JP2010200590A - Device for regenerative braking control of electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To favorably enhance the efficiency of recovering energy, while achieving a good breaking feeling, concerning a device for regenerative breaking control of an electric vehicle. <P>SOLUTION: The device for regenerative breaking control of the electric vehicle includes a first mechanical breaking torque estimation means 22 and a target regenerative breaking torque estimation means 23. The first mechanical breaking torque estimation means 22 sets a first mechanical breaking torque TmR which is an estimated value of a mechanical breaking torque by a first friction breaking apparatus 15b so as to be smaller than a first ideal breaking torque TIR which is a breaking torque when it is supposed that a breaking is made by maximum friction force between a driving wheel 11b and a road. The target regenerative breaking torque estimation means 23 calculates a difference between the first ideal breaking torque TIR and the first mechanical breaking torque TmR as a target regenerative breaking torque TC. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a regenerative braking control device that controls the amount of regenerative braking torque of an electric motor in an electric vehicle having a motor generator regeneratively driven by wheels and a friction braking device that brakes the wheels.

  In an electric vehicle that drives a wheel using an electric motor as a power source, control is performed to generate electric power by using the torque of driving wheels during braking and regenerate electric power (hereinafter referred to as “regenerative braking control”). The regenerative braking torque absorbed by the battery by the regenerative braking control is a torque for braking the vehicle (hereinafter referred to as “the brake braking torque consumed by a friction braking device such as a disc brake device or a drum brake device attached to the wheel”). It will work as "braking torque". As described above, there has been proposed a technique for improving energy recovery efficiency during braking by controlling the amount of regenerative braking torque when braking is performed by applying regenerative braking torque and friction braking torque to a wheel.

For example, Patent Document 1 below discloses a technique for controlling the regenerative braking torque applied to the electric drive wheels in accordance with the locking tendency of the electric drive wheels during braking. In this technique, it is said that the start of anti-skid control can be delayed, and regenerative braking can be continued during that time to improve energy recovery efficiency.
Patent Document 2 below discloses a technique for switching a control mode in accordance with the depressing force of a brake pedal in a vehicular braking apparatus capable of switching a braking mode. With this technology, the regeneration priority mode is selected during normal braking when the pedal effort of the brake pedal is equal to or less than a predetermined value, and mode switching to the normal mode is performed during sudden braking when the pedal effort of the brake pedal exceeds a predetermined value. ing. As a result, the electric drive wheels are prevented from being locked during regenerative braking and the regenerative braking can be continued, so that energy recovery efficiency can be improved.

JP 2003-174703 A JP-A-5-161213

  However, the techniques of Patent Documents 1 and 2 attempt to control the timing of regenerative braking by mode switching when the electrically driven wheels at the time of regenerative braking tend to be locked in order to continue regenerative braking torque. That is, the energy recovery efficiency is improved by continuing the regenerative braking torque when there is a tendency to lock, but the amount of regenerative braking torque itself during regenerative braking is not set or controlled.

Therefore, with the techniques of Patent Documents 1 and 2, it is difficult to realize good energy recovery efficiency by regenerative braking in accordance with the running state of the electric vehicle that changes from moment to moment.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a regenerative braking control device for an electric vehicle that can improve energy recovery efficiency by regenerative braking.

  The regenerative braking control device for an electric vehicle according to the present invention (Claim 1) is a regenerative braking control device for an electric vehicle, the motor generator connected to the drive wheel of the electric vehicle, and the drive wheel mechanically. A first friction braking device that brakes and a first ideal braking torque that is a braking torque when it is assumed that braking of the driving wheel is performed with a maximum frictional force between the road surface and the driving wheel. It is obtained by using a braking torque estimating means, a first mechanical braking torque estimating means for estimating a mechanical braking torque by the first friction braking device as a first mechanical braking torque, and the motor generator as a generator. Target regenerative braking torque estimating means for estimating a target regenerative braking torque as a target regenerative braking torque, and regenerative braking control for adjusting the regenerative braking torque by the motor generator within the range of the target regenerative braking torque. The first mechanical braking torque estimating means is set so that the first mechanical braking torque is smaller than the first ideal braking torque, and the target regenerative braking torque estimating means The difference between the first ideal braking torque estimated by the first ideal braking torque estimating means and the first mechanical braking torque estimated by the first mechanical braking torque estimating means is the target regenerative braking torque. As a feature.

  According to the regenerative braking control device for an electric vehicle of the present invention (Claim 2), the second friction for mechanically braking the rear wheel as the driving wheel and the front wheel of the electric vehicle according to Claim 1 A braking device, a second ideal braking torque estimating means for estimating a second ideal braking torque that is a braking torque when it is assumed that braking of the front wheel is performed with a maximum frictional force between the road surface and the driving wheel, An ideal braking torque map defining a relationship between the first ideal braking torque and the second ideal braking torque, wherein the first ideal braking torque estimating means is the first ideal braking torque estimating means estimated by the second ideal braking torque estimating means. The first ideal braking torque is estimated by applying two ideal braking torques to the ideal braking torque map.

  In addition, the regenerative braking control device for an electric vehicle according to the present invention (Claim 3) supports the actual deceleration detecting means for detecting the actual deceleration of the electric vehicle and the rear wheel. First vehicle weight calculation means for estimating the vehicle weight of the electric vehicle as a first vehicle weight; and second vehicle weight calculation means for estimating the vehicle weight of the electric vehicle supported by the front wheels as a second vehicle weight. The first ideal braking torque estimating means includes the actual deceleration detected by the actual deceleration detecting means, the first vehicle weight estimated by the first vehicle weight calculating means, and the second vehicle weight calculating means. The first ideal braking torque is estimated on the basis of the second weight estimated by the first weight, and the second ideal braking torque estimating means detects the actual deceleration detected by the actual deceleration detecting means and the first deceleration. By the first vehicle weight and the second vehicle weight calculation means estimated by the vehicle weight calculation means On the basis of the second vehicle weight estimated Te is characterized by estimating a second ideal braking torque.

