control device

Abstract

To provide a control device for a vehicle that is easy to suppress occurrence of slip while performing regenerative braking, in a system that performs control for reducing regenerative braking torque when a slip occurs during regenerative braking.SOLUTION: A control device (a CPU 42), which is a control device for a vehicle (a hybrid vehicle 100) equipped with at least a drive motor 16 (MG 2) that generates traveling motive power and a battery 18 that stores electric power, includes: a torque control unit 50 that performs torque control for the drive motor 16 when a slip occurs in the vehicle; a first torque calculation unit 44 that calculates a target torque value, based on an accelerator opening degree of the vehicle and an estimated vehicle body speed of the vehicle; and a second torque calculation unit 46 that calculates a restraining torque value, based on an amount of slip in the vehicle.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Various vehicles equipped with a driving system that uses a motor as a drive source have been put into practical use. For example, electric vehicles equipped with a rechargeable battery and driven solely by the driving force of a motor have been put into practical use. Hybrid vehicles that use both an internal combustion engine and a motor, such as series, parallel, and split hybrid vehicles, have also been put into practical use.

[0003] For example, in a vehicle equipped with a series hybrid system, when the output required of the drive motor is smaller than the output of the battery, the drive motor is driven by electric power from the battery, and drive force is transmitted from the drive motor to the drive wheels. On the other hand, when the output required of the drive motor exceeds the output of the battery, the engine's power is converted into electric power by a generator motor, and the drive motor is driven by the electric power from the generator motor, and drive force is transmitted from the drive motor to the drive wheels. Furthermore, when the vehicle decelerates, the drive motor operates in regenerative mode, and the power transmitted from the drive wheels to the drive motor is converted into electric power. At this time, the drive motor acts as resistance to the driving system, and this resistance acts as braking force (regenerative braking force) that brakes the vehicle. The electric power generated by the drive motor is stored in the battery and used to drive the drive motor. This improves the vehicle's fuel efficiency.

[0004] In the case of a vehicle that performs such regenerative driving, if it is determined that the wheels are prone to locking, for example, if slippage occurs, the vehicle may be equipped with a configuration that controls the regenerative braking torque to reduce it so that the wheels do not lock. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2014 / 057838 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a vehicle is traveling on a low-μ road, even if control to reduce the regenerative braking torque is executed, regenerative control itself is still performed, so torque is generated on the side that locks the vehicle. As a result, the possibility of slippage of the drive wheels cannot be ruled out, which may result in reduced maneuverability. Furthermore, if the regenerative braking torque is suddenly reduced, acceleration fluctuations may become large, which may cause discomfort to the occupants. For this reason, a gradual torque change process that gradually varies the torque may be adopted. In this case, even if slippage is detected and control to reduce the regenerative braking torque is executed, the torque control is slow, which may result in increased slippage.

[0007] The object of the present invention is to provide a vehicle control device that can easily suppress the occurrence of slippage while performing regenerative braking in a system that performs control to reduce regenerative braking torque when slippage occurs during regenerative braking. [Means for solving the problem]

[0008] To achieve the above object, the control device according to the present invention is a control device for a vehicle equipped with at least a drive motor that generates power for driving and a battery that stores electric power, and includes a torque control unit that controls the torque of the drive motor when the vehicle slips, a first torque calculation unit that calculates a target torque value based on the accelerator opening of the vehicle and an estimated vehicle speed of the vehicle, and a second torque calculation unit that calculates a suppression torque value based on the amount of slip of the vehicle. When slip occurs, the torque control unit compares the target torque value with the suppression torque value and performs torque control based on the magnitude relationship of the torque values. In this case, if the estimated vehicle speed of the vehicle is equal to or less than a predetermined value, a torque limit value is calculated based on the rotation speed of the drive motor, and the torque value selected as a result of the comparison is limited by the torque limit value. .

[0009] According to this configuration, the torque that more effectively suppresses slippage is specified between the target torque value and the suppression torque value calculated from the estimated vehicle speed, depending on the state of the vehicle when slippage occurs, thereby enabling regenerative braking to be performed while effectively reducing the amount of slippage. For example, in the low-speed range, the accuracy of the estimated vehicle speed tends to decrease. Therefore, by setting a torque limit value based on the rotation speed of the drive motor, it becomes easier to suppress heat generation in the drive motor when the wheels lock, and it becomes easier to improve the protection performance of the drive motor.

