Study On The Key Elements Of Parallel Operation Control Techniques Of Communication Inverters

Power supply system made up of some parallel operating inverters can meet the needs of different load magnitudes and achieve higher quality and reliability of power supply. It is propitious to the standardization and large scale manufacturing of the inverter modules. At the same time, with the growing usage of appliances powered by special suppliers, the market needs is developing enormously. The parallel operating control technology has a vast economic future and social benefits.Based on a practical research program, this dissertation focuses on the research of parallel operation control of modular inverters used in telecommunication. It makes deep research into the basic working principle as well as some key problems in the realization of the system.First, it analyzes the working principle and some features of the system, such as the circulating current characteristics, power distribution characteristics, and characteristics about closed loop regulation of voltage. Then it goes on to the study of some typical control methods, and designs on this basis, a parallel controller using a synchronization control strategy of racing to merging and a load-sharing strategy combined with feedback control and drooped control.This dissertation also works into data communicating techniques and electromagnetic compatibility design of inverters that can be used in parallel operating systems, which also are important factors in the realization of a parallel operating inverters power system. Needless to say, it is very important of the reliability of data communication among each parallel operating units. So we uses field bus communication of CAN technology here. Also is it well known that equipments used in telecommunication usually have to comply with rather strict qualifications on EMC, not to mention their power suppliers. This dissertation also works into this area in relation to the design of a real system.Just following this, are studies on power factor of inverters and the sharing of harmonic circulating current among units of a parallel operating inverters system. For inverters used in telecommunication with direct current inputs, the parameter powerfactor usually refers to their output power factor, which denotes their certain demands on the loads' character. The harmonic circulating current balancing is an important factor in the parallel operating control for it makes the units of the system to get .an equal power factor and makes foundation for the system to work stable and reliable.Then, at last, it gives results of some experiments.