Regenerative braking method for vehicle having electric motor

Abstract

A regenerative braking method for a vehicle having an electric motor. During an initial stage of a regenerative braking operation related to the vehicle having the electric motor, a flow rate of brake liquid as much as the amount of regenerative braking is delivered into a reservoir through opened exit valves of non-driving wheels, so as to generate a hydraulic braking force needed after subtracting the amount of regenerative braking from the amount of braking desired by a vehicle operator. When the amount of regenerative braking increases, exit valves of driving wheels are controlled to fulfill the total amount of braking desired by the vehicle operator. Also, when the amount of regenerative braking decreases, wheel pressures have to be increased to fulfill the vehicle operator's desire to brake. In the regenerative braking method for generating a residual amount of braking needed after subtracting the amount of regenerative braking, which corresponds to an amount generated by the electric motor, from the amount of braking desired by the vehicle operator, during the regenerative braking operation, based on a pressure difference between a pressure in the master cylinder and wheel pressures, entrance valves of the driving wheels are controlled to realize an operator's pedal feeling, and the exit valves of the driving wheels are controlled to allow the wheel pressures to follow a target pressure.