An protocol design for distributed logic controlled parallel operation UPS system

This paper presented a design for distributed logic controlled parallel operation UPS systems depending on cycle control. This design proposed a practical parallel operation according to the needs of real industrial application. This protocol ensures correct logic switching and stable information exchanges in toughly interfering application environment. Also this protocol gives the plug and play ability of parallel control bus. This design also proposed a digital way of parallel operation information exchange using the PWM modulator. A two stage DPLL is also presented for the precise synchronizing control. Using a flexible sample system and individual phase power calculating algorithm, it is possible to realize paralleled operation for UPS of different power capability. Experiment results shows this design can access a stable parallel operation with low circulating current.