JP2009038922A - Regenerative braking force controller for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately control a regenerative braking force in an electric vehicle while suppressing increases of a cost and time. <P>SOLUTION: A regenerative braking force controller includes a regenerative braking executing means 42 and an additional regenerative braking force calculating means 41. The regenerative braking executing means operates a motor generator 12 as a generator, and executes regenerative braking setting a usual regenerative braking force Tb as a target regenerative braking force TcB, when an accelerator pedal 16 is not trod. The additional regenerative braking force calculating means calculates an additional regenerative braking force Tbh according to a driving force value F showing a driving force which is produced by gravity exerting on the electric vehicle 12. The regenerative braking executing means 42 is constituted to execute the regenerative braking, obtaining the target regenerative braking force TcB by adding the additional regenerative braking force Tbh to the usual regenerative braking force Tb. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a regenerative braking force control device for an electric vehicle.

Conventionally, in an electric vehicle equipped with a motor generator, a technique for generating a regenerative braking force by operating the motor generator as a generator when the accelerator pedal is not depressed is known. This regenerative braking force can be used in place of the engine braking force in a general automobile equipped with an engine.
In the technique disclosed in Patent Document 1 below, as shown in FIG. 1 of the same document, the regenerative braking force is changed stepwise according to the shift range position in the shift lever device (9). It has become.
JP-A-6-70406

However, according to the technique of Patent Document 1, it is necessary for the driver himself to select the shift range position as appropriate according to changes in the traveling state of the electric vehicle (for example, speed, acceleration, inclination of the traveling road surface, etc.) A complicated operation is required.
In order to control the regenerative braking force more finely, it is necessary to increase the shift range position. In this case, the driver must select an appropriate shift range from a large number of shift range positions. Habituation is required.

In addition, although it is possible to use a technology (cooperative control) that cooperates with the brake force (normal braking force) and the braking force (regenerative braking force) when the motor generator operates as a generator, this cooperative control is possible. However, since the control content becomes very complicated, it takes time for programming, and there is a problem that the cost increases due to complicated control.
The present invention has been devised in view of such problems, and provides a regenerative braking force control device for an electric vehicle capable of appropriately controlling the regenerative braking force in the electric vehicle while suppressing an increase in cost and labor. The purpose is to provide.

  To achieve the above object, a regenerative braking force control device for an electric vehicle according to the present invention (claim 1) regenerates an electric vehicle having an accelerator pedal depressed by a driver and a motor generator mechanically connected to a wheel. A braking force control device, wherein when the accelerator pedal is not depressed, regenerative braking execution means for operating the motor generator as a generator and executing regenerative braking with a normal regenerative braking force as a target regenerative braking force, and the electric Driving force value calculating means for calculating a driving force value indicating a driving force generated by gravity acting on the automobile, and addition for calculating an additional regenerative braking force according to a change in the driving force value calculated by the driving force value calculating means Regenerative braking force calculation means, and the regenerative braking execution means adds the additional regenerative braking force calculated by the additional regenerative braking force calculation means to the normal regenerative braking force to generate the target regenerative braking force. It is characterized in that to perform as a power regenerative braking.

  According to a second aspect of the present invention, there is provided a regenerative braking force control device for an electric vehicle according to the present invention, wherein the acceleration detecting means for detecting the acceleration of the electric vehicle and the weight of the electric vehicle are detected. Vehicle weight detecting means, and the driving force value calculating means calculates the driving force value based on the acceleration detected by the acceleration detecting means and the vehicle weight detected by the vehicle weight detecting means. The additional regenerative braking force calculating means calculates the additional regenerative braking force as a value that offsets the driving force value calculated by the driving force value calculating means.

  According to a third aspect of the present invention, there is provided the regenerative braking force control device for an electric vehicle according to the present invention, wherein the regenerative braking execution means selectively inhibits the addition of the additional regenerative braking force. A feature switching means is further provided.

