Minimization of interconnected inductor for single-phase inverter with high-performance disturbance observer

Abstract

When a inductance of a single-phase grid-connected inverter is minimized, the effect of the disturbance to the current control such as the dead-time error voltage increases. This paper proposes a disturbance compensation method by using a high-performance disturbance observer. In particular, in the control system, the current controller is implemented by the digital signal processor, whereas the high-performance disturbance observer is implemented by the field-programmable gate array in order to suppress the disturbance at high switching frequency. This results in the improvement of the current control performance. With the experimental prototype, in case of the minimized inductance (%Z = 0.5%), the total harmonic distortion (THD) of the output current is improved from 11.1% to 2.9% at rated load by applying the proposed disturbance compensation method. Furthermore, with the proposed disturbance compensation method, it is confirmed that THD of the output current is improved by over 68% at all load range.