JP2009303342A - Electric vehicle, and method of controlling electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate appropriate braking force not uncomfortable to a driver in a vehicle with the accelerator or brake of the vehicle not operated when the vehicle is running on a gentle down slope. <P>SOLUTION: When the operating state of the vehicle's accelerator and that of the brake are off-state, a target torque determining means 5 that determines a target torque of an electric motor 2 carries out the following processing: when the inclination of a road surface grasped by an inclination grasping means 24 is a down slope grade and is gentle and its magnitude is smaller than a predetermined value, the target torque determining means determines a target torque so that regenerative torque with a target torque smaller than when the inclination is zero is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric vehicle including an electric motor as a driving power source and a regeneration control method for the electric vehicle.

In an electric vehicle in which an electric motor is mounted on a vehicle as a driving power source, regenerative braking of the electric motor is performed in a state where the accelerator pedal and the brake pedal are not operated, as seen in, for example, Patent Document 1 or Patent Document 2. This is known. In Patent Document 1 or Patent Document 2, the basic regeneration amount set by the regeneration amount adjustment switch is set to a reference gain that is set according to the rotation speed of the electric motor, and an increase / decrease gain that is set according to the gradient of the road surface. In addition, a technique is disclosed in which the regeneration amount of the electric motor is determined by multiplying the regenerative gain corresponding to the engine brake obtained by adding the above and the regenerative operation of the electric motor with the regeneration amount. In this case, in the techniques shown in Patent Documents 1 and 2, when the road surface has a slope near 0 (when the road surface is a flat road surface or a gentle road surface), the increase / decrease gain is set to 0 and the road surface is flat. The regenerative amount of the electric motor is made the same on the road surface and the gentle slope road surface.
PCT International Publication No. WO97 / 10966 Japanese Patent No. 3263844

  In the techniques shown in Patent Documents 1 and 2, when the operation of the accelerator pedal of the vehicle is canceled when traveling on a gentle slope downhill, the same as when traveling on a flat road by regenerative braking of the electric motor. A braking force acts on the vehicle.

  For this reason, the techniques found in Patent Documents 1 and 2 have the following disadvantages.

  That is, when the vehicle is traveling on a downhill road, when the accelerator operation of the vehicle is released, the driver empirically increases the speed of the vehicle by the action of gravity unless he / she intentionally operates the brake. I have a recognition that it is easy to do.

  However, on a gentle slope downhill road, the component of gravity acting on the vehicle in the direction parallel to the road surface is very small, so if the regenerative braking force of the electric motor acts on the vehicle in the same way as a flat road, the driver The degree of deceleration of the vehicle experienced by the vehicle becomes substantially the same as the degree of deceleration on a flat road. For this reason, in the techniques shown in Patent Documents 1 and 2, when the operation of the accelerator pedal is released during traveling on a gentle slope downhill, the braking force of the vehicle experienced by the driver becomes the braking force expected by the driver. There was the inconvenience that it felt stronger.

  Further, in the techniques disclosed in Patent Documents 1 and 2, the increase / decrease gain is uniquely determined according to the road gradient. For this reason, the road surface gradient is the same due to differences in disturbance factors such as the wind direction that the wind blows on the vehicle is a headwind or a tailwind, and the number of passengers in the vehicle (and hence the weight of the vehicle). However, it is easy to produce the dispersion | variation in the acceleration of the advancing direction of the vehicle which generate | occur | produces at the time of the regenerative driving | operation of an electric motor. As a result, there was a disadvantage that the driver himself / herself frequently operated the brake and the accelerator to adjust the vehicle speed.

  The present invention has been made in view of such a background, and an appropriate braking force that does not cause a sense of incongruity to the driver when the vehicle is traveling on a downhill road on a gentle slope and the accelerator or brake of the vehicle is not operated. It is an object of the present invention to provide an electric vehicle and a control method capable of generating the vehicle. In addition, when driving an electric vehicle on a downhill road, the electric motor is regenerated so that the vehicle can generate an acceleration suitable for the road gradient while reducing the influence of disturbance factors such as the wind direction and the number of passengers. An object is to provide an electric vehicle and a control method capable of driving.

  In order to achieve the above object, the electric vehicle of the present invention is an electric vehicle provided with an electric motor capable of selectively outputting drive torque and regenerative torque as a driving power source. Gradient grasping means for grasping, and target torque determining means for determining the target torque of the electric motor so that the target torque of the electric motor becomes the regenerative torque when the accelerator operation state of the vehicle is in an off state, Motor control means for controlling energization of the electric motor so that the output torque of the target torque is generated in the electric motor, and the target torque determining means is configured to determine whether an operation state of an accelerator of a vehicle and an operation state of a brake are In the off state, the slope grasped by the slope grasping means is a slope of a downhill road, and the magnitude of the slope is predetermined. If the predetermined torque is smaller than the predetermined value, the target torque is determined so that the target torque becomes a regenerative torque having a smaller magnitude than when the gradient grasped by the gradient grasping means is zero. (First invention). In the present specification, the fact that the slope of the road surface is 0 means that the road surface is a horizontal flat road.

  According to the first aspect of the invention, when the accelerator operating state and the brake operating state of the vehicle are in the off state, the target torque determined by the target torque determining means, and thus the output torque generated by the electric motor is When the slope grasped by the slope grasping means is a slope of a downhill road and the magnitude of the slope is smaller than a predetermined value (that is, the road surface on which the vehicle is traveling is a gentle slope) In the case of a slope, the regenerative torque is smaller than that in the case where the gradient grasped by the gradient grasping means is zero (that is, when the road surface on which the vehicle is traveling is a horizontal flat road). . For this reason, the vehicle braking force generated by the output torque generated by the electric motor when the accelerator operating state and the brake operating state are turned off when traveling on a gentle slope downhill road, When the vehicle is traveling at, the braking force is weaker than the braking force of the vehicle generated by the output torque generated by the electric motor when the accelerator operating state and the brake operating state are turned off. This allows the driver to experience the braking force of the vehicle (equivalent to an engine brake) when the accelerator operation state and the brake operation state of the vehicle are turned off during traveling on a gentle slope downhill. (Braking force) can be prevented from feeling too strong. Accordingly, it is possible to generate an appropriate braking force on the vehicle that does not give the driver a sense of incongruity when traveling on a gentle slope downhill.

  In the first aspect of the invention, the target torque determining means is configured so that the slope grasped by the slope grasping means is a slope of a downhill road when the accelerator operating state and the brake operating state of the vehicle are in an off state. When the magnitude of the gradient is larger than the predetermined value, the target torque becomes a regenerative torque having a larger magnitude than when the gradient grasped by the gradient grasping means is zero. Thus, it is preferable to determine the target torque (second invention).

  According to the second aspect of the present invention, when the accelerator operation state and the brake operation state of the vehicle are in the off state, the road surface on which the vehicle is traveling is a downhill road having a gradient magnitude greater than the predetermined value. In some cases, the target torque determined by the target torque determining means, and thus the output torque generated by the electric motor, is when the road surface on which the vehicle is traveling is a flat flat road (the road surface has a slope of 0). The regenerative torque is larger than that in the case). For this reason, the driver feels uncomfortable when the accelerator operation state and the brake operation state of the vehicle are turned off during traveling on a normal downhill road where the magnitude of the gradient is larger than the predetermined value. It is possible to suppress the vehicle speed from increasing in a short time while experiencing an appropriate braking force. As a result, the frequency of the driver's brake operation can be reduced.

  In the first aspect of the invention, a basic target torque of the electric motor, which is a regenerative torque when the operation state of the accelerator of the vehicle is in an off state, is determined according to the operation state of the accelerator. Basic target torque determining means, target acceleration determining means for determining a target acceleration of the vehicle when the vehicle is traveling on a downhill road according to a road surface gradient grasped by the gradient grasping means, and an actual vehicle It is preferable to provide actual acceleration grasping means for grasping actual acceleration that is acceleration. In this case, the target acceleration determining means is configured such that the slope grasped by the slope grasping means is a slope of a downhill road when the accelerator operating state and the brake operating state of the vehicle are off. And when the magnitude of the gradient is smaller than the predetermined value, it is assumed that the vehicle has traveled on the downhill road in a state where the output torque of the basic target torque is generated in the electric motor. Preferably, the target acceleration is determined so as to suppress the deceleration of the vehicle more than the acceleration generated in the vehicle. Further, the target torque determining means is configured such that the basic target torque is determined when the gradient grasped by the gradient grasping means is 0 when the accelerator operation state and the brake operation state of the vehicle are off. The basic target torque determined by the determining means is determined as the target torque, and when the gradient grasped by the gradient grasping means is a downhill slope, the actual acceleration grasped by the actual acceleration grasping means is determined. Preferably, the target torque is determined by correcting the basic target torque in accordance with the actual acceleration and the target acceleration so as to approach the target acceleration determined by the target acceleration determining means (third invention).

  According to the third aspect of the invention, when the accelerator operating state and the brake operating state are in an off state when the vehicle is traveling on a horizontal flat road, the target torque determined by the target torque determining means, As a result, the output torque generated by the electric motor becomes the basic target torque. On the other hand, if the accelerator operation state and the brake operation state are in the off state when the vehicle is traveling on the downhill road, the target torque determined by the target torque determining means is the actual acceleration of the vehicle. It is determined by correcting the basic target torque in accordance with the actual acceleration and the target acceleration so as to approach the target acceleration determined by the determining means. For this reason, the target torque of the electric motor, and hence the output torque, is feedback-controlled so that the actual acceleration approaches the target acceleration.

  In this case, when the vehicle is traveling on a downhill road, when the accelerator operating state and the brake operating state of the vehicle are in an off state, the target acceleration determined by the target acceleration determining means has a gradient magnitude. When the vehicle is traveling on a downhill road having a gentle slope smaller than the predetermined value, the output torque of the basic target torque is generated by the electric motor (that is, when the vehicle is traveling on a horizontal flat road) When the vehicle travels on the downhill road in a state where the electric motor generates a regenerative torque equivalent to the regenerative torque generated in the electric motor), the vehicle is decelerated more than the acceleration generated in the vehicle. It becomes the acceleration to suppress.

