Abstract: A grid side inverter system includes a grid side inverter, a phase locked loop controller arranged to determine a phase of a dq-frame dependent on a monitored grid voltage vector in the dq-frame and a reference grid voltage vector in the dq-frame, a current reference decision unit arranged to generate a reduction of at least one of an active and a reactive current reference, wherein a decision to generate the reduction is based on an electrical parameter relating to the phase difference of the monitored grid voltage vector and the PLL vector, a current controller arranged to determine control signals for the grid side inverter for controlling generation of active and reactive power to the grid dependent on the active and reactive current references and monitored active and a reactive grid currents in the dq-frame.

Abstract: This invention concerns a method of controlling a line side converter of a power converter system operating in an over-modulation range. The line side converter comprises a controller comprising a feedback control module configured to output a feedback control signal for modifying a drive signal received by a modulator. The method comprises determining a modulation index within the over-modulation range; and, controlling the feedback control module to adjust the feedback control signal based on the modulation index.