JP6058564B2 - Electric vehicle braking control device - Google Patents

Description

  The present invention relates to a braking control device for an electric vehicle including a brake-by-wire type friction braking means capable of controlling a braking force independently of a driver's operation and a motor generator for generating a regenerative braking force.

  Electronic control that does not depend on the driver's braking operation enables normal braking by friction braking means and regenerative braking by a motor / generator, and ABS (Antilock Brake System) or VSA (Vehicle Stability Assist) control. A brake device is known (see, for example, Patent Document 1). This brake device has a configuration in which an ABS hydraulic unit or a VSA hydraulic unit is combined with a motor-driven tandem cylinder that also uses a pedal simulator that is a pedal reaction force generator.

  The control unit of this brake device sets the reference value of the brake fluid pressure according to the amount of braking operation (the amount of depression of the brake pedal) by the driver as the target brake fluid pressure, and drives the motor drive cylinder so that the driver can The required hydraulic pressure is generated in the wheel cylinder. In addition, when the vehicle is an electric vehicle or a hybrid vehicle, the motor / generator may generate a regenerative braking force. When regenerative braking is performed, the friction braking force and the regenerative braking force with respect to the braking force requested by the driver are generated. Distribution control with braking force is performed.

  From the viewpoint of improving fuel efficiency, it is desirable that regenerative braking be performed frequently and with a large distribution. However, if regenerative braking is continued immediately after charging or when traveling on a long downhill, the battery becomes fully charged, and the battery may be deteriorated due to overcharging. Therefore, the battery is prevented from being overcharged by limiting regenerative braking when the battery is fully charged. On the other hand, if regenerative braking is uniformly restricted when fully charged, for example, when the vehicle is moving backward in the R position (reverse), the driver operates the transmission operating lever to move forward such as the D position. When switching to, a driving force is felt as if deceleration acceleration is lost because no braking force is generated.

  Therefore, the present applicant, when the battery is fully charged while running on a slope, prohibits regenerative braking and generates a braking force by friction braking, and cancels the regenerative braking prohibition and performs regenerative braking. When the braking force is controlled by any of the exception control that generates the braking force, and the vehicle's moving direction is the backward direction and the shift position is the switchback state of the forward position due to the driver's operation The invention has been proposed in which regenerative braking is performed by switching the braking force control from principle control to exception control (see Patent Document 1).

  Patent Document 1 discloses that the battery is overcharged even in the switchback state, and that the battery is fully charged with a storage amount smaller than the storage amount of the battery in the electrochemically fully charged state. The charge margin from this assumed full charge to the electrochemical full charge is left in the battery during normal operation (when control is performed in principle), and when exception control is performed in the switchback state. It also discloses that overcharge is prevented by using a charge margin (charging in the charge margin portion).

International Publication No. 2013/084682

  However, even if a charging margin is provided, if regenerative braking is performed in a state where the vehicle slides down at a low speed on an uphill road, regenerative electric power is generated although it is a small size. If it continues for a long time, the battery may be overcharged.

  The present invention has been made in view of such a background, and when the charge margin portion is charged only when the actual traveling direction of the vehicle and the traveling direction of the shift position are different from each other in the switchback state, An object of the present invention is to provide a braking control device for an electric vehicle that can reliably prevent the battery from being overcharged.

  According to one aspect of the present invention, such a problem is caused by friction braking means (5, 21) that generates a friction braking force (Tb) on the wheel (4) regardless of a driver's braking operation, and a battery ( 7) Driven by the power supply from 7) to generate a driving force (Td) in the wheel (4), and convert the rotational energy of the wheel (4) into regenerative electric power collected in the battery (7). 4) a motor / generator (2) for generating a regenerative braking force (Tr), the friction braking force (Tb) of the friction braking means (5, 21), and the driving force of the motor / generator (2) ( Td) and braking / driving force control means (8, 20) for controlling the regenerative braking force (Tr), and storage amount detection means (25) for detecting the storage amount (SOC) of the battery (7). Control of electric vehicle (1) In the control device, the braking / driving force control means (8, 20) is configured such that, when the charged amount (SOC) of the battery (7) is equal to or greater than a predetermined first full charge amount (step ST3: Yes), The principle control (step ST5) for prohibiting the regenerative braking force (Tr) and generating the braking force by the friction braking force (Tb) and the regenerative braking force (Tr) and allowing the regenerative braking force (Tr) When the braking force is generated by any one of the exceptional control (step ST7) that generates the braking force, and the storage amount (SOC) of the battery (7) is equal to or greater than a predetermined first full charge amount ( Step ST3: Yes), when the shift position (SP) and the traveling direction of the electric vehicle coincide with each other, when the switchback state differs from the normal state, the exception from the principle control. In the state where the control is further performed and the exceptional control is being performed, when the charged amount (SOC) of the battery (7) becomes equal to or larger than the second full charge amount larger than the first full charge amount (step ST11: Yes), this is achieved by providing a control device for an electric vehicle characterized by reducing the regenerative braking force (Tr) and increasing the friction braking force (Tb) (step ST13).