  Therefore, when the vehicle is traveling on a downhill road, when the accelerator operation state and the brake operation state are in an off state, the slope of the downhill road is a gentle slope smaller than the predetermined value. As a result, the target torque, and consequently the output torque generated by the electric motor, is a regenerative torque having a smaller magnitude than when the road surface on which the vehicle is traveling is a flat flat road. As a result, as described in relation to the first aspect of the invention, when traveling on a gentle slope downhill road, when the accelerator operation state and the brake operation state of the vehicle are turned off, the driver can experience it, It is possible to prevent the vehicle's braking force (braking force equivalent to engine braking) from being felt too strong.

  In addition, in the third aspect of the invention, when the vehicle is traveling on the downhill road, the target torque of the electric motor is feedback-controlled so that the actual acceleration of the vehicle approaches the target acceleration as described above. When the vehicle is traveling, the actual acceleration itself of the vehicle can be controlled to a target acceleration as a desired acceleration. As a result, when the vehicle is traveling on the downhill road, it is possible to cause the vehicle to generate acceleration suitable for the road surface gradient while reducing the influence of disturbance factors such as the wind direction and the number of passengers of the vehicle.

  In the third aspect of the invention, the target acceleration determining means is that the slope grasped by the slope grasping means is a slope of a downhill road when the accelerator operating state and the brake operating state of the vehicle are in an off state. In addition, when the magnitude of the gradient is larger than the predetermined value, it is assumed that the vehicle has traveled on the downhill road in a state where the output torque of the basic target torque is generated in the electric motor. In this case, it is preferable to determine the target acceleration so as to suppress the acceleration of the vehicle rather than the acceleration generated in the vehicle (fourth invention).

  According to the fourth aspect of the present invention, when the accelerator operation state and the brake operation state are OFF when the vehicle is traveling on the downhill road, the gradient of the downhill road is larger than the predetermined value. In this case, since the target acceleration is determined as described above, the target torque determined by the target torque determining means, and hence the output torque generated by the electric motor, is as a result that the road surface on which the vehicle is traveling is horizontal. The regenerative torque is larger than when the road is flat. As a result, as in the case of the second aspect of the invention, the accelerator operation state and the brake operation state of the vehicle are turned off during traveling on a normal downhill road where the magnitude of the gradient is larger than the predetermined value. In this case, it is possible to suppress the vehicle speed from increasing in a short time while allowing the driver to experience an appropriate braking force without causing a sense of incongruity. As a result, the frequency of the driver's brake operation can be reduced.

  In the fourth aspect of the invention, the target acceleration determined by the target acceleration determining means when the accelerator operating state and the brake operating state of the vehicle are in the off state is such that the gradient grasped by the gradient grasping means is a downhill road And the magnitude of the gradient is smaller than the predetermined value, it is an acceleration for decelerating the vehicle or an acceleration of 0, the gradient is a slope of a downhill road, and the When the magnitude of the gradient is larger than the predetermined value, it is preferable that the acceleration is an acceleration for accelerating the vehicle (fifth invention).

  According to the fifth aspect of the invention, when the vehicle is traveling on the downhill road, when the accelerator operation state and the brake operation state are in the off state, the downhill slope is smaller than a predetermined value. In this case, a braking force that does not increase the vehicle speed (a braking force that is substantially balanced with the traveling direction component of the vehicle in the gravity acting on the vehicle or larger than the traveling direction component). Occurs in the vehicle. Further, when the slope of the downhill road is a normal slope larger than a predetermined value, the braking force that allows the vehicle speed to be increased by the traveling direction component of the vehicle among the gravity acting on the vehicle is Occurs. For this reason, it is possible to cause the vehicle to generate a suitable braking force that does not feel uncomfortable for the driver.

  In order to achieve the above object, the regeneration control method for an electric vehicle according to the present invention is a downhill road of an electric vehicle provided with an electric motor capable of selectively outputting drive torque and regenerative torque as a driving power source. Determining the target torque of the electric motor so that the target torque of the electric motor becomes the regenerative torque when the operation state of the accelerator of the vehicle is in an off state. Controlling the energization of the electric motor so that the output torque of the target torque is generated in the electric motor, and the step of determining the target torque includes the accelerator of the vehicle when the vehicle is traveling on a downhill road When the operating state of the brake and the operating state of the brake are in the off state, the magnitude of the slope of the downhill road is smaller than a predetermined value , Than the gradient of 該降 slope is zero, the target torque so that the regenerative torque of magnitude smaller, and determines the target torque (sixth invention).

  According to the sixth aspect of the invention, when the accelerator operation state and the brake operation state of the vehicle are in the off state, the road surface on which the vehicle is traveling has a gentle gradient whose gradient is smaller than the predetermined value. In the case of a downhill road, the target torque of the electric motor is determined as in the first aspect of the invention. For this reason, as in the first aspect of the invention, when traveling on a gentle slope downhill road, when the accelerator operation state and the brake operation state of the vehicle are turned off, the driver can experience the vehicle It is possible to prevent the braking force (braking force equivalent to engine braking) from being felt too strong. Accordingly, it is possible to generate an appropriate braking force on the vehicle that does not give the driver a sense of incongruity when traveling on a gentle slope downhill.

  In the sixth aspect of the present invention, the step of determining the target torque includes the step of determining the slope of the downhill road when the accelerator operation state and the brake operation state of the vehicle are off when the vehicle travels on the downhill road. Is larger than the predetermined value, the target torque is set so that the target torque becomes a larger regenerative torque than when the slope of the downhill road is zero. It is preferable to determine (seventh invention).

  According to the sixth aspect of the present invention, when the accelerator operating state and the brake operating state of the vehicle are in the off state, the road surface on which the vehicle is traveling is a downhill road whose slope is larger than the predetermined value. In some cases, the target torque of the electric motor is determined as in the second invention. Therefore, as in the case of the second invention, when the accelerator operation state and the brake operation state of the vehicle are turned off during traveling on a normal downhill road where the magnitude of the gradient is larger than the predetermined value. In addition, it is possible to suppress the vehicle speed from increasing in a short time while allowing the driver to experience an appropriate braking force without any sense of incongruity. As a result, the frequency of the driver's brake operation can be reduced.

  In the sixth aspect of the invention, the basic target torque that is the basic target torque of the electric motor and that is the regenerative torque when the operation state of the accelerator of the vehicle is OFF is determined according to the operation state of the accelerator. And a step of determining a target acceleration of the vehicle when the vehicle travels on a downhill road according to a road surface gradient. In this case, the step of determining the target acceleration includes the step of determining the magnitude of the road surface gradient when the accelerator operation state and the brake operation state of the vehicle are off when the vehicle travels on a downhill road. Is smaller than the predetermined value, the acceleration generated in the vehicle when it is assumed that the vehicle has traveled on the downhill road in a state where the output torque of the basic target torque is generated in the electric motor. It is preferable that the target acceleration be determined so as to suppress deceleration of the vehicle. In the step of determining the target torque, the basic target torque is determined when the vehicle is traveling on a flat road having a gradient of 0 when the accelerator operation state and the brake operation state of the vehicle are off. By determining the target torque and correcting the basic target torque in accordance with the actual acceleration and the target acceleration so that the actual acceleration approaches the target acceleration when the vehicle is traveling on a downhill road, the target torque is corrected. Is preferably determined (eighth invention).

  According to the eighth aspect, similar to the third aspect, the target acceleration of the vehicle and the target torque of the electric motor when traveling on the downhill road are determined. As a result, as in the third aspect of the invention, when the vehicle's accelerator operation state and brake operation state are turned off during traveling on a gentle slope downhill, the driver can experience the vehicle It is possible to prevent the braking force (braking force equivalent to engine braking) from being felt too strong. In addition, when the vehicle is traveling on a downhill road, it is possible to cause the vehicle to generate acceleration suitable for the road surface gradient while reducing the influence of disturbance factors such as the wind direction and the number of passengers of the vehicle.

  In the eighth aspect of the invention, the step of determining the target acceleration includes the step of determining the target surface acceleration when the accelerator operating state and the brake operating state of the vehicle are off when the vehicle is traveling on a downhill road. When the magnitude of the gradient is larger than the predetermined value, the vehicle is assumed to have traveled on the downhill road in a state where the output torque of the basic target torque is generated in the electric motor. Preferably, the target acceleration is determined so as to suppress the acceleration of the vehicle from the generated acceleration (the ninth invention).

  According to the ninth aspect of the present invention, when the accelerator operation state and the brake operation state are OFF when the vehicle is traveling on the downhill road, the gradient of the downhill road is larger than the predetermined value. In this case, the target acceleration is determined as in the fourth invention. For this reason, as in the case of the fourth invention, when the accelerator operation state and the brake operation state of the vehicle are turned off while traveling on a normal downhill road where the magnitude of the gradient is larger than the predetermined value. In addition, it is possible to suppress the vehicle speed from increasing in a short time while allowing the driver to experience an appropriate braking force without any sense of incongruity. As a result, the frequency of the driver's brake operation can be reduced.

  Further, in the ninth aspect, the target acceleration determined in the step of determining the target acceleration when the operation state of the accelerator of the vehicle and the operation state of the brake are in the off state is grasped by the gradient grasping means. If the slope is a slope of a downhill road and the magnitude of the slope is smaller than the predetermined value, it is an acceleration for decelerating the vehicle or an acceleration of 0, and the slope is a slope of the downhill road. In addition, when the magnitude of the gradient is larger than the predetermined value, the acceleration is preferably an acceleration for increasing the speed of the vehicle (a tenth aspect of the invention).

  According to the tenth aspect, similar to the fifth aspect, the target acceleration at the time of traveling of the vehicle on the downhill road is determined. As a result, when the vehicle travels on the downhill road, the braking force of the vehicle is generated as in the fifth aspect of the invention. For this reason, it is possible to cause the vehicle to generate a suitable braking force that does not feel uncomfortable for the driver.