  According to the regenerative braking control device for an electric vehicle of the present invention (Claim 4), in addition to the configuration of Claim 3, the first vehicle detects the vehicle height of the electric vehicle on the rear wheel side as the first vehicle height. A height detecting means, a second vehicle height detecting means for detecting the vehicle height of the electric vehicle on the front wheel side as a second vehicle height, and a first for defining a relationship between the first vehicle height and the first vehicle weight. A vehicle weight map; and a second vehicle weight map that defines a relationship between the second vehicle height and the second vehicle weight, wherein the first vehicle weight calculation means is detected by the first vehicle height detection means. The first vehicle weight is calculated by applying the first vehicle height to the first vehicle weight map, and the second vehicle weight calculation means is configured to detect the second vehicle weight detected by the second vehicle height detection means. The second vehicle weight is calculated by applying the vehicle height to the second vehicle weight map.

  Further, the regenerative braking control device for an electric vehicle according to the present invention (Claim 5) adds the mechanical braking torque by the second friction braking device to the second in addition to the configuration according to any one of Claims 1 to 4. A second mechanical braking torque estimating means for estimating a mechanical braking torque; a brake pedal pressing force detecting means for detecting a pressing force of a brake pedal of the vehicle; and a relationship between the brake pedal pressing force and the first mechanical braking torque. A first mechanical braking torque map for defining; and a second mechanical braking torque map for defining a relationship between the brake pedal depression force and the second mechanical braking torque, wherein the second mechanical braking torque estimating means includes: Applying the brake pedal depression force detected by the brake pedal depression force detecting means to the second mechanical braking torque map to calculate the second mechanical braking torque, Estimating means is characterized by calculating a first mechanical braking torque by applying the brake pedal depression force detected by the brake pedal force detection means to the first mechanical braking torque map.

  An electric vehicle regenerative braking control device according to the present invention (Claim 6) includes the first mechanical braking torque map and the second mechanical braking map in addition to the configuration according to any one of Claims 1 to 5. The braking torque map shows the deceleration when the first mechanical braking torque and the first ideal braking torque have the same value and the second mechanical braking torque and the second ideal braking torque have the same value. The relationship between the first mechanical braking torque and the second mechanical braking torque is defined in a range that provides the maximum regenerative torque of the generator.

  Moreover, the regenerative braking control device for an electric vehicle according to the present invention (Claim 7) has the configuration according to any one of Claims 1 to 6, and the regenerative braking control means includes the first ideal braking torque and When braking is performed with the second ideal braking torque, ideal deceleration estimation means for estimating an ideal deceleration that is a deceleration generated in the vehicle, and the ideal deceleration detected by the ideal deceleration estimation means and the actual deceleration. Target regenerative braking torque for performing correction control for correcting the target regenerative braking torque when the absolute value of the difference from the actual deceleration detected by the deceleration detecting means deviates from the set predetermined range. And a correction means.

  In addition to the configuration according to any one of claims 1 to 7, the regenerative braking control means detects the vehicle speed of the electric vehicle. Vehicle speed detection means for performing regenerative braking control when the vehicle speed detected by the vehicle speed detection means is not a set vehicle speed threshold value.

  According to the regenerative braking control device for an electric vehicle of the present invention (Claim 1), energy regeneration efficiency can be improved while reliably decelerating the electric vehicle. In addition, even when braking of the electric vehicle is performed with the maximum frictional force between the driving wheel and the road surface, it becomes possible to reliably avoid the locking of the driving wheel during deceleration, so the driver is anxious even on a slippery road surface. Regenerative braking control can be performed without giving a sense of incongruity.

Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 2), the ideal braking torque of the rear wheel, that is, quickly and surely, without complicated calculation, by using the ideal braking torque map, that is, The first ideal braking torque can be obtained.
Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 3), the ideal braking torque of the rear wheels, that is, the first ideal based on the actual deceleration, the first vehicle weight, and the second vehicle weight. The braking torque can be accurately obtained, and the ideal braking torque of the front wheels, that is, the second ideal braking torque can also be accurately obtained based on the actual deceleration and the first and second vehicle weights.

Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 4), by using the first vehicle weight map, the vehicle weight on the rear wheel side can be quickly and reliably obtained without complicated calculations. That is, the first vehicle weight can be obtained. Similarly, by using the second vehicle weight map, the vehicle weight on the front wheel side, that is, the second vehicle weight can be obtained quickly and surely without performing complicated calculations.
Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 5), the brake pedal depression force that quickly reflects the driver's intention to decelerate is directly detected. It is possible to detect quickly, and the first mechanical braking torque and the second mechanical braking torque can be estimated quickly and reliably. Further, by using the first mechanical braking torque map, the first mechanical braking torque can be obtained quickly and reliably without performing complicated calculations. Similarly, by using the second mechanical braking torque map, the second mechanical braking torque can be obtained quickly and reliably without complicated calculations.

Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 6), the difference between the first mechanical braking torque and the first ideal braking torque can be made relatively large, so that the regenerative efficiency is increased. be able to.
Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 7), when the absolute value of the difference between the ideal deceleration and the actual deceleration is equal to or larger than a set predetermined range, Since the target regenerative braking torque correction control is performed while ensuring the braking effect within a predetermined range, the target regenerative braking torque suitable for the traveling state of the electric vehicle can be obtained quickly and reliably.

  Further, according to the regenerative braking control device for an electric vehicle of the present invention (Claim 8), the regenerative braking control is performed when the vehicle speed is not the set predetermined value. Therefore, when the electric vehicle is stopped, the regenerative braking control is not performed, and the regenerative braking control can be reliably performed at a time when it is necessary.

