Research On Least-Squares Off-line Parameter Identification Of Induction Motor Based On Virtual Rotation Vector Orientation

Now power electronics technology has become an important electrical discipline.The structure of induction motors is relatively simple and it is cheap.Induction motors have applications in many fields.To control the induction motor using the inverter,you need to get the motor parameters.Therefore,the accuracy of parameter identification of the motor by the inverter itself is an important factor for the control performance of the induction motor.This thesis studies the parameter identification of induction motors based on a twolevel inverter.Based on the two-level inverter,this thesis studies the SVPWM(SpaceVector Pulse Width Modulation)given voltage method and the least square method of induction motor Parameter identification.This thesis first introduces the mathematical model of the coordinate transformation of the induction motor and the SVPWM modulation method.Generally,the given voltage is injected on the a axis in the twophase stationary coordinate system α-β through SVPWM modulation.However,this voltage injection method will cause the problem that multiple switches of different bridge arms are switched at the same time.The non-π/3 integer multiple angle SVPWM given voltage method solves the problem of simultaneous switching of multiple switches of different bridge arms generated by the α axis voltage injection method.A dead band compensation strategy is added to the parameter identification,and the delay problem existing in the dead band compensation strategy is considered.The general least square method requires first and second derivatives of the voltage and current signals.The least square method based on the virtual rotation vector orientation proposed in this paper derives the linear equation of the least squares method in a synchronous coordinate system oriented under the virtual voltage vector.And combined with the non-π/3 integer angle SVPWM given voltage method,when single-phase AC power is applied,when the motor is at a standstill,all relevant parameters of the induction motor can be identified under the condition that the motor is at standstill.Compared with the ordinary least square method,the method has the advantages of avoiding the process of obtaining the first derivative and the second derivative,and the measured result has a small error.The PLECS simulation software was used to verify the above theory.The virtual rotation vector oriented least squares offline parameter identification simulation of the above-mentioned non-π/3 integer multiple angle given voltage was established.The simulation results show that the above method is correct.An experimental platform was set up,and software and hardware system design experiments were performed with STM32F103R8T6 as the core.The experimental results further verified the correctness and practical feasibility of the offline parameter identification algorithm proposed in this thesis.