Robust Control for the IPT System With Parametric Uncertainty Using LMI Pole Constraints

In the inductive power transfer (IPT) system, coil misalignment, load variation, and external disturbance will unavoidably cause power fluctuation and worsen system performances. Currently, robust control has been successfully introduced in the IPT system for promoting its stability and performances. However, due to the diversity of poles distribution, all possible IPT subsystems always show different overshoot, settling time, and resistance capacity to uncertainty factors. So, robust control design for the IPT system via pole placement constraints in linear matrix inequality (LMI) region is studied in this paper. An IPT system model with structured parametric uncertainty relevant to mutual inductance and load is first established. Based on the derived closed-loop system with a two-degrees-of-freedom control structure, a method of variable replacement is then proposed to transform the robust D-stability problem with pole region constraints into the LMI form, which can be solved to obtain a robust controller. After analyzing the influence of the LMI region change on poles distribution and system performances, an optimized robust controller is finally chosen. Experimental results show that a robust controller can reach the prescribed dynamic performances even if mutual inductance or load may change into another value, and also a good steady-state performance by resisting parametric uncertainty and external disturbance.