Vehicle control system and vehicle control method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025045769_13082026_PF_FP_ABST
Abstract
Description
Vehicle control system and vehicle control method
[0001] The present invention relates to a vehicle control system and a vehicle control method.
[0002] The motor traction control device for a vehicle disclosed in Patent Document 1 includes at least one motor equipped in a power source for driving drive wheels, motor traction control means for detecting the driving slip of the drive wheels and restoring the grip of the drive wheels by motor torque down control, and the motor traction control means includes a component protection control unit for performing torque down control to protect motor drive circuit components when driving slip occurs, a drivability control unit for performing torque down control to ensure road surface transmitted driving force when driving slip occurs, and a selection unit for selecting either one of the torque down amounts of the component protection control unit and the drivability control unit.
[0003] Japanese Patent Application Laid-Open No. 2006-115588
[0004] However, in the case of a system in which the torque down amount for component protection to be implemented in the latter stage is estimated and, on the premise that the estimated torque down amount is applied, in the former stage, a slip control torque in which the required torque is decreased to suppress slip is set, and torque down for component protection is implemented for such slip control torque, the torque down amount for component protection assumed in the former stage may deviate from the actual value. And when such an assumed deviation occurs and the total torque down amount becomes excessive, it will become a cause of stumble and shock.
[0005] Therefore, an object of the present invention is to provide a vehicle control system and a vehicle control method that can stably suppress the torque down amount from becoming excessive even when torque down control for component protection intervenes during slip control.
[0006] Therefore, in one embodiment, the vehicle control system according to the present invention includes: a request torque acquisition unit that acquires a request torque required for the motor based on the vehicle's acceleration request; a slip control torque acquisition unit that acquires a slip control torque that reduces the drive torque relative to the request torque and suppresses wheel slip; a protection torque acquisition unit that reduces the drive torque relative to the request torque and suppresses overcurrent and overvoltage of the inverter that controls the motor; a torque arbitration unit that arbitrates the drive torque based on the relationship between a first torque reduction amount obtained by subtracting the slip control torque from the request torque and a second torque reduction amount due to the protection torque; and a current control unit that performs current control of the motor based on a final drive torque obtained by subtracting the second torque reduction amount from the arbitrated torque.
[0007] Furthermore, in one embodiment, the vehicle control method according to the present invention acquires a required torque for the motor based on the vehicle's acceleration request, acquires a slip control torque that reduces the drive torque relative to the required torque and suppresses wheel slip, acquires a protection torque that reduces the drive torque relative to the required torque and suppresses overcurrent and overvoltage of the inverter controlling the motor, arbitrates the drive torque based on the relationship between a first torque reduction amount obtained by subtracting the slip control torque from the required torque and a second torque reduction amount due to the protection torque, and performs current control of the motor based on the final drive torque obtained by subtracting the second torque reduction amount from the arbitrated torque.
[0008] According to the present invention, even if torque reduction control for component protection intervenes during slip control, it is possible to reliably prevent the amount of torque reduction from becoming excessive.
[0009] This is an overall configuration diagram showing one aspect of a vehicle's control system. This is a control block diagram representing one aspect of drive torque control. This is a flowchart showing one aspect of a drive torque control procedure including torque arbitration. This is a time chart illustrating the change in drive torque when torque arbitration is not performed. This is a time chart illustrating the change in drive torque when torque arbitration is performed. This is a control block diagram showing one aspect of drive torque control to address single-wheel slip. This is a flowchart illustrating one aspect of a drive torque control procedure to address single-wheel slip. This is a time chart illustrating the change in drive torque when drive torque control to address single-wheel slip is performed.
[0010] Hereinafter, embodiments of the vehicle control system and vehicle control method according to the present invention will be described with reference to the drawings. Figure 1 is an overall configuration diagram showing one aspect of the vehicle control system. The vehicle 1 is equipped with a pair of left and right front wheels 1FL, 1FR and a pair of left and right rear wheels 1RL, 1RR.
[0011] Furthermore, it is a four-wheel drive electric vehicle having a front motor 10 that provides driving torque to the front wheels 1FL and 1FR, and a rear motor 20 that provides driving torque to the rear wheels 1RL and 1RR. Vehicle 1 may be a front-wheel drive vehicle equipped only with the front motor 10, or a rear-wheel drive vehicle equipped only with the rear motor 20.