1 is a schematic diagram illustrating an overall configuration of a vehicle to which a regenerative braking control device for an electric vehicle according to an embodiment of the present invention is applied. It is a block diagram showing typically the principal part composition of the regenerative braking control device of the electric vehicle concerning one embodiment of the present invention. It is a map which prescribes | regulates the relationship between the pedal effort used by the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention, and front-and-rear wheel braking torque. It is a map which prescribes | regulates the relationship between the output voltage of a vehicle height sensor, and vehicle weight used for estimation of the vehicle weight by the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention. It is a map which prescribes | regulates the relationship between a vehicle weight weight and a gravity center height used for estimation of the gravity center height of an electric vehicle by the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention. It is a map which prescribes | regulates the relationship between the front-wheel braking torque and rear-wheel braking torque used for the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention. It is a map used for the weight correction method by the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention. It is a flowchart which shows typically the control procedure by the regenerative braking control apparatus of the electric vehicle which concerns on one Embodiment of this invention.

[1. overall structure]
The regenerative braking control device of this embodiment is applied to the electric vehicle 10. As shown in FIG. 1, the electric vehicle 10 includes a front wheel (front wheel) 11a and a rear wheel (rear wheel) 11b. The front wheel 11a is provided with a front wheel side mechanical brake device (second friction braking device) 15a, and the rear wheel 11b is provided with a rear wheel side mechanical brake device (first friction braking device) 15b. In the electric vehicle 10, two rear wheels 11 b are mechanically connected to a motor (motor generator) 14 via a gear box 12, and the rear wheels 11 b are driven by the motor 14. Yes.

  As shown in FIGS. 1 and 2, the electric vehicle 10 includes an EVEC (Electric Vehicle Electronic Control Unit) 3, an MCU (Motor Control Unit) 4, and an ASCU (Active Stability) as electronic control units related to braking control. Control Unit) 5 is provided. Each of these electronic control units 3, 4, 5 is an electronic control device constituted by a microcomputer, and is provided as an LSI device in which a microprocessor, a memory and the like are integrated.

  The EV ECU 3 includes an acceleration sensor (actual deceleration detecting means) 1 for detecting a braking deceleration (actual deceleration) GR acting on the vehicle body of the electric vehicle 10, presence / absence of depression of the brake pedal 9, and depression of the brake pedal. Brake pedal depression force sensor (brake pedal depression force detecting means) 17 for detecting force, front axle vehicle height sensor (second vehicle height) h2 for detecting the front axle height (second vehicle height) h2, which is the height of the electric vehicle 10 at the front wheels 11a. Vehicle height detection means) 18a and rear axle vehicle height sensor (first vehicle height detection means) 18b for detecting rear axle vehicle height (first vehicle height) h1, which is the vehicle height of the electric vehicle 10 at the rear wheel 11b, are connected. ing. These pieces of detection information are input to the EV ECU 3.

  Each wheel 11a, 11b is provided with a speed sensor (vehicle speed detecting means) 13 for detecting the number of rotations. The rotational speeds of the wheels 11a and 11b detected by the speed sensor 13 are input to the ASCU 5. The ASCU 5 calculates the vehicle speed V based on the input rotation speeds of the wheels 11 a and 11 b, and the vehicle speed V calculated here is also input to the EV ECU 3.

The EV ECU 3 is a higher-level electronic control unit than the MCU 4 and the ASCU 5. In other words, the EV ECU 3 has a function of managing the MCU 4 and the ASCU 5 in an integrated manner, and has jurisdiction over the timing of control executed by the MCU 4 and the ASCU 5 and the setting and instruction of the control amount.
The MCU 4 receives specific instructions from the EV ECU 3, calculates specific control voltage and control current values, and transmits a control signal to the motor 14. The motor 14 functions as both a motor and a generator according to a control signal from the MCU 4.

  The ASCU 5 receives an instruction from the EV ECU 3 and controls an H / U (Hydraulic Unit) 16 to individually control the mechanical brake devices 15a and 15b of the wheels 11a and 11b. As a result, the ASCU 5 has a so-called ASC function, and a braking force corresponding to the grip force of the wheels 11a and 11b can be applied to the wheels 11a and 11b to improve posture stability. Yes.

  H / U 16 is an actuator for controlling the brake fluid pressure introduced into each mechanical brake device 15a, 15b. This H / U 16 is connected to the brake master cylinder 8 by hydraulic piping, and receives the brake hydraulic pressure input via the brake booster 7 when the brake pedal 9 is depressed, thereby controlling the mechanical brake devices 15a and 15b. It is supposed to be.

[2. EVECU]
A control configuration relating to regenerative braking control during regenerative braking of the electric vehicle 10 will be described in detail.
When the accelerator pedal (not shown) is released and the brake pedal 9 is depressed, the EV ECU 3 sets a regenerative torque amount corresponding to an engine brake in a general vehicle powered by the engine, and the motor 14 Is to control. In order to further increase the regeneration efficiency, it is necessary to increase the amount of regenerative torque as much as possible. However, if the amount of regenerative torque is set too large, excessive braking force will be applied, and excessive braking force against the driver's will can be obtained even for the driver who drives the electric vehicle 10. Become. Thereby, the operation feeling of the driver is impaired. Therefore, this EV ECU 3 controls the amount of regenerative torque of the motor 14 via the MCU 4 so as to increase the regenerative efficiency as much as possible without causing anxiety or discomfort to the occupant of the electric vehicle 10 including the driver. ing.

  The memories of the EV ECU 3 are all program software, including a front wheel side ideal braking torque estimating unit (second ideal braking torque estimating unit) 19, a rear wheel side ideal braking torque estimating unit (first ideal braking torque estimating unit) 20, and a front wheel side. Mechanical braking torque estimation unit (second mechanical braking torque estimation unit) 21, rear wheel side mechanical braking torque estimation unit (first mechanical braking torque estimation unit) 22, target regenerative braking torque estimation unit (target regenerative braking torque) Estimation means) 23, regenerative braking control section (regenerative braking control means) 2, front axle weight calculation section (second vehicle weight calculation means) 24, rear axle weight calculation section (first vehicle weight calculation means) 25, ideal A deceleration estimation unit (ideal deceleration estimation unit) 26 and a target regenerative braking torque correction unit (target regenerative braking torque correction unit) 27 are provided.