According to the regenerative braking force control device for an electric vehicle of the present invention, the target value of the regenerative braking force is changed according to the change of the driving force value indicating the driving force generated by the gravity acting on the electric vehicle, thereby reducing the cost and labor. It is possible to appropriately control the regenerative braking force in the electric vehicle while suppressing the increase of. (Claim 1)
Also, by changing the target value of the regenerative braking force so as to offset the driving force value, even when regenerative braking is performed when the electric vehicle is traveling downhill, Decelerate at the same deceleration. (Claim 2)
In addition, since the change of the target value of the regenerative braking force according to the change of the driving force value can be turned on and off, the regenerative braking force intended by the driver can be appropriately obtained. (Claim 3)

Hereinafter, a regenerative braking force control device for an electric vehicle according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing the overall configuration, and FIG. 2 is a schematic diagram showing the control contents. FIG. 3 is a schematic flowchart showing regenerative braking force calculation control.
As shown in FIG. 1, the electric vehicle 10 is provided with a motor generator 12 mechanically connected to wheels 11. The motor generator 12 is fed from a battery 14 via an inverter 13 and can operate as an AC motor.

Further, the motor generator 12 can be operated as an AC generator that generates power by being driven by the wheels 11.
Whether the motor generator 12 operates as an electric motor or a generator is switched by a circuit (not shown) in the motor generator 12 according to a command from an ECU (Electronic Control Unit) 31 described later. To be selected.

The motor generator 12 includes a reduction gear (not shown). Note that the reduction gear ratio Gr of the reduction gear is constant.
The output torque (+ torque) of the motor generator 12 that operates as an electric motor or the regenerative torque (−torque) of the motor generator 12 that operates as an electric generator is controlled by an accelerator pedal detected by an accelerator pedal position sensor 15. Based on factors such as the position of the pedal 16 and the position of the shift lever 18 in the shift device 17, an instruction from the ECU 31 is received.

The motor generator 12 is provided with a rotation speed sensor (rotation speed detection means) 19 so that the rotation speed of the motor generator 12 can be detected. The detection result of the rotation speed sensor 19 is read by the ECU 31.
The inverter 13 converts DC power supplied from the battery 14 into AC power and supplies it to the motor generator 12. At this time, the inverter 13 can change the frequency of the AC power.

Further, the inverter 13 converts AC power output from the motor generator 12 operating as a generator into DC power and supplies it to the battery 14.
The inverter 13 is operated under the control of the ECU 31.
The battery 14 stores DC power supplied via the inverter 13 from the motor generator 12 operating as a generator, or stores DC power supplied from an external charger (not shown).

The shift device 17 selects the operation mode of the motor generator 12, and includes a shift lever 18 that can select the drive position D, neutral position N, and reverse position R, a hold mode button (regeneration mode switching means) H, have.
The position of the shift lever 18 and the on / off state of the hold mode button H in the shift device 17 are certified by a shift mode certification unit 32 (described later) of the ECU 31.

The ECU 31 is an electronic control unit having a CPU, a memory, an interface, etc., not shown.
Further, in the memory of the ECU 31, all of them are software as a shift mode recognition unit 32, an accelerator position recognition unit 33, a motor power generation switching unit 34, a vehicle speed calculation unit 35, an acceleration calculation unit 36, a vehicle specification storage unit 37, A driving force value calculation unit 38, a normal regenerative braking force storage unit 39, an additional regenerative braking force calculation unit 41, and a regenerative braking force command unit 42 are provided.

Among these, the shift mode recognition unit 32 recognizes whether the shift lever 18 of the shift device 17 is in the drive position D, the neutral position N, or the reverse position R, and also holds the hold mode button H. Certifies whether is on or off.
The accelerator position authorization unit 33 authorizes the depression amount Acc of the accelerator pedal 16 based on the detection result of the accelerator pedal position sensor 15.

When the accelerator pedal depression amount Acc recognized by the accelerator pedal position recognition unit 33 is substantially zero, the motor generator switching unit 34 switches the circuit in the motor generator 12 to the generator mode, thereby The generator 12 is operated as a generator.
In addition, when the accelerator pedal depression amount Acc certified by the accelerator pedal position certification unit 33 is not substantially zero (Acc ≠ 0), the motor power generation switching unit 34, in other words, the accelerator pedal 16 is depressed. If so, the motor generator 12 is operated as a motor by switching the circuit in the motor generator 12 to the motor mode.