[0010] Furthermore, the torque control unit of the control device according to the present invention may be configured to issue a torque command to the drive motor using the suppression torque value when the suppression torque value is greater than the target torque value.

[0011] According to this configuration, slippage can be effectively suppressed, making it easier to ensure stable steering performance.

[0012] Furthermore, when the suppression torque value is smaller than the target torque value, the torque control unit of the control device according to the present invention may issue a torque command to the drive motor while gradually changing the target torque value.

[0013] According to this configuration, for example, when the suppression torque value is smaller, since the slip amount is small, the target torque value is gradually changed while being instructed, which can contribute to ensuring and improving the amount of regeneration while suppressing an increase in the slip amount. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a control device for a vehicle equipped with a motor that can easily suppress the occurrence of slippage while performing regenerative braking. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an exemplary schematic block diagram showing a system configuration of a vehicle including a control device according to an embodiment. [Figure 2] FIG. 2 is an exemplary schematic block diagram illustrating the configuration of the control device according to the embodiment. [Figure 3] FIG. 3 is an exemplary diagram showing a calculation map of the torque of the drive motor (MG2) used in the control device according to the embodiment. [Figure 4] FIG. 4 is an exemplary timing chart of torque control in the control device according to the embodiment. [Figure 5] FIG. 5 is a timing chart showing a comparative example of torque control. [Figure 6] FIG. 6 is an exemplary flowchart showing the flow of torque control in the control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a case will be described in which the technology of the present embodiment is applied to a hybrid vehicle equipped with a series hybrid system as an example of a vehicle system that runs using a motor as a drive source.

[0019] FIG. 1 is an exemplary schematic block diagram showing a system configuration of a hybrid vehicle 100 including a control device according to an embodiment.

[0020] The hybrid vehicle 100 is equipped with a series hybrid system 10. The hybrid system 10 includes an internal combustion engine 12, a generator motor (MG1) 14, a drive motor (MG2) 16, a battery 18, a PCU (Power Control Unit) 20, and the like.

[0021] The engine 12 is, for example, a gasoline engine.

[0022] The generator motor 14 is, for example, a permanent magnet synchronous motor. The rotating shaft of the generator motor 14 is mechanically connected to the crankshaft of the engine 12 via a gear (not shown). For example, an engine output gear is supported on the crankshaft of the engine 12 so as not to rotate relative to it, and a motor gear is supported on the rotating shaft of the generator motor 14 so as not to rotate relative to it, and the engine output gear and the motor gear are meshed.

[0023] The drive motor 16 is, for example, a permanent magnet synchronous motor that is larger than the generator motor 14. The rotating shaft of the drive motor 16 is connected to a drive train 22 of the hybrid vehicle 100. The drive train 22 includes a differential gear, and the power of the drive motor 16 is transmitted to the differential gear, and then distributed and transmitted from the differential gear to drive wheels 24 consisting of left and right front wheels or rear wheels. This causes the left and right drive wheels 24 to rotate, and the hybrid vehicle 100 moves forward or backward. The wheels to which the driving force of the drive motor 16 is not transmitted are driven wheels 26.

[0024] The battery 18 is a battery pack made up of a combination of a plurality of secondary batteries. The secondary batteries are, for example, lithium ion batteries. The battery 18 outputs DC power of, for example, about 200 to 350 V (volts).

[0025] The PCU 20 is a unit for controlling the driving of the generator motor 14 and the drive motor 16, and includes a first inverter 28, a second inverter 30, and a converter 32.

[0026] When starting the engine 12, the DC power output from the battery 18 is boosted by the converter 32, the boosted DC power is converted to AC power by the first inverter 28, and the AC power is supplied to the generator motor 14. This causes the generator motor 14 to perform power running, and the engine 12 is motored (cranked) by the generator motor 14. When the rotation speed of the crankshaft of the engine 12 has increased to the rotation speed required for starting due to motoring, the ignition plug of the engine 12 is sparked, and the engine 12 starts.

[0027] When the hybrid vehicle 100 is running, the drive motor 16 is powered and generates power.