[2-1. Front wheel side mechanical braking torque estimation unit 21, rear wheel side mechanical braking torque estimation unit 22]
The memory of the EVECU 3 records a mechanical braking torque map 28 (first mechanical braking torque map, second mechanical braking torque map) shown in FIG. In this mechanical braking torque map 28, the front wheel side mechanical braking torque (second mechanical braking torque) TmF, which is the estimated actual value of the mechanical braking torque by the front wheel side mechanical brake device 15a, and the brake pedal depression force F are shown. The correspondence relationship between the rear wheel side mechanical braking torque (first mechanical braking torque) TmR, which is an estimated actual value of the mechanical braking torque by the rear wheel side mechanical brake device 15b, and the brake pedal depression force F is It is prescribed. The mechanical braking torque map 28 defines a characteristic that the front and rear wheel side mechanical braking torques TmF and TmR increase as the brake pedal depression force F increases. Further, since the mechanical braking torque map 28 applies a larger load to the front wheel side than to the rear wheel side during regenerative braking, the front wheel side mechanical braking torque TmR is greater than the rear wheel side mechanical braking torque TmR. The braking torque TmF is set to be larger. Note that when the brake pedal depression force F is F _1, the rate of change of the front wheel mechanical braking torque TmF and rear wheel mechanical braking torque TmR suddenly changes is due to the performance of the brake booster 7 .

The front wheel side mechanical braking torque estimating unit 21 applies the brake pedal depression force F detected by the brake pedal depression force sensor 17 to the mechanical braking torque map 28 so as to obtain the front wheel side mechanical braking torque TmF. It has become.
Similarly, the rear wheel side mechanical braking torque estimation unit 22 applies the brake pedal depression force F detected by the brake pedal depression force sensor 17 to the mechanical braking torque map 28, thereby rear wheel side mechanical braking torque. TmR is obtained.
The front wheel side mechanical braking torque TmF obtained by the front wheel side mechanical braking torque estimating unit 21 and the rear wheel side mechanical braking torque TmR obtained by the rear wheel side mechanical braking torque estimating unit 22 will be described later. It is sent to the target regenerative control torque estimation unit 23 of the EVECU 3.

[2-2. Front axle weight calculator 24, Rear axle weight calculator 25]
The vehicle weight map (first vehicle weight map, second vehicle weight map) 29 shown in FIG. 4 is recorded in the memory of the EVECU 3. The vehicle weight map 29 includes a correspondence relationship between the output voltage of the front axle vehicle height sensor 18a and the front axle weight (second vehicle weight) WF, and the output voltage and rear axle weight (first axle weight) of the rear axle vehicle height sensor 18b. (1 vehicle weight) Correspondence with WR is defined.

The front axle weight calculation unit 24 applies the vehicle height (second vehicle height) h2 of the electric vehicle 10 in the front wheels 11a detected by the front axle height sensor 18a to the vehicle weight map 29, so that the front wheels 11a The weight (front axle weight) WF of the electric vehicle 10 supported by the vehicle is obtained.
Similarly, the rear axle vehicle weight calculation unit 25 applies the vehicle height (first vehicle height) h1 of the electric vehicle in the rear wheel 11b detected by the rear axle vehicle height sensor 18b to the weight map 29. The weight (rear axle weight) WR of the electric vehicle 10 supported by the rear wheel 11b is obtained.

  Further, the rear axle weight calculation unit 25 adds the front axle weight WF and the rear axle weight WR, thereby adding the total weight of the electric vehicle 10 that is the actual gross weight obtained by adding the weight of the occupant, cargo, etc. to the vehicle body weight. W is required. Further, the rear axle weight calculation unit 25 uses the front axle weight WF and the rear axle weight WR to determine the height from the ground contact surface (that is, the road surface) of each wheel 11a, 11b to the center of gravity of the entire electric vehicle 10 (the center of gravity height). H) H is calculated. Specifically, the center of gravity height map 32 shown in FIG. 5 is recorded in the memory of the EV ECU 3. The center-of-gravity height map 32 defines the correspondence between the total vehicle weight W (front axle weight WF + rear axle weight WR) and the center of gravity height H. The center-of-gravity height map 32 defines a characteristic that the center-of-gravity height H increases as the total vehicle weight W increases. The rear axle weight calculation unit 25 obtains the center of gravity height H by applying the total vehicle weight W to the center of gravity height map 32.

Further, the front axle weight calculation unit 24 and the rear axle weight calculation unit 25 are based on a load correction coefficient Kw calculated by a target regenerative braking torque correction unit 27 described later, and the following equations (1) and (2 ) And (3), the front axle weight WF _c after load correction, the rear axle weight WR _c after load correction, and the total vehicle weight W _c after load correction are calculated.
WF _c = WF × Kw (1)
WR _c = WR × Kw (2)
W _c = WF _c + WR _c (3)

[2-3. Front wheel side ideal braking torque estimation unit 19, rear wheel side ideal braking torque estimation unit 20]
The front-wheel-side ideal braking torque estimating unit 19 is the braking torque when it is assumed that the maximum frictional force between the road surface and the front wheel 11a is assumed in relation to the frictional force between the front wheel 11a and the road surface assumed on various road surfaces, that is, The front wheel side ideal braking torque (second ideal braking torque) TIF, which is the maximum braking torque of the front wheel 11a in a range where the front wheel 11a is not locked, is estimated. More specifically, the front wheel side ideal braking torque estimating unit 19 calculates the front wheel side ideal braking torque TIF using the following equations (4) and (5).

In the above formulas (4) and (5), the parameters used are as follows.
Total vehicle weight W
Front axle weight WF
Center of gravity height H
Braking deceleration GR
Radius Rf of front wheel 11a
Wheelbase L
Further, the BF obtained in the equation (4) is the braking torque when the front wheel 11a is braked on the road surface having a friction coefficient equivalent to the braking deceleration GR, that is, the maximum control of the front wheel 11a in the range where the front wheel 11a is not locked. It is the front wheel side ideal braking force that is power.