  In the second or seventh aspect of the invention, the target torque, which is the regenerative torque, is increased as the slope of the downhill road where the vehicle is traveling is larger than the predetermined value. It is desirable to determine the torque. Thereby, the braking force of the vehicle suitable for the magnitude of the gradient of the downhill road can be generated.

  In the fourth or ninth invention, the target acceleration is set so that the target acceleration is increased in the vehicle speed increasing direction as the gradient of the downhill road where the vehicle is traveling is larger than the predetermined value. It is desirable to decide. As a result, the vehicle can be driven with the braking force and acceleration of the vehicle suitable for the magnitude of the gradient of the downhill road.

  An embodiment of the present invention will be described with reference to FIGS. First, an overall system configuration of the electric vehicle according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing the system configuration.

  As shown in FIG. 1, an electric vehicle 1 according to the present embodiment (hereinafter simply referred to as a vehicle 1) includes an electric motor 2 as a driving power source, a fuel cell 3 as a power source of the electric motor 2, and A battery 4, a vehicle control unit 5 that sequentially determines a target torque that is a target value of an output torque of the electric motor 2, a motor control unit 6 that controls energization of the electric motor 2 in accordance with the target torque, and a vehicle 1 The electric motor 2 or not shown so that the wheel speed of each wheel (the rotation speed of each wheel or the vehicle speed converted value of the rotation speed) is matched with the actual vehicle speed of the vehicle 1 (so as to prevent slipping of each wheel). And a wheel speed control device 7 for adjusting a driving force or a braking force applied to each wheel of the vehicle 1 from the brake device.

  The output shaft 2a of the electric motor 2 is connected to drive wheels 9 and 9 (two front wheels or two rear wheels in the illustrated example) via a power transmission mechanism 8 including a transmission, a differential gear device, and the like. The output torque of the electric motor 2 is transmitted to the drive wheels 9 through the power transmission mechanism 8. The drive wheels 9, 9 are two front wheels or rear wheels in the illustrated example, but both the front wheels and the rear wheels may be drive wheels.

  The electric motor 2 has an armature winding (not shown) electrically connected to the fuel cell 3 and the battery 4 via a power drive unit 10 (hereinafter referred to as PDU 10) and a power supply control unit 11 (hereinafter referred to as VCU 11). Connected.

  Here, the VCU 11 is an electronic circuit unit including a DC / DC converter (not shown) and the like, and a voltage (power supply voltage of the electric motor 2) supplied from the fuel cell 3 or the battery 4 to the PDU 10 is passed through the DC / DC converter. The battery 4 is charged with the electric power output from the fuel cell 3, or the electric power generated from the electric motor 2 through the PDU 10 is charged into the battery 4 during the regenerative operation of the electric motor 2. It has a function.

  The PDU 10 is an electronic circuit unit including an inverter circuit (not shown). The PDU 10 controls the on / off of each switch element of the inverter circuit according to a control command given from the motor control unit 6, thereby The battery 3 or the battery 4 and the electric motor 2 have a function of performing energization in both directions. The power running operation and regenerative operation of the electric motor 2 can be selectively performed by controlling the inverter circuit of the PDU 10. Here, the power running operation is an operation in which the electric motor 2 outputs a driving torque as a driving force from the output shaft 2 a to the driving wheels 9 and 9. During this powering operation, the inverter circuit of the PDU 10 is controlled so that the electric power of the fuel cell 3 or the battery 4 output from the VCU 11 is supplied to the electric motor 2. In addition, the regenerative operation is an operation in which the electric motor 2 generates power using the kinetic energy of the vehicle 1 transmitted from the drive wheels 9 and 9 side. During this regenerative operation, the inverter circuit of the PDU 10 is controlled so that the electric power generated by the electric motor 2 is output to the VCU 11 (and thus the battery 4 is charged via the VCU 11). During regenerative operation, the electric motor 2 outputs a regenerative torque that serves as a braking force to the drive wheels 9 and 9 from the output shaft 2a.

  The wheel speed control device 7 is configured by a known traction control system, antilock brake system, or a side-slip prevention device having a function in which these are integrated. Therefore, although detailed description in the present specification is omitted, the wheel speed control device 7 adjusts the output torque of the electric motor 2 in a situation where wheel slippage occurs or drives each drive from the electric motor 2. By adjusting the power distribution to the wheels 9, 9 via the power transmission mechanism 8, or adjusting the braking force of each wheel by the brake device or its distribution, the wheel speed of each wheel is matched with the actual vehicle speed. .

  The vehicle control unit 5 is an electronic circuit unit including a microcomputer and the like, and includes a vehicle speed sensor 12 (vehicle speed detection means) that detects the vehicle speed of the vehicle and an accelerator sensor 13 (accelerator operation detection that detects the operation state of the accelerator of the vehicle 1. Means) and a brake sensor 14 (brake operation detecting means) for detecting the operation state of the brake of the vehicle 1, each detection data is inputted. In this case, the accelerator sensor 13 detects an amount of depression of an accelerator pedal (not shown) of the vehicle 1 (hereinafter referred to as an accelerator operation amount), and outputs the detected value to the vehicle control unit 5 as detection data of an accelerator operation state. The brake sensor 14 detects a depression force (hereinafter referred to as a brake operation amount) of a brake pedal (not shown) of the vehicle 1 and outputs the detected value to the vehicle control unit 5 as detection data of a brake operation state.

  Supplementally, a state where the detected value of the accelerator operation amount = 0 is a state where the accelerator is not operated (accelerator is off), and a state where the detected value of the accelerator operation amount is not 0, This is a state where the accelerator is on (the accelerator is on). Therefore, the detected value of the accelerator operation amount also has a function as detection data of the accelerator on / off state. Similarly, the state where the detected value of the brake operation amount = 0 is a state where the brake is not operated (the brake is off), and the state where the detected value of the brake operation amount ≠ 0 is the state where the brake is operated. It is a state that has been made. Therefore, the detected value of the brake operation amount also has a function as detection data of the on / off state of the brake.

  Further, the vehicle control unit 5 has a wheel speed control on / off indicating whether or not the wheel speed control processing by the wheel speed control device 7 is being executed (whether or not the wheel speed control device 7 is operating). Data is input from the wheel speed control device 7. Hereinafter, a state in which the wheel speed control device 7 is operating and a state in which the wheel speed control device 7 is not operating are referred to as an on state and an off state, respectively.

  Then, the vehicle control unit 5 performs a process to be described later using the vehicle speed detection value, the accelerator operation amount detection value, the brake operation amount detection value, and the wheel speed control on / off data input as described above. The target torque of the electric motor 2 is sequentially determined by executing the calculation processing cycle. Note that the target torque of the electric motor 2 means the target drive torque when the electric motor 2 is in the power running operation, and means the target regenerative torque during the regenerative operation. In this embodiment, for the sake of convenience, the target drive torque is a positive value and the target regenerative torque is a negative value.

  Supplementally, the vehicle control unit 6 realizes the target torque determining means in the present invention by its function.

  The motor control unit 6 is an electronic circuit unit including a microcomputer and the like. The target torque of the electric motor 2 is input from the vehicle control unit 5, and the electric motor 2 is output from a rotation speed sensor 15 attached to the electric motor 2. The detected value of the rotational speed of the output shaft 2a (hereinafter referred to as motor rotational speed) is input. Then, using these input values, the motor control unit 6 determines an energization current of the armature winding for making the actual output torque of the electric motor 2 coincide with the target torque, and uses the determined energization current as an electric machine. A control command for the inverter circuit of the PDU 10 is generated so as to flow through the slave winding and output to the PDU 10. Thereby, the energization of the electric motor 2 is controlled so that the electric motor 2 generates the output torque of the target torque.

  The motor control unit 6 corresponds to the motor control means in the present invention.

  Supplementally, in the ON state of the wheel speed control device 7, the target torque of the electric motor 2 may be changed from the target torque determined by the vehicle control unit 5. In such a case, the motor control unit 6 controls energization of the armature winding of the electric motor 2 in accordance with the changed target torque.

  Next, more detailed functions of the vehicle control unit 5 will be described with reference to FIG. FIG. 2 is a block diagram showing main functions of the vehicle control unit 5. In addition, since the process of the vehicle control unit 5 is sequentially executed in a predetermined calculation processing cycle, in the following description, the variable value in the current (current) calculation processing cycle is set to the current value, the previous (previous) The variable value in the calculation processing cycle is sometimes referred to as the previous value. Further, in order to distinguish the current value from the previous value, subscripts (k) and (k−1) may be attached to each. “K” is an integer value that means time in a discrete time system.

  As a functional configuration, the vehicle control unit 5 has a basic target torque determination unit 21 that sequentially determines a basic target torque Trs, which is a basic required value of the target torque of the electric motor 2, according to the detected values of the vehicle speed and the accelerator operation amount. And a brake regeneration correction amount determination unit 22 that sequentially determines a brake regeneration correction amount ΔTrb (≦ 0), which is a correction amount of the regeneration torque of the electric motor 2, in accordance with a detected value of the brake operation amount. The basic target torque determination unit 21 corresponds to basic target torque determination means in the present invention.

  In this case, the basic target torque determination unit 21 determines the map (relationship between the vehicle speed, the accelerator operation amount, and the basic target torque) from the input vehicle speed (current value) and the detected value of the accelerator operation amount (current value). The basic target torque Trs is determined based on a map defining The basic target torque Trs is determined so as to be a drive torque (> 0) when the accelerator operation state is the on state. The basic target torque Trs as the drive torque is basically determined so that the greater the accelerator operation amount or the higher the vehicle speed, the greater the drive torque. Further, when the accelerator operating state is in the off state (including the case where the brake operating state is in the off state), the basic target torque Trs is determined to be a regenerative torque (<0) equivalent to the engine brake. Is done. The basic target torque Trs as the regenerative torque is a braking that causes the vehicle 1 to generate a relatively weak braking force that gently decelerates the vehicle 1 when the vehicle 1 is traveling on a flat road (horizontal road surface). Torque.

