JP6153875B2 - 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, if the battery is switched back when it is fully charged, even if switching to exception control and regenerative braking is performed, regenerative braking continues and the battery is overcharged while traveling on a slope. There is a risk of becoming. In order to reliably avoid overcharging of the battery , it is conceivable that braking force is generated by friction braking even when the battery is switched to the fully charged state. However, if a braking force is generated by friction braking when the switchback state is entered or when the switchback state is entered, a torque shock occurs at the timing when the switchback state and the other normal state are switched.

  Specifically, when the shift position changes from the switchback state where the traveling direction of the shift position is forward and the actual traveling direction of the vehicle is backward to the normal state where the actual traveling direction of the vehicle is forward, the brake of the friction brake It is necessary to switch from the torque to the power running torque of the motor for acceleration, and a torque shock is generated at the time of this switching. On the other hand, when traveling on an uphill road, when the shift position travels forward and the actual travel direction of the vehicle is forward, the vehicle slides backward and switches to the switchback state. Since the power running torque is suddenly limited and switched to the brake torque of the friction brake, a torque shock is generated at the time of this switching.

  The present invention has been made in view of such a background, and provides a braking control device for an electric vehicle capable of preventing a torque shock at the time of switching between a switchback state and a normal state while preventing overcharge of the battery. With the goal.

  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 to be 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). Braking the electric vehicle (1) The braking / driving force control means (8, 20) is a storage device for the battery in a switchback state where the traveling direction of the shift position (SP) is different from the traveling direction of the electric vehicle (1). This is achieved by providing a braking control device for an electric vehicle that controls the distribution of the friction braking force (Tb) and the regenerative braking force (Tr) based on (SOC) and vehicle speed (Vs).

  According to this vehicle brake device, the braking force (acceleration force in the traveling direction of the shift position) can be exerted by controlling the distribution of the friction braking force and the regenerative braking force even in the switchback state. It is possible to prevent excessive regenerative power from being generated and the battery from being overcharged. In addition, since the distribution of regenerative braking force is controlled based not only on the amount of electricity stored in the battery but also on the vehicle speed, it is possible to prevent torque shock by reducing the friction braking force when switching between the driving force of the motor / generator. Can be.

  Further, according to one aspect of the present invention, the braking / driving force control means (8, 20) includes a first regeneration limit value (RPL1) set based on a storage amount (SOC) of the battery, a vehicle speed ( Of the second regenerative limit value (RPL2) set based on the absolute value of Vs), the regenerative braking force (Tr) can be limited based on a larger value (RPL).

  When only the first regenerative limit value based on the amount of charge of the battery is used, there is a risk that the regenerative braking force is limited, so that the gradual switching of the friction braking force suitable for preventing torque shock cannot be performed. . Therefore, the second regenerative limit value based on the absolute value of the vehicle speed is used in combination, and the regenerative braking force is limited based on a larger value of the two limit values. It can be prevented that gradual switching cannot be performed.

  According to another aspect of the present invention, the braking / driving force control means (8, 20) switches the regenerative braking force (Tr) to the driving force (Td) of the motor / generator (2). It may be configured to be set to be maximized sometimes.

  According to this configuration, the friction braking force can be minimized when switching between the driving force of the motor / generator and the torque shock can be reliably prevented.

  Thus, according to the present invention, it is possible to provide a braking control device for an electric vehicle that can prevent a torque shock at the time of switching between a switchback state and a normal state while preventing overcharge of the battery.

Schematic block diagram of an automobile to which the present invention is applied 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 Schematic diagram showing the concept of braking / driving force control The graph which shows the relationship between an electrical storage rate and the 1st regenerative power limit value Graph showing the relationship between vehicle speed absolute value and regenerative power limit value 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 wheels 4 are provided with friction brakes 5 for applying 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 applied by one of the exception control and the exceptional control in which the braking force is applied 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 car 1 traveling forward in the D position moves backward (slids down) due to the driving force being smaller than the slope resistance on the uphill road. In this process, the above-described switchback state occurs. In the time chart of FIG. 2, the driver requested driving force determined by the shift position SP and the accelerator operation amount A is shown in (a), the vehicle speed Vs is shown in (b), and the running state of the automobile 1 is shown in (c). Yes.

