Sensorless Resonant Frequency Tracking Control of LOM Based on Linear Super-Twisting Sliding Mode Observer With FOGI

For the linear compressor driven by linear oscillatory machine (LOM), it is necessary to implement the position sensorless resonant frequency tracking control to guarantee the system reliability and obtain the maximum output efficiency. To improve the control performance, this article proposes a linear super-twisting sliding mode observer (LSTSMO) with fourth-order generalized integrator (FOGI)-based resonant frequency tracking control method. First, based on the operating characteristics of LOM, a novel filtering of stroke-current product (FSCP) method is designed to track the system resonant frequency, which has the advantages of simple structure, easy implementation, and small computational complexity. In addition, the LSTSMO with FOGI is deigned to obtain the accurate stroke signal used for FSCP method, which can significantly improve the observation accuracy by suppressing the sliding chattering and eliminating the influence of dc components. Through the above method, high-performance position sensorless resonant frequency tracking control can be achieved. Experimental results verify the superiority of the proposed method.