  In this embodiment, the basic target torque Trs is determined according to the detected value of the vehicle speed and the accelerator operation amount. However, the basic target torque Trs is determined only according to the detected value of the accelerator operation amount. Also good.

  Also, the brake regeneration correction amount determination unit 22 is based on a preset table (a table that defines the relationship between the brake operation amount and the brake regeneration correction amount) from the input brake operation amount detection value (current value). Thus, the brake regeneration correction amount ΔTrb is determined. The brake regeneration correction amount ΔTrb is added to the basic target torque Trs to correct the basic target torque Trs in the regeneration direction (in the negative direction). The brake regeneration correction amount ΔTrb is basically set so that the torque obtained by correcting the basic target torque Trs by the brake regeneration correction amount ΔTrb increases in the regeneration direction as the brake operation amount increases. It is determined. Note that the brake regeneration correction amount ΔTrb when the brake operation amount is 0 (when the brake is off) is determined to be 0.

  The vehicle control unit 5 further includes an acceleration calculation unit 23 that calculates (estimates) an actual acceleration Ar as an actual acceleration of the vehicle 1 (acceleration in the traveling direction of the vehicle), and a gradient of the road surface on which the vehicle 1 is traveling (vehicle 1) and a target in the traveling direction of the vehicle 1 when the brake and accelerator operation states are both off when the vehicle 1 travels on the downhill road. A target acceleration determining unit 25 that determines the acceleration Ac, and a downhill regenerative correction amount ΔTrd that is a correction amount of the regenerative torque of the electric motor 2 to bring the actual acceleration Ar closer to the target acceleration Ac when the vehicle 1 travels on the downhill road. The electric motor 2 is obtained by correcting the downhill road regeneration correction amount determination unit 26 that determines (≦ 0) and the basic target torque Trs by the brake regeneration correction amount ΔTrb and the downhill road regeneration correction amount ΔTrd. And a target torque determining section 27 for determining a target torque Trc. The acceleration calculating unit 23, the gradient estimating unit 24, and the target acceleration determining unit 25 correspond to the actual acceleration grasping unit, the gradient grasping unit, and the target acceleration determining unit in the present invention, respectively.

  In this case, the detected value of the vehicle speed is sequentially input to the acceleration calculation unit 23. Then, the acceleration calculation unit 23 sequentially calculates the temporal change rate (differential value) of the input detection value of the vehicle speed as the actual acceleration Ar. In addition, you may make it detect the actual acceleration of the advancing direction of the vehicle 1 with the acceleration sensor with which the vehicle 1 was equipped.

  The gradient estimation unit 24 also includes the latest value (that is, the previous value Tr) of the detected vehicle speed value (current value), the actual acceleration Ar (current value), and the target torque Trc already determined by the target torque determination unit 27. (k-1)) are sequentially input. Since the current output torque of the electric motor 2 is controlled to the previous value Tr (k-1) of the target torque Trc, the previous value Tr (k-1) is the current actual output of the electric motor 2. It corresponds to torque.

  Then, the gradient estimation unit 24 basically estimates the gradient of the road surface on which the vehicle 1 is traveling by executing arithmetic processing described later using these input values, and estimates the gradient. The value is output to the target acceleration determination unit 25. In this case, in this embodiment, the estimated value of the gradient is 0 on a flat road, a positive value on an uphill road, and a negative value on a downhill road. In addition to the input values described above, the gradient estimation unit 24 includes the wheel speed control on / off data (current value), the detected brake operation amount (current value), and the detected vehicle speed (current value). Are entered. And the gradient estimation part 24 also performs the process which adjusts the estimated value of the gradient output to the target acceleration determination part 25 suitably according to the predetermined judgment process based on these input values.

  In addition, the estimated value of the gradient (current value) obtained by the gradient estimating unit 24 and the detected value of the vehicle speed (current value) are sequentially input to the target acceleration determining unit 25. Then, when the input estimated value of the gradient is an estimated value of the slope of the downhill road, the target acceleration determining unit 25 determines the target acceleration of the vehicle 1 according to the estimated value of the gradient and the detected value of the vehicle speed. Ac is determined as described below.

  Further, the target acceleration Ac (current value) and the actual acceleration Ar (current value) are input to the downhill road regeneration correction amount determination unit 26. The downhill regenerative correction amount determining unit 26 basically determines the downhill road regenerative correction amount ΔTrd by executing arithmetic processing described later using these input values. The descending slope regenerative correction amount ΔTrd is added to the basic target torque Trs to correct the basic target torque Trs in the regenerative direction (in the negative direction). The descending slope regeneration correction amount ΔTrd is basically set so that the torque obtained by correcting the basic target torque Trs by the descending slope regeneration correction amount ΔTrd becomes a torque that can bring the actual acceleration Ar close to the target acceleration Ac. It is determined. In addition to the above input values, the detected value (current value) of the accelerator operation amount and the brake operation amount is also input to the descending slope regeneration correction amount determination unit 26. Then, the descending slope regeneration correction amount determination unit 26 also performs processing such as gradually decreasing the descending slope regeneration correction amount ΔTrd (approaching it to 0) in accordance with these input values.

  Next, the control process of the vehicle control unit 5 having the above functional configuration will be described in more detail with reference to FIGS. 3 is a flowchart showing the overall processing of the vehicle control unit 5, FIG. 4 is a flowchart showing the subroutine processing of STEP 2 in FIG. 3, FIG. 5 is a flowchart showing the subroutine processing of STEP 22 in FIG. 4, and FIG. FIG. 7A and FIG. 7B are tables showing tables used in STEP 25 of FIG.

  The vehicle control unit 5 sequentially executes the processing shown in the flowchart of FIG. 3 at a predetermined calculation processing cycle.

  The vehicle control unit 5 first determines the basic target torque Trs (current value) of the electric motor 2 by the basic target torque determination unit 21 (STEP 1). In this case, as described above, the basic target torque Trs is determined based on the map from the detected value (current value) of the vehicle speed and the accelerator operation amount.

  Next, the vehicle control unit 5 determines the downhill road regeneration correction amount ΔTrd (current value) (STEP 2). Although details of the processing in STEP 2 will be described later, by executing the processing of the acceleration calculating unit 23, the gradient estimating unit 24, the target acceleration determining unit 25, and the downhill regenerative correction amount determining unit 26, the downhill regenerative correction amount is executed. ΔTrd is determined.

  Next, the vehicle control unit 5 determines the brake regeneration correction amount ΔTrb (current value) by the brake regeneration correction amount determination unit 22 (STEP 3). In this case, as described above, the brake regeneration correction amount ΔTrb is determined from the detected value (current value) of the brake operation amount based on the table.

  Note that the processing order of STEPs 1 to 3 may be arbitrarily changed.

  Next, the vehicle control unit 5 calculates the target torque Trc (current value) of the electric motor 2 by the target torque determination unit 27 (STEP 4). In this case, the basic target torque Trs is corrected by adding the downhill road regeneration correction amount ΔTrd and the brake regeneration correction amount ΔTrb determined in STEPs 2 and 3 to the basic target torque Trs determined in STEP 1 (in FIG. 3). (See the formula for.) Then, the corrected torque value (= Trs + ΔTrd + ΔTrb) is determined as the target torque Trc. When the brake operating state is in the off state, ΔTrb = 0, so that the basic target torque Trs is substantially corrected only by the downhill road regeneration correction amount ΔTrd, and Trc = Trs + ΔTrd. In a situation where ΔTrb = ΔTrd = 0, the target torque Trc matches the basic target torque Trs.

  The above processes of STEP1 to STEP4 are executed at a predetermined calculation processing cycle, and thereby the target torque Trc is sequentially determined.

  Supplementally, when the vehicle is traveling on a horizontal flat road or an uphill road by the process of the downhill road regeneration correction amount determining unit 26 according to the processing of STEP 2 described later in detail (except immediately after the transition from the downhill road) The downhill road regeneration correction amount ΔTrd is held at zero. For this reason, while the vehicle is traveling on a horizontal flat road or an uphill road, basically, Trc = Trs + ΔTrb. Therefore, when the accelerator operating state and the brake operating state are turned off while the vehicle is traveling on a horizontal flat road or an uphill road, the target torque Trc of the electric motor 2 is basically the basic target torque Trs. Regenerative torque that matches

  The target torque Trc determined in this way is sequentially input from the vehicle control unit 5 to the motor control unit 6. At this time, the motor control unit 6 controls the energization current of the armature winding of the electric motor 2 and outputs the output torque of the target torque Trc from the electric motor 2 as described above.

  As described above, in the ON state of the wheel speed control device 7, the target torque Trc of the electric motor 2 determined by the vehicle control unit 5 may be changed. In this case, the target torque after the change is changed. Is output from the electric motor 2, the motor control unit 6 controls the energization current of the armature winding of the electric motor 2.

  The processing of STEP2 is executed as shown in the flowchart of FIG. That is, the vehicle control unit 5 first calculates the actual acceleration Ar (current value) as described above by the acceleration calculation unit 23 (STEP 21). Next, the vehicle control unit 5 uses the gradient estimation unit 24 to estimate the gradient of the road surface on which the vehicle 1 is currently traveling (STEP 22).

  The processing of STEP 22 is executed as shown in the flowchart of FIG. In other words, the gradient estimation unit 24 is generated in the vehicle 1 when the output torque (≈the previous value Trc (k−1) of the target torque Trc) currently output by the electric motor 2 is transmitted to the drive wheels 9 and 9. The driving force to be calculated is calculated (STEP 31). The driving force is obtained by using the driving torque of the driving wheels 9, 9 determined from the previous value Tr (k−1) of the target torque Trc of the electric motor 2 and the reduction ratio of the power transmission mechanism 8. Calculated by dividing by effective radius. The effective radius of the drive wheels 9, 9 is a predetermined fixed value. Further, the reduction ratio of the power transmission mechanism 8 is determined according to the current speed ratio (detected value or command value) of the transmission provided in the power transmission mechanism 8.

  Supplementally, when the current output torque of the electric motor 2 is the regenerative torque (when Tr (k-1) <0), the driving force calculated in STEP 1 is a negative value, and the negative value is The actual driving force functions as a braking force.

