Low cost compound current sharing control for inverters in parallel operation

A compound control scheme for inverters in parallel operation is proposed. The synchronization control is decoupled from current sharing control by local feedback. In each inverter module, the sinusoidal reference of output voltage is generated in digital manner, the phase angle of which is determined by a sharing synchronous square-wave signal. Based on average method, the current sharing is realized through simple analog circuits. The amplitude of the reference voltage is also regulated according to the circulating current to improve load balance performance. All the control circuits for parallel operation, sharing a digital synchronous signal and an analog current reference, are equally distributed in the modules. Theoretical analysis and experimental results are presented to demonstrate the performance of the proposed control scheme of parallel operation.