIG. Each step in FIG. 11 will be described below. The "positive torque determination threshold" is a motor torque threshold set to a positive torque value close to zero (for example, about 5 Nm). "Low torque determination threshold" and "negative torque determination threshold" refer to motor torque thresholds set to a negative torque value (for example, about -50 Nm). It is given as a torque judgment value. A torque region equal to or higher than the positive torque determination threshold is referred to as a "positive torque region". A region from the low torque determination threshold to the positive torque determination threshold is called a “low torque region”. A region below the negative torque determination threshold is referred to as a “negative torque region”.

In step S1, following the start, a drive torque command (=target drive torque) is calculated, and the process proceeds to step S2.

In step S2, following the calculation of the drive torque command in step S1, torque region determination is performed to determine whether the calculated target drive torque exists in the negative torque region. If YES (exists in the negative torque region), proceed to step S3, and if NO (does not exist in the negative torque region), proceed to step S7.

In step S3, it is determined whether or not the target driving torque is equal to or higher than the low torque determination threshold, following the determination in step S2 that the vehicle is in the negative torque region. If YES (target drive torque≧low torque determination threshold), the process proceeds to step S4, and if NO (target drive torque<low torque determination threshold), the process proceeds to RETURN.

In step S4, subsequent to the determination in S3 that the target driving torque≧the low torque determination threshold value, a timer 1 count is started, and the process proceeds to step S5.

In step S5, following the start of timer 1 counting in step S4, it is determined whether timer 1 (elapsed time by timer 1) is equal to or longer than the low torque determination time. If YES (timer 1≧low torque determination time), proceed to step S6, and if NO (timer 1<low torque determination time), proceed to RETURN.

In step S6, following the determination in step S5 that timer 1≧low torque determination time, torque region determination=low torque is set, timer 1 is reset, and the routine proceeds to RETURN.

In step S7, it is determined whether or not the target drive torque is equal to or less than the negative torque determination threshold, following the determination in step S2 that the negative torque region is not present. If YES (target drive torque≦negative torque determination threshold), the process proceeds to step S8, and if NO (target drive torque>negative torque determination threshold), the process proceeds to step S11.

In step S8, following the judgment in S7 that the target drive torque is smaller than or equal to the negative torque determination threshold value, a timer 2 count is started, and the process proceeds to step S9.

In step S9, following the start of timer 2 counting in S8, it is determined whether or not timer 2 (elapsed time by timer 2) is equal to or longer than the negative torque determination time. In the case of YES (timer 2≧negative torque determination time), the process proceeds to step S10, and in the case of NO (timer 2<negative torque determination time), the process proceeds to RETURN.

In step S10, following the determination in step S9 that timer 2≧negative torque determination time, torque region determination=negative torque is set, timer 2 is reset, and the process proceeds to return.
It is determined that the second clutch 5 (CL2) remains in the half-clutch state due to the target slip amount in the engine start control, and the process proceeds to step S8.

In step S11, it is determined whether or not the target drive torque is equal to or greater than the positive torque determination threshold, following the determination in S7 that the target drive torque is greater than the negative torque determination threshold. If YES (target drive torque≧positive torque determination threshold), the process proceeds to step S12, and if NO (target drive torque<positive torque determination threshold), the process proceeds to RETURN.

In step S12, following the determination in S11 that the target drive torque is greater than or equal to the positive torque determination threshold value, timer 3 count is started, and the process proceeds to step S13.

In step S13, following the start of timer 3 count in step S12, it is determined whether timer 3 (elapsed time by timer 3) is equal to or longer than the positive torque determination time. If YES (timer 3≧positive torque determination time), the process proceeds to step S14, and if NO (timer 3<positive torque determination time), the process proceeds to RETURN.

In step S14, following the determination in step S13 that timer 3≧positive torque determination time, torque region determination=positive torque is set, timer 3 is reset, and the process proceeds to RETURN.

FIG. 12 shows the flow of the motor torque limiting process during the damping control operation executed by the damping control section 22a of the motor controller 22. As shown in FIG. Each step in FIG. 12 will be described below.

In step S21, subsequent to the start, a torque region determination calculation is performed according to the flow chart of FIG. 11, and the process proceeds to step S22.