  While the vehicle 1 is traveling, the vehicle 1 is traveling at the vehicle speed (b) during the period from the time point t0 to the time point t1 where the driver requested driving force realized by the power running torque Td of the motor / generator 2 in FIG. Vs is kept constant on the plus side. When the driver required driving force decreases at time t1 and becomes lower than the gradient resistance, the vehicle speed Vs in (b) decreases, becomes negative at time t2, and the vehicle 1 enters a backward (sliding down) state. 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 actual traveling direction of the automobile 1 as shown in (c).

  Further, since the vehicle speed Vs becomes negative at the time point t2 and the driver required driving force in (a) remains on the positive side, the driver request realized by the power running torque Td of the motor / generator 2 in the same direction until the time point t1. The driving force is switched so as to be exerted by the regenerative torque Tr of the motor / generator 2 being reversely rotated at the time point t2. On the other hand, since the vehicle speed Vs cannot be maintained at 0 only by the regenerative torque Tr, the deficient driving force is provided by the braking force of the friction brake 5 (brake torque Tb that attempts to suppress the reverse) after time t2.

  The regenerative torque Tr is gradually set to be small after the time t2, and becomes 0 at the time t3. That is, the regenerative torque Tr is set so that the switching point with the power running torque Td of the motor / generator 2 becomes the largest value. The magnitude of the regenerative torque Tr is set so as to gradually decrease depending on the vehicle speed Vs. Details will be described later. On the other hand, the brake torque Tb of the friction brake 5 is gradually increased as opposed to the regenerative torque Tr so that the total driving force matches the driver request driving force.

  When the driver required driving force in (a) becomes the same magnitude as the gradient resistance at time t4, the vehicle speed Vs in (b) becomes constant. The time point t4 is an arbitrary point according to the operation of the driver, and there is no context between the time point t3.

Then, at the time t2 when the driver-requested driving force is switched from the driving torque in the normal state to the braking torque in the switchback state, the switching is only performed from the power running torque Td of the motor / generator 2 to the regenerative torque Tr. It is possible to prevent front and rear G from being generated in the automobile 1 due to force fluctuation.

FIG. 3 shows that in a switchback state in which the vehicle 1 is moving backward (sliding down) while being in the D position on the uphill road, the vehicle 1 that has been traveling backward moves forward because the driving force is greater than the gradient resistance. The change of each item when it changes to the normal state is shown. In the time chart of FIG. 3, as in FIG. 2, the driver requested driving force determined by the shift position SP and the accelerator operation amount A is set to (a), the vehicle speed Vs is set to (b), and the running state of the vehicle 1 is ( Each of them is shown in c).

  While the vehicle 1 is moving backward (sliding down), the vehicle speed in (b) is from the time point t10 to the time point t11 in which the driver required driving force realized by the brake torque Tb of the friction brake 5 in (a) is equivalent to the gradient resistance. Vs is kept constant on the minus side. When the driver-requested driving force increases at time t11 and becomes greater than the gradient resistance, the vehicle speed Vs in (b) increases and becomes positive at time t13, and the vehicle 1 enters a forward state. At this time, since the actual traveling direction of the automobile 1 matches the traveling direction (forward) of the shift position SP (D position), the switchback state is changed to the normal state.

  The driver-requested driving force (a) is realized by the brake torque Tb of the friction brake 5 until time t11. Further, after time t13 when the vehicle speed Vs of (b) becomes positive, the driver-requested driving force is realized by the power running torque Td of the motor / generator 2.