[0028] When the output required of the drive motor 16 is smaller than the output of the battery 18, the hybrid vehicle 100 runs in EV mode. That is, the engine 12 is stopped, power generation by the generator motor 14 is not performed, and power is supplied from the battery 18 to the drive motor 16, which is then driven by the power.

[0029] On the other hand, when the output required of the drive motor 16 exceeds the output of the battery 18, the hybrid vehicle 100 runs in HV mode. That is, the engine 12 is operated and the generator motor 14 is operated in a generating mode (regenerative operation), whereby the power of the engine 12 is converted into AC power by the generator motor 14. The AC power from the generator motor 14 is then converted into DC power by the first inverter 28, and the DC power output from the first inverter 28 is converted into AC power by the second inverter 30. The AC power is supplied to the drive motor 16, thereby driving the drive motor 16.

[0030] Furthermore, when the remaining capacity of the battery 18 falls below a predetermined level, the generator motor 14 operates to generate electricity while the engine 12 is running, regardless of whether the drive motor 16 is running or stopped. At this time, AC power from the generator motor 14 is converted to DC power by the first inverter 28, and the DC power output from the first inverter 28 is stepped down by the converter 32. The stepped-down DC power is then supplied to the battery 18, thereby charging the battery 18.

[0031] When the hybrid vehicle 100 decelerates, the drive motor 16 undergoes regenerative operation, and power transmitted from the drive wheels 24 to the drive motor 16 is converted into AC power. At this time, the drive motor 16 acts as a resistor in the traveling drive system, and this resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 100. At this time, in the PCU 20, the AC power supplied from the drive motor 16 to the second inverter 30 is converted into DC power by the second inverter 30, and the DC power output from the second inverter 30 is stepped down by the converter 32. The stepped-down DC power is then supplied to the battery 18, thereby charging the battery 18.

[0032] Hybrid vehicle 100 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU has a microcontroller unit (microcomputer), which incorporates, for example, a central processing unit (CPU), a nonvolatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The plurality of ECUs are connected to an in-vehicle network 34 that enables two-way communication using a controller area network (CAN) communication protocol. Various sensors required for control are connected to each ECU, and detection signals from the connected sensors are input to each ECU. In addition to the detection signals input from the various sensors, information required for control is also input to each ECU from other ECUs.

[0033] FIG. 1 shows an ECU 36, one of the multiple ECUs, that controls the hybrid system 10. The ECU 36 is connected to an accelerator sensor 38 and a wheel speed sensor 40 that detects the wheel speeds of the drive wheels 24 and the driven wheels 26. The accelerator sensor 38 outputs a detection signal corresponding to the amount of depression of an accelerator pedal operated by the driver. The wheel speed sensor 40 outputs a detection signal, which is a pulse signal synchronized with the rotation of the drive wheels 24 and the driven wheels 26 that rotate as the hybrid vehicle 100 travels. The ECU 36 determines the accelerator opening, which is the ratio of the current accelerator pedal depression amount to the maximum accelerator pedal depression amount, from the detection signal from the accelerator sensor 38. The ECU 36 also determines the frequency of the detection signal (pulse signal) from the detection signal from the wheel speed sensor 40 and converts the frequency into wheel speed. The left and right drive wheels 24 are each provided with a wheel speed sensor 40a, and the left and right driven wheels 26 are each provided with a wheel speed sensor 40b. Therefore, while the hybrid vehicle 100 is running, it is possible to detect, for example, whether or not there is slippage and the stability of the vehicle (whether or not there is skidding) based on the rotational state of each wheel. Also, based on the detection signals of each wheel speed sensor 40, it is possible to calculate an estimated vehicle speed and the like to be used for torque control of the drive motor 16 of the hybrid vehicle 100.

[0034] 2 is an exemplary schematic block diagram showing the configuration of a control device implemented by the CPU 42 included in the ECU 36. When performing control to reduce regenerative braking torque when slippage occurs during regenerative braking, the control device of this embodiment implements torque control that makes it easier to suppress slippage while still ensuring regenerative braking.