Further, the rear wheel side ideal braking torque estimation unit 20 is made with the maximum frictional force between the road surface and the rear wheel 11b in the relationship between the rear wheel 11b and the frictional force of the road surface where the rear wheel 11b is assumed on various road surfaces. The rear wheel side ideal braking torque (first ideal braking torque) TIR that is the maximum braking torque of the rear wheel 11b in a range where the rear wheel 11b is not locked. More specifically, the rear wheel side ideal braking torque estimation unit 20 calculates the rear wheel side ideal braking torque TIR using the following equations (6) and (7).

In the above formulas (6) and (7), the parameters used are as follows.
Total vehicle weight W
Rear axle weight WR
Center of gravity height H
Braking deceleration GR
Radius Rr of rear wheel 11b
Wheelbase L
Further, the BR obtained in the equation (6) is the braking torque when the rear wheel 11b is assumed to be braked on the road surface having a friction coefficient equivalent to the braking deceleration GR, that is, the rear wheel 11b in a range where the rear wheel 11b is not locked. It is the front wheel side ideal braking force that is the maximum braking force of

  The map shown in FIG. 6 shows that the relationship between the front wheel side ideal braking torque TIF and the rear wheel side ideal braking torque TIR is a quadratic curve (hereinafter referred to as “ideal braking torque curve C”) according to the above equations (5) and (7). Created). The ideal braking torque curve C is used as an ideal braking torque map (ideal braking torque map) 30 that defines the relationship between the first ideal braking torque TIR and the second ideal braking torque TIF.

  On the other hand, the relationship between the front wheel side mechanical braking torque TmF and the rear wheel side mechanical braking torque TmR is defined as a straight line B shown in FIG. 6 (hereinafter referred to as “mechanical braking torque straight line B”). This is because, as shown in FIG. 3, the relationship between the brake pedal depression force F and the front and rear wheel side mechanical braking torques TmF and TmR is in principle a proportional relationship.

[2-4. Target regenerative braking torque estimation unit 23]
The target regenerative braking torque estimating unit 23 estimates and calculates a target regenerative braking torque (target regenerative braking torque) TC that is a target of the regenerative braking torque obtained by using the motor 14 as a generator. Specifically, in the present embodiment, the front wheel 11a is not connected to the motor 14, the regenerative braking torque cannot be obtained from the front wheel 11a side, and the regenerative braking torque can be obtained only from the rear wheel 11b side. . That is, the front wheel side ideal braking torque TIF and the front wheel side mechanical braking torque TmF always have the same value. Therefore, the target regenerative braking torque estimating unit 23 calculates the rear wheel side ideal braking torque TIR and the rear wheel side mechanical braking torque TmR. The difference is calculated as the target regenerative braking torque TC.

[2-5. Regenerative braking control unit 2]
Each of the regenerative braking control units 2 includes an ideal deceleration estimation unit 26 and a target regenerative braking torque correction unit 27 as subprograms.
The ideal deceleration estimation unit 26 applies the front wheel side ideal braking torque TIF obtained by the above equation (5) to the front wheel 11a and the rear wheel side ideal braking torque TIR obtained by the above equation (7). When acting on the rear wheel 11b, an ideal deceleration GX, which is a deceleration generated in the electric vehicle 10, is estimated. The ideal deceleration GX is defined as the same curve as the ideal braking torque curve C shown in FIG.

  In this ideal braking torque map 30, the intersection Z between the mechanical braking torque straight line B and the ideal braking torque curve C is called “Zet critical” by some persons skilled in the art. In the zet critical Z, the front wheel side ideal braking torque TIF and the front wheel side mechanical braking torque TmF have the same value, and the rear wheel side ideal braking torque TIR and the rear wheel side mechanical braking torque TmR have the same value. In other words, the zet critical Z is a point that defines the front wheel side mechanical braking torque TmF and the rear wheel side mechanical braking torque TmR in which the target regenerative braking torque TC becomes 0 and the regenerative braking torque cannot be obtained.

Further, the zet critical Z is determined by the inclination of the mechanical braking torque straight line B. Then, as the inclination of the mechanical braking torque line B is smaller, the value of the ideal deceleration GX at the zet critical Z is increased, and as a result, the target regenerative braking torque TC is also increased.
Here, the inclination of the mechanical braking torque straight line B is determined in a range not exceeding the deceleration (about 2.4 in the present embodiment) when the maximum value of the regenerative braking torque of the motor generator 14 is reached. . In this embodiment, in order to increase the target regenerative braking torque TC, the mechanical braking torque straight line B is set so that the ideal deceleration GX at the zet critical Z is 1.1. In a general vehicle, the setting range of the mechanical braking torque line B is set so that the ideal deceleration GX at the mechanical braking torque is about 0.5 to 0.8.

  Further, as shown in FIG. 7, a correction map 31 describing a correspondence relationship between the deceleration difference GXR between the ideal deceleration GX and the braking deceleration GR and the load correction coefficient Kw is recorded in the memory of the EV ECU 3. . In the correction map 31, when the absolute value | GXR | of the deceleration difference GXR exceeds a predetermined range ΔG, a load correction coefficient Kw is read by a target regenerative braking torque correction unit 27 described later. .

The target regenerative braking torque correction unit 27 calculates the above-described deceleration difference GXR (that is, the difference between the ideal deceleration GX and the braking deceleration GR), and applies this deceleration difference GXR to the correction map 31. The load correction coefficient Kw is obtained.
Further, the front and rear wheel side ideal braking torque estimation units 19 and 20 have the load corrected vehicle total weight W _c calculated by the target regenerative braking torque estimation unit 23, the load corrected front axle weight WF _c , and the load corrected By substituting the rear axle weight WR _c into the total vehicle weight W, the front axle weight WF, and the rear axle weight WR in the above formulas (1) and (3), the front and rear wheel side ideal braking force BF _c after the load correction is performed. , BR _c are calculated. Further, the front and rear wheel side ideal braking torque estimation units 19 and 20 apply the front and rear wheel side ideal braking forces BF _c and BR _c after load correction to the above formulas (2) and (4), respectively, so that The front and rear wheel side ideal braking torques TIF _c and TIR _c are calculated. Therefore, based on the load correction coefficient Kw calculated by the target regenerative braking torque correction unit 27, the values of the front and rear wheel side ideal braking torques TIF and TIR are corrected, and further, correction control of the target regenerative braking torque TC is performed. It will be.

