Parallel operation of sinusoid wave inverters without control interconnections

This paper presents a control scheme which allows wireless-paralleled inverters to share linear or nonlinear load. It can be used in large scale uninterruptible power supply (UPS) systems and distributed power systems. This control scheme is based on digital signal processor (DSP) to measure output power of high performance inverter modules, and it based on frequency-droop and amplitude-droop scheme to control the output voltage. The high performance inverter modules have inner filter capacitor current loops; and the output voltage can maintain high-quality sine-wave. An experiment system was built to verify this control scheme, and the results indicate the inverters in parallel connection realize load current sharing.