Research Of Controling Low-speed Performance For Induction Motor Of Hybrid Electric Bus

Energy crisis and environmental problems of today has been the subject of the human need to resolve the two, The conventional internal combustion engine vehicle emissions in the fuel and contrary to the wishes of mankind has been working with in recent years, hybrid electric vehicles in the world become a hot new vehicle development. Motor drive system as a hybrid of the auxiliary power source, its rational and effective control also is critical. Hybrid buses complex operating conditions, which made the motor drive system with high reliability, high performance, high efficiency and low cost requirements. In this paper, motor drive for hybrid electric bus system for research on direct torque control inherent in the traditional analysis of the issues, especially for low-speed research and improvement issues, mainly to do research on the following:This paper summarizes the significance of the research background, describes the recent development of hybrid buses and hybrid buses overview of the composition, structure, work and energy flow process, and summarizes the HEV motor drive system, special requirements, by comparing Advantages and disadvantages of AC variable speed control strategy is obtained as a direct torque control system for motor control systems, and described the problem to be solved.For this paper to study the motor, the motor according to hybrid buses the special requirements of the standard cycle conditions, the liberation of a specific brand hybrid buses for the motor selection and matching. By looking to the vehicle parameters, and based on the current use of the engine, motor matching method, the required peak power motor, rated power, maximum speed and other parameters were calculated, and ultimately determine the motor model.Through the understanding of the motor model, and compared motor control strategies, based on hexagonal flux trajectory and circular flux based direct torque control theory are introduced. Build circular flux trajectory based on the Simulink simulation model of direct torque control, including introduction of a model. The motor torque, flux calculation; stator flux position calculation and judgments; and switch the table settings. The simulation results are analyzed and found the process of conventional direct torque control flux and torque ripple, especially under the more serious run at low speed, and the reasons for the fluctuation analysis of the width of the hysteresis comparator, such as stator resistance Adjusted, elaborated on the control of space vector modulation method for improvement.At the last,in the verification,in consideration of that the electric motor and contravariant link based on Simulink are idealized and are different from electric motor in actual motion in terms of parameter changes,etc. There for, we use AMESim as our simulation software. First, we set up the full car model of hybrid electric bus, and then analyse the actual motion of electric motor on the basis of cycle condition, isolate the driving system of electric motor, set up a AMESim physical model including induction machine, inverter, direct-current power supply and each sensors. The control module is controlled by the direct torque control based on Simulink. According to the simulation result of AMESim-Simulink unite simulation and Simulink, we test and verify the feasibility of the method effectively.