Regenerative braking control method and regenerative braking control device

1. A regenerative braking control device comprising a control circuit that controls a drive source that generates a regenerative brake force and that is installed in a vehicle that is switchable by a selection of a driver between a first driving mode in which the driver executes manual control and a second driving mode in which automatic control is executed, wherein

the manual control includes at least adjusting, based on an operation of the driver, a speed of the vehicle and a distance between the vehicle and at least another vehicle,

the automatic control includes at least automatically adjusting the speed of the vehicle and the distance between the vehicle and at least another vehicle, and

a first upper limit of regenerative deceleration in the first driving mode due to the regenerative brake force is set smaller than a second upper limit of the regenerative deceleration in the second driving mode, wherein

in the second driving mode,

a first required acceleration is calculated on a basis of a driving-force instruction from the driver,

a driving-force command value output to the drive source is changed at a rate of change greater than or equal to a rate of change of the first required acceleration.

2. The regenerative braking control device according to claim 1 , wherein

a difference between the first upper limit and the second upper limit is equal to or smaller than a predetermined value.

3. The regenerative braking control device according to claim 1 , wherein

a rate of change of an upper limit of the regenerative deceleration during a transition between the first driving mode and the second driving mode falls within a predetermined range.

4. The regenerative braking control device according to claim 1 , wherein

the second upper limit is a maximum value of the regenerative brake force that can be generated by the drive source.

5. The regenerative braking control device according to claim 1 , wherein

the regenerative deceleration in the first driving mode is calculated on a basis of a command value received from the driver through an input device through which the driver inputs a requirement for an acceleration or a deceleration.

6. The regenerative braking control device according to claim 5 , wherein

the input device is an accelerator pedal.

7. The regenerative braking control device according to claim 1 , wherein

in the second driving mode,

when the first required acceleration is equal to or greater than zero, the first required acceleration is set as the driving-force command value, and

when the first required acceleration is below zero, the driving-force command value is changed at a rate of change greater than the rate of change of the first required acceleration.

8. The regenerative braking control device according to claim 7 , wherein

when the first required acceleration is below zero,

a value obtained by dividing the second upper limit at a timing of starting the driving-force instruction by the first upper limit at the timing is calculated as a predetermined coefficient, and

a value obtained by multiplying the first required acceleration by the predetermined coefficient is calculated as an override upper-limit acceleration, and either a second required acceleration on a basis of the automatic control or the override upper-limit acceleration, whichever is greater in value, is defined as the driving-force command value.

9. The regenerative braking control device according to claim 1 , wherein

when a required deceleration is above the first upper limit in the first driving mode, the required deceleration is generated using the drive source and a friction brake installed in the vehicle.

10. The regenerative braking control device according to claim 1 , wherein

when a required deceleration is above the second upper limit in the second driving mode, the required deceleration is generated using the drive source and a friction brake installed in the vehicle.