Simulation of the Combined Braking Control System for Hybrid Electric Vehicles

Simulation model of the combined braking control system for hybrid electric vehicles is proposed. The model shows working processes of the braking system with actuating friction mechanisms and an electro-hydraulic drive and regenerative braking system with an electrodynamic mechanism. The electrodynamic mechanism of regenerative braking is formed by switching the traction motor to the generator operating mode. At the same time braking effect is transmitted through the transmission to the drive wheels. The combined control of two brake systems of an electric vehicle is carried out by the driver when acting on one common control element - the brake pedal. Pushing on the braking pedal, driver generates the given control signal- desirable level of electric vehicle deceleration. In accordance with the given control signal, the law of control can be selected in the simulation model - the control function (electric vehicle deceleration) is proportional to the pedal effort or the control function is proportional to the set value of deceleration. In this case, the control system is adaptive and corrects the control signal in accordance with the control function. The control signal is applied simultaneously to the regenerative brake system and to the electro-hydraulic braking drive of the friction brake mechanisms. But at first the regenerative brake system is triggered, due to the higher working operation speed. The deceleration generated in this case is compared with the value set by the driver. If the potential of electrodynamic braking provides for electric vehicle the set value of deceleration, then the friction brake mechanisms do not turn on. Electric vehicle speed change causes a change of the electrodynamic braking potential ability. When the potential of electrodynamic braking becomes less than the value set by the driver and the controlled deceleration decreases, the friction mechanisms are activated.