  According to this control device for an electric vehicle, even when the amount of charge of the battery is equal to or more than a predetermined first full charge amount in the switchback state, the charge margin portion is charged by performing exception control. When the regenerative braking force is generated and the second full charge amount is larger than the first full charge amount, the regenerative braking force can be reduced to reliably prevent the battery from being overcharged.

  Further, according to one aspect of the present invention, the braking / driving force control means is configured such that the amount of charge (SOC) of the battery (7) is the first full charge in a state where the braking force is generated by the exception control. When it becomes more than the 2nd full charge amount larger than the amount, the regenerative braking force (Tr) can be gradually reduced.

  It is difficult to change the reduction of the regenerative braking force and the increase of the frictional braking force by the same amount at the same time, and the braking force changes if there is a difference between the change timing or the change amount. Therefore, by adopting such a configuration, a sudden change in the braking force is prevented when shifting from a state in which the braking force is generated only by the regenerative braking force to a state in which the braking force is also generated by the friction braking force. Thus, the occurrence of torque shock (abrupt change in longitudinal acceleration) can be suppressed.

  As described above, according to the present invention, when the charge margin portion is charged only when the actual traveling direction of the electric vehicle and the traveling direction of the shift position are different, the battery is overcharged. Thus, it is possible to provide a braking control device for an electric vehicle that can reliably prevent the occurrence of the failure.

The block diagram of the control apparatus of the electric vehicle to which this invention was applied Time chart showing the operation when moving forward through the switchback state immediately after charging The graph which shows the relationship between an electrical storage rate and the 1st regenerative power limit value The graph which shows the relationship between an electrical storage rate and the 2nd regenerative power limit value Time chart showing the operation when a car traveling forward on an uphill road moves backward and descends Time chart showing the operation when a car that has been going up the slope is going up and climbing Flowchart of regenerative torque distribution control by the brake device shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In this specification, acceleration, deceleration, acceleration force, deceleration force, acceleration, deceleration, and the like are based on the traveling direction of the shift position SP selected by the operation lever (hereinafter simply referred to as “the traveling direction of the operation lever”). Shall be. For example, when the operation lever is in the D (drive) position (the operation direction of the operation lever is forward) and the electric vehicle (hereinafter simply referred to as the automobile 1) is moving backward (the actual movement direction is rearward), When the vehicle speed Vs approaches 0, it is expressed that the automobile 1 is accelerating (forward).

  Further, the driving and driving force are in principle the operation and the force to move the vehicle 1, and the braking and braking force are the operation and the stopping to stop the vehicle 1 in principle. Although it is the force which is going to be made, these are exceptionally used on the basis of the advancing direction of an operation lever. For example, when the operating lever is in the D (drive) position, the acceleration or acceleration force forward by the motor / generator 2 is referred to as driving or driving force in accordance with the principle, and the acceleration by the motor / generator 2 or braking device (reverse acceleration). In this specification, deceleration according to the display method and acceleration force (also deceleration force) are referred to as braking or braking force. On the other hand, in the switchback state where the traveling direction of the operating lever and the actual traveling direction of the vehicle 1 are contradictory, such as when the vehicle 1 is moving backward despite the operation lever being in the D (drive) position, Braking and braking force by the regenerative torque Tr of the motor / generator 2 rotating in the direction opposite to the traveling direction of the operation lever (corresponding to the regenerative braking force of claim 1), and braking and braking force by the friction brake 5 ( (Corresponding to the friction braking force of claim 1) may be referred to as driving or driving force.

  FIG. 1 is a schematic block diagram of an automobile 1 according to this embodiment. The automobile 1 includes a motor / generator 2 that generates power, and a rotation shaft of the motor / generator 2 is connected to a wheel 4 via a transmission 3 or the like. The wheel 4 is provided with a friction brake 5 for generating a friction braking force.

