Study On Control Strategy Of Parallel Hybrid Electric Vehicle

With the increase of vehicle population,energy shortage and environmental pollution has become a global problem to face.The automotive industry has invested heavily in research and development of new energy vehicles to deal with environmental and policy pressure and challenges.However,the domestic bus field did not show enough effort and enthusiasm on new energy light bus because their backward technology and little government support,so its hard to please their priceoriented terminal customers.For light bus which production and sales are of absolute advantage of the whole bus field,the research is devoted to transformate them to hybrid power with a general and feasible scheme,and this scheme can be mass produce and promote in the near future.So it should be coaxial parallel hybrid scheme which is characterized by simple and compact structure and has practical significance and application value in view of current technology and other restrictions.The main research content of this paper is:(1)Considering the working conditions and target characteristics,a coaxial parallel hybrid model is constructed,the main components are matched,and also the whole vehicle model is built in the Cruise software.Then some rule based algorithm are applied: Use clear threshold value rules to control energy flow and distribution,while fuzzy rules to make power recovery.The HCU strategy Object is created and compiled in Matlab/Simulink environment with C subroutin,linking to Cruise using dynamic link libraries.Subsequently,how do both the threshold value parameters themselves and their matching interactions effect on vehicle fuel economy is verified by orthogonal analysis.thereby,improvement of primary parameters is implemented with a pleasantly surprising numerical result,which shows that the improved values can overcome adaptability problems in the much rigid rules algorithm.(2)For the conversion process of driving and braking modes,definiting starting and distribution strategies of both engine and motor is the initial step.At this phase,this paper using exhaustive method to enumerate all conversion process on the principle of finite machine by using stateflow in Simulink environment.To minimize negative effects of torque and speed fluctuates caused by dynamic process of mode transition,a coordinated control strategy includes both steady-state control and transient-state control is involved.The transient-state,aiming to reduce CVT input speed fluctuation so as to reduce system torque fluctuation,can control engine speed and torque as well as clutch engagement,disengagement and friction.Simulation results show that the proposed transient-mode strategy can significantly improved system volatile,thereby achieve a smooth conversion process.(3)At the end of this paper,the research contents were summarized and the suggestion of further study were given: When lots of more excellent key products,such as Atkinson engine,high efficient speed-matching motor,high energy-density and power-density graphene battery,be invented in the near future;As well as the prospect of new control method,such as global optimization,neural networks and genetic algorithms,be practicability developed and widespread applied.There must have a revolution in new energy light bus field and even lead to the entire automobile industry.