Study On The Control System Of Full Digital And Parallel Operation Inverters

The output performances and reliability of inverters are more and more important along with information technology developing.This dissertation bases study of control system of full digital and parallel operation inverter, to improve output performances and reliability of inverters. With parallel Technology, the performances, reliability and maintainability of inverter power system can be enhanced greatly and the capability of power system can be enlarged easily. Digital control and intelligence is the trend of inverters, is the foundation of realizing inverters' reliable parallel operation.A new control concept- repetitive control has been adopted. On analyzing its disadvantage, the compound control strategy based on PID and repetitive control has been put forward. The results of experimentation prove that this compound control strategy brings good dynamic and static performance.A distributed logic control mode is used in this parallel operation system, so all the inverter modules in the system are equal. To realize better performance of share current, a method is present to restrain the circumfluence. That is using reactive info to regulate the amplitude of voltage to achieve reactive power equilibrium and using active info to regulate the phase of the voltage to achieve active power equilibrium. The results of experiment tell it is an effective method of share current.A strategy of synchronization control, which combines competition coequality and priority, is mentioned in the paper and uses digital phase-lock loop to track synchronization signal. This control strategy makes the parallel inverters system synchronize well.Output current-limiting is an important measure to guarantee normal operation of inverter. Two current-limiting methods are proposed in this paper.