Speed Sensorless Vector Control For Induction Motor On Electric Vehicle Based On Motor Parameter Identification

The temperature change and the speed change of electric vehicle will make the rotor time constant change dramatically, which causes the inaccuracy of magnetic field orientation and make the vector control lose control. Motor parameter identification has been a key problem in the study of the operation control of electric vehicle. In this paper, the technology of parameter identification is studied.By using Bode diagram analysis of rotor flux ratio function, it proves that the rotor time constant will have a great influence on the motor control performance. So the identification of rotor time constant is needed.Traditional off-line parameter identification is affected by a particular environment. And the off-line identification based on the inverter is affected by the switching time and dead time of a switch. So a new method of off-line identification of motor parameters is discussed in this paper. Firstly, it calculates the parameters of equivalent circuit and magnetic circuit of the motor by finite element method and obtains the rotor time constant and other parameters under the specific condition of the motor. Then the parameters of the motor are automatically optimized by the program optimization method. In the end, the method is applied to the control of electric vehicle and it achieves some good performence.In view of the complexity and variability of motor parameters, there is a need to conduct on-line identification of motor parameters. This paper derives the model reference adaptive rotor time constant identification system based on the reactive power of the excitation. It eliminates the identification error caused by the influence of the temperature on the stator resistance in the conventional identification method. It uses the Popov super stability principle to design the adaptive law and proves the stability of the system. It provides an accurate speed signal for the identification system by the model reference adaptive speed identification method based on the input reactive power.It uses Matlab/Simulink to simulate the parameter identification system of a 10 kW asynchronous motor. Simulation results show that the estimated value of the rotor flux will deviate from the actual value when the rotor flux changes, which leads to fail magnetic field orientation. Comparing the two methods of rotor time constant identification, the results show that model reference adaptive rotor time constant identification method based on the excitation reactive power can quickly follow the given values. And it is not affected by the stator resistance variation. It verifys the feasibility of this method of discussion.At last, it uses DSP processing chip TMS320F28035 of TI in the motor control test bench. It designs and debugs the vector control algorithm program in environment of CCS5.0. It verifies the validity of the method by experiments. Finally, it analyzes the results and put forward suggestions for improvement.