Flux Estimation and Control Based On High-Gain Observer for Variable Reluctance Actuator Using the Measured Current Only

Measuring magnetic flux plays a crucial role in developing a linearized controller for a variable reluctance actuator. However, the method used for measuring magnetic flux may have limitations that render it invalid under different operating conditions. This paper presents a flux estimation and control method based on the Extended High-Gain Observer (EHGO) approach for reluctance actuators, utilizing only the measured current. Initially, the dynamic model of the reluctance actuator is formulated in terms of the current in the coil, considering the magnetic field as unknown. Subsequently, EHGO is designed to use the measured current to estimate the magnetic field and magnetic flux. Finally, a feedforward controller is introduced to utilize the estimated magnetic field for achieving tracking performance of the desired magnetic flux. The analysis of the error bound in tracking errors demonstrates that minimizing the estimation error of the magnetic field reduces the tracking error. The effectiveness of the proposed flux estimator and control approach is evaluated through numerical simulations. The results illustrate the EHGO's capability to achieve accurate magnetic flux estimation, improving the tracking performance of the feedforward controller and minimizing tracking errors.