  Next, the gradient estimation unit 24 executes the processing of the vehicles STEP32 to STEP35, and calculates acceleration resistance, rolling resistance, air resistance, and gradient resistance as running resistance acting on the vehicle 1, respectively.

  In this case, the acceleration resistance is calculated by the following equation (1).

Acceleration resistance [kN]
= (Total vehicle weight [kN] + rotational partial inertia weight [kN])
X (acceleration [m / s ² ] / gravity acceleration [m / s ² ])
...... (1)

In this equation (1), “total vehicle weight” is a gravity-converted value of the total mass of the vehicle 1 (product of total mass and gravitational acceleration), and “rotational partial inertia weight” is the rotation of the power transmission system of the vehicle 1. The moments of inertia of the parts (the output shaft 2a of the electric motor 2, the rotating shaft and gear of the power transmission mechanism 8, the drive wheels 9, 9 and the like) are weight-converted by matching the total vehicle weight with the unit system. These “total vehicle weight” and “rotational partial inertia weight” are set to predetermined fixed values in this embodiment. Then, the acceleration resistance is calculated by calculating the right side of Expression (1) using the actual acceleration Ar (current value) of the vehicle 1 calculated in STEP 21 as the value of “acceleration” in Expression (1). Is done.

  Further, the rolling resistance is given by the following equation (2).

Rolling resistance [kN] = rolling resistance coefficient x (total vehicle weight [kN] x cos (gradient))
(2)

Here, cos (gradient) ≈ 1 in the normal road surface gradient. Therefore, in this embodiment, the rolling resistance is calculated by the following equation (3).

Rolling resistance [kN] = rolling resistance coefficient × total vehicle weight [kN] (3)

In this case, the “total vehicle weight” necessary for the calculation of Expression (3) is set to a predetermined fixed value as described above. Further, the “rolling resistance coefficient” is also set to a predetermined fixed value. Note that the previous value already obtained by the gradient estimator 24 may be used as the value of the gradient, and the rolling resistance may be obtained by the equation (2). Further, when the “total vehicle weight” and the “rolling resistance coefficient” are fixed values, the rolling resistance calculated by the equation (3) is a constant value. Therefore, the value of the rolling resistance is set to a fixed value in advance. You may keep it.

  The air resistance is calculated by the following equation (4).

Air resistance [kN]
= Air resistance coefficient [kN · h ² / m ² · km ² ]
× Vehicle front projection area [m ² ] × Vehicle speed [km / h] × Vehicle speed [km / h]
(4)

“Air resistance coefficient” and “front projected area” in the equation (4) are fixed values determined in advance in the present embodiment. Then, the air resistance is calculated by performing the calculation of the right side of Expression (4) using the detected value (current value) of the vehicle speed as the value of “vehicle speed” in Expression (4).

  The gradient resistance is calculated by the following equation (5) from the driving force calculated in STEP 31 and the acceleration resistance, rolling resistance, and air resistance calculated in STEP 32-35.

Gradient resistance = Driving force-Acceleration resistance-Rolling resistance-Air resistance (5)

This equation (5) is an equation representing a balance relationship between the driving force of the vehicle 1 and the running resistance (the sum of acceleration resistance, rolling resistance, air resistance, and gradient resistance). The gradient resistance calculated by the equation (5) is a positive value when the vehicle 1 is traveling on the uphill road, and is a negative value when the vehicle 1 is traveling on the downhill road.

  Here, the following relational expression (6) is established between the gradient resistance and the gradient of the road surface.

Gradient resistance [kN] = Total vehicle weight [kN] × sin (gradient) (6)

Note that in the case of a normal road surface gradient, when the unit of the gradient (inclination angle) is [rad], sin (gradient) ≈gradient [rad], so equation (6) is approximately expressed by the following equation ( 7).

Gradient resistance [kN] = Total vehicle weight [kN] × Gradient [rad] (7)

Therefore, if the slope resistance is known, the slope of the road surface can be estimated based on the equation (6) or (7). In this case, the gradient resistance, and hence the gradient, are determined by the processing of STEP 31 to 35 described above, the previous value Trc (k-1) of the target torque Trc as the current output torque value of the electric motor 2, and the detected value of the vehicle speed. (Current value) and actual acceleration Ar (current value) can be used for calculation. Therefore, in this embodiment, the target torque Trc (k-1), the detected value of the vehicle speed, and the actual acceleration Ar are input to the gradient estimation unit 24, and the above calculation processing is performed from these input values. The slope of the road surface is estimated. This is the principle of the gradient estimation process in this embodiment.

  However, in the situation where the operation state of the wheel speed control device 7 is in the on state, the situation where the brake operation state is in the on state, or the situation where the vehicle speed is low, it is calculated by the above calculation process. The accuracy of the estimated value of the gradient is likely to decrease.

  Therefore, in the present embodiment, the gradient estimation unit 24 says that in STEP 36 following STEP 35, the operation state of the wheel speed control device 7 is on, the brake operation state is on, and the vehicle speed is low. It is determined whether or not any of the conditions (a predetermined condition that causes an error in the estimated value of the gradient) is satisfied. In this case, whether or not the operation state of the wheel speed control device 7 is on is determined based on the wheel speed control on / off data (current value) input to the gradient estimation unit 24. Further, whether or not the brake operation state is on is determined based on a detected value (current value) of the brake operation amount input to the gradient estimation unit 24. Whether or not the vehicle speed is low depends on whether or not the detection value (current value) of the vehicle speed input to the gradient estimation unit 24 is smaller than a predetermined vehicle speed (for example, 7 km / h). To be judged.

  If the determination result in STEP 36 is negative, the road surface gradient can be accurately estimated. Therefore, the gradient estimation unit 24 uses the equation (6) or (6) from the gradient resistance obtained in STEP 35. The estimated value of the gradient is calculated based on 7) (STEP 37). That is, the estimated value of the gradient is updated. Further, the gradient estimation unit 24 sets (activates) a timer for timekeeping in STEP38, starts timekeeping by the timer, and ends the processing in FIG. 5 (processing in STEP22) in the current calculation processing cycle. In this case, the estimated value of the gradient newly calculated in STEP 37 is output to the target acceleration determining unit 25. Note that the timer is used to count the time during which the determination result of STEP 36 is continuously positive. In the situation where the determination result of STEP 36 is negative, the timer is sequentially set in STEP 38. Substantial timing by is not performed.

  On the other hand, if the determination result in STEP 36 is affirmative, the gradient estimation unit 24 further determines whether or not the time counted by the timer started in STEP 37 has exceeded a predetermined time (for example, 3 seconds) (STEP 39). ). At this time, when the time measured by the timer is equal to or shorter than the predetermined time and the determination result in STEP 39 is negative, the gradient estimation unit 24 does not update the estimated value of the gradient in the current processing cycle. 5 is terminated. In this case, the estimated value of the gradient is held at a value immediately before the determination result of STEP 36 becomes affirmative, and the value is output to the target acceleration determination unit 25. In addition, when the time measured by the timer exceeds the predetermined time and the determination result of STEP 39 is affirmative, in other words, when the determination result of STEP 36 is affirmative and exceeds the predetermined time, The gradient estimation unit 24 resets the estimated value of the gradient to 0 as the value of the gradient on the flat road (STEP 40), and ends the processing of FIG. 5 in the current calculation processing cycle. Accordingly, in this case, the gradient value (= 0) on the flat road is output to the target acceleration determination unit 25 as the estimated value of the gradient.

  In a situation where the determination result of STEP 36 is affirmative by the processing of the gradient estimation unit 24 (a situation where a condition that causes an error in the estimated value of the gradient is satisfied), until the duration of the situation exceeds a predetermined time, The calculation / update of the estimated value of the gradient is interrupted, and the estimated value of the gradient output to the target acceleration determination unit 25 is held at the value immediately before the situation is reached. Furthermore, if the situation continues beyond a predetermined time, the estimated value of the gradient output to the target acceleration determining unit 25 is reset to zero.

  As a result, it is possible to prevent a situation in which the target acceleration determining unit 25, which will be described in detail later, determines an inappropriate target acceleration Ac with respect to the actual gradient using the estimated value of the gradient having a large error. .

  The above is the details of the processing of the gradient estimation unit 24 in STEP22. Note that the execution order of the processing of STEPs 31 to 34 may be arbitrarily changed. Further, the processing of STEP 36 may be executed before the processing of STEP 31 to 35, and if the determination result is negative, the processing of STEP 31 to 35 and STEP 37 may be executed. Further, the processing of STEP 38 may be executed when a situation in which the judgment result in STEP 36 is negative changes to a situation in which it is positive.

  Further, in the present embodiment, any one of the conditions that the operation state of the wheel speed control device 7 is on, the brake operation state is on, and the vehicle speed is low is assumed to be an error in the estimated value of the gradient. In STEP 36, whether or not the condition is satisfied is determined as a predetermined condition that becomes a factor. However, other conditions may be added to the determination condition in STEP 36 as necessary. Further, the wheel speed control device 7 is not always necessary, and when the wheel speed control device 7 is omitted, the conditions relating to the wheel speed control device 7 may be omitted from the judgment conditions of STEP 36.

  Returning to the description of FIG. 4, after the vehicle control unit 5 estimates the road surface gradient by the gradient estimation unit 24 as described above, the vehicle 1 travels based on the estimated value (current value) of the gradient. It is determined whether or not the road surface is a downhill road (STEP 23). In this case, it is determined whether or not the road is a downhill road depending on whether or not the estimated value of the gradient is a negative value. In addition, when the estimated value of the gradient is a negative value and the absolute value of the value is equal to or greater than a predetermined value near 0, the road surface may be determined to be a downhill road. In other words, even if the estimated value of the gradient is a negative value, if the absolute value is very small, it may be determined that the road surface is not a downhill road.

  If the determination result in STEP 23 is affirmative, the vehicle control unit 5 determines the target acceleration Ac by the target acceleration determining unit 25 (STEP 24).

