Research on the Stability and Brake Padel Comfort of Vehicle Regeneration Braking

Abstract: Braking energy of vehicle have not been reclaimed and reused yet. Kinetic energy when braking changes into heat by friction, and brake appraratus are worn prematurely, which increased use cost for auto. Energy regenerative braking converts braking kinetic energy into electric one and reuses it, which improve auto comprehensive utilization of energy. But braking performance of original car with only hydraulic braking system is changed when added regenerative braking system, which deteriorate vehicle stability and braking pedal comfort. How to realize harmony control between regenerative braking and hydraulic one, and how to make full used of motor regenerative braking, to maximize reclaiming energy on the premise of running stability, are problems urgently needed to be solved. Aiming at these problems the paper has done as followed:Firstly, a suit of pressure regulating device which can adjust front and rear hydraulic braking force automatically according to strategies of friction and motor braking force distribution is designed. After analyzing characteristic of regenerative braking and constraints of energy reclaiming, with the trait of a switched reluctance motor (SRM), a regenerative braking system scheme based on a double SRM front brake with duplex energy storage is presented. The controlling model of SRM braking is built. With a simplified equivalent circuit of the duplex energy storage, an energy model for storage is established.Secondly, a full vehicle dynamics model for regenerative braking is generated. A control strategy of SRM anti-lock regenerative braking based on fuzzy sliding mode variable structure control and a harmony strategy of SRM brake with hydraulic anti-lock brake are proposed. According to motor braking power, the brake intensities are classified. Strategies of brake force distribution for front rear wheels and for friction motor are established. Also, a car body stability control model based on double motor braking force control is put forward.Theoretical analysis of influencing factors of regenerative braking pedal comfortableness is carried out. Brake pedal model and its structure are designed. For achieving the same pedal comfort with original hydraulic braking system, a pedal comfort control strategy based on trajectory tracking is advanced.Integrated control of regenerative braking stability is modeled, which take a harmony controller as center, vehicle stability controller, regenerative braking controller, energy reclaiming controller and hydraulic braking controller are interdependent and mutually-restrained, so that integrated controlling is carried out.Finally, method of modular hierarchical design is adopted in building of regenerative braking hardware-in-the-loop (HIL) test bench. The above control theories of regenerative braking are validated on the test bench.Simulation calculation and test results showed that the theories and methods of auto regenerative braking can improve energy recovery of brake efficiently, realize good braking stability and braking pedal comfortableness. By further study on theories and methods of regenerative braking, this paper provides theoretical basis and new concept for developing and design of auto regenerative braking.The major innovations in this paper are as follows:1) A kind of regenerative braking system scheme based on a double SRM front brake with duplex energy storage of lead-acid battery paralleling with ultra-capacitor is presented.2) Based on original hydraulic braking system, a suit of pressure regulating device which can adjust front and rear hydraulic braking force automatically according to strategies of friction and motor braking force distribution is designed, so that the problem of harmony work between regenerative braking and hydraulic one is solved in structure.3) With a simplified equivalent circuit of the duplex energy storage, an energy modeling method for storage is adopted.4) A method of inputting reverse voltage to SRM to implementing anti lock braking is put forward. And strategy of SRM anti-lock regenerative braking based on fuzzy sliding mode variable structure control is proposed.5) A concept of regenerative braking stability integrated controller is modeled.6) Method of modular hierarchical design is adopted in the building of regenerative braking HIL test bench. The test system can not only fulfill the needs of regenerative braking research but also has good expansibility…
Key words: regenerative braking; hydraulic braking; motor ABS control; harmony control; stability; integration; HIL test bench

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