[0035] The CPU 42 reads and executes programs installed and stored in a non-volatile storage device, thereby realizing various modules in the control device for executing torque control of the hybrid system 10. The modules realized in the CPU 42 include a first torque calculation unit 44, a second torque calculation unit 46, a VSC control unit 48, a torque control unit 50, etc. The VSC control unit 48 may be realized in a separate ECU.

[0036] The first torque calculation unit 44 calculates a "target torque value" based on the accelerator opening of the hybrid vehicle 100 and the estimated vehicle speed of the hybrid vehicle 100 as one of the torque values ​​to be referenced when determining the torque value when performing regenerative braking control. As described above, the accelerator opening can be obtained from a detection signal acquired from the accelerator sensor 38. Furthermore, the estimated vehicle speed of the hybrid vehicle 100 can be estimated based on the wheel speed of the driven wheels 26 detected by the wheel speed sensor 40b.

[0037] As described above, in the case of a so-called "series hybrid vehicle" such as the hybrid vehicle 100 of this embodiment, when decelerating with the accelerator released, a regenerative torque is commanded to the drive motor 16 (MG2) directly connected to the axle of the drive wheels 24, and the running energy is converted into charging power for the battery 18. In this case, the regenerative torque is determined by referring to a map such as that shown in FIG. 3 based on the accelerator pedal position, the rotation speed of the drive motor 16, the shift state, etc. In FIG. 3, the vertical axis represents the command torque during regeneration of the drive motor 16, and the horizontal axis represents the rotation speed of the drive motor 16. In FIG. 3, for example, the relationship between the rotation speed of the drive motor 16 (MG2) and the command torque during regeneration is shown for accelerator pedal position 0% (solid line 52a), accelerator pedal position 10% (dashed line 52b), and accelerator pedal position 20% (dotted line 52c). For example, in FIG. 3, the vicinity of region A represents the medium speed range of the hybrid vehicle 100, and the vicinity of region B represents the low speed range. As shown in Figure 3, in the medium speed range A, as the accelerator pedal is released, the torque command value gradually shifts to the negative side, increasing regenerative braking and power generation through regeneration. In addition, in the low speed range B, where the vehicle speed has decreased due to regenerative braking, the torque command value gradually shifts to the positive side. In other words, the regenerative braking force decreases, allowing for smooth deceleration.

[0038] However, when the hybrid vehicle 100 is traveling on a low μ road or the like and slippage occurs, if the regenerative braking torque is determined based on the wheel speed of the drive wheels 24 (the rotation speed of the drive motor 16), a torque command is issued in the direction that causes the drive wheels 24 to brake (lock), which may result in an increase in slippage.

[0039] 3 is converted into the wheel speed (rotational speed) of the driven wheels 26, and calculates a target torque value that serves as a torque command value for the drive motor 16 during regenerative braking using the accelerator opening and the rotational speed of the driven wheels 26, i.e., the estimated vehicle speed of the hybrid vehicle 100. In other words, selection of a command torque that would further increase regenerative braking due to the drive wheels 24 being braked (locked) and their rotational speed decreasing is avoided. In other words, even if slippage occurs, the command torque is determined by the rotational speed of the driven wheels 26, so it is possible to avoid selection of a command torque for the drive motor 16 that is further on the negative side (torque that increases slippage).

[0040] Furthermore, second torque calculation unit 46 calculates a suppression torque value based on the amount of slip of hybrid vehicle 100 as one of the torque values ​​to be referenced when determining a torque value for executing regenerative braking control. Hybrid vehicle 100 may be equipped with, for example, a well-known VSC (Vehicle Stability Control) system as a system for suppressing slip. The VSC system is a system that automatically controls braking devices (disc brakes, drum brakes, etc.) arranged on each of the four wheels and the power of the drive wheels (engine output, etc. in the case of a vehicle using an engine as a drive source) to maintain vehicle stability when an on-board sensor (for example, a wheel speed sensor or an acceleration sensor) detects skidding of the vehicle.

[0041] In this embodiment, the VSC control unit 48 performs the above-described VSC system control, such as obtaining the amount of slip and outputting a request flag that requests torque control for suppressing slippage to the drive motor 16 when slippage occurs. Therefore, when the second torque calculation unit 46 obtains the amount of slippage and the request flag of the hybrid vehicle 100 via the VSC control unit 48, it calculates a torque control value (suppression torque value) for the drive motor 16 that drives the drive wheels 24 so as to stabilize the behavior of the hybrid vehicle 100. The suppression torque can be determined so as to perform output control of the drive motor 16 (control of positive and negative torque) in the same way as torque control when controlling the output of a drive source in a well-known VSC system.