The vehicle speed calculation unit 35 calculates the vehicle speed V of the electric vehicle 10 based on the rotation speed of the motor generator 12 detected by the rotation speed sensor 19.
The acceleration calculation unit (acceleration detection means) 36 calculates the acceleration Ga of the electric vehicle 10 by differentiating the vehicle speed V calculated by the vehicle speed calculation unit 35.
The vehicle specification storage unit (vehicle weight detection means) 37 stores the weight W of the electric vehicle 10, the dynamic load radius R of the wheels 11, and the reduction gear ratio Gr of the reduction gear. The dynamic load radius R refers to the distance from the center of rotation of the wheel 11 to the ground contact surface in a state where the wheel 11 is actually mounted on the electric vehicle 10 and a prescribed air pressure is maintained.

  The driving force value calculation unit (driving force value calculation means) 38 has the shift lever 18 at the drive position D, the acceleration Ga calculated by the acceleration calculation unit 35 from zero is larger than zero (Ga> 0), and When the accelerator pedal depression amount Acc certified by the accelerator pedal position certification unit 33 is zero (Acc = 0), the vehicle weight W is read from the vehicle specification storage unit 37 and the following equation (1) is used. A value (driving force value) F indicating a driving force generated by gravity acting on the electric vehicle 10 is calculated.

F = W × Ga (1)
The normal regenerative braking force storage unit 39 is a target value of regenerative braking force (normally) when the accelerator pedal depression amount Acc becomes zero (Acc = 0) when the electric vehicle 10 is traveling on flat ground (normal time). Regenerative braking force) Tb is stored.
The additional regenerative braking force calculation unit (additional regenerative braking force calculation means) 41 is a target value of regenerative braking force (additional regenerative braking force) necessary to cancel the driving force value F calculated by the driving force value calculation unit 38. Tbh is calculated.

Specifically, the additional regenerative braking force calculation unit 41 reads the dynamic load radius R and the reduction ratio Gr from the vehicle specification storage unit 37, and then calculates the additional regenerative braking force Tbh using the following equation (2). It is supposed to be.
Tbh = F × R / Gr (2)
The regenerative braking force command unit (regenerative braking execution means) 42 generates a command regenerative braking force (target regenerative braking force) TcB according to the accelerator pedal depression amount Acc, the shift lever position of the shift device 17 and the on / off of the hold mode button H. The motor generator 12 is controlled to set and generate the command regenerative braking force TcB.

  That is, when the accelerator pedal 16 is not depressed (Acc = 0) and the hold mode button H of the shift device 12 is on, the regenerative braking force command unit 42 By adding the additional regenerative braking force Tbh calculated by the additional regenerative braking force calculating unit 41 to the normal regenerative braking force Tb, that is, the command regenerative braking force TcB is set by the following equation (3). Yes.

TcB = Tb + Tbh (3)
On the other hand, when the accelerator pedal 16 is not depressed and the hold mode button H of the shift device 17 is off, the normal regenerative braking force Tbh calculated by the additional regenerative braking force calculation unit 41 is used. The normal regenerative braking force Tb stored in the braking force storage unit 39 is set as the command regenerative braking force TcB as it is, and regenerative braking is executed. That is, when the hold mode button H is off, addition of the additional regenerative braking force Tbh is prohibited.

The regenerative braking force command unit 42 performs regenerative control by controlling the power generation load of the motor generator 12 so as to generate the command regenerative braking force TcB obtained by the above equation (2) or (3). It is supposed to run.
Since the regenerative braking force control device for an electric vehicle according to one embodiment of the present invention is configured as described above, the following operations and effects are achieved.

As shown in step S <b> 11 of FIG. 2, first, the ECU 31 reads the detection results of the accelerator position sensor 15 and the rotation speed sensor 19.
Further, the shift mode recognition unit 31 of the ECU 31 recognizes the position of the shift lever 18 in the shift device 17 and also recognizes whether the hold mode button H is on or off (step S12).

