Research On Inverter And Its Parallel Control Technique

With the fast development of modern electronics technologies, the research and development of power technology have made corresponding achievements. Then, SPWM inverter power is widely used in areas such as communication, finance, aviation, medical and military, etc. To improve the capacity and reliability of power, module power has been one of the streams of SPWM inverter. In order to improve the performance and practicability of the inverter, based on a practical research program, this paper focuses on the single control and parallel operation techniques. A control concept—double loop control has been adopted. On analyzing the disadvantage of single loop transient feedback control, the compound control strategy based on output voltage and inductance-current feedback current SPWM control has been put forward. Simulations have been preformed using software Pspice and MATLAB. The results of simulations prove that this compound control strategy brings good dynamic and static performance. Parallel inverters can expand capacity and realize redundancy in power supply system, so they are now considered as one of the most important part in the field of inverter technology. The parallel inverters can expand the capacity so that they greatly improve the power system's flexibility and thus the system's volume and weight are remarkably reduced. The current stress of the power switch is considerably lessened which means higher reliability, lower cost and higher power density. Because of the redundancy, the parallel system can improve the reliability furthermore. Models of parallel system are established to analyze the principle of the parallel operation. The existence of circumfluence in the paralleling operation system makes the system work abnormally. Comparison and analysis about the several styles of parallel controlling are given, which benefits the design and implement of parallel controlling system. 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 the current information which exchange from the two inverters as the reference of inner loop and applying robust control as outer loop. This method achieves good power equilibrium. The experimental results of output voltage, circumfluence,single and parallel of two UPS are given and analyzed at the end of this paper. The results prove that the UPS has good static and transient performance, and can parallel with high reliability.