  In this case, in the present embodiment, the target acceleration determining unit 25 determines the target acceleration Ac by adding the target acceleration correction value Ac2 corresponding to the vehicle speed to the basic value Ac1 of the target acceleration corresponding to the estimated value of the gradient. To do.

  More specifically, the target acceleration determining unit 25 determines a table (gradient and target acceleration) set in advance as shown by a solid line graph a in FIG. 6A from the estimated gradient value (current value). The basic value Ac1 is obtained based on a table that defines the relationship with the basic value Ac1.

  Here, a two-dot chain line graph b in FIG. 6A shows the basic target torque Trs (= regenerative torque, hereinafter referred to as a flat road basic regenerative torque) when the accelerator operating state is in the OFF state. When it is assumed that the vehicle 1 traveled on a downhill road while being output to the electric motor 2, acceleration generated in the vehicle 1 (hereinafter referred to as acceleration during downhill road traveling by a flat road basic regenerative torque) The relationship with the slope of the slope is shown. In this case, in this embodiment, as described above, when the accelerator operation state and the brake operation state are turned off while the vehicle is traveling on a horizontal flat road or an uphill road, the target torque of the electric motor 2 is set. Trc is basically a regenerative torque that matches the basic target torque Trs. Accordingly, the flat road basic regenerative torque is determined as the target torque Trc of the electric motor 2 when the accelerator operating state and the brake operating state are both turned off while the vehicle is traveling on a horizontal flat road. Is the regenerative torque to be played. Further, as shown by the graph b in FIG. 6A, the acceleration at the time of traveling on the downhill road by the flat road basic regenerative torque is accompanied by the magnitude (absolute value) of the slope (<0) of the downhill road increasing from zero. Thus, the acceleration on the deceleration side (<0) of the vehicle 1 increases monotonously from the acceleration on the acceleration side (> 0). In this case, when the downhill road acceleration by the flat road basic regenerative torque is smaller than a certain value | θx |, the gradient (<0) of the downhill road slope (<0), the gravitational force acting on the vehicle is reduced. Since the magnitude of the traveling direction component of the vehicle is smaller than the braking force of the vehicle due to the flat road basic regenerative torque, the acceleration on the deceleration side of the vehicle 1 (<0) is obtained. Further, when the magnitude (absolute value) of the slope (<0) of the downhill road is larger than | θx |, the acceleration during running on the downhill road is the vehicle traveling direction component of the gravity acting on the vehicle. Since the magnitude is larger than the braking force of the vehicle due to the flat road basic regenerative torque, the acceleration on the acceleration side of the vehicle 1 (> 0).

  And the table shown with the solid line graph a of FIG. 6A is set as follows with respect to the acceleration at the time of traveling on the downhill road by the flat road basic regenerative torque.

  That is, when the magnitude (absolute value) of the slope (<0) of the downhill road is larger than a predetermined value | θx |, the basic value Ac1 is when the downhill road is driven by the flat road basic regenerative torque. The table shown by the graph a is set so as to be an acceleration that suppresses the acceleration of the vehicle rather than the acceleration. In this case, the basic value Ac1 is the acceleration (> 0) on the acceleration side of the vehicle. Further, in the present embodiment, the predetermined value | θx | is the magnitude of the gradient at which the acceleration during downhill road traveling by the flat road basic regenerative torque is 0 (or almost 0).

  The basic value Ac1 continuously increases in the speed increasing direction with a slope smaller than the acceleration during traveling on the downhill road due to the flat road basic regenerative torque as the magnitude of the gradient increases from the predetermined value | θx |. . The basic value Ac1 when the magnitude of the gradient coincides with the predetermined value | θx | is the same value as the acceleration value during downhill road traveling by the flat road basic regenerative torque (0 in the example of the present embodiment). . Therefore, as the magnitude of the gradient increases from the predetermined value | θx |, the absolute value of the difference between the basic value Ac1 and the acceleration when traveling on the downhill road due to the flat road basic regenerative torque increases continuously and monotonously from zero. Go.

  If the slope of the downhill road (<0) is smaller than the predetermined value | θx |, the basic value Ac1 reduces the vehicle speed more than the acceleration during downhill road driving by the flat road basic regenerative torque. A table indicated by a graph a is set so that the acceleration is suppressed. In this case, the basic value Ac1 is 0 or acceleration (<0) on the deceleration side of the vehicle. Then, the magnitude of the slope of the downhill road (<0) is a magnitude within a range between the predetermined value | θx | and a predetermined value | θy | (> 0) predetermined in advance. If this is the case, the basic value Ac1 is kept at the value of acceleration during downhill road traveling by the flat road basic regenerative torque when the magnitude of the gradient matches | θx | (0 in the example of this embodiment). Be drunk. When the slope of the downhill road (<0) is smaller than | θy | (when the slope is in a range between 0 and | θy |), the basic The value Ac1 continuously changes in the deceleration direction with a larger slope than the acceleration on the downhill road by the flat road basic regenerative torque as the magnitude of the gradient becomes smaller. Note that the basic value Ac1 in the case where the magnitude of the gradient is 0 is the same value (<0) as the acceleration value when traveling on the downhill road by the flat road basic regenerative torque. Therefore, when the gradient of the downhill road (<0) is smaller than the predetermined value | θx |, the basic value Ac1 and the flat road are increased as the gradient increases from 0 to | θy |. The absolute value of the difference from the acceleration when traveling on the downhill road due to the basic regenerative torque continuously increases monotonically from zero. Further, as the magnitude of the gradient increases from | θy | to | θx |, the absolute value of the difference between the basic value Ac1 and the acceleration when traveling on the downhill road due to the flat road basic regenerative torque continuously decreases monotonously. To go. In other words, the absolute value of the difference between the basic value Ac1 and the acceleration on the downhill road caused by the flat road basic regenerative torque is a predetermined value | θy | intermediate between the magnitude of the gradient 0 and | θx |. It changes continuously according to the gradient so that the peak value (maximum value) is sometimes taken.

  In addition, when the slope of the road surface in which the inclination angle with respect to the horizontal plane is α [deg] is defined as the slope of tan α × 100 [%], the predetermined value | θx | is, for example, a slope of about 5 to 10%. The basic value Ac1 is an acceleration of about 0.1 to 0.3 G when the road surface has a slope of, for example, 40%.

  In this embodiment, the basic value Ac1 of the target acceleration is determined from the estimated value of the gradient based on the table indicated by the solid line a in FIG. 6A set as described above.

  Further, the target acceleration determining unit 25 sets a table (correction value Ac2 for vehicle speed and target acceleration) set in advance as shown by the solid line c graph in FIG. The correction value Ac2 is obtained based on a table that defines the relationship between Here, in the table indicated by the solid line c in FIG. 6B, the correction value Ac2 becomes a value on the acceleration side (> 0) as the vehicle speed decreases in a low speed range where the vehicle speed is lower than the predetermined value Vx. In addition, the correction value Ac2 is set to 0 in the middle / high speed range where the vehicle speed exceeds the predetermined value Vx. The predetermined value Vx is a vehicle speed of about 10 to 20 [km / h], for example. The correction value Ac2 is an acceleration of about 0.05 to 0.1 G at the maximum.

  Then, the target acceleration determining unit 25 determines the target acceleration Ac by adding the basic value Ac1 and the correction value Ac2 obtained as described above. In this case, since the correction value Ac2 is 0 when the vehicle travels in the middle / high speed range where the detected value of the vehicle speed exceeds the predetermined value Vx, the basic value Ac1 is determined as it is as the target acceleration Ac. Further, when the vehicle travels in a low speed range where the detected value of the vehicle speed is smaller than the predetermined value Vx, an acceleration obtained by correcting the basic value Ac1 by the correction value Ac2 in the speed increasing direction (positive direction) is determined as the target acceleration Ac.

  Here, in the present embodiment, the target acceleration Ac is corrected in the speed increasing direction from the basic value Ac1 when the vehicle travels in a low speed range in which the detected value of the vehicle speed is smaller than the predetermined value Vx for the following reason. That is, in the low speed range, it is easier for the driver to feel the change in the vehicle speed than in the middle / high speed range. For this reason, if the target acceleration Ac in the low speed range is set to the same level as the target acceleration Ac (= basic value Ac1) in the medium / high speed range, a sense of deceleration in the low speed range is easily experienced. Therefore, in the present embodiment, the target acceleration Ac in the low speed range is set to be an acceleration in the speed increasing direction as compared with the target acceleration Ac in the medium / high speed range.

  The above is the details of the processing of the target acceleration determination unit 25 in STEP24.

  The target acceleration Ac (= Ac1) determined in the situation where the detected value of the vehicle speed becomes a medium / high speed vehicle speed greater than the predetermined value Vx by the processing of the target acceleration determination unit 25 is an estimated value of the road surface gradient. When the vehicle 1 travels on a downhill road whose magnitude is larger than the predetermined value | θx |, the acceleration (this embodiment) can suppress the acceleration of the vehicle more than the acceleration during downhill road travel due to the flat road basic regenerative torque. In the form, acceleration on the acceleration side (> 0)). Further, the target acceleration Ac (= Ac1) determined in a situation where the detected value of the vehicle speed becomes a medium / high speed vehicle speed greater than the predetermined value Vx is such that the estimated value of the road gradient is the predetermined value | θx. When the vehicle 1 travels on a gentle slope downhill road that is smaller than |, acceleration that can suppress deceleration of the vehicle rather than acceleration during downhill road travel due to flat road basic regenerative torque (in this embodiment, 0 or the deceleration side) Acceleration (<0)).