[0012] Power is transmitted between the front motor 10 and the front wheels 1FL and 1FR via a reduction gear 11, a differential gear 12, and the front axles 13FL and 13FR. Power is also transmitted between the rear motor 20 and the rear wheels 1RL and 1RR via a reduction gear 21, a clutch 22, a differential gear 23, and the axles 24RL and 24RR.
[0013] When the clutch 22 is engaged, power is transmitted between the rear motor 20 and the rear wheels 1RL and 1RR. On the other hand, when the clutch 22 is disengaged, no power is transmitted between the rear motor 20 and the rear wheels 1RL and 1RR.
[0014] Each of the four wheels 1FL, 1FR, 1RL, and 1RR has a wheel speed sensor 2FL, 2FR, 2RL, and 2RR, respectively, for detecting the wheel speed. The front motor 10 also has a front wheel resolver 14 for detecting the rotational speed of the front motor 10, and the rear motor 20 has a rear wheel resolver 25 for detecting the rotational speed of the rear motor 20.
[0015] Vehicle 1 has a low-voltage battery 31 and a high-voltage battery 32. The low-voltage battery 31 is, for example, a lead-acid battery. The high-voltage battery 32 is, for example, a lithium-ion battery or a nickel-metal hydride battery, and is charged by power boosted by a DC-DC converter 33.
[0016] Furthermore, vehicle 1 has braking devices 40FL, 40FR, 40RL, and 40RR provided on each wheel 1FL, 1FR, 1RL, and 1RR, which apply braking force to each wheel 1FL, 1FR, 1RL, and 1RR. The braking devices 40FL, 40FR, 40RL, and 40RR generate frictional braking force by, for example, pressing brake pads against brake rotors using brake fluid pressure or an electric motor. The generation of frictional braking force by each braking device 40FL, 40FR, 40RL, and 40RR is controlled by a brake controller 55.
[0017] Furthermore, vehicle 1 includes a drive force controller 51, a front motor controller 52, a rear motor controller 53, a battery controller 54, and a brake controller 55. The controllers 51, 52, 53, 54, and 55, which are control units, share information with each other via a bus 56 that constitutes an in-vehicle network such as a CAN (Controller Area Network).
[0018] The drive force controller 51 acquires information from various sensors, including an accelerator pedal sensor 61 that detects the amount of accelerator pedal operation by the driver, a transmission shift position sensor 62, a front wheel resolver 14, and a rear wheel resolver 25. The drive force controller 51 then calculates the required torque according to the amount of accelerator pedal operation by the driver. Furthermore, the drive force controller 51 calculates the required front torque that the front motor 10 should output and the required rear torque that the rear motor 20 should output, according to the required distribution torque. The required distribution torque is the required value of the torque distribution ratio between the front wheels 1FL, 1FR and the rear wheels 1RL, 1RR, and is set appropriately according to the driving conditions.
[0019] The front motor controller 52 controls the power supplied to the front motor 10 based on the front torque requirement. The rear motor controller 53 controls the power supplied to the rear motor 20 based on the rear torque requirement.
[0020] The battery controller 54 monitors the charge and discharge state of the high-voltage battery 32, as well as the individual cell units that make up the high-voltage battery 32. Based on the charge and discharge state of the high-voltage battery 32, the battery controller 54 calculates an upper limit for the required torque. The upper limit for the required torque is the maximum torque allowed for the front motor 10 and the rear motor 20. When the charge level of the high-voltage battery 32 is low, the battery controller 54 changes the upper limit for the required torque to a value smaller than normal.
[0021] The brake controller 55 acquires information from various sensors, such as the brake pedal sensor 63 which detects the amount of brake pedal operation by the driver. The brake controller 55 then calculates the required braking force according to the amount of brake pedal operation by the driver and controls the braking force generated by the braking devices 40FL, 40FR, 40RL, and 40RR. The brake controller 55 also outputs information on the regenerative cooperative brake required torque calculated based on the amount of brake pedal operation to the drive force controller 51, which enables the motors 10 and 20 to generate regenerative braking torque.
[0022] Figure 2 is a control block diagram showing one mode of drive torque control by a drive force controller 51 and motor controllers 52 and 53. As will be described later, the drive force controller 51 is a higher-level controller that outputs a command for the required torque to the motor controllers 52 and 53. On the other hand, the motor controllers 52 and 53, which control the energization of the motors 10 and 20 in accordance with the command for the required torque obtained from the drive force controller 51, are lower-level controllers.