And the vehicle speed calculation part 35 calculates the vehicle speed V of the electric vehicle 10 based on the rotation speed of the motor generator 12 detected by the rotation speed sensor 19 (step S13).
Moreover, the acceleration calculation part 36 calculates the acceleration Ga of the electric vehicle 10 by differentiating the vehicle speed V calculated by the vehicle speed calculation part 35 (step S14).
Thereafter, the command regenerative braking force TcB is calculated by a subroutine (step S15), and the regenerative braking force command unit 42 controls the motor generator 12 to generate the calculated command regenerative braking force TcB (step S16).

Here, calculation of the command regenerative braking force TcB will be described with reference to FIG.
The shift mode recognition unit 32 recognizes that the shift lever 18 is in the drive position D (Yes route in step S21), and the shift mode recognition unit 32 recognizes that the hold mode button H is on (step S22). Yes route), and the acceleration Ga of the electric vehicle 12 calculated by the acceleration calculation unit 36 is zero or more (Yes route of step S23), and the depression amount of the accelerator pedal 33 by the accelerator pedal position recognition unit 33 When Acc is zero (Yes route of step S24), the driving force value calculation unit 38 reads the vehicle weight W from the vehicle specification storage unit 37, and calculates the driving force value F using the above equation (1). (Step S25).

Thereafter, the additional regenerative braking force calculation unit 41 reads the dynamic load radius R and the reduction ratio Gr from the vehicle specification storage unit 37, and then calculates the additional regenerative braking force Tbh using the above equation (2). The calculated additional regenerative braking force Tbh is recorded in a memory (not shown) of the ECU 31 (step S26).
Then, the regenerative braking force command unit 42 reads the normal regenerative braking force Tb from the normal regenerative braking force storage unit 39, and the additional regenerative braking force calculated by the additional regenerative braking force calculation unit 41 with respect to the read normal regenerative braking force Tb. The power Tbh is applied, that is, the command regenerative braking force TcB is set by the above equation (3) (step S27).

  On the other hand, when any one of the conditions from steps S21 to S24 is not satisfied (No route from steps S21 to S24), the additional regenerative braking force calculation unit 41 does not calculate the additional regenerative braking force Tbh. In addition, the additional regenerative braking force Tbh calculated in the previous cycle and recorded in the memory is set to zero, that is, addition of the additional regenerative braking force Tbh is prohibited (step S28).

Thereafter, the regenerative braking force command unit 42 reads the normal regenerative braking force Tb stored in the normal regenerative braking force storage unit 39, and sets the read normal regenerative braking force Tb as the command regenerative braking force TcB as it is (step S29). .
As described above, according to the regenerative braking force control device for an electric vehicle according to the embodiment of the present invention, the regenerative braking force according to the change in the driving force value F indicating the driving force generated by the gravity acting on the electric vehicle 10. By changing the command regenerative braking force TcB, which is the target value, the regenerative braking force in the electric vehicle 10 can be appropriately controlled while suppressing an increase in cost and labor.

Further, by changing the command regenerative braking force TcB so as to cancel the driving force value F, even when regenerative braking is performed when the electric vehicle 10 is traveling downhill, Can be decelerated at the same deceleration.
That is, in an electric vehicle to which the conventional technology is applied, when the regenerative braking force intended by the driver cannot be obtained, it is assumed that the driver frequently uses the foot brake. However, using a lot of foot brakes is not preferable because it not only accelerates wear of the brake pads but also causes heat generation of the brake device.

  Moreover, there is a problem peculiar to an electric vehicle that the power consumption in the battery increases as the number of times the brake pedal is depressed. This is because the negative pressure in the brake booster that assists the depression of the brake pedal is generated by an electric motor pump in the case of an electric vehicle. The same problem arises even in a structure that assists the depression of the brake pedal directly by the torque of the electric motor.