  Further, the target acceleration Ac (= Ac1 + Ac2) determined in a situation where the detected value of the vehicle speed becomes a low speed vehicle speed smaller than the predetermined value Vx is the target acceleration Ac () determined as described above at the medium / high speed vehicle speed. = Ac1), the acceleration is increased in the acceleration direction by the correction value Ac2. In this case, when the vehicle 1 travels on a gentle slope downhill where the estimated value of the road surface gradient is smaller than the predetermined value | θx | It is an acceleration that can suppress the deceleration of the vehicle rather than the acceleration when traveling on a downhill road by the basic regenerative torque. On the other hand, when the vehicle 1 travels on a downhill road where the estimated value of the slope of the road surface is larger than the predetermined value | θx |, the estimated value of the slope is a value close to | θx |. In some cases, the target acceleration Ac is slightly larger in the speed increasing direction than the acceleration on the downhill road due to the flat road basic regenerative torque. In other cases, the target acceleration Ac is an acceleration that suppresses the acceleration of the vehicle more than the acceleration when traveling downhill by the flat road basic regenerative torque.

  Supplementally, in the present embodiment, the target acceleration Ac is determined by adding the correction value Ac2 to the basic value Ac1, but the target acceleration Ac is obtained by multiplying the basic value Ac1 by a correction coefficient corresponding to the vehicle speed. It may be determined. In addition, a map in which the tables of FIGS. 6A and 6B are integrated is created, and the target acceleration Ac is determined directly from the estimated value of the gradient and the detected value of the vehicle speed based on the map. It may be. Further, instead of the tables of FIGS. 6A and 6B, the basic value Ac1 and the correction value Ac2 may be determined using an arithmetic expression that approximates the relationship defined by the tables. Further, the correction of the basic value Ac1 may be omitted, and the basic value Ac1 may be determined as it is as the target acceleration Ac without depending on the vehicle speed. Further, when the estimated value of the gradient is larger than the predetermined value | θx |, the upper limit value of the target acceleration Ac is the acceleration at the time of traveling on the downhill road by the flat road basic regenerative torque or a value slightly smaller than that. When the acceleration obtained by adding the correction value Ac2 to the basic value Ac1 becomes larger in the acceleration direction than the upper limit value, the target acceleration Ac may be limited to the upper limit value.

  Returning to the description of FIG. 4, the vehicle control unit 5 determines the target acceleration Ac by the target acceleration determination unit 25 as described above, and then executes the processing of the downhill regeneration correction amount determination unit 26 in STEPs 25 to 29.

  At this time, the downhill regenerative correction amount determination unit 26 first determines whether or not the accelerator operation state is on based on the detected value (current value) of the accelerator operation amount (STEP 25). If the determination result is negative, the descending slope regeneration correction amount determination unit 26 further determines whether or not the actual acceleration Ar (current value) is larger than the target acceleration Ac (current value). (STEP 26).

  If the determination result is affirmative, the downhill regenerative correction amount determination unit 26 further determines whether or not the brake operation state is an on state (STEP 27).

  The downhill regenerative correction amount determination unit 26 determines that when the determination result of STEP 27 is negative, that is, when both the accelerator and brake operation states are off and Ar> Ac, Ar> Ac. The slope regeneration correction amount ΔTrd is increased by a predetermined value from the previous value (STEP 28), and the processing of the current calculation processing cycle is terminated. In this case, since ΔTrd ≦ 0 in this embodiment, increasing ΔTrd in STEP 28 means increasing the magnitude (absolute value), in other words, the regenerative torque component of the electric motor 2 by ΔTrd. Means to increase. Therefore, the processing of STEP 28 is performed by adding a negative predetermined value to ΔTrd or subtracting a positive predetermined value from ΔTrd. The downhill road regeneration correction amount ΔTrd is initialized to 0 when the vehicle control unit 5 is activated.

  If the determination result in STEP 27 is affirmative (when the brake operation state is on), the downhill regeneration correction amount determination unit 26 does not update the downhill regeneration correction amount ΔTrd (previous time). The processing of the current computation processing cycle is terminated. As a result, when the brake operating state changes from the off state to the on state during traveling of the vehicle 1 on the downhill road, an increase in the downhill road regeneration correction amount ΔTrd is limited (prohibited).

  On the other hand, when the determination result of STEP 23 is negative (when the road surface on which the vehicle 1 is traveling is a flat road or an uphill road), or when the determination result of STEP 25 is positive (on a downhill road) Actual acceleration when the accelerator operating state is turned on during traveling) or when the determination result of STEP 26 is negative (when the accelerator operating state is off during traveling on a downhill road) When Ar is equal to or less than the target acceleration Ac), the descending slope regeneration correction amount determination unit 26 decreases the descending slope regeneration correction amount ΔTrd by a predetermined value from the previous value (STEP 29), and this arithmetic processing The cycle processing is terminated. Note that reducing ΔTrd in STEP 29 means reducing the magnitude (absolute value), in other words, reducing the regenerative torque component of the electric motor 2 due to ΔTrd. Accordingly, the processing of STEP 29 is performed by adding a positive predetermined value to ΔTrd or subtracting a negative predetermined value from ΔTrd. Further, since the downhill regeneration correction amount ΔTrd is 0 or a negative value in this embodiment (because the lower limit value of the absolute value is 0), when the downhill regeneration correction amount ΔTrd is decreased in STEP29. Is a positive value, the descending slope regeneration correction amount ΔTrd is set to zero.

  The processing in STEPs 25 to 29 described above is the details of the processing of the downhill road regeneration correction amount determination unit 26.

  When the vehicle 1 travels on a downhill road by the processing of the downhill road regeneration correction amount determination unit 26, if both the accelerator and brake operation states are off, the magnitude of the actual acceleration Ar and the target acceleration Ac is small or large. Depending on the relationship, the processing of STEP 28 or 29 is sequentially performed. That is, in the situation where Ar> Ac, the absolute value of the descending slope regeneration correction amount ΔTrd (≦ 0) is gradually increased, and in the situation where Ar <Ac, the absolute value of the descending slope regeneration correction amount ΔTrd is gradually decreased. Is done.

  In this case, in a situation where both the accelerator and brake operating states are in the OFF state, the target torque Trc of the electric motor 2 is obtained by adding the downhill regenerative correction amount ΔTrd to the flat road basic regenerative torque as the basic target torque Trs. Regenerative torque. For this reason, the magnitude of the regenerative torque output by the electric motor 2 gradually increases to a value larger than the flat road basic regenerative torque in a situation where Ar> Ac. In a situation where Ar <Ac, the magnitude of the regenerative torque output by the electric motor 2 gradually decreases and approaches the flat road basic regenerative torque. Therefore, the regenerative torque output from the electric motor 2 is increased or decreased so that the braking force of the vehicle 1 by the regenerative torque brings the actual acceleration Ar closer to (accelerates) the target acceleration Ac. In other words, the output torque of the electric motor 2, and hence the braking force of the vehicle 1, is feedback-controlled so that the actual acceleration Ar approaches (accelerates) the target acceleration Ac.

  In this case, in this embodiment, since the target acceleration Ac is determined as described above, the electric motor 2 in the case where the accelerator and the brake are both in the off state when the vehicle is traveling on the downhill road. The target torque Trc is basically determined with a tendency as shown by the solid line graph d in FIG. That is, when traveling on a gentle slope downhill road where the estimated value of the road surface gradient is smaller than the predetermined value | θx |, the target torque Trc is set to a flat road with both the accelerator and brake operating states turned off. Thus, the regenerative torque is smaller than the flat road basic regenerative torque, which is the target torque Trc when the vehicle 1 is driven. For this reason, it is possible to prevent the driver from feeling that the braking force of the vehicle is too strong. It should be noted that the magnitude of the target torque Trc when traveling on a gentle slope downhill road where the estimated value of the road surface gradient is smaller than the predetermined value | θx | is such that the road surface gradient is | θx | In a form that takes a local minimum value when it coincides with the predetermined value | θy | in the meantime, it continuously changes according to the gradient of the road surface.

  Further, when traveling on a downhill road where the estimated value of the road surface gradient is larger than the predetermined value | θx |, the target torque Trc is normally in the case where both the accelerator and brake operating states are in the off state. The regenerative torque is larger than the flat road basic regenerative torque, which is the target torque Trc when the vehicle 1 is driven on a flat road. In this case, the magnitude of the target torque Trc continuously and monotonously increases as the gradient increases. For this reason, it is possible to prevent the vehicle 1 from being increased in a short time by applying a braking force suitable for the magnitude of the slope of the downhill road to the vehicle 1 without performing a braking operation.

  Further, when the vehicle 1 travels on the downhill road, the regenerative torque of the electric motor 2 is fed back so that the actual acceleration Ar of the vehicle 1 approaches the target acceleration Ac corresponding to the gradient of the road surface by increasing / decreasing the downhill road regeneration correction amount ΔTrd. Since the electric motor 2 is controlled, the electric motor 2 can generate an acceleration suitable for the gradient of the road surface irrespective of disturbance factors such as the direction of the wind blowing on the vehicle 1 and the number of passengers of the vehicle 1. Regenerative operation can be performed. Since the acceleration of the vehicle 1 on the downhill road becomes an acceleration suitable for the gradient, the vehicle 1 can appropriately travel on the downhill road without requiring frequent operation of the brake and the accelerator.

  Further, in the present embodiment, while the vehicle 1 is traveling on the downhill road, in a situation where Ar> Ac, the driver performs the brake operation with the accelerator operation state turned off, and the brake operation state is changed. As long as the situation where Ar> Ac continues when the state is changed from the OFF state to the ON state, the determination results of STEP 26 and STEP 27 are both positive, and thus the increase in the downhill regenerative correction amount ΔTrd is limited (prohibited). And held at the value immediately before the start of the brake operation. For this reason, it is possible to prevent an excessive braking force unintended by the driver from being generated in the vehicle 1. Note that if Ar ≦ Ac by the brake operation, the determination result in STEP 26 is negative, so the downhill regeneration correction amount ΔTrd gradually decreases. As a result, the output torque of the electric motor 2 gradually approaches the target torque obtained by correcting the basic target torque Trs by the brake regeneration correction amount ΔTrb.

  Further, when the driver performs the accelerator operation while the vehicle 1 is traveling on the downhill road, and the accelerator operation state is changed from the off state to the on state, the determination result of STEP 25 becomes affirmative. The regeneration correction amount ΔTrd gradually decreases regardless of the magnitude relationship between the actual acceleration Ar and the target acceleration Ac. As a result, the output torque of the electric motor 2 gradually approaches the basic target torque Trs as the drive torque. For this reason, the vehicle speed of the vehicle 1 can be increased according to the driver's intention while preventing a sudden change in the output torque of the electric motor 2.

