“…The ripple force is mainly caused by cogging force, flux harmonics, and current errors, among which cogging force is the main reason (Zhang et al, 2022a). Typically, according to the compensation principle, the compensation strategies of the ripple force can be divided into two types: The first type is to reduce the ripple force as much as possible by changing the motor structure at the physical level, and the second type is to identify the ripple force through some observers (Bi et al, 2022; Chang et al, 2023; Cho and Nam, 2016; Han et al, 2019), adaptive control (Tan et al, 2004), neural network (Ding et al, 2022; Heydarzadeh et al, 2018), and robust control (Huang et al, 2021; Li et al, 2022; Liu et al, 2022b). The first-type method has different solutions for different motors, while increases structural complexity and motor cost, but produces limited effect, so the feasibility rate is not high.…”