A digital communication system for a control strategy employed in the parallelism of three-phase voltage source inverter

This paper describes a theoretical and experimental study on a digital communication system, which is employed in a control strategy for parallelism of three-phase voltage inverter (VSI). This control strategy only needs that all VSIs use a same voltage reference and thus it ensures the sharing of the load current and avoids current circulation among the inverters during transient and steady-state operation. Therefore, the communication among the inverter is implemented to transmit only the voltage reference. The paper proposes this communication system based on two bus, one that uses the own electrical grid and is called of Voltage Reference bus and another makes by CAN bus. The first puts the reference voltage of all inverters in synchronism and the second keeps the reference voltage in synchronism even during a fault of electrical grid. The proposed system was digitally implemented in a TMS320F2812 DSP and was verified through experimental results with a 10 kVA prototype, which has the parallel operation of two three-phase VSIs.