[0042] When slippage occurs in the hybrid vehicle 100, the torque control unit 50 compares the target torque value calculated by the first torque calculation unit 44 with the suppression torque value calculated by the second torque calculation unit 46, and performs torque control of the drive motor 16 based on the magnitude relationship of the torque values.

[0043] For example, if the comparison in torque control unit 50 shows that the suppression torque calculated by second torque calculation unit 46 is greater than the target torque calculated by first torque calculation unit 44, that is, if slippage is suppressed on the VSC system side, torque control of drive motor 16 is performed using the suppression torque. In this case, torque control unit 50 of hybrid vehicle 100 disables the gradual change processing of command torque that is normally performed on drive motor 16 to suppress sudden changes in torque fluctuations, so that the behavior of drive wheels 24 that the VSC system intends to achieve can be quickly achieved.

[0044] On the other hand, if the comparison result in the torque control unit 50 indicates that the suppression torque calculated by the second torque calculation unit 46 is smaller than the target torque calculated by the first torque calculation unit 44, i.e., if the amount of slippage is small, torque control of the drive motor 16 is performed using the target torque. As described above, the target torque value is determined based on the accelerator pedal position, estimated vehicle speed, etc., and indicates the amount of torque required by the driver. As described above, by determining the target torque value of the drive motor 16 based on the estimated vehicle speed, a torque value that is likely to suppress the increase in slippage of the drive wheels 24 even when slippage is occurring is selected. If the suppression torque is smaller than the target torque, this indicates that the amount of slippage is small. Therefore, when performing regenerative braking control, the torque control unit 50 performs torque control of the drive motor 16 using a target torque that can suppress the increase in the amount of slippage. In this case, the torque control unit 50 enables gradual change processing of the command torque for the drive motor 16 to suppress sudden changes in torque fluctuations, thereby reducing the discomfort felt by occupants of the hybrid vehicle 100 due to sudden changes in acceleration. In this way, by using the target torque value, it is possible to contribute to securing and improving the amount of regeneration while suppressing an increase in the amount of slippage, and it is also possible to contribute to improving the riding comfort of the hybrid vehicle 100.

[0045] When the vehicle speed of the hybrid vehicle 100 is below a predetermined value, the accuracy of calculating the estimated vehicle speed of the hybrid vehicle 100 based on the detection signal from the wheel speed sensor 40 tends to decrease. As a result, the accuracy of the target torque value calculated from the accelerator pedal position and the estimated vehicle speed may decrease. Therefore, when the vehicle is traveling at a low speed where the accuracy of the estimated vehicle speed decreases, the estimated vehicle speed of the hybrid vehicle 100 may be corrected by the rotation speed of the drive motor 16. In this case, the torque control unit 50 may set the limit torque value to a value determined by the actual rotation speed of the drive motor 16, for example, by referring to the accelerator pedal position of 0% (solid line 52a) in FIG. 3. In this way, by setting a torque limit value when the drive motor 16 is rotating at a low speed, if the drive wheels 24 are locked (including when the hybrid vehicle 100 is stopped), the torque command value can be set to be equal to or less than the torque limit value, thereby suppressing excessive heat generation from the drive motor 16.

[0046] FIG. 4 is an exemplary timing chart of torque control in the control device (CPU 42) configured as described above.

[0047] For example, if the accelerator pedal is released while the hybrid vehicle 100 is running, the accelerator opening degree changes as shown by line 54. At this time, the vehicle speed of the hybrid vehicle 100 (the rotation speed of the drive motor 16) gradually decreases. When the accelerator is released, a gradual change process (solid line M1) is executed to prevent a sudden change in the torque of the drive motor 16 (MG2) as shown by the dashed line M0, so as not to cause discomfort to the passengers of the hybrid vehicle 100.