  The motor / generator 2 is connected to an inverter 6 (power converter) via a three-phase connection. The battery 6 is connected to the inverter 6 and the inverter 6 is driven to control the motor / generator 2. A motor ECU (Electronic Control Unit) 8 to be controlled is connected.

  The battery 7 is energy storage, and a lithium ion secondary battery, a nickel hydride secondary battery, a capacitor, or the like can be used. In this embodiment, a lithium ion secondary battery is used.

  The battery 7 has a built-in charge / discharge circuit 22 that controls the charge / discharge current. While controlling the charging / discharging current of the charging / discharging circuit 22, the SOC detecting unit 25 that detects the state of charge (SOC) that is the storage state of the battery 7 and the regenerative limiting unit 26 that limits the charging current (regenerative power). Is connected to the battery 7. The storage rate SOC and the like of the battery 7 detected by the battery ECU 9 are supplied to the motor ECU 8.

  The motor ECU 8 includes an operation amount of the accelerator pedal 10 detected as an accelerator operation amount A by the operation amount sensor 12, an operation amount of the brake pedal 13 detected as a brake operation amount B by the operation amount sensor 14, and a shift position sensor 16. The operating position of the select lever 15 detected as the shift position SP by the above, the vehicle speed Vs detected by the vehicle speed sensor 17, the motor rotational speed Nm detected by the rotational speed sensor such as the resolver constituting the motor / generator 2, and the motor rotational direction. Md and the like are respectively supplied. The shift position SP includes a P (Parking) position, an R (reverse) position, an N (neutral) position, a D (drive) position, and a B (brake) position. The motor rotation direction Md includes forward rotation (forward movement), stop and reverse rotation (backward movement).

  A brake ECU 20 is further connected to the motor ECU 8. The brake ECU 20 drives the hydraulic pressure modulator 21 based on the brake operation amount B supplied from the operation amount sensor 14 and generates a friction braking force on the wheel 4 via the friction brake 5. The brake ECU 20 constitutes a brake-by-wire that can generate friction braking force on the wheels 4 regardless of the driver's brake operation by driving the hydraulic pressure modulator 21.

  The motor ECU 8 controls the drive of the motor / generator 2 by setting the driving force (including the power running torque Td and the regenerative torque Tr) to be generated by the motor / generator 2 in accordance with the shift position SP and the accelerator operation amount A. When the motor / generator 2 is operated as a generator by cooperative control with the brake ECU 20 and a regenerative braking force is generated on the wheels 4, the regenerative electric power of the motor / generator 2 is supplied by cooperative control with the battery ECU 9. The battery 7 is made to recover through the inverter 6. In this way, the motor ECU 8, the brake ECU 20, and the battery ECU 9 perform cooperative control of the braking force by regenerative braking and the braking force by friction braking.

  Each of the motor ECU 8, the battery ECU 9, and the brake ECU 20 is a computer including a microcomputer, and includes a CPU (central processing unit), a memory ROM (including EEPROM), a RAM (random access memory), In addition, it has input / output devices such as an A / D converter and D / A converter, a timer as a timer, etc., and the CPU reads and executes the programs recorded in the ROM, thereby performing various functions. It functions as an implementation unit (function implementation means), such as a control unit, a calculation unit, and a processing unit.

  The battery ECU 9, the motor ECU 8, and the brake ECU 20 are communicably connected, for example, using data mutually through a communication line (not shown) related to a communication network such as a CAN (Controller Area Network). Note that the communication network may be a wireless network.

  In this embodiment, as described above, the battery ECU 9 functions as the SOC detection unit 25 that detects the storage rate SOC of the battery 7 and regenerative current (regeneration) that is charged to the battery 7 from the motor / generator 2 through the inverter 6. It functions as a regeneration limiting unit 26 or the like that limits power).

  The motor ECU 8 functions as a full charge state determination unit 23 that determines whether or not the battery 7 is fully charged based on the storage rate SOC, and further, based on the determination result of the full charge state determination unit 23, etc. 1 functions as a braking force control unit 24 or the like for controlling the braking force with respect to 1. The fully charged state determination unit 23 may be provided in the battery ECU 9, and the regeneration limiting unit 26 of the battery ECU 9 may be provided in the motor ECU 8.

