Design And Implementation Of 30 KW AC Power Dynamometer Control System

Environmental protection and energy shortage force the engine to improve performance,and put forward higher requirements for testing technology and equipments.AC electrical dynamometer that tests the driving motor performance in the power system is the main equipment.In the indoor bench test system,the dynamometer simulates the mechanical load when the vehicle running in the road to measure the parameters,such as the output speed,torque.There is a big gap between the domestic and foreign AC dynamometer control system,and did not form a unified program for the equipment.It is of great significance to study the high-level AC power dynamometer control system for the development of domestic dynamometer technology and automobile and other industries.Based on the indoor test bench system of electric vehicle,the 30 kW AC power dynamometer system is studied.The research contents of this paper are as follows:The basic structure of the AC power dynamometer system is studied,and the operation principle of the electric dynamometer is analyzed with the stability of the motor running and the power generating operation.The mathematical model of dynamometer is constructed and the principle of dynamometer is studied.The speed and torque working mode of the dynamometer,and the application of each mode are analyzed.According to the power dynamometer control system design requirements to choose the control system hardware design,the control mode of system which is originally controlled by PLC is changed to PC direct control.The hardware structure of the power dynamometer control system is constructed.Through the RS485 bus Modbus communication protocol,communication connection circuit between the host computer and the frequency converter is built.The principle of speed measurement and torque measurement of torque sensor is analyzed,and the data acquisition,processing method.The software function module of the power dynamometer control system is designed.The control strategy of the power dynamometer is studied emphatically.Based on the combination of PID and nine-point control,the dynamic switching PID control based on nine-point control is designed and the control strategy is simulated.According to the equipment connection,analyze the communication protocol.The mobile weighted average filtering algorithm is designed to realize the data processing of the rotational torque signal and improve the measurement accuracy.Use the modular design of the control to achieve the entire control system software design.According to the demand for power dynamometer test,the control system is experimented.Because of the working mode of the dynamometer,the constant speed mode and the torque mode test are respectively carried out to verify that the power dynamometer can switch the various working modes.The stability and dynamic performance of the AC power dynamometer under the control strategy are verified by the condition test.The experimental results show the steady-state performance and dynamic performance of the dynamometer in each mode,and the dynamic switching capability of the dynamometer and the power generation operation.AC power dynamometer control system can run smoothly in the speed and torque of working mode,and in the electric state and power generation state to achieve rapid dynamic switching.The system response capability,with high stability and dynamic performance,achieve 30 kW AC Design of Control System for Power Dynamometer.