  On the other hand, at a certain time t12 from time t11 to time t13, the regenerative torque Tr starts to be output again. In the present embodiment, the regenerative torque Tr starts to be output gradually from the time t12 after the time t11 due to the increase (absolute value decreases) of the vehicle speed Vs in (b), and the time when the vehicle speed Vs turns positive. Immediately before t13, 100% of the driving force is borne. That is, the regenerative torque Tr is set according to the vehicle speed Vs, and is maximized when switching to the power running torque Td of the motor / generator 2. The driving force borne by the braking force of the friction brake 5 gradually decreases from time t12 so that the total driving force matches the driver request driving force, and is 0 at time t13.

  After the vehicle speed Vs in (b) turns positive at time t13, the driver-requested driving force in (a) is realized by the power running torque Td of the motor / generator 2 rotating in the forward rotation direction. Then, at a time point t13 when the driver-requested driving force is gradually switched from the brake torque Tb of the friction brake 5 to the regenerative torque Tr of the motor / generator 2 and switched from the reverse state to the forward state, from the regenerative torque Tr of the motor / generator 2. Since only switching to the power running torque Td is performed, it is possible to prevent the front and rear G from being generated in the automobile 1 due to fluctuations in the driving force.

  2 and 3 both show the case where the switchback state and the normal state are switched during traveling in the D position, but a similar event may occur during traveling in the R position. In both the examples of FIGS. 2 and 3, the driver requested driving force is changed on the uphill road where the gradient resistance is constant, so that the switchback state and the normal state are switched, but the driver changes the shift position SP. Sometimes a similar event can occur.

  FIG. 4 is a diagram schematically showing the concept of such braking / driving force control. FIG. 4 shows the power running torque Td and regenerative torque Tr of the motor / generator 2 and the brake torque of the friction brake 5 when the horizontal axis is the vehicle speed Vs, the vertical axis is the driver required driving force, and the driver required driving force is constant. The change of Tb is shown.

  As shown in FIG. 2, when switching from the normal state to the switchback state, the vehicle speed Vs decreases with time, so that each torque changes from the right side to the left side in the drawing. That is, the regenerative torque Tr is set to 100% of the driver requested driving force when switching to the power running torque Td, decreases with a decrease in the vehicle speed Vs, and becomes 0% at a predetermined vehicle speed.

  On the other hand, when the switchback state is changed to the normal state as shown in FIG. 3, the vehicle speed Vs increases with time, so that each torque changes from the left side to the right side in the drawing. That is, the regenerative torque Tr starts to be output from a predetermined vehicle speed, increases as the vehicle speed Vs increases, and becomes 100% of the driver requested driving force when switching to the power running torque Td.

  As the predetermined vehicle speed is set smaller (the absolute value is larger), the change in the brake torque Tb of the friction brake 5 becomes smaller. Therefore, even if the response of the friction brake 5 is low, the desired performance (set brake torque Tb) can be obtained. It can be demonstrated.

  On the other hand, FIG. 5 shows a charging current, that is, a regenerative power limit value (hereinafter, referred to as a first regenerative power limit value RPL1) set corresponding to the value of the storage rate SOC of the battery 7. The first regenerative power limit value RPL1 becomes a smaller value regardless of the vehicle speed Vs as the storage rate SOC approaches the full charge rate, and the storage rate SOC is the full charge rate so that charging is limited at the full charge rate. 0 when the value is. The full charge rate may be 100% of the battery storage limit, or may be a value smaller than 100% that is arbitrarily set so as to leave a charge margin before reaching the storage limit (100%).

  Thus, the first regenerative power limit value RPL1 is set to a small value regardless of the vehicle speed Vs when the storage rate SOC is relatively large. Therefore, if the storage rate SOC is large when switching between the switchback state and the normal state, the first regenerative power limit value RPL1 may be small and the regenerative torque Tr in FIG. 4 may not be output.

  Therefore, in the present embodiment, as shown in FIG. 6, the value of the regenerative power corresponding to the regenerative torque Tr in FIG. 4 corresponding to the vehicle speed Vs is set as the second regenerative power limit value RPL2, and in the switchback state, the first A larger value of the regenerative power limit value RPL1 and the second regenerative power limit value RPL2 is adopted as the final regenerative power limit value RPL. As a result, when switching between the switchback state and the normal state, more precisely, the gradual switching of the friction braking force suitable for preventing torque shock is ensured between the vehicle speed Vs and 0 to a predetermined vehicle speed. Is done.

