On-line Parameter Identification Strategy Of Pmsm Considering Inverter Nonlinearity

Permanent magnet synchronous motor(PMSM)has the advantages of high power density,high reliability and high efficiency,and is widely used in industry,transportation and household appliances.In order to make permanent magnet synchronous motor have excellent dynamic performance and reliable operation,vector control,maximum torque current per ampere and sensorless control methods are widely used at present.Because a large number of control methods are based on the mathematical model of the motor,their control performance depends on the accuracy of the motor parameters.In addition,in order to obtain the parameters of the motor in real time,the full rank voltage equation needs to be constructed by signal injection.However,the nonlinear factors of the inverter cause the distortion of the injected signal,which affects the identification results.Therefore,this paper mainly studies the on-line identification strategy of PMSM parameters considering the nonlinear factors of the inverter.Considering that the mathematical model of permanent magnet synchronous motor rotating coordinate system has the problem of poor rank,an online parameter identification method based on high frequency voltage injection is studied.Firstly,the operation principle of the motor is analyzed,and the mathematical model of the motor in the rotating coordinate system is obtained through coordinate transformation.The high-frequency sinusoidal voltage signal was injected to construct the full-rank voltage equation,and the online parameter identification results were obtained by using the amplitude and phase information of the high-frequency voltage and current signals.The influence of the frequency of the high-frequency voltage signal on the online parameter identification was analyzed.By selecting the appropriate frequency of the injection signal,the sinusoidal degree of the injection signal can be guaranteed and the influence on the motor operation can be avoided.On the basis of theoretical analysis,parameters such as resistance,inductance and flux linkage are obtained accurately through simulation,which verifies the effectiveness of the proposed method.A nonlinear self-learning and compensation strategy for inverters considering the influence of zero axis voltage is studied.The characteristic that the zero axis voltage is not zero in the system with inverter nonlinearity is analyzed.By injecting slope current into the direct axis,the relation between phase error voltage and current in the full current interval is obtained.At the same time,considering the influence of zero-axis voltage on the nonlinear self-learning of the inverter,and considering the characteristic that the zero-axis voltage changes with the electric Angle,the electric Angle with zero axis voltage is selected to carry out the self-learning to suppress its influence.During the operation of the motor,the error voltage characteristics are used to compensate the inverter nonlinearity.Finally,the experimental results show that the proposed method can effectively reduce the current harmonics and prove its effectiveness.The on-line parameter identification method of PMSM based on inverter nonlinear compensation is studied.Firstly,by analyzing the factors that cause the distortion of the output voltage of the inverter,the relationship between the switching frequency,dead time and voltage modulation depth and the error voltage is obtained.According to the trigonometric function relationship among the instruction voltage signal,the actual output voltage signal and the phase current signal,the mathematical model of the influence of the nonlinear factors of each inverter on the on-line identification of the motor parameters is established.The validity of the proposed method is verified by experiments on a 2.2KW experimental platform.