Research On Electric Vehicle Braking Energy Recovery

In today’s world, as the rapid development of science and technology, automobile industry has been a rapid development also. Today’s technology of automobile has a great changes with nineteenth Century’s automobile industry, even compared with a decade ago. Due to the advent of the automobile, car quickly shorten the distance between people, even thousands of miles away can be reach in one day. It provide a very convenient way for people to exchange information in the world. However, due to the rapid increase in the number of cars, cars’ gas emissions caused serious pollution to the environment of the earth. In order to reduce the impact on the environment of the world, people pay more and more attention to all kinds of new energy vehicles, such as the electric vehicles which use the electric energy as its power source. The regenerative braking technology is the most important way to improve the operating factor of energy, especially when the battery technology have not yet achieved a breakthrough. The regenerative braking technology has significantly raised the vehicle mileage.We first need to understand is what is called regenerative braking. The regenerative braking force is the one of braking torque of electric vehicles. At the same time, the regenerative braking force make the motor to generate electricity for later use. Then the energy storage principle of the regenerative braking system is analyzed, and also indicate the regenerative braking force’s range according to the requirements of vehicle brake. Then talks about the structure of regenerative braking, illustrates the role of the hydraulic control unit. The braking force when electric vehicle brake come from the regenerative braking force and the hydraulic braking force, and the energy that electric cars can recycle mainly comes from regenerative braking force. In order to coordinate the range of the regenerative braking and hydraulic braking force, you need to know the vehicle wheel cylinder and braking master cylinder’s pressure value. This article firstly focuses on the working characteristic analysis of some key components of the hydraulic control unit, such as the pressure increasing valve, relieve valve and the low pressure accumulator. Then established their mathematical model, and simulated using the AMESim software. This paper studied the braking process of electric vehicles, and divided it into seven states. According to the working characteristics of the hydraulic control unit, a braking pressure estimative algorithm of the brake master cylinder and the wheel cylinder was established.The simulation model is established by MATLAB/Simulink software, and verify the braking pressure estimative algorithm which is proposed in this paper through an experimental platform which belongs to a cooperative company. The simulation and experimental results show the feasibility of the algorithm. When the electric car brake, the estimate value can be used to compared with the sensor measured value, thus improving the reliability of vehicle braking.