Online Identification Of The Rotor Flux Linkage In Permanent Magnet Synchronous Motors With Position Signal Injection

Permanent magnet synchronous motor(PMSM)duo to the advantages of high efficiency,reliable operation and high power density,is widely used in new energy power generation,electric vehicles,aerospace,etc.With the increase of service time,it is prone to demagnetization fault duo to high temperature,high current impact,vibration and etc.The monitor of magnetization state,the diagnosis of demagnetization fault and the prediction of irreversible demagnetization can be achieved by flux linkage online identification,and thus the safety and reliability of the motor operation are improved.Firstly,in order to solve the rank-deficient problem of the PMSM mathematical model which caused the coupling between rotor flux and stator resistance,an online flux linkage identification method based on position triangular signal injection is proposed.The symmetrical triangular wave signal is added into the rotor position,The rank-full equation of flux identification is obtained by subtracting d-axis voltage on the negative injection signals from d-axis voltage on the positive injection signals,and then combining with the extended Kalman filter algorithm,a flux observer is obtained to identify flux linkage.On the one hand,the nonlinearities of inverters and the inductance and stator resistance parameters of motor are eliminated at the same time,which improve the performance of online flux linkage identification and simultaneously solve the rank-deficient problem.On the other hand,the disturbance of dq-axis currents and torque are very small after injecting the signal,so that it is suitable for surface-mounted PMSM(SPMSM)and interior PMSM(IPMSM).Secondly,it is expounded about the principle of frequency and amplitude selection of injected position signal.The influence of rotor position error on the accuracy of flux linkage identification is analyzed.To improve the accuracy of flux linkage identification,a rotor initial position identification method based on high frequency(HF)orthogonal square wave voltage injection is proposed to improve the initial position identification accuracy.Firstly,the HF voltage signals are injected into the stationary reference frame(SRF),and then the HF response currents in the SRF are used to identify the rotor magnetic pole position.Secondly,a low-frequency sinusoidal current signal is injected into d-axis to identify rotor magnetic polarity.Finally,the rotor initial position is obtained by the magnetic pole position and magnetic pole polarity identification resultsIn the end,the proposed methods of the flux linkage and identification accuracy improvement scheme in this paper are implemented on a 1.5kW IPMSM system and a 2.2kW SPMSM system respectively.The experimental results show that the proposed methods are accurate and effective.