In step S22, subsequent to the torque region determination calculation in S21, it is determined whether or not torque region determination=positive torque or brake OFF. If YES (torque region determination=positive torque or brake OFF), proceed to step S23. If NO (torque region determination=not positive torque or brake OFF), proceed to step S25.

In step S23, following the determination in step S22 that torque region determination=positive torque or brake OFF, limit determination=OFF, the timer is reset, and the process proceeds to step S24.

In step S24, following the restriction determination in S23=OFF, the timer is reset, the upper limit torque is set to +A and the lower limit torque is set to -A, and the process proceeds to the return.

Here, "upper limit torque +A, lower limit torque -A" means that the motor torque is not limited and torque fluctuation within the operation limit range (±A) of the motor torque in damping control is allowed.

In step S25, it is determined whether or not the torque region determination=low torque following the determination in S23 that the torque region determination=positive torque or the brake is not OFF. If YES (torque region determination=low torque), proceed to step S26, and if NO (torque region determination=not low torque), proceed to step S31.

In step S26, subsequent to the determination in S25 that the torque region is not low torque, it is determined whether the damping control is OFF→ON or whether the damping determination is ON. If YES (the damping control is OFF→ON or the damping determination is ON), proceed to step S27; if NO (the damping control is OFF→ON or the damping determination is not ON) Go to step S32.

In step S27, following the determination in step S26 that the damping control is OFF→ON or that the damping determination is ON, a timer count is started, the limit determination is set to ON, and the process proceeds to step S28.

In step S28, it is determined whether or not the timer is less than the time T1 following the timer count and limit determination=ON in S27. If YES (timer<time T1), the process proceeds to step S29, and if NO (timer≧time T1), the process proceeds to step S30.

Here, the "time T1" is determined by the maximum time obtained by experiments or the like, in which the malfunction becomes high when the damping control is restarted.

In step S29, following the determination in step S28 that the timer<time T1, the upper limit torque is set to +C and the lower limit torque is set to -B, and the process proceeds to RETURN.

Here, "upper limit torque +C" means that the motor torque is limited to zero or a value close to zero. The lower limit torque -B indicates that the torque is further limited than the operation limit range (-A) of the motor torque in damping control. That is, the absolute values of A, B, and C, which are the motor torque limit values, have a relationship |C|<|B|<|A|.

In step S30, following the determination that timer≧time T1 in step S28, the limit determination is turned off, and the process proceeds to step S32.

In step S31, subsequent to the torque region determination=not low torque (torque region determination=negative torque) in step S25, limit determination=OFF, the timer is reset, and the process proceeds to step S32.

In step S32, determination of NO in step S26, or limit determination in step S30 = OFF, or limit determination in step S31 = OFF, timer reset, upper limit torque +B, lower limit torque = -B. , proceed to return.

Here, "upper limit torque +B, lower limit torque = -B" means that torque is further limited beyond the operation limit range (±A) of motor torque in damping control.

Next, the action of the first embodiment will be described separately for "problem of motor torque limiting technique during damping control in comparative example" and "motor torque limiting action during damping control in first embodiment".

[Issues in motor torque limiting technology during damping control in comparative example]
Comparative Example 1 is a control in which the motor torque operating range in damping control is restricted more than usual only during brake operation in a scene where the vehicle is stopped after braking deceleration. In Comparative Example 1, as shown in FIG. 13, as the motor torque operation limit range in damping control, the motor torque is given by the torque limit ±B in the negative torque section until just before deceleration and stop, and is given by the torque limit ±B in the positive torque section. given by A.

In the case of Comparative Example 1, as shown in FIG. 13, from time t1 to time t2, damping control is prohibited due to the fact that the deceleration downshift is in progress. is resumed. After time t2, the reaction force from the tires becomes a disturbance factor in the F/B control system of damping control, and when damping control is resumed after the shift ends, the control system stabilizes from time t2 to time t3. Until then, the motor torque fluctuates more than necessary. In other words, the damping control during brake deceleration may cause a malfunction if the damping control is turned from OFF to ON during deceleration due to disturbance caused by the brake. Normally, the motor operates to reduce the fluctuation based on the fluctuation of the input rotation, but in the event of malfunction, the motor torque operates regardless of the fluctuation of the input rotation.