[0048] It is assumed that at time Ts, the hybrid vehicle 100 slips due to a low μ road or the like. In this case, the first torque calculation unit 44 calculates the target torque value (solid line Q) based on the accelerator opening (accelerator 0% in this case) and the estimated vehicle speed (vehicle speed based on the detection result of the wheel speed sensor 40b of the driven wheels 26).

[0049] Subsequently, when slip is detected at time Tss, that is, when the VSC request flag is set to ON by the VSC control unit 48 (solid line 58), the second torque calculation unit 46 calculates a suppression torque value based on the amount of slip. Then, the torque control unit 50 compares the target torque value calculated by the first torque calculation unit 44 with the suppression torque value calculated by the second torque calculation unit 46, and selects the minimum torque value as the command torque for the drive motor 16 based on the magnitude relationship of the torque values.

[0050] For example, if the suppression torque value is greater than the target torque value, the torque control unit 50 selects the suppression torque value as the command torque value for the drive motor 16 and disables the gradual change process (solid line 60a). As a result, the acceleration (deceleration) is gradually adjusted (solid line 62a), and the vehicle speed of the hybrid vehicle 100 is such that the rotation speed of the drive motor 16 (rotation speed of the drive wheels 24: solid line 56a) and the rotation speed of the driven wheels 26 (dotted chain line 56b) do not deviate too much, a slip-suppressed state is maintained, and the driving performance (steerability) of the hybrid vehicle 100 can be stabilized. In terms of vehicle speed, dashed line 56c shows the progression of the vehicle speed of the hybrid vehicle 100 when no slippage is occurring, and the rotation speed of the drive motor 16 (rotation speed of the drive wheels 24: vehicle speed shown by solid line 56a) and the rotation speed of the driven wheels 26 (vehicle speed shown by dot-dash line 56b) do not deviate significantly from dashed line 56c, indicating that the speed is reduced while slippage is suppressed.

[0051] On the other hand, for example, if the target torque value is greater than the suppression torque value, the torque control unit 50 selects the target torque value as the command torque value for the drive motor 16 (dashed line 60b). In this case, the target torque value after gradual change control (gradual change control M1) is commanded as the command torque. As a result, even if the drive motor 16 is subjected to regenerative braking control, the amount of regeneration can be ensured while suppressing the increase in slip. Then, as a result of the gradual change control, the acceleration (deceleration) is gradually adjusted (solid line 62b). As a result, the vehicle speed of the hybrid vehicle 100 is such that the rotation speed of the drive motor 16 (rotation speed of the drive wheels 24: solid line 56a) and the rotation speed of the driven wheels 26 (dotted line 56b) do not deviate significantly, maintaining a state in which slip is suppressed, and stabilizing the driving performance of the hybrid vehicle 100.

[0052] FIG. 5 is an exemplary timing chart showing a comparative example in which the command torque of the drive motor 16 (MG2) is always determined based on the rotation speed of the drive motor 16 when regenerative braking control is executed.

[0053] When the accelerator pedal is released while the hybrid vehicle 100 is traveling, the accelerator opening degree changes as shown by line 54. At this time, the vehicle speed of the hybrid vehicle 100 (the rotation speed of the drive motor 16 (MG2)) gradually decreases. When the accelerator is released, a gradual change process (solid line M1) is executed to prevent a sudden change in the torque of the drive motor 16 as shown by the dashed line M0, so as not to cause discomfort to the passengers of the hybrid vehicle 100.

[0054] Assume that at time Ts, the hybrid vehicle 100 experiences a slip due to a low-μ road or the like. In this case, the command torque for the drive motor 16 is determined by referring to the map shown in FIG. 3 using the accelerator pedal position (0% accelerator pedal position in this case) and the rotation speed of the drive motor 16, which has been reduced due to regenerative braking. As a result, the command torque for the drive motor 16 is selected to be negative, the rotation speed of the drive motor 16 is further reduced (solid line 64a), and control to lock the drive wheels 24 is strengthened. In other words, the deviation from the rotation speed of the driven wheels 26 (dotted-chain line 64b) increases. In other words, the slip increases. Furthermore, even when the hybrid vehicle 100 continues to decelerate and reaches a low speed range, and the command torque is selected to be positive according to the map in FIG. 3, the command torque is not corrected abruptly (two-dot chain line M2) but instead a gradual change process M3 is performed. This delay in slip suppression control (selection of a positive command torque) (solid line 66a) may cause the slip to increase. At this time, the acceleration (deceleration) of the hybrid vehicle 100 becomes unstable (solid line 68a) due to the expansion of the slip, which may lead to a deterioration in the running performance and steering performance of the hybrid vehicle 100.