[3. flowchart]
A control procedure in the regenerative braking control device will be described with reference to FIG. This flow is repeatedly performed at a predetermined cycle set in advance.
First, in step A10, it is determined whether or not the ignition switch is operated by the EV ECU 3, and if it is operated, the process proceeds to step A20. On the other hand, if the ignition switch is not operated, the process returns to step A10 again.

In step A20, the vehicle speed V calculated by the ASCU 5 is read by the EV ECU 3. In step 30, the EVECU3, it is determined whether the vehicle speed V is the vehicle speed threshold V _th is, the process proceeds to step A40 if the vehicle speed V is the vehicle speed threshold V _th. On the other hand, when the vehicle speed V is not the vehicle speed threshold value _Vth , the process returns to step A10. Note that the vehicle speed threshold value V _th is set to zero.

  In step A40, the output voltage of the front and rear axle vehicle height sensors 18a and 18b (that is, the front and rear axle vehicle heights h2 and h1) is read by the EV ECU 3. In subsequent step A50, the front axle weight calculation unit 24 calculates the front axle weight WF by applying the output voltage of the front axle vehicle height sensor 18a read in step A40 to the front axle vehicle weight map 29. Further, the rear axle weight calculation unit 25 calculates the rear axle weight WR by applying the output voltage of the rear axle vehicle height sensor 18b read in step A40 to the vehicle weight map 29, and also calculates the front axle weight WF and the rear axle weight WF. A value obtained by adding the shaft weights WR is calculated as the total vehicle weight W.

  In step A60, the brake pedal depression force sensor 17 determines whether or not the brake switch based on the brake pedal operation has been turned on. Here, if the brake switch is on, it means that the brake switch has been operated. In this case (Yes route of step A60), the process proceeds to step A70. On the other hand, when the brake pedal is not operated (No route of step A60), the process returns to step A10.

In step A70, the brake pedal depression force F detected by the brake pedal depression force sensor 17 and the braking deceleration GR detected by the acceleration sensor 1 are read by the EV ECU 3.
In Step A80, the front wheel side mechanical braking torque estimating unit 21 determines the brake pedal depression force F as a front wheel side mechanical braking torque map (second machine) that defines the relationship between the brake pedal depression force F and the front wheel side mechanical braking torque TmF. By applying the dynamic braking torque map; FIG. 3) 28, the front wheel side mechanical braking torque TmF is estimated. In addition, the rear wheel side mechanical braking torque estimating unit 22 determines the brake pedal depression force F, and the rear wheel side mechanical braking torque map (the first wheel braking force map) that defines the relationship between the brake pedal depression force F and the rear wheel side mechanical braking torque TmR. Mechanical braking torque map; FIG. 3) By applying to 28, the rear wheel side mechanical braking torque TmR is estimated.

  Thereafter, in step A90, the rear wheel side ideal braking torque estimation unit 20 has the front wheel side mechanical braking torque TmF equal to the front wheel side ideal braking torque TIF based on the front wheel side mechanical braking torque TmF set in step A80. The rear wheel side ideal braking torque TIR when (TmF = TIF) is estimated and calculated. Specifically, the rear wheel side ideal braking torque estimation unit 20 estimates and calculates the first ideal braking torque TIR by applying the front wheel side mechanical braking torque TmF to the ideal braking torque map 30 (see FIG. 6). .

In step A100, the target regenerative braking torque estimating unit 23 estimates and calculates the target regenerative braking torque TC (= TIR-TmR).
Thereafter, in step A110, the regenerative braking torque amount of the motor 14 is controlled by the target regenerative braking torque estimation unit 23 so as to be the target regenerative braking torque TC calculated in step A100.

In step A120, the ideal deceleration estimating unit 26 estimates and calculates an ideal deceleration GX that is a deceleration in the front wheel side ideal braking torque TIF and the rear wheel side ideal braking torque TIR.
Thereafter, in step A130, the target regenerative braking torque correction unit 27 reads the deceleration difference GXR (GX-GR). If the absolute value | GXR | of the deceleration difference GXR is equal to or greater than the predetermined range ΔG, the process proceeds to Step A140 (Yes route of Step A130). On the other hand, when the absolute value | GXR | of the deceleration difference GXR is smaller than the predetermined range ΔG, the process returns to Step A60 (No route of Step A130). This is because, as shown in FIG. 7, when | GXR | is within ΔG, Kw is 1.0, and correction of W, WF, and WR by this Kw is unnecessary.

In step A140, the target regenerative braking torque correction unit 27 reads the load correction coefficient Kw by applying the deceleration difference GXR to the correction map 31.
In subsequent step A150, the target regenerative braking torque correction unit 27 calculates the above-described formula (1), for the vehicle gross weight W, the front axle weight WF, and the rear axle weight WR based on the load correction coefficient Kw read in step A140. Correction control is performed using (2) and (3), and the process returns to step A60.

  As described above, the flow of steps A60 to A150 is repeated, so that the target regenerative braking torque TC is corrected, and the braking torque applied to the electric vehicle 10 is controlled within a range that does not feel uncomfortable for the driver. Is done.

[4. effect]
Thus, in the regenerative braking control device according to the present embodiment, the rear wheel side mechanical braking torque TmR is set smaller than the rear wheel side ideal braking torque TIR, and the target regenerative braking torque TC is set to the rear wheel side mechanical braking torque. The rear wheel side ideal braking torque TIR is subtracted from the braking torque TmR. Thereby, it is possible to increase the efficiency of regenerative power generation while reliably realizing the deceleration of the electric vehicle 10, and also when the braking of the electric vehicle 10 is performed with the maximum frictional force between the rear wheel 11b and the road surface, Since it is possible to reliably avoid the rear wheel 11b from being locked during deceleration, the regenerative braking control can be performed without causing the driver anxiety or discomfort.

