Improved indirect current control for utility-interactive inverter system with critical load

This paper proposes an improved indirect current control for utility interactive inverter system where an additional inner current loop is introduced without adding any additional sensor. By introducing the additional loop, cross-coupling terms in LCL filter plant is fully cancelled and the voltage regulation performance is improved. Additionally, the state-space model of the proposed controller is derived and accordingly the controller can precisely be designed to achieve desired control performance. Experimental results from 1kW three-phase utility interactive inverter with critical load are included to validate the proposed concept.