Improved Passivity of Grid-Connected Impedance using Asymmetric Dual-Edge Modulators

This paper proposes double-sampling asymmetric dual-edge digital pulse-width modulation (ADE-DPWM) as a means of passivization of the power electronic converter’s (PEC’s) admittance. As a consequence of control-loop delays, PEC’s admittance may exhibit non-passive zones around and above the cross-over frequency of the inner control loop, possibly reducing the stability margin of the interconnected microgrid. An effective way of preventing destabilization of poorly damped grid resonances is to shape PEC’s admittance to improve the passivity region below half of the switching frequency. This paper shows that, due to its zero phase delay, double-sampling ADE-DPWM improves the passivity of the input admittance. The experimental validation performed on a single-phase current-controlled voltage-source converter showcased passivity benefits of the ADE-DPWM compared to the state-of-the-art double-sampling trailing-triangle edge DPWM.