  Further, when the road surface on which the vehicle 1 is traveling changes from a downhill road to a flat road or an uphill road, the determination result in STEP 23 becomes negative, so the downhill road regeneration correction amount ΔTrd is determined by the actual acceleration Ar and the target acceleration Ac. It gradually decreases regardless of the magnitude relationship. As a result, the output torque of the electric motor 2 gradually approaches the basic target torque Trs or a value obtained by correcting this with the brake regeneration correction amount ΔTrb. For this reason, immediately after the road surface changes from a downhill road to a flat road or an uphill road, a sudden change in the output torque of the electric motor 2 can be prevented.

  In the above-described embodiment, the road surface gradient is estimated by the above-described calculation process. However, the road surface gradient may be detected by an inclination sensor provided in the vehicle.

  In the embodiment, the downhill regenerative correction amount ΔTrd when the accelerator and brake operation states are both in the off state is increased or decreased by a predetermined value according to the magnitude relationship between the actual acceleration Ar and the target acceleration Ac. However, the downward slope regeneration correction amount ΔTrd may be determined from the deviation between the actual acceleration Ar and the target acceleration Ac by a feedback law such as a PI law or a PID law.

  In the embodiment, the target acceleration Ac of the vehicle 1 is set so that the actual acceleration Ar follows the target acceleration Ac. For example, the target torque Trc and the road surface as shown by the graph d in FIG. Estimated value (or detection value) of road surface gradient when a table or calculation formula showing the relationship with the gradient is determined in advance and both the accelerator and brake operation states are off when traveling on a downhill road. ), The target torque of the electric motor 2 may be determined based on the table. However, in order to control the acceleration of the vehicle 1 on the downhill road to a suitable acceleration regardless of the disturbance factor, it is desirable to set the target acceleration Ac as in the above embodiment.

The figure which shows the whole system configuration | structure of the electric vehicle in one Embodiment of this invention. The block diagram which shows the function of the vehicle control unit with which the electric vehicle of embodiment was equipped. The flowchart which shows the whole process of the vehicle control unit of FIG. FIG. 4 is a flowchart showing a subroutine process of STEP 2 in FIG. 3. The flowchart which shows the subroutine processing of STEP22 of FIG. 6A and 6B are diagrams showing tables used in the processing of STEP 25 in FIG. The graph which shows the relationship between the target torque of the electric motor at the time of driving | running | working on the downhill road of the vehicle of embodiment, and the gradient of a road surface.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric vehicle, 2 ... Electric motor, 5 ... Vehicle control unit (target torque determination means), 6 ... Motor control unit (motor control means), 21 ... Basic target torque determination part (basic target torque determination means), 23 ... Acceleration calculating section (acceleration grasping means), 24... Gradient estimating section (gradient grasping means), 25... Target acceleration determining section (target acceleration determining means).

Claims (10)

In an electric vehicle equipped with an electric motor capable of selectively outputting drive torque and regenerative torque as a driving power source,
A slope grasping means for grasping the slope of the road surface on which the vehicle is traveling;
Target torque determining means for determining the target torque of the electric motor so that the target torque of the electric motor becomes a regenerative torque when the operation state of the accelerator of the vehicle is an off state;
Motor control means for controlling energization of the electric motor so as to generate an output torque of the target torque in the electric motor,
The target torque determining means, when the accelerator operating state and the brake operating state of the vehicle are in an off state, the slope grasped by the slope grasping means is a downhill slope, and the slope When the magnitude of is smaller than a predetermined value determined in advance, the target torque is a regenerative torque having a smaller magnitude than when the slope grasped by the slope grasping means is zero. An electric vehicle characterized by determining the target torque. The electric vehicle according to claim 1,
The target torque determining means, when the accelerator operating state and the brake operating state of the vehicle are in an off state, the slope grasped by the slope grasping means is a downhill slope, and the slope When the magnitude of the target torque is larger than the predetermined value, the target torque is set so that the target torque becomes a larger regenerative torque than when the slope grasped by the slope grasping means is zero. The electric vehicle characterized by determining. The electric vehicle according to claim 1,
Basic target torque determining means for determining a basic target torque that is a basic target torque of the electric motor and is a regenerative torque when the operation state of the accelerator of the vehicle is in an off state, according to the operation state of the accelerator; Target acceleration determining means for determining the target acceleration of the vehicle when traveling on the downhill road according to the gradient of the road surface grasped by the gradient grasping means, and grasping the actual acceleration which is the actual acceleration of the vehicle And an actual acceleration grasping means, wherein the target acceleration determining means is configured such that when the accelerator operation state and the brake operation state of the vehicle are off, the gradient grasped by the gradient grasping means If it is a gradient and the magnitude of the gradient is smaller than the predetermined value, the output torque of the basic target torque is generated in the electric motor. Than acceleration generated in the vehicle when it is assumed that was running of the vehicle in the downhill in slope in state a means for determining the target acceleration so as to suppress the deceleration of the vehicle,
The target torque determining means is configured to determine the basic target torque determining means when the gradient grasped by the gradient grasping means is 0 when the accelerator operation state and the brake operation state of the vehicle are in an off state. Is determined as the target torque, and when the gradient grasped by the gradient grasping means is a slope of a downhill road, the actual acceleration grasped by the actual acceleration grasping means is determined as the target torque. An electric vehicle characterized in that the target torque is determined by correcting the basic target torque in accordance with the actual acceleration and the target acceleration so as to approach the target acceleration determined by the acceleration determining means. In the electric vehicle according to claim 3,
The target acceleration determining means, when the accelerator operating state and the brake operating state of the vehicle are in an off state, the slope grasped by the slope grasping means is a slope of a downhill road, and the slope Is larger than the predetermined value, it is generated in the vehicle when it is assumed that the vehicle has traveled on the downhill road with the output torque of the basic target torque generated in the electric motor. An electric vehicle characterized in that the target acceleration is determined so as to suppress the acceleration of the vehicle from the acceleration to be performed. The electric vehicle according to claim 4, wherein
The target acceleration determined by the target acceleration determining means when the operation state of the accelerator of the vehicle and the operation state of the brake are in an off state, the gradient grasped by the gradient grasping means is a slope of a downhill road, And, when the magnitude of the gradient is smaller than the predetermined value, it is an acceleration for decelerating the vehicle or an acceleration of 0, the gradient is a gradient of a downhill road, and the magnitude of the gradient is An electric vehicle characterized by acceleration that accelerates the vehicle when greater than a predetermined value. A regenerative control method at the time of traveling on a downhill road of an electric vehicle provided with an electric motor capable of selectively outputting drive torque and regenerative torque as a power source for traveling,
Determining a target torque of the electric motor so that the target torque of the electric motor becomes a regenerative torque when the operation state of the accelerator of the vehicle is an off state;
Controlling the energization of the electric motor to generate an output torque of the target torque in the electric motor,
In the step of determining the target torque, when the vehicle is traveling on a downhill road, when the accelerator operation state and the brake operation state of the vehicle are in an off state, the slope of the downhill road is determined in advance. The target torque is determined so that the target torque is a regenerative torque having a smaller magnitude than when the slope of the downhill road is 0 when the slope is smaller than the predetermined value. A regenerative control method for an electric vehicle. In the regeneration control method of the electric vehicle according to claim 6,
In the step of determining the target torque, when the vehicle is traveling on a downhill road, when the accelerator operation state and the brake operation state of the vehicle are in an off state, the magnitude of the gradient of the downhill road is the predetermined value. The target torque is determined so that the target torque becomes a larger regenerative torque than the case where the magnitude of the slope of the downhill road is 0 when the slope is larger than the value. A regenerative control method for an electric vehicle. In the regeneration control method of the electric vehicle according to claim 6,
Determining a basic target torque, which is a basic target torque of the electric motor and is a regenerative torque when the operation state of the accelerator of the vehicle is in an off state, according to the operation state of the accelerator; And determining the target acceleration of the vehicle when the vehicle is traveling according to the gradient of the road surface. The step of determining the target acceleration includes operating an accelerator of the vehicle when the vehicle is traveling on a downhill road. When the state and the brake operation state are in the off state, and the magnitude of the road gradient is smaller than the predetermined value, the output torque of the basic target torque is generated in the electric motor. When it is assumed that the vehicle has traveled on the downhill road, the target acceleration is determined so as to suppress the deceleration of the vehicle rather than the acceleration generated in the vehicle. Tsu is a flop,
The step of determining the target torque includes the step of determining the basic target torque when the vehicle is traveling on a flat road having a gradient of 0 when the accelerator operation state and the brake operation state of the vehicle are off. The target torque is determined by correcting the basic target torque according to the actual acceleration and the target acceleration so that the actual acceleration approaches the target acceleration when the vehicle is traveling on a downhill road. A regenerative control method for an electric vehicle. In the regeneration control method of the electric vehicle according to claim 8,
In the step of determining the target acceleration, when the vehicle is traveling on a downhill road, when the accelerator operation state and the brake operation state of the vehicle are in an off state, the magnitude of the gradient of the road surface is the predetermined value. Is greater than the acceleration generated in the vehicle when it is assumed that the vehicle has traveled on the downhill road in a state where the output torque of the basic target torque is generated in the electric motor. A regeneration control method for an electric vehicle, wherein the target acceleration is determined so as to suppress acceleration. In the regeneration control method of the electric vehicle according to claim 9,
The target acceleration determined in the step of determining the target acceleration when the operation state of the accelerator of the vehicle and the operation state of the brake are in the off state is the gradient obtained by the gradient grasping means is the gradient of the downhill road. If the gradient is smaller than the predetermined value, the vehicle is decelerating or zero acceleration, the gradient is a downhill gradient, and the gradient is large. A regeneration control method for an electric vehicle, characterized in that if the speed is greater than the predetermined value, the acceleration is an acceleration for accelerating the vehicle.