Research On Constant Speed Cruise Control Of Electric Vehicle

Constant speed cruise is widely used in conventional vehicles. As the electric vehicle changes the power system structure of the conventional vehicle, constant speed cruise control method of conventional vehicles can not be used on electric vehicles directly. Therefore, constant speed cruise control method of electric vehicle is researched in this paper.The electric vehicle studied in this paper is a pure electric vehicle which is reconstructed by a conventional gas engine vehicle, the main content of this paper is the control strategy of electric vehicle constant speed cruise, and vehicle speed program approach in the cruise process when the vehicle speed deaccelerates from the speed when the driver responses the accelerator pedal and stops to the cruising speed last time.With the research for control strategy of electric vehicle constant speed, an electric vehicle model is developed firstly combined with the application characteristics of electric vehicle cruise control, which is verified according to the datas from actual vehicle. As there are some shortcomings of constant speed cruise control approach in conventional gas engine vehicle , this paper takes the difficulty of acquiring precise vehicle parameters and the influence from road grade to constant speed cruise control into consideration when develop the control approach of constant speed cruise in electric vehicle, and an H 2 /H∞robust control approach of electric vehicle cruise control is proposed. Which not only satisfies the closed loop system stability when the vehicle load changes for instance, and some other situations, but also can suppress the influence from road grade effectively. And then we can solve the problem with the approach of linear LMI.In the research of the speed program approach, how to optimize the vehicle speed according to an ideal curve speed that not only satisties the driving demand and comfort, but also can maximize energy optimization becomes the key to the research. Analyzing speed optimization proposal firstly, and then an optimization approach is proposed, the vehicle speed transition process aims at maximum of the energy recovered in fixed time to program the control torque to the motor on the premise of satisfying constraints. The problem of speed optimization is solved based on rolling optimization concept, as the computing time is so long, it is an off-line solving process. And is implemented with table looking-up and interpolating.Finally, based on the development concept of pattern V, implementation and test for the algorithm of constant speed cruise is finished. Rapid prototyping of constant speed cruise algorithm, the vehicle controller uint software architecture and hardware in the loop simulation technology of the constant speed cruise control algorithm, which are the three aspects of constant speed cruise control strategy implementation techniques are described here firstly. Then simulate and verify the control effect in the high precise vehicle dynamic simulation environment with different road circumstances. The hardware in loop simulation process and results have been described and analyzed in detail.The test results show that, the cruise control approach studied in this paper is a good speed closed-loop control approach which can suppress the influence from road grade effectively, and also has a good robust performance to the parameter uncertainty such as load changes. While the speed program approach optimize the vehicle speed according to an ideal curve speed, which satisties the driving demand and comfort, and optimize the energy at the same time.