Two-Degree-of-Freedom H∞ Robust Control Optimization for the IPT System With Parameter Perturbations

Robust control can maintain robust stability and robust performance for an inductive power transfer (IPT) system in a comparatively larger perturbation range of parameters. However, it ignores the transient performance requirements and influence of open-loop properties on a resulting controller. So a method of improving two-degree-of-freedom (2DOF) H infinity robust control for the IPT system is proposed. Based on the generalized state-space averaged model, the distribution of poles and zeroes under mutual-inductance and load perturbations with a bounded range is investigated in detail. An expected closed-loop transfer function is added in a 2DOF control structure with a prefilter and feedback controller, to introduce the transient performance requirements. Then, a generalized plant including the model of the IPT system is defined and its state-space realization for standard robust control configuration is also derived. Finally, controllers with different performances are designed referring to the mutual-inductance and load features. Simulation and experiment results show that the 2DOF H infinity robust controller designed with parameters that maximize the modulus value of a dominant pole can reach the prescribed performances for the IPT system, with settling time and overshoot of no more than 5 ms and 2% in startup and reference tracking processes, and restoring time of no more than 5 ms when parameter perturbation occurs.