[0023] The drive force controller 51 has functional units including a drive force control unit 51A, a slip control unit 51B, and a torque arbitration unit 51C. The drive force control unit 51A calculates the required torque, which is the required value of the drive torque generated by the motors 10 and 20, based on the vehicle speed and the amount of accelerator pedal operation. In other words, the drive force control unit 51A has the function of a required torque acquisition unit that acquires the required torque required by the motors 10 and 20 based on the acceleration request of the vehicle 1.
[0024] Furthermore, the drive force control unit 51A uses the vehicle speed estimated from the rotational speed information of each motor 10, 20 detected by resolvers 14, 25, or the vehicle speed estimated from the wheel speed information detected by wheel speed sensors 2FL, 2FR, 2RL, 2RR, as the vehicle speed used to calculate the required torque. In addition, when the drive force control unit 51A obtains information on the regenerative cooperative brake required torque, it subtracts the regenerative cooperative brake required torque from the required torque to calculate the required torque after accepting the regenerative cooperative brake.
[0025] The slip control unit 51B calculates the drive torque limit value during acceleration, or in other words, the upper limit value of the drive torque, from the vehicle speed and the target wheel speed for slip control. Then, the slip control unit 51B calculates a slip control torque that limits the requested torque calculated by the drive force control unit 51A to stay within the range of the drive torque limit value, and outputs it to the torque arbitration unit 51C.
[0026] In detail, the slip control unit 51B compares the requested torque calculated by the drive force control unit 51A with the drive torque limit value. If the requested torque calculated by the drive force control unit 51A is less than or equal to the drive torque limit value, the slip control unit 51B outputs the requested torque calculated by the drive force control unit 51A as the slip control torque. If the requested torque calculated by the drive force control unit 51A exceeds the drive torque limit value, the slip control unit 51B outputs the drive torque limit value as the slip control torque.
[0027] In other words, the slip control unit 51B has the function of a slip control torque acquisition unit that acquires a slip control torque that reduces the driving torque in response to the torque requested by the driver and suppresses wheel slip. Furthermore, the slip control unit 51B can further limit the slip control torque according to the upper limit of the requested torque based on the charge / discharge state of the high-voltage battery 32 calculated by the battery controller 54, and output the final limited requested torque to the torque arbitration unit 51C.
[0028] The torque arbitration unit 51C obtains information on slip control torque to suppress wheel slip from the slip control unit 51B. The torque arbitration unit 51C also obtains information on the amount of torque reduction (in other words, protection torque) for overcurrent and overvoltage protection of the inverter 71 that controls the motors 10 and 20, which will be explained in detail later, from the overcurrent and overvoltage protection control unit 52A of the motor controllers 52 and 53. The torque arbitration unit 51C then arbitrates the drive torque based on the relationship between the first torque reduction amount, which is the amount of torque reduction obtained by subtracting the slip control torque from the required torque, and the second torque reduction amount, which is the amount of torque reduction due to the protection torque for overcurrent and overvoltage protection of the inverter 71, and outputs the arbitration result as the arbitrated torque to the motor controllers 52 and 53. The details of the torque arbitration process in the torque arbitration unit 51C will be explained in detail later.
[0029] On the other hand, the motor controllers 52 and 53 have functional units: an overcurrent / overvoltage protection control unit 52A, a torque subtraction unit 52B, and a current control unit 52C. The overcurrent / overvoltage protection control unit 52A monitors the current and voltage of the inverter 71, which is a drive circuit component of the motors 10 and 20, and sets a second torque reduction amount to reduce the drive torque so that the current and voltage of the inverter 71 do not exceed the allowable values. In other words, the overcurrent / overvoltage protection control unit 52A has the function of a protection torque acquisition unit that acquires a protection torque to suppress overcurrent and overvoltage of the inverter 71 that controls the motors 10 and 20 by reducing the drive torque relative to the required torque.
[0030] The torque subtraction unit 52B subtracts the second torque reduction amount set by the overcurrent / overvoltage protection control unit 52A from the mediated torque obtained from the torque arbitration unit 51C of the drive force controller 51 to obtain the final drive torque (final drive torque = mediated drive torque - second torque reduction amount), and outputs the information of the obtained final drive torque to the current control unit 52C. The current control unit 52C performs current control of the motors 10 and 20 based on the final drive torque obtained from the torque subtraction unit 52B, that is, the final drive torque command value with slip control and overcurrent / overvoltage protection applied.