Therefore, in Comparative Example 1, due to a malfunction of the damping control, the motor torque characteristic is reduced to torque limit +B between time t2 and time t3 as shown in the motor torque command characteristic within the frame indicated by arrow D in FIG. characteristics along the limits of In this case, as shown in the acceleration characteristics within the frame indicated by arrow D in FIG. 13, there is a problem that the deceleration temporarily decreases between time t2 and time t3, giving a feeling of acceleration.

Therefore, in order to solve the above problem, in the control of Comparative Example 1, the motor torque operation range in the damping control is set to the limit amount during braking only in the low torque region where the influence of the damping control on the driving force fluctuation is large. Comparative example 2 is a control for further increasing the value. In Comparative Example 2, as the motor torque operation limit range in damping control, the torque limit +0 and the torque limit -B are given in the low torque section, and the motor torque is given by the torque limit ±B in the negative torque section until just before deceleration and stop. be done.

However, in Comparative Example 2, if the operating range of the motor torque in the positive direction during damping control is greatly restricted by the torque restriction +C in the low torque section, the scene immediately after the start of braking deceleration is greatly restricted because the motor torque is greatly restricted. Then, a new problem arises in that the driving force fluctuation becomes worse.

That is, as shown by arrow E in FIG. 14, in the scene immediately after the start of braking deceleration, it was necessary to correct the motor torque to the positive side by damping control in order to suppress twisting due to a sudden change in drive torque. However, as shown by the arrow F in FIG. 14, in order to prevent malfunction of the damping control, the upper and lower torque limits (+0, -B) of the damping control are limited in the low torque section. Therefore, the motor torque could not be corrected to the positive side.

As a result, when the brake is turned ON from EV driving, the input torque suddenly changes at the point where the target drive torque shifts from positive torque to negative torque, and as is clear from the acceleration fluctuation characteristics around time t3 in FIG. Driving force fluctuation due to torsion occurred.

[Motor Torque Limiting Action During Damping Control in Embodiment 1]
The torque control of the first embodiment has been made with a focus on the above problem. Until the torque reaches the negative torque determination threshold on the negative side, the motor torque operation limitation in the damping control is relaxed. On the other hand, when the target drive torque switches from the negative side to the positive side, which is lower than the negative torque determination threshold during braking, the motor torque operation limit range in damping control is maintained until the target drive torque reaches the positive torque determination threshold. It is a feature that allows the implementation of a narrowing motor torque limit. The motor torque limiting action during damping control will be described below with reference to the time chart of FIG.

First, in a scene in which the vehicle is decelerated and stopped by depressing the brake while traveling in the EV mode, the scene immediately after the start of braking deceleration from brake operation start time t1 to time t3 is defined as "positive torque determination".

That is, at time t1 when the AT input torque (=target driving torque in EV mode) is higher than the positive torque determination threshold, the flow chart of FIG. , S14, torque region determination=positive torque. After that, when the AT input torque becomes equal to or lower than the negative torque determination threshold value at time t2, the flow of S1→S2→S7→S8→S9→RETURN is repeated in the flowchart of FIG. Then, when the AT input torque is equal to or less than the negative torque determination threshold value for the time of timer 2, continuous determination proceeds from S9 to S10 → RETURN at time t3, and in S9, the torque region is determined to be negative torque. be.

Therefore, from the brake operation start time t1 to time t3, the flow proceeds to S21→22→S23→S24→RETURN in the flowchart of FIG. The lower limit torque is -A. Therefore, in the scene immediately after the start of braking deceleration, as shown in the motor torque characteristics within the frame indicated by the arrow G in FIG. 15, the motor torque is allowed to be corrected to the positive side by damping control.

As a result, when the brake is turned on from EV driving, even if the input torque suddenly changes when the target drive torque shifts from positive torque to negative torque, the motor torque is corrected to the positive side by damping control, and the driving at the start of braking deceleration Force fluctuations can be reduced.