  Here, the braking force control unit 24 of the motor ECU 8 basically applies braking force to the automobile 1 by regenerative braking of the motor / generator 2 when the battery 7 is not fully charged during traveling. When the battery 7 is in a fully charged state during traveling, the regenerative braking of the motor / generator 2 is prohibited and the braking control by the friction brake 5 to apply the braking force to the vehicle 1 and the regenerative braking are performed. The braking force is generated by any one of the exception control that permits and applies the braking force to the automobile 1 by regenerative braking.

  The braking force control unit 24 operates the driver's select lever 15 (the shift operation from the D position to the R position or the R position to the D position) that reverses the traveling direction of the automobile 1 from the front to the rear or from the rear to the front, or When the vehicle 1 enters a switchback state in which the actual traveling direction of the vehicle 1 and the traveling direction of the shift position SP are different due to reversal of the traveling direction of the vehicle 1 (from forward to backward or from backward to forward), the braking force Has a function to switch the control from the principle control to the exception control. It should be noted that a state other than the switchback state (when the actual traveling direction of the automobile 1 and the traveling direction of the shift position SP coincide with each other, or when the automobile 1 is stopped) is referred to as a normal state. .

  The operation of the motor ECU 8 as the control device of the automobile 1 according to this embodiment basically configured as described above will now be described with reference to the time chart of FIG.

  The time chart of FIG. 2 shows the change of each item when the shift position SP is switched to the forward running without stopping after the automobile 1 is moved backward once after charging at the charging station. In particular, the switchback state described above has occurred. In the time chart of FIG. 2, the shift position SP detected by the motor ECU 8 is (a), the accelerator operation amount A is (b), and the driver required driving force determined by the shift position SP and the accelerator operation amount A is ( c), the vehicle speed Vs is shown in (d), the driving state based on the actual traveling direction of the automobile 1 is shown in (e), and the storage rate SOC of the battery 7 detected by the motor ECU 8 through the battery ECU 9 is shown in (f). Show.

  The driver requested driving force in (c) is a motor torque MT (including power running torque Td and regenerative torque Tr) calculated by the motor ECU 8, and this item includes a final regenerative power limit value to be described later. The regenerative torque limit value corresponding to RPL is indicated by a one-dot chain line, and the distinction between power running and regeneration is indicated. The traveling state of the automobile 1 in (e) is based on the motor rotation direction Md. If the motor rotation direction Md is the forward rotation direction, the vehicle is moving forward, and if the motor rotation direction Md is the reverse rotation direction, the vehicle is traveling backward. If is 0, it will be stopped.

  First, during charging, the shift position SP in (a) is set to the P position, and the traveling state of the automobile 1 in (e) is a stopped state. After the completion of charging, the storage rate SOC of the battery 7 in (f) is in the first fully charged state by charging. The first fully charged state can be the electrochemically fully charged state of the battery 7, but when the battery 7 is charged more than the electrochemically fully charged state by regenerative braking at the time of switchback described later, the battery 7 is deteriorated. Therefore, the full charge state is considered to be a full charge when the storage state is equal to or higher than the first full charge rate smaller than the electrochemical full charge state. On the other hand, the second full charge value is larger than the first full charge rate (in this embodiment, a value smaller than the power storage limit (100%) of the battery 7 corresponding to the amount of power stored in the electrochemical full charge state). A second full charge rate for determining that the battery is in the charged state is set.

  When the driver starts traveling after the charging is completed, at time t1, the shift position SP in (a) is switched to the R position, and when the accelerator operation amount A in (b) increases, the driver requested driving force in (c). Increases on the negative side (backward). This driver-requested driving force is realized by the power running torque Td in the reverse direction of the motor / generator 2. When the motor torque MT is output, the vehicle speed Vs in (d) increases to the minus side (reverse direction), and the traveling state of the automobile 1 in (e) becomes the reverse state. In addition, the storage rate SOC of (f) slightly decreases.

  Thereafter, when the accelerator operation amount A in (b) becomes 0 at time t2, the driver requested driving force in (c) also becomes 0, and the vehicle speed Vs in (d) is kept substantially constant by the inertia of the automobile 1. In this state, when the driver performs a shift operation from time t3 to time t4 and the shift position SP in (a) is switched to the D position, the traveling state of the automobile 1 in (e) remains in the reverse state. A switchback state occurs in which the actual traveling direction of the vehicle (rearward) and the traveling direction of the shift position SP (forwardward) are different.