[0031] The current control unit 52C controls the on / off state of each switching element constituting the inverter 71, for example, by vector control. In the case of vector control when motors 10 and 20 are three-phase synchronous motors, the current control unit 52C determines the d-axis command voltage and q-axis command voltage by current control based on the d-axis command current and q-axis command current obtained from the final drive torque, and the d-axis current and q-axis current obtained from the detected values of the U-phase current, V-phase current, and W-phase current of motors 10 and 20. Furthermore, the current control unit 52C performs two-phase to three-phase conversion to convert the d-axis command voltage and q-axis command voltage into U-phase command voltage, V-phase command voltage, and W-phase command voltage based on the motor rotation position information. Then, the current control unit 52C controls the on / off state of each switching element of the inverter 71, which is a three-phase bridge circuit, by PWM (Pulse Width Modulation) based on the U-phase command voltage, V-phase command voltage, and W-phase command voltage.
[0032] Figure 3 is a flowchart illustrating one aspect of the procedure for drive torque control including torque arbitration processing, or in other words, one aspect of the process of a vehicle control method. In step S101, the torque arbitration unit 51C determines whether or not overcurrent / overvoltage protection is intervening, for example, based on whether or not the second torque reduction amount for overcurrent / overvoltage protection obtained from the overcurrent / overvoltage protection control unit 52A is zero. Here, if the second torque reduction amount for overcurrent / overvoltage protection is zero, the torque arbitration unit 51C determines that overcurrent / overvoltage protection is not intervening. On the other hand, if the second torque reduction amount for overcurrent / overvoltage protection is not zero, and the final drive torque is reduced by the second torque reduction amount, the torque arbitration unit 51C determines that overcurrent / overvoltage protection is intervening.
[0033] Then, if the overcurrent / overvoltage protection is not intervening, in step S102, the torque arbitration unit 51C outputs the command value of the slip control torque as the arbitrated torque. At this time, since the second torque reduction amount for overcurrent / overvoltage protection is zero, the torque subtraction unit 52B outputs the slip control torque as is without subtracting it. In other words, if the overcurrent / overvoltage protection is not intervening, in step S102, the command value of the slip control torque is directly provided to the current control unit 52C as the final drive torque.
[0034] On the other hand, if the overcurrent / overvoltage protection is in an intervention state, in step S103, the torque arbitration unit 51C determines whether the first torque reduction amount for slip control, obtained by subtracting the slip control torque from the required torque, is greater than the second torque reduction amount for overcurrent / overvoltage protection. In other words, when the overcurrent / overvoltage protection is in an intervention state, the torque arbitration unit 51C determines the relative magnitude of the first torque reduction amount for slip control and the second torque reduction amount for overcurrent / overvoltage protection. The relative magnitude of the torque reduction amounts refers to the relative magnitude of the absolute values of the torque reduction amounts.
[0035] Here, if the first torque reduction amount is greater than the second torque reduction amount, applying the first torque reduction amount for slip control will satisfy the requirement for reducing the drive torque for overcurrent and overvoltage protection. Therefore, if the torque subtraction unit 52B further corrects the drive torque reduction by only the second torque reduction amount, the final torque reduction amount will be excessive, which can cause stumbles and shocks.
[0036] Therefore, if the first torque reduction amount is greater than the second torque reduction amount, the torque arbitration unit 51C, in step S104, calculates the torque after arbitration by adding the second torque reduction amount to the slip control torque, that is, by increasing the slip control torque by the absolute value of the second torque reduction amount. Then, in step S106, the torque subtraction unit 52B subtracts the second torque reduction amount from the after arbitration torque to obtain the final drive torque, and outputs the command for the obtained final drive torque to the current control unit 52C.
[0037] Here, since the post-arrangement torque is the slip control torque plus the second torque reduction amount, the result of the torque subtraction unit 52B subtracting the second torque reduction amount from the post-arrangement torque is the slip control torque, and consequently, the torque reduction due to the second torque reduction amount is not applied. In other words, the torque arbitration unit 51C takes into account that the subsequent torque subtraction unit 52B will perform a reduction correction of the drive torque by the second torque reduction amount, and increases the drive torque in advance by the second torque reduction amount, thereby effectively rendering the subtraction process in the torque subtraction unit 52B, or in other words, the drive torque correction process for overcurrent and overvoltage protection, ineffective.