[0055] With respect to vehicle speed, dashed dot-dash line 64c indicates the transition of vehicle speed of hybrid vehicle 100 when no slippage is occurring, and when no slippage is occurring, the command torque to drive motor 16 transitions according to dashed line 66b. As a result, the transition of acceleration (deceleration) of hybrid vehicle 100 is stable (solid line 68b), which indicates that smooth deceleration and regeneration can be ensured without causing discomfort to passengers in hybrid vehicle 100.

[0056] In this way, by specifying the torque that more effectively suppresses slip between the target torque value and the suppression torque value calculated from the estimated vehicle speed, the amount of slip can be effectively reduced while performing regenerative braking.

[0057] FIG. 6 is an exemplary flowchart showing the flow of torque control processing in the control device (CPU 42) configured as described above.

[0058] While the hybrid vehicle 100 is traveling, the control unit (CPU 42) of the ECU 36 of the hybrid vehicle 100 constantly calculates a target torque value in the first torque calculation unit 44 based on the accelerator opening, estimated vehicle speed, etc. (S100). Furthermore, the torque control unit 50 uses the map shown in FIG. 3 for example, when the accelerator opening is 0%, to look up the map using the actual rotation speed of the drive motor 16 (MG2) and calculates a torque limit value (S102). Furthermore, the second torque calculation unit 46 constantly acquires the amount of slip from the VSC system and executes reception processing for a suppression torque value corresponding to the acquired amount of slip and a request flag (S104).

[0059] Then, based on the wheel speeds of the driving wheels 24 and driven wheels 26 obtained from each wheel speed sensor 40, if slippage occurs and a suppression flag is acquired from the VSC system (Yes in S106), the torque control unit 50 compares the suppression torque value calculated in S104 with the target torque value calculated in S100 (S108).

[0060] If the comparison result in the torque control unit 50 is that the suppression torque value is greater than the target torque value (Yes in S108), the torque control unit 50 disables the gradual change processing during regenerative braking control of the drive motor 16 (S110), executes torque control of the drive motor 16 using the suppression torque value (S112), and proceeds to S100 to continue processing for the next control cycle.

[0061] On the other hand, if the torque control unit 50 determines in S106 that slip has occurred and cannot confirm that a suppression flag has been acquired from the VSC system (No in S106), or if it determines in S108 that the suppression torque value is not greater than the target torque value (No in S108), the torque control unit 50 enables gradual change processing during regenerative braking control of the drive motor 16 (S114).Then, the torque control unit 50 executes torque control of the drive motor 16 using the target torque value after the gradual change processing as the torque command value (S116), and proceeds to S100 to continue processing for the next control cycle.

[0062] By repeatedly executing such torque control, it is possible to perform control that makes it easy to suppress the occurrence of slippage while performing regenerative braking, and it is also possible to stabilize the running performance (steering performance) of the hybrid vehicle 100.

[0063] (Effects of this embodiment) As described above, the control device (CPU 42) according to this embodiment is a control device for a hybrid vehicle 100 equipped with at least a drive motor 16 (MG2) that generates power for driving and a battery 18 that stores electric power, and includes a torque control unit 50 that controls the torque of the drive motor 16 when slippage occurs in the hybrid vehicle 100, a first torque calculation unit 44 that calculates a target torque value based on the accelerator opening of the hybrid vehicle 100 and an estimated vehicle speed of the hybrid vehicle 100, and a second torque calculation unit 46 that calculates a suppression torque value based on the amount of slippage of the hybrid vehicle 100. When slippage occurs, the torque control unit 50 compares the target torque value with the suppression torque value and performs torque control based on the magnitude relationship of the torque values. Therefore, by issuing a command for the torque that more effectively suppresses slippage, between the target torque value and the suppression torque value calculated from the estimated vehicle speed, depending on the state of the vehicle when slippage occurs, the amount of slippage can be effectively reduced while performing regenerative braking.