  When the driver depresses the accelerator pedal 10 at time t5 in the switchback state and the accelerator operation amount A in (b) increases, the driver requested driving force in (c) increases to the plus side (forward). At this time, since the motor / generator 2 is reversely rotated, the driver requested driving force is realized by the regenerative torque Tr of the motor / generator 2 being reversely rotated until the time point t6 when the vehicle speed Vs in (d) becomes zero. The motor / generator 2 generates power by generating the regenerative torque Tr, and collects the generated regenerative power in the battery 7. At this time, if the vehicle 1 is traveling on a flat road, there is basically no generation of regenerative power that is greater than the amount of power consumed when the vehicle 1 moves backward. In the case where the electric power when the vehicle 1 is moved backward is small and the storage rate SOC of the battery 7 maintains the first full charge rate. The storage rate SOC of the battery 7 may exceed the first full charge rate. Although details will be described later, in the switchback state, even if the storage rate SOC of the battery 7 in (f) exceeds the first full charge rate, the generation of the regenerative braking force and the charging to the battery 7 are not controlled by exception control. Will continue.

  After that, when the vehicle speed Vs in (d) exceeds 0 at time t6 and the traveling state of the automobile 1 in (e) becomes the forward traveling state, the actual traveling direction of the vehicle (forward) and the traveling direction of the shift position SP (forward) And the switchback state is canceled (becomes a normal state). Further, the driver requested driving force (c) is realized by the power running torque Td of the motor / generator 2 in the forward rotation direction. Therefore, the storage rate SOC of the battery 7 in (f) starts to decrease again.

  Thereafter, until time t7, the accelerator operation amount A in (b) and the driver-requested driving force in (c) are maintained, the vehicle speed Vs in (d) increases, and the accelerator operation amount in (b) at time t7. When A becomes 0, the driver requested driving force in (c) also becomes 0, and the vehicle speed Vs in (d) is kept substantially constant due to the inertia of the automobile 1.

  FIG. 3 shows a charging current corresponding to the value of the storage rate SOC of the battery 7, that is, a regenerative power limit value (hereinafter referred to as a first regenerative power limit value RPL1) by a solid line. The first regenerative power limit value RPL1 is a constant value from 0 to the first full charge rate, and when the charge rate SOC exceeds the first full charge rate, the first regenerative power limit value RPL1 is 0. It is said that. Thereby, the first regenerative power limit value RPL1 in the normal state is charged from the first full charge rate to the power storage limit (100%) of the battery 7 so as to limit the power storage rate SOC with the first full charge rate. Regulate regenerative braking to leave a margin.

  On the other hand, when the regenerative braking is uniformly limited according to the storage rate SOC, when the switchback state occurs in the first fully charged state, the braking force is not generated, and thus the driving feel that the deceleration acceleration is lost. turn into. Therefore, in the present embodiment, a regenerative power limit value (hereinafter referred to as a second regenerative power limit value RPL2) for allowing regenerative braking at a low vehicle speed at which the regenerative power amount is considered to be low is set and switched back. In the state, a larger value of the first regenerative power limit value RPL1 and the second regenerative power limit value RPL2 is adopted as the final regenerative power limit value RPL.

  FIG. 4 shows the second regenerative power limit value RPL2 corresponding to the absolute value | Vs | of the vehicle speed Vs by a solid line. By setting the second regenerative power limit value RPL2 in this way, regenerative braking is performed at a relatively low vehicle speed Vs as in the switchback state. In particular, as shown in FIG. 4, when the absolute value | Vs | of the vehicle speed Vs is small, a large regenerative electric power is allowed, so that the vehicle speed Vs is more accurately determined when switching from the switchback state to the normal state. During the period from when the regeneration secured MAX vehicle speed becomes zero, a gradual switching of the friction braking force suitable for preventing torque shock is ensured.

  In the time chart of FIG. 2, the regenerative torque limit value indicated by the one-dot chain line in the item of the driver required driving force (c) is a value corresponding to the first regenerative power limit value RPL1 of FIG. 3. Note that (c) shows the regenerative torque limit value corresponding to the first regenerative power limit value RPL1 only on the plus side, but the regenerative torque limit value having the same absolute value as that on the plus side also exists on the minus side.