In addition, by using the ideal braking torque map 30, the rear wheel side ideal braking torque TIR can be obtained quickly and reliably without complicated calculations.
Further, according to the regenerative braking control device, the rear wheel side ideal braking torque TIR and the front wheel side ideal braking torque TIF can be accurately obtained based on the braking deceleration GR, the front axle weight WF, and the rear axle weight WR. it can.

Further, by using the vehicle weight map 29, the front axle weight WF and the rear axle weight WR can be obtained quickly and reliably without performing complicated calculations.
Further, since the brake pedal depression force F that directly reflects the driver's intention to decelerate is directly detected, the brake hydraulic pressure of the front and rear wheel side mechanical brake devices 15a and 15b and the displacement amount of the caliper (not shown). It is possible to detect the driver's intention to decelerate at a timing earlier than that of detecting the front wheel, and the front wheel side mechanical braking torque TmF and the rear wheel side mechanical braking torque TmR can be estimated quickly and reliably. Further, by using the mechanical braking torque map 28, the front wheel side mechanical braking torque TmF and the rear wheel side mechanical braking torque TmR can be obtained quickly and reliably without performing complicated calculations.

Further, by setting the inclination of the mechanical braking torque straight line B so that the ideal deceleration GX at the zet critical Z is 1.1, the rear wheel side mechanical braking torque TmR and the rear wheel side ideal braking torque TIR are set. Can be made relatively large, and the regeneration efficiency can be increased.
In addition, the correction map 31 performs correction control of the target regenerative braking torque TC when the absolute value of the difference between the ideal deceleration GX and the braking deceleration GR is equal to or greater than a set predetermined range value ΔG. Therefore, when the difference between the ideal deceleration GX and the braking deceleration GR is small and it is not necessary to correct the front and rear wheel side ideal braking torques TIF and TIR, it is possible to prevent the correction control from being performed. A target regenerative braking torque suitable for 10 driving environments can be obtained quickly and reliably.

  In addition, since it is determined whether the ignition switch is on and whether the vehicle speed V is 0, regenerative braking is not required on the main body, such as when the electric vehicle 10 where people get on and off is stopped. It is possible to prevent the regenerative braking control from being performed at any time, that is, to carry out the regenerative braking control reliably at a necessary time.

[6. Others]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
In the embodiment described above, the brake pedal depression force F is directly detected by the brake pedal depression force sensor 17 in order to realize quick control. However, a brake fluid pressure sensor is used instead of the brake pedal depression force sensor 17. Is also possible. In that case, on the hydraulic piping connecting the brake master cylinder 8 and the H / U 16, the brake fluid pressure for detecting whether or not the brake pedal 9 is depressed and the brake fluid pressure in the master cylinder 8 caused by the depression of the brake pedal 9 are detected. A sensor (not shown) is interposed. The detection information here is input to the EV ECU 3.

  Moreover, although the above-mentioned embodiment demonstrated the case where the ideal deceleration GX in the zet critical Z was set to 1.1, it is not limited to this. For example, as shown in FIG. 6, the mechanical braking torque straight line B can be appropriately set within a range not exceeding the deceleration when the regenerative braking torque of the motor generator becomes maximum. This is because the regenerative braking torque of the motor 14 can be obtained in any mechanical braking torque setting range as long as the target regenerative braking torque TC does not become zero. In order to set the target regenerative braking torque TC higher, the zet critical Z is preferably 1.0 or more. More specifically, in the specification of the motor generator 14 in the present embodiment, the deceleration when the maximum value of the regenerative braking torque is 2.4 is 2.4. Therefore, the zet critical Z is 1.0 to 2.4. It will be set in the range.

In the above-described embodiment, the value of the vehicle speed threshold value V _th is set to 0, but the value is not limited to this value. In other words, the vehicle speed threshold value V _th is a value provided to prevent the regenerative braking control from being performed when a person gets on and off, that is, when the electric vehicle 10 is stopped. Any value that can be determined is acceptable.
In the above-described embodiment, the rear-wheel drive electric vehicle has been described. However, the present invention can be applied to both a front-wheel drive electric vehicle and a four-wheel drive electric vehicle.

  The present invention can be used in the vehicle manufacturing industry.

1 Accelerometer (actual deceleration detection means)
2 Regenerative braking control unit (regenerative braking control means)
10 Electric car (electric car)
11a Front wheel (front wheel)
11b Rear wheel (rear wheel, drive wheel)
13 Speed sensor (vehicle speed detection means)
14 Motor (motor generator)
15a Front wheel side mechanical brake device (second friction braking device)
15b Rear wheel side mechanical brake device (first friction braking device)
17 Brake pedal depression force sensor (brake pedal depression force detection means)
18a Front axle height sensor (second vehicle height detection means)
18b Rear axle height sensor (first vehicle height detection means)
19 Front wheel side ideal braking torque estimating section (second ideal braking torque estimating means)
20 Rear wheel side ideal braking torque estimating section (first ideal braking torque estimating means)
21 Front wheel side mechanical braking torque estimating section (second mechanical braking torque setting means)
22 Rear wheel side mechanical braking torque estimating section (first mechanical braking torque setting means)
23 target regenerative braking torque estimating unit (target regenerative braking torque estimating means)
24 Front axle weight calculation unit (second weight calculation means)
25 Rear axle weight calculation unit (first weight calculation means)
26 Ideal deceleration estimation unit (ideal deceleration estimation means)
27 Target regenerative braking torque correction unit (target regenerative braking torque correction means)
28 Mechanical braking torque map (first mechanical braking torque map, second mechanical braking torque map)
29 Weight map (1st weight map, 2nd weight map)
GR braking deceleration (actual deceleration)
GX Ideal deceleration (ideal deceleration)
WF Front axle weight (2nd vehicle weight)
WR Rear axle weight (first vehicle weight)
h2 Front axle height (second height)
h1 Rear axle height (first vehicle height)
V Vehicle speed (vehicle speed)
_Vth vehicle speed threshold (vehicle speed threshold)
F Brake pedal effort (brake pedal effort)
TC Target regenerative braking torque (Target regenerative braking torque)
TIF Front wheel side ideal braking torque (2nd ideal braking torque)
TIR Rear wheel side ideal braking torque (first ideal braking torque)
TmF Front wheel side mechanical braking torque (second mechanical braking torque)
TmR Rear wheel side mechanical braking torque (first mechanical braking torque)

