Orthogonal-Flux-Estimation and Enhanced PLL for Sensorless Control of Switched Reluctance Motors With Fault-Tolerant

In order to reduce the cost of the sensor for switched reluctance motors (SRMs) and improve the accuracy of position estimation, a sensorless control strategy based on the orthogonal flux linkage and improved phase-locked loop (PLL) is proposed in this article, along with a fault-tolerant control scheme to ensure operational performance under single-phase fault conditions. The proposed control strategy is applied during the medium-high speed stage. First, the nonlinear rotor flux linkage containing position and speed information is expanded into a Fourier form. By using a dual second-order generalized integrator quadrature signal generator, the DC bias and high-order harmonics are eliminated, and a set of mutually orthogonal flux linkage signals is generated. Then, the differential of the motor speed is taken as the extended state variable of the extended state observer, the rotor estimated position and speed can be obtained by using the extended state observer-based phase-locked loop to process the orthogonal signals. Furthermore, a fault-tolerant control strategy is proposed to enhance the performance of this control strategy in the case of single-phase fault. Finally, a comparative experiment is conducted on a six-phase 12/10 SRM against the traditional method. The experimental results show that this control strategy not only validates the superiority of the proposed sensorless control strategy, but also demonstrates its satisfactory estimation performance under single-fault conditions.