Next, in the scene of deceleration and stop, the scene during braking deceleration from the switching time t3 to the negative torque determination from the positive torque determination to the time t6 is referred to as "negative torque determination".

That is, at time t3 when the AT input torque (=target drive torque in EV mode) is lower than the negative torque determination threshold, the flow proceeds from S1 to S2 to S3 in the flowchart of FIG. Until time t5 when the target drive torque becomes equal to or greater than the low torque determination threshold value in S3, the torque region determination=negative torque is maintained. After that, when the AT input torque becomes equal to or higher than the low torque determination threshold at time t5, the flow of S1→S2→S3→S4→S5→RETURN is repeated in the flowchart of FIG. When the state in which the AT input torque is equal to or higher than the low torque determination threshold continues for the time of timer 1, the continuous determination proceeds from S5 to S6 → RETURN at time t6, and in S6, the torque region determination is set to low torque. be.

Therefore, from the brake operation start time t3 to time t6, in the flow chart of FIG. +B, lower limit torque -B.

As a result, in the scene during braking deceleration, except for the damping control prohibition section during shifting from time t4 to time t5, the torque operation range of the AT input torque is limited by the upper and lower limit torque ±B. Be in control.

Next, in the braking deceleration stop scene, the braking deceleration stop scene from the time t6 immediately before the braking stop to the braking stop time t9 is determined as "low torque determination".

That is, from time t6 to time t8 when the AT input torque (=target drive torque in EV mode) is from the negative torque determination threshold to the positive torque determination threshold, S1→S2→S7→S11→ The flow to return is repeated, and the torque region determination=low torque is maintained. After that, when the AT input torque becomes equal to or higher than the positive torque determination threshold at time t8, the flow of S1→S2→S7→S11→S12→S13→RETURN is repeated in the flowchart of FIG. When the state in which the AT input torque is equal to or higher than the positive torque determination threshold continues for the time of timer 3, at time t9, the continuous determination proceeds from S13 to S14 → RETURN, and in S14, torque region determination=positive torque. be.

Therefore, from time t6 immediately before brake stop to brake deceleration stop scene from time t6 to brake stop time t9, in the flow chart of FIG. Based on the "low torque determination", the upper limit torque is set to +C and the lower limit torque is set to -B. Therefore, in the scene immediately after the start of braking deceleration, correction of the motor torque to the positive side by damping control is restricted as shown in the motor torque characteristics within the frame indicated by the arrow H in FIG. Then, at time t7 after the timer time T1 has elapsed from time t6, the flow proceeds from S28 to S30→S32→RETURN, and in step S32, the upper limit torque is switched to +B and the lower limit torque is -B. .

As a result, in the case of the first embodiment, when the deceleration downshift ends at time t5 and damping control is resumed, the motor torque increases more than necessary from time t6 to time t7 until the control system stabilizes. fluctuate. However, as shown in the motor torque characteristics within the frame indicated by the arrow H in FIG. 15, between time t6 and time t7, it is possible to suppress driving force fluctuations in the damping control reactivation scene during brake deceleration.

As described above, the hybrid vehicle torque control method and torque control apparatus of the first embodiment have the following effects.

(1) A motor (motor/generator 2) is provided as a drive source for running.
A torque control method for an electric vehicle (hybrid vehicle) that performs damping control to output a motor torque command for a motor, which is obtained by adding a motor torque for canceling changes in vehicle behavior to a motor torque for obtaining a target driving torque of the vehicle.
During braking, when the target drive torque switches from the positive side higher than the positive torque determination threshold value set near zero torque to the negative side, vibration suppression control is performed until the target drive torque reaches the negative torque determination threshold value on the negative side. Relax the operating limit of the motor torque in
During braking, when the target drive torque switches from the negative side, which is lower than the negative torque determination threshold value, to the positive side, the motor torque operation limit range in damping control is narrowed until the target drive torque reaches the positive torque determination threshold value. Allows motor torque limiting to be enforced (FIG. 15).
In this manner, the motor torque operation limit in damping control is varied depending on the switching direction of the target driving torque. As a result, it is possible to provide a torque control method for an electric vehicle (hybrid vehicle) that achieves both reduction of driving force fluctuation in the braking deceleration start scene and suppression of driving force fluctuation in the damping control reactivation scene during braking deceleration. can.

