| Pure electric vehicle,as a relatively safe and clean green transportation,plays an important role in the development of the city.The motor driving system is the core of the electric vehicle,and its reliability and control effect are directly related to the performance of the vehicle.Because of its advantages such as simple structure,low cost,high reliability and wide speed range,three-phase asynchronous motor has been widely used in the field of electric vehicle.Considering the development of control,communication and computer technology,the software and hardware platform of three-phase asynchronous motor control system is designed and developed considering the key technologies such as magnetic flux weakening optimization.This paper makes discussions on the vector control system of asynchronous motor control system and the principle of weak magnetic control,compared with permanent magnet motor,although induction motor field weakening control more easily,but is constrained by the power battery voltage.In the weak magnetic region,maximizing the utilization of the bus voltage and maximizing the stable output torque are the key considerations in the design of the motor controller.With the development of space vector pulse width modulation technology,it is found that using SVPWM switch modulation results can be equivalent to the sum of vector voltage,and PWM switching cycle can be equivalent to the current maximum stator voltage.This method can optimize the voltage parameters which are difficult to obtain in the weak magnetic method of voltage limit.In this paper,vector control systems with different magnetic flux weakening methods are built,and the development of software algorithms is provided for the design and development of the following control systems.After that,this article selected the motor grade SH7142 which was developed by Renesas Corporation as the main control chip,and completed the design of the controller hardware and software around the chip.The hardware system mainly includes power module,detection module,driver module,protection module and communication module.The software system mainly includes two parts: motor controller,strategy control module and motor algorithm control module.Considering the vehicle fault diagnosis system design module,protection module and vehicle control module in the strategy module,and the optimization of the weak magnetic control algorithm and PI parameter dynamic tuning algorithm is embedded into the motor vector control algorithm model.The control software adopts the modular and layered design idea,which makes the vehicle safety and driving experience improved effectively.The design of the late PC experimental platform using Vector’s CANoe software to build real-time monitoring system and parameters calibration system,bench test was carried out using the motor control system of AVL electric power measurement,completed the calibration of the system parameters,and completed by comparison and analysis of test data and different characteristics of weak magnetic motor control,to verify the effectiveness of the optimization algorithm of weak magnetic control.Finally,the performance of the motor controller is verified through the test of the vehicle running conditions,and the motor controller performs well in the whole vehicle to meet the design requirements. |