[0038] As a result, when the requirement for reducing the drive torque for overcurrent / overvoltage protection is met by applying the first torque reduction amount for slip control, applying the second torque reduction amount further prevents excessive torque reduction, which can cause stumbling and shocks. Furthermore, since the torque arbitration unit 51C performs torque correction based on the second torque reduction amount determined by the overcurrent / overvoltage protection control unit 52A, in other words, the value of the torque reduction amount actually used in the torque reduction processing by the torque subtraction unit 52B, it is possible to stably obtain an appropriate torque that is neither too much nor too little as the arbitrated torque, and consequently as the final drive torque, thereby stably suppressing stumbling and shocks.
[0039] On the other hand, if the first torque reduction amount is the same as or less than the second torque reduction amount, the torque arbitration unit 51C outputs the driver-requested torque as the arbitrated torque in step S105. When the first torque reduction amount is less than or equal to the second torque reduction amount, it means that the torque reduction for overcurrent / overvoltage protection is implemented, and the requirement for a reduction in drive torque for slip control is met.
[0040] Therefore, torque reduction due to the first torque reduction amount is unnecessary, and it is sufficient to perform a correction for the reduction in drive torque at the second torque reduction amount. Accordingly, the torque arbitration unit 51C cancels the torque reduction due to the first torque reduction amount by using the arbitrated torque as the driver's requested torque, and the torque subtraction unit 52B reduces the requested torque by the second torque reduction amount, and the result is used as the final drive torque. In this way, by applying both the first and second torque reduction amounts, excessive torque reduction can be prevented, while slip suppression and inverter protection can be achieved.
[0041] Figure 4 is a time chart illustrating the change in drive torque when the drive force controller 51 does not have a torque arbitration unit 51C and outputs the slip control torque directly to the motor controllers 52 and 53, in other words, when torque arbitration is not performed. When a slip condition occurs where the drive wheel speed exceeds the target wheel speed, the slip control unit 51B of the drive force controller 51 reduces the required torque to generate the slip control torque.
[0042] Furthermore, based on the occurrence of overcurrent and overvoltage due to slippage, the overcurrent and overvoltage protection control unit 52A of the motor controllers 52 and 53 sets a second torque reduction amount for overcurrent and overvoltage protection, and the torque subtraction unit 52B subtracts the second torque reduction amount from the slip control torque, and the result is the final drive torque. In other words, even if slip control and overcurrent / overvoltage protection can be achieved by applying the larger of the first torque reduction amount for slip control and the second torque reduction amount for overcurrent and overvoltage protection, both the first torque reduction amount for slip control and the second torque reduction amount for overcurrent and overvoltage protection are applied individually. As a result, the torque reduction amount becomes excessive, causing the acceleration of the vehicle 1 to drop, resulting in stumbles and shocks.
[0043] In contrast, Figure 5 is a time chart illustrating the change in drive torque when the drive force controller 51 is equipped with a torque arbitration unit 51C, in other words, when torque arbitration is performed. The torque arbitration unit 51C outputs the arbitrated torque by adding the second torque arbitration amount for overcurrent / overvoltage protection to the slip control torque, provided that the first torque reduction amount for slip control and overcurrent / overvoltage protection can be achieved by applying the first torque reduction amount.
[0044] Further, when the first torque reduction amount for slip control is less than or equal to the second torque reduction amount for overcurrent / overvoltage protection, and slip control and overcurrent / overvoltage protection can be achieved by applying the second torque reduction amount, the torque mediation unit 51C outputs the driving torque requested by the driver as the post - mediation torque. That is, the torque mediation unit 51C sets the post - mediation torque so that the requested torque is reduced by the larger of the first torque reduction amount and the second torque reduction amount to become the final driving torque.
[0045] As described above, in the vehicle control method executed by the driving force controller 51 and the motor controllers 52, 53, the driving torque is reduced with respect to the requested torque to obtain the slip control torque, and the driving torque is reduced with respect to the requested torque to obtain the protection torque for suppressing the overcurrent and overvoltage of the inverter 71 that controls the motors 10, 20. Then, the driving torque is mediated based on the magnitude relationship between the first torque reduction amount obtained by subtracting the slip control torque from the requested torque and the second torque reduction amount by the protection torque, and the current control of the motors 10, 20 is performed based on the final driving torque obtained by subtracting the second torque reduction amount from the mediated post - mediation torque.
