In this paper, to finely accommodate large-range wave frequencies on same sea areas, a spring resonance mechanism is created to facilitate maximal power tracking control of a direct-drive wave energy converter (DWEC) that is expected to be equipped on same sea areas, whereby the spring-resonance-assisted module is devised by mover-coaxial springs and reshapes the resonant-frequency pertaining to a specific spectrum. By virtue of modeling the spring-resonance-assisted DWEC system, a finite-time disturbance observer (FDO) is deployed to rapidly compensate environmental disturbances. Accordingly, the FDO-based integral sliding-mode (ISM) control framework is proposed, to accurately achieve the resonance between the DWEC buoy and wave, thereby contributing to spring-resonance-assisted maximal power tracking control (SR-MPTC) of the DWEC. Simulation studies and comprehensive comparisons demonstrate that the proposed SR-MPTC scheme performs remarkably fast adaptation and accurately maximal power tracking in the presence of disturbances and spring resonance assistance.
Maximum power point tracking control for mechanical rectification wave energy converter