  If the storage rate SOC in (f) exceeds the first full charge rate due to regenerative braking from time t5 to time t6 due to the ascending slope of the travel path, the regenerative torque limit value shown in (c) is It becomes a smaller value corresponding to the regenerative power limit value RPL2. Specifically, the regenerative torque limit value is such a magnitude that the regenerative braking force can be exerted at the time point t6 when the absolute value | Vs | of the vehicle speed Vs becomes the smallest, and the absolute value | Vs | When the vehicle speed is greater than the vehicle stop determination vehicle speed in FIG. 4, the vehicle speed decreases according to the vehicle speed Vs.

  FIG. 5 shows the change of each item when the car 1 traveling forward in the D position moves backward (slids down) because the driving force becomes smaller than the gradient resistance on the uphill road. Among them, the switchback state described above has occurred. In the time chart of FIG. 5, the driver requested driving force determined by the shift position SP and the accelerator operation amount A is shown in (a), and the vehicle speed Vs is shown in (b).

  While the automobile 1 is traveling, the automobile 1 is at the vehicle speed of (b) during the period from time t10 to time t11 when the driver requested driving force realized by the power running torque Td of the motor / generator 2 of (a) is equivalent to the gradient resistance. Vs is kept constant on the plus side. When the driver-requested driving force decreases at time t11 and becomes lower than the gradient resistance, the vehicle speed Vs in (b) decreases, becomes negative at time t12, and the vehicle 1 moves backward (slids down). At this time, since the shift position SP remains at the D position (forward), the traveling direction of the shift position SP is different from the traveling direction of the automobile 1.

  Further, since the vehicle speed Vs becomes negative at time t12 and the driver required driving force in (a) remains on the positive side, the driver required driving force realized by the motor torque MT in the same direction until time t11 is At t12, the motor / generator 2 that is rotating in reverse is switched so as to be exerted by the regenerative torque Tr. On the other hand, since the vehicle speed Vs cannot be maintained at 0 only by the regenerative torque Tr, the insufficient driving force is covered by the brake torque Tb that attempts to suppress the reverse of the friction brake 5.

  The regenerative torque limit value (corresponding to the first regenerative power limit value RPL1) in the switchback state indicated by the alternate long and short dash line in (a) is set to a relatively large value at time t12. When this state continues and the storage rate SOC in (d) exceeds the first full charge rate at time t13, the first regenerative power limit value RPL1 becomes 0, so the regenerative torque limit value is the second regenerative power. It becomes a smaller value corresponding to the limit value RPL2. However, if this state continues further on the slope, the storage rate SOC in (d) further increases and reaches the second full charge rate at time t15.

  Then, even if the regenerative torque limit value does not change, the control unit 11 gradually reduces the regenerative torque Tr and gradually increases the brake torque Tb so as to ensure the driver's requested driving force. Then, regenerative torque Tr is set to zero. Since the regenerative torque Tr is also generated after time t15, the storage rate SOC in (d) slightly increases from the second full charge rate after time t15, but stops rising before reaching the power storage limit. To do.

  That is, in the present embodiment, the charging power amount (charging margin usage amount), which is an integrated value of the power charged in the battery 7 after the storage rate SOC reaches the first full charge rate at time t13, and the second full charge. The difference between the rate and the first full charge rate (charge margin) is compared, and when both become the same value, the regenerative torque Tr is gradually reduced. On the other hand, after the power storage rate SOC reaches the first full charge rate, the regenerative braking may be regulated based on the duration of the regenerative braking performed in the switchback state.

  FIG. 6 shows that in a state where the automobile 1 is moving backward (sliding down) while being in the D position on the uphill road, the driving force 1 is greater than the gradient resistance, so that the automobile 1 that has been traveling forward turns forward. The change of each item when changing from the switchback state to the normal state is shown. In the time chart of FIG. 6, as in FIG. 5, the driver required driving force determined by the shift position SP and the accelerator operation amount A is shown in (a), and the vehicle speed Vs is shown in (b).

  While the vehicle 1 is moving backward (sliding down), the vehicle 1 keeps the vehicle speed Vs of (b) constant on the negative side between the time t20 and the time t21 when the driver requested driving force of (a) is equal to the gradient resistance. ing. The driver requested driving force is realized by the brake torque Tb of the friction brake 5 because the storage rate SOC in (d) is equal to or higher than the second full charge rate. When the driver-requested driving force increases at time t21 and becomes greater than the gradient resistance, the vehicle speed Vs in (b) increases and becomes positive at time t23, and the vehicle 1 enters the forward state. At this time, since the traveling direction of the automobile 1 and the traveling direction (forward) of the shift position SP (D position) coincide with each other, the switchback state is changed to the normal state.