Claims (8)

A regenerative braking control device for an electric vehicle,
A motor generator connected to the drive wheels of the electric vehicle;
A first friction braking device for mechanically braking the drive wheel;
First ideal braking torque estimating means for estimating a first ideal braking torque that is a braking torque when it is assumed that braking of the driving wheel is performed with a maximum frictional force between the road surface and the driving wheel;
First mechanical braking torque estimating means for estimating a mechanical braking torque by the first friction braking device as a first mechanical braking torque;
Target regenerative braking torque estimating means for estimating a target of regenerative braking torque obtained by using the motor generator as a generator as a target regenerative braking torque;
Regenerative braking control means for executing regenerative braking control for adjusting the regenerative braking torque by the motor generator within the range of the target regenerative braking torque,
The first mechanical braking torque estimating means includes
Setting the first mechanical braking torque to be smaller than the first ideal braking torque;
The target regenerative braking torque estimation means includes:
The difference between the first ideal braking torque estimated by the first ideal braking torque estimating means and the first mechanical braking torque estimated by the first mechanical braking torque estimating means is used as the target regenerative braking torque. A regenerative braking control device for an electric vehicle, characterized by: A rear wheel as the drive wheel;
A second friction braking device for mechanically braking the front wheels of the electric vehicle;
Second ideal braking torque estimating means for estimating a second ideal braking torque that is a braking torque when it is assumed that braking of the front wheel is performed with a maximum frictional force between the road surface and the front wheel;
An ideal braking torque map that defines a relationship between the first ideal braking torque and the second ideal braking torque;
The first ideal braking torque estimating means includes:
The electric power according to claim 1, wherein the first ideal braking torque is estimated by applying the second ideal braking torque estimated by the second ideal braking torque estimating means to the ideal braking torque map. A regenerative braking control device for automobiles. An actual deceleration detecting means for detecting an actual deceleration of the electric vehicle;
First vehicle weight calculation means for estimating the vehicle weight of the electric vehicle supported by the rear wheel as a first vehicle weight;
A second vehicle weight calculation means for estimating the weight of the electric vehicle supported by the front wheel as a second vehicle weight;
The first ideal braking torque estimating means includes:
The actual deceleration detected by the actual deceleration detecting means, the first vehicle weight estimated by the first vehicle weight calculating means, and the second vehicle weight estimated by the second vehicle weight calculating means. Based on the first ideal braking torque,
The second ideal braking torque estimating means includes:
The actual deceleration detected by the actual deceleration detecting means, the first vehicle weight estimated by the first vehicle weight calculating means, and the second vehicle weight estimated by the second vehicle weight calculating means. The regenerative braking control device for an electric vehicle according to claim 2, wherein the second ideal braking torque is estimated based on the second ideal braking torque. First vehicle height detection means for detecting the vehicle height of the electric vehicle on the rear wheel side as a first vehicle height;
Second vehicle height detection means for detecting the vehicle height of the electric vehicle on the front wheel side as a second vehicle height;
A first vehicle weight map defining a relationship between the first vehicle height and the first vehicle weight;
A second vehicle weight map defining a relationship between the second vehicle height and the second vehicle weight;
The first vehicle weight calculation means includes:
Calculating the first vehicle weight by applying the first vehicle height detected by the first vehicle height detection means to the first vehicle weight map;
The second vehicle weight calculation means includes:
4. The regeneration of an electric vehicle according to claim 3, wherein the second vehicle weight is calculated by applying the second vehicle height detected by the second vehicle height detection means to the second vehicle weight map. Braking control device. Second mechanical braking torque estimating means for estimating a mechanical braking torque by the second friction braking device as a second mechanical braking torque;
Brake pedal depressing force detecting means for detecting the depressing force of the brake pedal of the vehicle;
A first mechanical braking torque map defining a relationship between the brake pedal depression force and the first mechanical braking torque;
A second mechanical braking torque map defining a relationship between the brake pedal depression force and the second mechanical braking torque;
The second mechanical braking torque estimating means includes
Calculating the second mechanical braking torque by applying the brake pedal pressing force detected by the brake pedal pressing force detecting means to the second mechanical braking torque map;
The first mechanical braking torque estimating means includes
5. The first mechanical braking torque is calculated by applying the brake pedal pressing force detected by the brake pedal pressing force detecting means to the first mechanical braking torque map. The regenerative braking control device for an electric vehicle according to claim 1. In the first mechanical braking torque map and the second mechanical braking torque map,
The deceleration when the first mechanical braking torque and the first ideal braking torque have the same value and the second mechanical braking torque and the second ideal braking torque have the same value is the regenerative braking torque of the motor generator. The electric vehicle according to claim 5, wherein a relationship between the first mechanical braking torque and the second mechanical braking torque is defined within a range not exceeding a deceleration in a case where the maximum value is. Regenerative braking control device. The regenerative braking control means includes
Ideal deceleration estimating means for estimating an ideal deceleration that is a deceleration generated in the vehicle when braking is performed with the first ideal braking torque and the second ideal braking torque;
When the absolute value of the difference between the ideal deceleration detected by the ideal deceleration estimation unit and the actual deceleration detected by the actual deceleration detection unit deviates from a set predetermined range, The regenerative braking control device for an electric vehicle according to any one of claims 1 to 6, further comprising target regenerative braking torque correction means for performing correction control for correcting the target regenerative braking torque. The regenerative braking control means includes
Vehicle speed detecting means for detecting the vehicle speed of the electric vehicle,
The regenerative braking of an electric vehicle according to any one of claims 1 to 7, wherein regenerative braking control is performed when the vehicle speed detected by the vehicle speed detecting means is not a set vehicle speed threshold value. Control device.

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