[0046] Thereby, while achieving both slip control and inverter protection, it is possible to prevent the torque reduction amount from becoming excessive and causing a drop in the acceleration of the vehicle 1. Further, since the torque mediation unit 51C obtains the second torque reduction amount set by the overcurrent / overvoltage protection control unit 52A and sets the post - mediation torque based on such second torque reduction amount, it is possible to cancel the torque reduction based on the second torque reduction amount more stably and with higher accuracy than when mediating based on the estimated result of the second torque reduction amount.
[0047] Incidentally, when the driving force controller 51, the brake controller 55, etc. have application software such as a BLSD (Brake Limited Slip Differential), in a single-wheel slip state where one of the left and right wheels slips, a braking force by a friction brake is applied to the slipping wheel. At this time, since the increase in the frictional braking force and the torque-down control for overcurrent / overvoltage protection overlap, there is a possibility that an excessive reduction in the driving torque may occur. Therefore, an aspect of a vehicle control system configured to be able to suppress an excessive reduction in the driving torque due to an increase in the frictional braking force caused by single-wheel slip will be described below.
[0048] FIG. 6 is a control block diagram of the driving force controller 51, the motor controllers 52 and 53, and the brake controller 55, which is configured to be able to suppress an excessive reduction in the driving torque when the BLSD operates in a single-wheel slip state and a frictional braking force is applied to the slipping wheel. In FIG. 6, the same reference numerals are assigned to the same elements as in FIG. 2, and detailed descriptions thereof are omitted.
[0049] Here, the slip control unit 51B of the driving force controller 51 has a BLSD function of outputting a frictional braking force request, which is a request for the frictional braking force to be applied to the slip wheel, which is the slipping wheel of the left and right wheels in a single-wheel slip state, to the brake controller 55. In addition, a responsiveness correction unit 51D is added to the driving force controller 51.
[0050] The responsiveness correction unit 51D corrects the response of the frictional braking force request obtained from the slip control unit 51B in consideration of the response delay of the actual frictional braking force with respect to the braking force command, and outputs it as the corrected frictional braking force request. That is, the responsiveness correction unit 51D estimates the actual frictional braking force that changes late with respect to the hydraulic pressure command based on the frictional braking force request by delaying the response of the frictional braking force request in slip control.
[0051] On the other hand, the brake controller 55 has the following functional units: a braking force-hydraulic conversion unit 55A, an ABS (Anti-lock Brake System) 55B, an ESC (Electronic Stability Control) 55C, and a hydraulic pressure control unit 55D. The braking force-hydraulic conversion unit 55A converts information on friction braking force requests (in other words, BLSD control requests) in a one-wheel slip state, obtained from the slip control unit 51B of the drive force controller 51, into hydraulic pressure information for the hydraulic braking system, and outputs it as a hydraulic pressure command to the hydraulic pressure control unit 55D.
[0052] Furthermore, the ABS 55B is a functional unit that performs braking control to prevent the tires from locking up and the steering wheel from becoming unresponsive when the driver applies the brakes suddenly. The ESC 55C is a functional unit that performs braking control to stabilize the attitude of the vehicle 1. The hydraulic control unit 55D controls the hydraulic pressure supplied to the brake devices 40FL, 40FR, 40RL, and 40RR of each wheel in response to commands from the braking force-hydraulic conversion unit 55A, the ABS 55B, and the ESC 55C.
[0053] The motor controllers 52 and 53 are equipped with a protective torque correction unit 52D. The protective torque correction unit 52D acquires information on the corrected friction braking force request from the responsiveness correction unit 51D, and also acquires information on the second torque reduction amount (in other words, protective torque) for overcurrent and overvoltage protection of the inverter 71 that controls the motors 10 and 20 from the overcurrent and overvoltage protection control unit 52A.
[0054] The protective torque correction unit 52D then corrects the second torque reduction amount based on the corrected friction braking force request to determine the second torque reduction amount after mediation (in other words, the overcurrent / overvoltage protection torque after mediation) and outputs it to the torque subtraction unit 52B. The protective torque correction unit 52D also sets the compensation torque reduction amount to be output to the torque mediation unit 51C based on the corrected friction braking force request and the second torque reduction amount.
[0055] Figure 7 is a flowchart showing the processing functions of the torque arbitration unit 51C, the torque subtraction unit 52B, the responsiveness correction unit 51D, and the protective torque correction unit 52D. In step S201, the responsiveness correction unit 51D determines whether or not a friction braking force request has occurred in a one-wheel slip state, in other words, whether or not BLSD has intervened.