(2) The automatic transmission 3 is provided in the driving system from the motor (motor/generator 2) to the drive wheels 7.
When damping control is prohibited by the start of shift control of the automatic transmission 3 during deceleration by braking and restarted by the end of shift control, damping is performed only for a predetermined time (time T1) after the damping control is restarted. Motor torque limitation is implemented to narrow the motor torque operation limitation range in control (FIG. 12).
In this way, by minimizing the time during which the motor torque operation is greatly restricted during damping control, torsional vibration of the power train system is suppressed when the motor torque fluctuates during re-acceleration or re-deceleration. You can lower the frequency.

(3) Limiting the motor torque to the positive torque side (upper limit torque = +C) when implementing the motor torque limitation that narrows the motor torque operation limitation range in damping control during braking (Fig. 12).
In this way, by restricting the significant restriction of the motor torque operation during damping control to the positive side, even if the motor torque is re-accelerated or re-decelerated while being greatly restricted, the power train system will not be affected. Torsional vibration can be reduced by damping control. However, although vibration reduction by damping control cannot be achieved 100%, vibration can be reduced more than if damping control does not operate at all.

(4) In the brake deceleration start scene, even if the motor torque falls below the positive torque determination threshold, until it reaches the negative torque determination threshold, the motor torque is not limited, and the motor torque operation limit range in damping control is not implemented. Torque fluctuation is allowed (Fig. 12).
In this way, by allowing the operation of the motor torque during damping control, it is possible to reduce torsional vibration of the power train system by damping control even if the input torque fluctuates greatly at the start of brake deceleration. can.

(5) A torque control device for an electric vehicle (hybrid vehicle) includes a torque region determination processing section 20a and a damping control section 22a.
The torque region determination processing unit 20a
When the target drive torque switches from the positive side higher than the positive torque determination threshold value set near zero torque to the negative side, until the negative torque determination threshold value set to the negative side is reached, the torque region determination is changed to positive torque determination. do.
When the target drive torque switches from the negative side to the positive side, which is lower than the negative torque determination threshold, the torque range determination is changed to low torque determination until the target drive torque reaches the positive torque determination threshold from the negative low torque determination threshold. do.
The damping control unit 22a
If the torque region determination is a positive torque determination, the motor torque operation limitation in damping control during braking is relaxed.
If the torque region determination is a low torque determination, the motor torque limitation is allowed to narrow the operation limitation range of the motor torque in the damping control during braking (FIGS. 11 and 12).
In this manner, the motor torque operation limit in damping control is varied depending on the switching direction of the target driving torque. As a result, it is possible to provide a torque control device for an electric vehicle that achieves both reduction of driving force fluctuation in the braking deceleration start scene and suppression of driving force fluctuation in the damping control reactivation scene during braking deceleration.

The torque control method and torque control device for an electric vehicle according to the present disclosure have been described above based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and design changes and additions are permitted as long as they do not deviate from the gist of the invention according to each claim of the scope of claims.

In the first embodiment, the damping control unit 22a, when resuming the damping control due to the end of the shift control during brake deceleration, reduces the motor torque in the damping control only for a predetermined time (time T1) after resuming the damping control. An example of implementing motor torque limitation to narrow the operation limitation range has been shown. However, as shown in the motor torque characteristics surrounded by arrow H' in FIG. It is good also as an example which implements the motor torque limitation which narrows.

In the first embodiment, the damping control unit 22a limits the motor torque only on the positive torque side (upper limit torque = +C) when performing motor torque limitation to narrow the motor torque operation limit range in damping control during brake operation. An example limited to However, as the damping control unit, when the motor torque is limited by narrowing the motor torque operation limit range in the damping control during braking, the motor torque is limited on both the positive torque side and the negative torque side. It is good as

Embodiment 1 shows an example in which the torque control method and torque control device of the present disclosure are applied to a hybrid vehicle having a power train structure called one-motor, two-clutch. However, the torque control method and torque control device of the present disclosure may be applied to an electric vehicle having a motor chisel as a drive source for running, or having an EV mode and a power train structure other than the first embodiment. It can also be applied to a hybrid vehicle equipped with.

