Power System Matching And The Design Of The Motor Controller On Electric City Bus

With the increasing of the car used, the problem of energy and pollution has tempered with the development of human being. In recent years, the worldwide automobile industry is busy in developing and researching the clean and energy saving cars. From Hybrid Vehicle,Fuel Cell Vehicle to Solar Cars,Pure Electric Vehicles, Universities and automobile companies around the world have invested a huge amount of research funds, which promoted substantially to the developing process of the new energy vehicle.In the period of"10th Five-Year Plan", China invested a lot of funds on R&D of the Hybrid Electric Vehicle, however, in the period of"11th Five-Year Plan", the States changed its R&D policy to focus on the pure electric car, particularly in the pure electric bus.The electric bus industry of china maintains basic synchronization with the advanced international level, since large universities and enterprises have been researching for many years. Urban electric bus has a strong practicality in the current technical conditions with its fixed routes, which has become the focus of study Electric Car industry.The purpose of this paper is to study the development and design of the urban electric bus, whose research results and conclusions are as follows:1,Considering the working conditions and requirements of the operating environment of ordinary city bus, the author analysis the power needed and continued driving mileage requirements of developing electric bus and then completing the EV6105 power system matching. In the aspect of motor, I chose such an Asynchronous induction motor whose power is 95kW peak power is 140kW, basic speed is 1500 r/min, peak speed is 5000r/min.In the aspect of transmission system, I tested that the ordinary transmission can meet the requirements of the electric bus at first. At the same time, I presented a new transmission mode with two transmissions plus a major reducer drive mode. In this way, the two stalls are respectively the climbing lane stalls and the traveling crane stalls, which greatly simplify the driver's operation. The matching results are as follows: the slowdown-ratio of the main reducer is 6.33. Two pole transmissions were direct stalls and climb stalls with its variable transmission ratio of 4.6.For the battery, I chose rated voltage of 384V, 600Ah capacity of lithium ion batteries.2,The ADVISOR2002 software running in Matlab platforms is an electric vehicle simulation software, which is the most commonly used by colleges for the electric vehicle power and continued driving mileage performance simulation. This article makes a simulation to matching vehicles with the ADVISOR2002 software and the sources of parameters used are as follows: One is based on matching results, which include auto body parameters, transmission parameters, the electrical characteristic curve outside, the numbers of battery and the value of single-section voltage; Another is under the similar product parameters in practice, including asynchronous motor efficiency curve,the resistance of the battery SOC,temperature curve,the quality of batteries,cooling area,heat capacity,thermal conductivity,voltage range and so on. The simulation results tallies with the expected goal, but it also raise some areas needing improvement, including: battery capacity,Main reducer and so on.3,Motor Controllers in the Electric Vehicles are the most important key technologies, The quality of its functions has a great impact on the power and the economy of the energy consumption. To design Motor Controller, we should take each part of the vehicles into account, including battery system, signal acquisition system, Driver control panel and energy recovery systems, which is a very complex control assembly.Avoiding analyzing the outside of the controller, this paper specialized in the purpose on the controlling the motor power and torque and completed the hardware and software design of core circuit in the car's motor controller. For hardware circuits, I selected DSP products TMS320LF2407A of TI Co. as a CPU of controller, three analog signals input respectively are accelerating pedal input and two asynchronous motor stator current signals input. Two digital signal input from the digital encoder output Acquisition rotor angular displacement signal. The DSP has a unique interface PWM output, through driving isolation system control Motor Drive Circuit. Software, the PWM signal is generated by means of a voltage space vector PWM (SVPWM). The SVPWM have two implementing methods of hardware and software, which have their own characteristics. For the simple reason, this paper chose the latter one.4,Apart from meeting the requirements of power, the designing goal of the controller should also have a good economy. Customary international economy indicators of energy consumption in electric vehicles are the rate of energy consumption。This paper analyzes the influencing factors of energy consumption economy of urban electric buses, including: vehicle, transmission, auxiliary electrical factors and electrical motor's efficiency factors which affect greatly. The author starts from the four losses of asynchronous motor (loss stator copper, iron loss stator and rotor copper loss and stray loss), according to Motor Vector Control principle, presents the "best decoupling point" method, reducing the total loss of motor, thereby improving efficiency. There are many "best decoupling point" methods at home and abroad, however, a loss of control model,the search algorithm control,Minimum stator current control always be used frequently.