[0056] Then, if a friction braking force request occurs in a one-wheel slip state, the responsiveness correction unit 51D performs a response correction in step S202 that takes into account the response delay of the actual friction braking force generated, and obtains information on the corrected friction braking force request. On the other hand, if a friction braking force request does not occur in a one-wheel slip state, the response correction in step S202 is bypassed, and the process proceeds to step S203.
[0057] In step S203, the torque arbitration unit 51C determines whether or not overcurrent / overvoltage protection is intervening. If overcurrent / overvoltage protection is not intervening, in step S204, the torque arbitration unit 51C outputs the command value of the slip control torque as the drive torque after torque arbitration, and the torque subtraction unit 52B outputs the command value of the slip control torque without subtracting it.
[0058] On the other hand, if the overcurrent / overvoltage protection is in an intervention state, in step S205, the protection torque correction unit 52D determines whether the second torque reduction amount for overcurrent / overvoltage protection is greater than the torque reduction amount corresponding to the corrected friction braking force requirement. If the second torque reduction amount for overcurrent / overvoltage protection is greater than the torque reduction amount corresponding to the corrected friction braking force requirement, in step S206, the protection torque correction unit 52D sets the mediated second torque reduction amount to "mediated second torque reduction amount = second torque reduction amount - torque reduction amount corresponding to the corrected friction braking force requirement".
[0059] In other words, if the second torque reduction amount for overcurrent / overvoltage protection is greater than the torque reduction amount corresponding to the corrected friction braking force requirement, and the torque reduction requirement for overcurrent / overvoltage protection is not satisfied by the friction braking force requirement, the torque reduction unit 52B will reduce the torque by the amount that the torque reduction requirement for overcurrent / overvoltage protection is not satisfied by the friction braking force requirement. Also, in step S206, the protective torque correction unit 52D sets the compensated torque reduction amount to the second torque reduction amount for overcurrent / overvoltage protection.
[0060] On the other hand, if the torque reduction amount corresponding to the corrected friction braking force requirement is greater than or equal to the second torque reduction amount for overcurrent / overvoltage protection, in step S207, the protection torque correction unit 52D sets the second torque reduction amount after mediation to zero and sets the compensation torque reduction amount to the torque corresponding to the friction braking force requirement. In other words, if the torque reduction requirement for overcurrent / overvoltage protection is satisfied by the friction braking force requirement, the torque reduction for overcurrent / overvoltage protection is unnecessary, and the torque subtraction unit 52B prevents the torque reduction for overcurrent / overvoltage protection from being performed.
[0061] In step S208, the torque arbitration unit 51C determines whether the first torque reduction amount for slip control is greater than the compensation torque reduction amount. If the first torque reduction amount is greater than the compensation torque reduction amount, applying the first torque reduction amount for slip control will satisfy the torque reduction requirement for the compensation torque reduction amount.
[0062] Therefore, if the first torque reduction amount is greater than the compensated torque reduction amount, the torque arbitration unit 51C, in step S209, calculates the torque after arbitration as the slip control torque plus the compensated torque reduction amount, that is, the slip control torque increased by the absolute value of the compensated torque reduction amount. This prevents an additional torque reduction by the compensated torque reduction amount.
[0063] On the other hand, if the first torque reduction amount is less than or equal to the compensation torque reduction amount, the torque arbitration unit 51C outputs the driver-requested torque as the arbitrated torque in step S210. The condition that the first torque reduction amount is less than or equal to the compensation torque reduction amount means that the torque reduction by the compensation torque reduction amount satisfies the requirement for a reduction in drive torque for slip control.
[0064] In this case, since torque reduction due to the first torque reduction amount is unnecessary, the torque arbitration unit 51C cancels the torque reduction due to the first torque reduction amount by using the arbitrated torque as the driver-requested torque. Then, in step S211, the torque subtraction unit 52B subtracts the second post-arrangement torque reduction amount from the arbitrated torque to obtain the final drive torque, and outputs the command for the obtained final drive torque to the current control unit 52C. As described above, if torque reduction is performed taking into account the torque reduction due to the friction braking force applied in the one-wheel slip state, even if the torque reduction for overcurrent / overvoltage protection and the friction braking force applied in the one-wheel slip state overlap, an excessive reduction in drive torque is suppressed.