1 engine 2 motor/generator (motor)
3 Automatic transmission 4 First clutch 5 Second clutch 6 Differential gear 7 Drive wheel 10 CL1 input rotation sensor 11 CL1 output rotation sensor 12 AT input rotation sensor 13 AT output rotation sensor 14 First solenoid valve 15 Second solenoid valve 20 Integrated controller 20a Torque region determination processing unit 20b Engine start control unit 21 Engine controller 22 Motor controller 22a Damping control unit 23 Brake switch 25 AT controller

Claims (5)

Equipped with a motor as a drive source for running,
A torque control method for an electric vehicle that performs damping control for outputting a motor torque command obtained by adding a motor torque amount due to the opposite phase characteristic of the driving force fluctuation characteristic to the motor torque for obtaining the target driving torque of the vehicle. ,
When the torque range defined by the upper limit torque and the lower limit torque that allow torque fluctuations in the target drive torque is referred to as the operation limit range of the motor torque in the damping control,
During braking, when the target drive torque switches from the positive side higher than the positive torque determination threshold set near zero torque to the negative side, until the target drive torque reaches the negative torque determination threshold on the negative side, the Implementing a motor torque limit that sets the motor torque operation limit range in damping control to a torque range that allows correction of the motor torque ,
During braking, when the target drive torque switches from the negative side lower than the negative torque determination threshold to the positive side, the motor torque in the damping control is reduced until the target drive torque reaches the positive torque determination threshold. A torque control method for an electric vehicle, wherein motor torque limitation is performed so that an operation limitation range is narrower than a torque range when the target driving torque is switched from a positive side to a negative side . In the torque control method for an electric vehicle according to claim 1,
An automatic transmission is provided in a drive system from the motor to the drive wheels,
When the damping control is prohibited by the start of shift control of the automatic transmission during deceleration by braking and the damping control is restarted by the end of the shift control, the damping control is performed only for a predetermined time after the damping control is restarted. A torque control method for an electric vehicle, characterized in that the motor torque is limited by narrowing the operation limit range of the motor torque in the electric vehicle. In the torque control method for an electric vehicle according to claim 2,
1. A torque control method for an electric vehicle, characterized in that when a motor torque is limited to narrow an operation limit range of motor torque in damping control during brake operation, the motor torque is limited only to the positive torque side. In the torque control method for an electric vehicle according to any one of claims 1 to 3,
In the brake deceleration start scene, even if the motor torque falls below the positive torque determination threshold, until the motor torque reaches the negative torque determination threshold, the motor torque is not limited, and the operation limit range of the motor torque in damping control is set. A torque control method for an electric vehicle, characterized by allowing torque fluctuations. a torque region determination processing unit that calculates a target driving torque of a vehicle having a motor as a drive source for traveling and determines a torque region of the target driving torque;
a vibration suppression control unit that controls the motor to output a motor torque command obtained by adding a motor torque corresponding to the reverse phase characteristic of the driving force fluctuation characteristic to the motor torque for obtaining the target driving torque;
In a torque control device for an electric vehicle comprising
The torque region determination processing unit
When the target driving torque switches from the positive side higher than the positive torque determination threshold value set near zero torque to the negative side, until the negative torque determination threshold value set to the negative side is reached, the torque region determination is changed to positive torque determination. year,
When the target drive torque switches from the negative side lower than the negative torque determination threshold to the positive side, the torque region determination is performed until the target drive torque reaches the positive torque determination threshold from the low torque determination threshold on the negative side. Judgment of low torque,
The damping control unit is
When the torque range defined by the upper limit torque and the lower limit torque that allow torque fluctuations in the target drive torque is referred to as the operation limit range of the motor torque in the damping control,
If the torque region determination is a positive torque determination, the motor torque is limited so that the operation limit range of the motor torque in the damping control during braking is a torque range in which correction of the motor torque is allowed ,
When the torque region determination is a low torque determination, the motor torque is limited so that the motor torque operation limit range in damping control during braking is a torque range narrower than the torque range in the positive torque determination . A torque control device for an electric vehicle, characterized by:

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