On the other hand, in the present invention, by controlling regenerative braking so that an appropriate deceleration is generated in the electric vehicle 10, a situation in which the frequency of using the foot brake by the driver is increased, and the brake pads are consumed. The heat generation of the brake device and the power consumption of the battery 14 can be suppressed.
Further, by operating the hold mode button H, the change of the command regenerative braking force TcB according to the change of the driving force value F can be selectively turned on / off, so that the regenerative braking force control more in line with the driver's intention. Can be realized.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the case where the reduction ratio Gr of the reduction gear incorporated in the motor generator 12 is constant has been described. However, the present invention is not limited to this. For example, the reduction ratio Gr may be variable, and a reduction ratio sensor that detects the variable reduction ratio Gr as needed may be provided.

In the above-described embodiment, the case where the shift device 17 is provided with the hold button H has been described as an example. However, the present invention is not limited to this. For example, instead of the hold button H, the shift lever 18 may select the hold position.
In the above-described embodiment, the case where the vehicle weight W of the electric vehicle 10 is considered to be constant and the vehicle weight W is stored in the vehicle specification storage unit 37 has been described as an example. It is not a thing. For example, a vehicle weight sensor that detects the vehicle weight W in real time may be provided, and the detected vehicle weight W may be used at any time.

  In the above-described embodiment, the case where the accelerator position recognition unit 33 recognizes the depression amount Acc of the accelerator pedal 16 has been described as an example. However, the present invention is not limited to this. For example, in an electric vehicle provided with an accelerator pad operated by a driver's hand, the accelerator position recognition unit 33 may recognize the operation amount of the accelerator pad. That is, the accelerator position authorization unit 33 may be authorized to determine whether or not the driver requests acceleration.

1 is a schematic block diagram illustrating an overall configuration of a regenerative braking force control device for an electric vehicle according to an embodiment of the present invention. It is a typical whole flowchart which shows the control content by the regenerative braking force control apparatus of the electric vehicle which concerns on one Embodiment of this invention. It is a typical flowchart which shows calculation control of the regenerative braking force by the regenerative braking force control apparatus of the electric vehicle which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric vehicle 11 Wheel 12 Motor generator 16 Accelerator pedal 35 Acceleration calculation part (acceleration detection means)
37 Vehicle specification storage unit (vehicle weight detection means)
38 Driving force value calculation unit (driving force value calculation means)
41 Additional regenerative braking force calculation unit (additional regenerative braking force calculation means)
42 Regenerative braking force command section (Regenerative braking force command means)
Ga acceleration F driving force value Tb normal regenerative braking force Tbh additional regenerative braking force W vehicle weight H hold mode button (regenerative mode switching means)

Claims (3)

A regenerative braking force control device for an electric vehicle having an accelerator pedal stepped on by a driver and a motor generator mechanically connected to wheels.
Regenerative braking execution means for operating the motor generator as a generator when the accelerator pedal is not depressed and executing regenerative braking with a normal regenerative braking force as a target regenerative braking force;
Driving force value calculating means for calculating a driving force value indicating a driving force generated by gravity acting on the electric vehicle;
An additional regenerative braking force calculating means for calculating an additional regenerative braking force according to a change in the driving force value calculated by the driving force value calculating means,
The regenerative braking execution means
A regenerative braking force control device for an electric vehicle, wherein the regenerative braking is executed by adding the additional regenerative braking force calculated by the additional regenerative braking force calculating means to the normal regenerative braking force to obtain the target regenerative braking force. Acceleration detecting means for detecting the acceleration of the electric vehicle;
Vehicle weight detecting means for detecting the weight of the electric vehicle,
The driving force value calculating means calculates the driving force value based on the acceleration detected by the acceleration detecting means and the vehicle weight detected by the vehicle weight detecting means,
The electric vehicle according to claim 1, wherein the additional regenerative braking force calculating means calculates the additional regenerative braking force as a value that cancels the driving force value calculated by the driving force value calculating means. Regenerative braking force control device. The regenerative braking force control device for an electric vehicle according to claim 1 or 2, further comprising regenerative mode switching means for selectively prohibiting addition of the additional regenerative braking force by the regenerative braking execution means.

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