[0065] Figure 8 is a time chart illustrating the change in drive torque when the second torque reduction amount and the compensated torque reduction amount are set by the protection torque correction unit 52D. Here, the second torque reduction amount for overcurrent and overvoltage protection is corrected by the amount of torque reduction due to the friction braking force applied in the one-wheel slip state. Therefore, even if the increase in friction braking force due to one-wheel slip and the torque reduction requirement for inverter protection coincide, the drive torque will not decrease excessively, and the drop in acceleration will be suppressed.
[0066] The technical ideas described in the above embodiments can be used in appropriate combinations, provided that no contradictions arise. Furthermore, although the content of the present invention has been specifically described with reference to preferred embodiments, it will be obvious to those skilled in the art that various modifications can be taken based on the basic technical ideas and teachings of the present invention.
[0067] For example, the motor controllers 52 and 53 can internally include drive circuits for motors 10 and 20, including an inverter 71. Furthermore, the drive force controller 51 and the motor controllers 52 and 53 can be configured by housing a first microcomputer functioning as the drive force controller 51 and a second microcomputer functioning as the motor controllers 52 and 53 in a single enclosure. Additionally, the transmission of information regarding the second torque reduction amount from the motor controllers 52 and 53 to the drive force controller 51 can be performed via a third controller.
[0068] 1...Vehicle, 1FL, 1FR...Front wheels, 1RL, 1RR...Rear wheels, 10, 20...Motor, 51...Drive force controller, 51A...Drive force control unit (requested torque acquisition unit), 51B...Slip control unit (slip control torque acquisition unit), 51C...Torque arbitration unit, 52, 53...Motor controller, 52A...Overcurrent / overvoltage protection control unit (protection torque acquisition unit), 52B...Torque subtraction unit, 52C...Current control unit, 71...Inverter
Claims
1. A vehicle control system equipped with a motor that provides driving torque to wheels, comprising: a requested torque acquisition unit that acquires a requested torque required for the motor based on the acceleration request of the vehicle; a slip control torque acquisition unit that acquires a slip control torque that reduces the driving torque relative to the requested torque and suppresses slip of the wheels; a protection torque acquisition unit that reduces the driving torque relative to the requested torque and suppresses overcurrent and overvoltage of the inverter that controls the motor; a torque arbitration unit that arbitrates the driving torque based on the relationship between a first torque reduction amount obtained by subtracting the slip control torque from the requested torque and a second torque reduction amount due to the protection torque; and a current control unit that performs current control of the motor based on a final driving torque obtained by subtracting the second torque reduction amount from the arbitrated torque arbitrated by the torque arbitration unit.
2. A vehicle control system according to claim 1, wherein the torque arbitration unit determines the arbitrated torque as the slip control torque plus the second torque reduction amount due to the protection torque when the first torque reduction amount is greater than the second torque reduction amount, and determines the requested torque as the arbitrated torque when the first torque reduction amount is the same as or less than the second torque reduction amount.
3. A vehicle control system according to claim 1, further comprising: a responsiveness correction unit that corrects the responsiveness of a friction braking force request, which is a request for friction braking force to be applied to the slipping wheel among the left and right wheels, output from the slip control torque acquisition unit; and a protective torque correction unit that corrects the protective torque based on the torque corresponding to the corrected friction braking force request corrected by the responsiveness correction unit and outputs it to the torque arbitration unit.
4. A vehicle control system according to claim 1, wherein the vehicle control system comprises a drive force controller and a motor controller including an inverter, the drive force controller comprises a requested torque acquisition unit, a slip control torque acquisition unit and a torque arbitration unit, and the motor controller comprises a protection torque acquisition unit and a current control unit.
5. A vehicle control method performed by a control unit of a vehicle equipped with a motor that provides driving torque to wheels, comprising: obtaining a required torque required for the motor based on an acceleration request of the vehicle; obtaining a slip control torque that reduces the driving torque relative to the required torque and suppresses wheel slip; obtaining a protection torque that reduces the driving torque relative to the required torque and suppresses overcurrent and overvoltage of the inverter controlling the motor; mediating the driving torque based on the relationship between a first torque reduction amount obtained by subtracting the slip control torque from the required torque and a second torque reduction amount due to the protection torque; and performing current control of the motor based on a final driving torque obtained by subtracting the second torque reduction amount from the mediated torque.