  The driver requested driving force in (a) is before the time t23, and until the time t22 when the absolute value | Vs | This is realized by the brake torque Tb. The predetermined value TH is a value that is small enough to cause the motor / generator 2 that is rotating in the reverse direction to be rotated forward by power supply.

  On the other hand, if the entire amount of the driver-requested driving force is switched from the braking torque Tb to the power running torque Td of the motor / generator 2 at a time t23 when the vehicle speed Vs of (b) becomes positive, a torque shock is generated. At t23, the power running torque Td of the motor / generator 2 starts to be output, while the brake torque Tb of the friction brake 5 gradually decreases. The power running torque Td of the motor / generator 2 bears 100% of the driving force at time t23 when the vehicle speed Vs in FIG. After time t23, the driver-requested driving force (a) is realized by the power running torque Td of the motor / generator 2 rotating in the forward rotation direction. In addition, since electric power is supplied to the motor / generator 2 after the time t22, the storage rate SOC in (d) gradually decreases.

  Thus, even when the storage rate SOC is equal to or higher than the second full charge rate and regenerative braking is not performed, switching from the brake torque Tb of the friction brake 5 to the regenerative torque Tr of the motor / generator 2 is instantaneous. This is not performed manually, but gradually from time t22 to time t23, so that torque shock at the time of switching is suppressed.

  FIG. 7 shows a flowchart of the distribution control of the driver-requested driving force, which is cooperatively controlled by the motor ECU 8, the battery ECU 9, and the brake ECU 20, to the regenerative torque Tr.

  The motor ECU 8 calculates a driver required driving force required for the automobile 1 based on the accelerator operation amount A detected by the operation amount sensors 12 and 14 (step ST1). Next, the motor ECU 8 refers to a characteristic table as shown in FIG. 3 and sets a first regenerative power limit value RPL1 corresponding to the storage rate SOC (step ST2). Thereafter, motor ECU 8 determines whether or not power storage rate SOC is equal to or higher than the first full charge rate (step ST3).

  When it is determined in step ST3 that the storage rate SOC is equal to or higher than the first full charge rate (Yes), the motor ECU 8 next determines whether or not the vehicle 1 is in a switchback state (step ST4). If it is determined in step ST4 that the switchback state is not set (No), the motor ECU 8 sets the first regenerative power limit value RPL1 to the final regenerative power limit value RPL (step ST5). On the other hand, when it is determined Yes in step ST4, the motor ECU 8 refers to the characteristic table shown in FIG. 4 and sets the second regenerative power limit value RPL2 corresponding to the absolute value of the vehicle speed Vs (step ST6). ) Of the first regenerative power limit value RPL1 and the second regenerative power limit value RPL2, the larger value is set as the final regenerative power limit value RPL (step ST7).

  Thereafter, the motor ECU 8 determines whether or not the regenerative power by the regenerative braking that is currently being performed is larger than the first regenerative power limit value RPL1 (step ST8). By accumulating the value obtained by subtracting the regenerative power limit value RPL1, the amount of power used for charging margin WHCHG, that is, the amount of power recovered by the battery 7 exceeding the first full charge rate is calculated. On the other hand, when the determination result in step ST8 is No, the motor ECU 8 holds the previous value as the charging margin power consumption WHCHG (step ST10).

  Next, motor ECU 8 determines whether or not power storage rate SOC is greater than or equal to the second full charge rate (step ST11). When it is determined in step ST11 that the storage rate SOC is less than the second full charge rate (No), the motor ECU 8 determines that the driver requested driving force is within the range of the final regenerative power limit value RPL set in step ST5 or step ST7. Is assigned to the regenerative torque Tr (step ST12), and the above procedure is repeated. In step ST12, if it is in the stitchback state (step ST4: Yes), the regenerative torque Tr is set to 0, and if it is not in the stitchback state (step ST4: No), the regenerative torque Tr is It is limited by the second regenerative power limit value RPL2 corresponding to the absolute value | Vs | of the vehicle speed Vs in FIG.

