Accurate State Space Resonators for the Implementation of Integral Dominant Voltage Controllers for LC Filter based Inverters

Integral dominant controllers are attractive for stationary frame voltage regulation for LC filter-based voltage source inverter (VSIs) owing to their passive impedance response in grid connected operation. However, the digital implementation of these controllers in fixed point arithmetic has been challenging since the transfer function coefficients are susceptible to rounding errors in the commonly used Direct Form Two (DFII and DFIIt) realisations. Furthermore, the conventionally used forward-backward Euler dual-integrator and Tustin realisations produce steady state errors due to resonant peak deviations. This paper proposes state space resonant (SSR) realisations for integral dominant controllers which can be efficiently captured in fixed point arithmetic, thereby offering better accuracy of the resonance and ease of implementation. The theoretical development of the SSRs is supported with simulation and matching experimental results.