Flux Linkage Observation Using an Improved MRAS Observer in Case of Uniform Demagnetization of IPMSM

To realize the online observation of the flux linkage of interior permanent magnet (PM) synchronous machine for electric vehicles after uniform demagnetization under multiple operating conditions, an improved model reference adaptive system (MRAS) flux linkage observer is proposed based on a novel double closed-loop control approach in this article. First, a double closed-loop control strategy of interior permanent magnet synchronous motor (IPMSM) is established employing maximum torque per ampere (MTPA) and sliding mode controller (SMC). The MTPA significantly improves the current utilization and system efficiency, and the SMC is applied to replace the traditional PI velocity loop controller to increase the anti-interference capability of the whole system. Then, the MRAS and single neuron adaptive proportional integral (SNPI) algorithm are adopted to develop an SNPI-MRAS flux linkage observer, which can modify the adaptive law of the MRAS online and overcome the shortage of low observation accuracy of traditional PI-MRAS flux observer when the machine parameters change. Next, a feedback gain matrix term is inserted in the SNPI-MRAS, which can guarantee that the linear forward channel of the SNPI-MRAS is a strictly positive real matrix. Finally, the effectiveness of the proposed method is verified. The outcomes demonstrate that the proposed method can effectively improve the dynamic response of the observer and increase its accuracy and convergence speed.