Sensorless Estimation of Relative Angular Position and Speed in a Linear-Rotary Reluctance Actuator with High Influence of Eddy Currents

Earlier, we have proposed a novel linear-rotary reluctance actuator for application in directly actuated electromagnetic dog clutches. The actuator capability to generate not only axial force to couple or decouple two rotating elements mechanically but also reluctance torque to reduce their speed difference represents its big advantage comparing to common systems used for this purpose. However, the speed synchronization in the rotary operation mode requires the use of at least two angular encoders. The system complexity and manufacturing costs can be significantly reduced if the relative angular position and speed between the rotating counterparts of the actuator are estimated sensorless. The main challenge is that methods of sensorless position estimation presented for reluctance machines in the past are not (directly) applicable due to the much higher influence of eddy currents caused by the unlaminated magnetic circuit. In this work, we propose two different algorithms for sensorless estimation of the relative angular position and speed between the rotating parts of the actuator for lower and higher relative speeds. United, they supplement the method of sensorless control for the linear operation mode, which is developed in a separate paper, so that the actuator can be applied without any encoders. Both operation types (idle operation and active torque generation) are considered. The algorithms have been verified experimentally by manufacturing an actuator prototype and creating supposed operation conditions on the developed testrig.