  On the other hand, when it is determined in step ST11 that the storage rate SOC is greater than or equal to the second full charge rate (Yes), the motor ECU 8 gradually decreases within the range of the final regenerative power limit value RPL set in step ST5 or step ST7. Thus, the driver request driving force is assigned to the regenerative torque Tr (step ST13), and the above procedure is repeated. In step ST13, if the stitchback state is set (step ST4: Yes), the regenerative torque Tr is set to 0. If the stitchback state is not set (step ST4: No), the regenerative torque Tr is set. 4 is limited by the second regenerative power limit value RPL2 corresponding to the absolute value | Vs | of the vehicle speed Vs in FIG.

  Returning to step ST3, when it is determined that the storage rate SOC is less than the first full charge rate (No), the motor ECU 8 sets the first regenerative power limit value RPL1 to the final regenerative power limit value RPL (step ST14). ), The charging margin use electric energy WHCHG is reset (step ST15). Thereafter, the motor ECU 8 assigns the driver requested driving force to the regenerative torque Tr within the range of the final regenerative power limit value RPL set in step ST14 (step ST16), and repeats the above procedure. In step ST16, the regenerative torque Tr is limited by the relatively large regenerative torque limit value shown in FIG.

  As described above, when the storage rate SOC of the battery 7 is equal to or higher than the first full charge rate (step ST3: Yes), and when in the switchback state (step ST4: Yes), the absolute value of the vehicle speed Vs in FIG. From the principle control in which the final regenerative power limit value RPL is set in step ST5 without using the second regenerative power limit value RPL2 corresponding to | Vs |, the final regenerative power limit is set in step ST7 using the second regenerative power limit value RPL2. When the control is switched to the exception control for setting the value RPL, and the power storage rate SOC of the battery 7 is greater than or equal to the second full charge rate larger than the first full charge rate in the state where the exception control is being performed (step ST11: Yes). In step ST13, the regenerative torque Tr is effectively reduced by gradually decreasing the regenerative torque Tr and gradually increasing the brake torque Tb. While use can be prevented reliably that the battery 7 is overcharged.

  In the present embodiment, the regenerative torque Tr is gradually reduced in step ST13, so that a sudden change in braking force is prevented and the occurrence of torque shock is suppressed.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the specific configuration, arrangement, quantity, numerical value, specific control mode, and the like of each member or part can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all the components of the braking device of the automobile 1 shown in the above embodiment are not necessarily essential, and can be appropriately selected.

1 automobile 2 motor generator 4 wheel 5 friction brake (friction braking means)
7 Battery 8 Motor ECU (braking / driving force control means)
20 Brake ECU (braking / driving force control means)
21 Hydraulic modulator (friction braking means)
25 SOC detector (electric storage amount detection means)
SOC power storage rate (power storage)
SP Shift position Tb Brake torque (friction braking force)
Td Power running torque (driving force)
Tr regenerative torque (regenerative braking force)

Claims (2)

Friction braking means for generating friction braking force on the wheels regardless of the driver's braking operation;
A motor / generator that is driven by the power supply from the battery to generate a driving force for the wheel, and that generates a regenerative braking force for the wheel by converting the rotational energy of the wheel into regenerative power that is collected in the battery;
Braking / driving force control means for controlling the friction braking force of the friction braking means and the driving force and regenerative braking force of the motor / generator;
A braking control device for an electric vehicle provided with a storage amount detection means for detecting a storage amount of the battery,
The braking / driving force control means includes:
When the stored amount of the battery is greater than or equal to a predetermined first full charge amount, the regenerative braking force is prohibited and the principle control for generating the braking force by the friction braking force and the regenerative braking force is allowed and the regenerative braking force is allowed to occur. The braking force is generated by any one of the exceptional control and the exceptional control for generating the braking force by the braking force,
When the storage amount of the battery is equal to or greater than a predetermined first full charge amount, when the shift position is different from the normal state where the traveling direction of the shift position and the traveling direction of the electric vehicle coincide with each other, When regenerative braking force is switched from the principle control to the exception control and the charged amount of the battery becomes greater than or equal to the second full charge amount larger than the first full charge amount in the state where the exception control is performed. And an apparatus for controlling the electric vehicle, wherein the friction braking force is increased.   The braking / driving force control means is configured to regenerate the battery when the charged amount of the battery becomes equal to or larger than a second full charge amount larger than the first full charge amount in a state where the braking force is generated by the exception control. 2. The control apparatus for an electric vehicle according to claim 1, wherein the braking force is gradually reduced.

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