  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. 5 and sets a first regenerative power limit value RPL1 corresponding to the storage rate SOC (step ST2). Thereafter, the motor ECU 8 determines whether or not the automobile 1 is in a switchback state (step ST3).

  If it is determined in step ST3 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 ST4), and the driver request drive obtained in step ST1. The force is assigned to the regenerative torque Tr within the range of the final regenerative power limit value RPL based on the vehicle speed Vs (step ST5), and the above procedure is repeated. In this case, since the switchback state is not established, the regenerative torque Tr is set to 0, and all of the driver requested driving force is assigned to the power running torque Td of the motor / generator 2.

  On the other hand, when it is determined in step ST3 that the switchback state is set (Yes), the motor ECU 8 refers to a characteristic table as shown in FIG. 6 and the second regenerative power limit value corresponding to the absolute value of the vehicle speed Vs. RPL2 is set (step ST6), and the larger one of the first regenerative power limit value RPL1 and the second regenerative power limit value RPL2 is set as the final regenerative power limit value RPL (step ST7).

  Thereafter, the motor ECU 8 assigns the driver required driving force obtained in step ST1 to the regenerative torque Tr within the range of the final regenerative power limit value RPL based on the vehicle speed Vs (step ST5), and repeats the above procedure. In this case, since the switchback state is set, the regenerative torque Tr is set to a value corresponding to the vehicle speed Vs, and the remaining driver-requested driving force is assigned to the brake torque Tb of the friction brake 5.

  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 electric vehicle of the above embodiment may be an electric vehicle or a hybrid vehicle. Furthermore, 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 shown in the above embodiment are not necessarily essential, and can be selected as appropriate.

1 Automobile (electric vehicle)
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)
RPL final regenerative power limit value RPL1 first regenerative power limit value (first regenerative limit value)
RPL2 2nd regenerative power limit value (2nd regenerative limit value)
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)
Vs Vehicle speed

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 power supply from a battery to generate a driving force for the wheel, and 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, in a normal state in which the traveling direction of the shift position and the traveling direction of the electric vehicle coincide with each other, executes either one of the principle control and the exceptional control to generate a braking force, A driving force is generated in the motor generator;
The principle control sets a first regeneration limit value so that the larger the charged amount is, based on the charged amount of the battery, when the charged amount of the battery is less than a predetermined full charge amount, While the distribution of the friction braking force and the regenerative braking force is controlled so as to be allocated to the regenerative braking force within the range of the first regenerative limit value, the braking force is generated, while the charged amount of the battery is a predetermined full charge. When the rate is greater than or equal to the rate, the regenerative braking by the motor / generator is prohibited and the braking force is generated by the friction braking force.
In the exception control, the friction braking force and the regenerative braking force are set such that the regenerative braking is permitted and assigned to the regenerative braking force within the range of the first regenerative limit value regardless of the amount of charge of the battery. Control the distribution to generate braking force,
The braking / driving force control means sets the first regeneration limit value based on the amount of charge of the battery in a switchback state in which the traveling direction of the shift position and the traveling direction of the electric vehicle are different , and the absolute speed of the vehicle is Based on the value, the second regeneration limit value is set so as to decrease as the absolute value of the vehicle speed increases, and within the range of larger values of the first regeneration limit value and the second regeneration limit value. brake control apparatus for an electric vehicle, characterized in that to generate a control to the braking force distribution between the friction braking force and the regenerative braking force to assign to the regenerative braking force. In the switchback state, the braking / driving force control means is configured to control the friction braking force based on a vehicle speed so that the regenerative braking force is maximized when the regenerative braking force and the driving force of the motor / generator are switched. 2. The braking control device for an electric vehicle according to claim 1, wherein distribution of the motor and the regenerative braking force is controlled.

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