[0064] Furthermore, when the suppression torque value is greater than the target torque value, the torque control unit 50 of the control device according to the present invention may use the suppression torque value to issue a torque command to the drive motor. With this configuration, for example, slippage can be effectively suppressed, making it easier to ensure stable steering performance.

[0065] Furthermore, when the suppression torque value is smaller than the target torque value, the torque control unit 50 of the control device according to the present invention may be configured to gradually change the target torque value while issuing a torque command to the drive motor 16. According to this configuration, for example, when the suppression torque value is smaller, the amount of slip is small, so the target torque value is gradually changed while being commanded, which can contribute to ensuring and improving the amount of regeneration while suppressing an increase in the amount of slip.

[0066] Furthermore, in the control device according to the present invention, when the estimated vehicle speed of the hybrid vehicle 100 is equal to or lower than a predetermined value, the torque control unit 50 may calculate a torque limit value based on the rotation speed of the drive motor 16 and limit the torque value selected as a result of the comparison by the torque limit value. With this configuration, for example, in the low speed range, the estimation accuracy of the estimated vehicle speed tends to decrease, so by setting a torque limit value based on the rotation speed of the drive motor 16, it becomes easier to suppress heat generation in the drive motor 16 when the drive wheels 24 lock, and it becomes easier to improve the protection performance of the drive motor 16.

[0067] In the above-described embodiment, torque control has been described for the case where slippage occurs during deceleration. However, even when slippage occurs during acceleration of hybrid vehicle 100, a comparison may be made between a target torque value calculated based on the accelerator opening and estimated vehicle speed and a suppression torque value calculated based on the amount of slippage, and based on the comparison result, it may be determined whether to use the target torque value or the suppression torque value as the torque command value when slippage occurs.

[0068] In the above-described embodiment, a series hybrid vehicle 100 has been described as an example of a vehicle system that runs using a motor as a drive source. However, the type of vehicle system that can be equipped with the technology of this embodiment does not matter as long as the vehicle performs regenerative control and regenerative braking. A vehicle system that runs using a motor as a drive source may be, for example, an electric vehicle that is equipped with a rechargeable battery and runs solely on the driving force of the motor, and the technology of the above-described embodiment can be applied thereto and similar effects can be obtained. Furthermore, in addition to the above-described series hybrid vehicle 100, the technology of the above-described embodiment can also be applied to hybrid vehicles such as parallel and split hybrid vehicles and similar effects can be obtained.

[0069] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, this embodiment is included within the scope and spirit of the invention, and is also included in the inventions and their equivalents described in the claims. [Explanation of symbols]

[0070] 10 Hybrid System 12 Engine (internal combustion engine) 14 Generator motor (MG1) 16 Drive motor (MG2) 18 Battery 20 PCU 24 drive wheels 26 Driven wheels 28 1st inverter 30 Second inverter 32 Converter 36 ECU 38 Accelerator sensor 40, 40a, 40b Wheel speed sensor 42 CPU 44 First torque calculation unit 46 Second torque calculation unit 48 VSC control unit 50 Torque control section 100 Hybrid Vehicles

Claims

1. A control device for a vehicle equipped with at least a drive motor that generates power for running and a battery that stores electric power, a torque control unit that controls the torque of the drive motor when a slip occurs in the vehicle; a first torque calculation unit that calculates a target torque value based on an accelerator opening degree of the vehicle and an estimated vehicle speed of the vehicle; a second torque calculation unit that calculates a suppression torque value based on a slip amount of the vehicle; Equipped with When the slip occurs, the torque control unit compares the target torque value with the suppression torque value, and executes the torque control based on the magnitude relationship of the torque values. When the estimated vehicle speed of the vehicle is equal to or less than a predetermined value, the torque control unit calculates a torque limit value based on the rotation speed of the drive motor, and limits the torque value selected as a result of the comparison by the torque limit value. Control device.

2. The control device according to claim 1 , wherein the torque control unit issues a torque command to the drive motor using the suppression torque value when the suppression torque value is greater than the target torque value.

3. The control device according to claim 1 , wherein, when the suppression torque value is smaller than the target torque value, the torque control unit issues a torque command to the drive motor while gradually changing the target torque value.

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